Q

1 5

r ;r

t

B Ml 41

f^Mi fi^i'il p-i-N r- & u v^-i-n ?

^^te*«e^* ^pj.^^1, 4*^-Ti»^** ^^(mr. '%&•*;'<'" ^j;^4iM *f'"' -"•".* ^ ..tifi, l>- ',>»•'" ,.-!r^ v-

.*"V*v;>. /?-

^s'*^ /--V "t%/^: ^

»

I2§!

*a»

Stf

zm

5SP'

/

:\jJ^,A A ? ,_'*;V

0 L, C~<LL£sisL,cxm

VEGETATION OF PHILIPPINE
MOUNTAINS

THE RELATION BETWEEN THE ENVIRONMENT AND
PHYSICAL TYPES AT DIFFERENT ALTITUDES

IS"

.?5

BY

WILLIAM H. BROWN

MANILA

BUREAU OF PRINTING

1919

^^v^^M

VEGETATION OF PHILIPPINE
MOUNTAINS

THE RELATION BETWEEN THE ENVIRONMENT AND
PHYSICAL TYPES AT DIFFERENT ALTITUDES

BY

WILLIAM H. BROWN

159649

MANILA

BUREAU OF PRINTING

1919

Department of Agriculture and Natural Resources

BUREAU OF SCIENCE

Manila

Publication No. i li

(Actual date of publication, November 15, 1919.)

CONTENTS

Page.

Illustrations ._ 5

Introduction 13

Parang Vegetation 18

Dipterocarp Forest . ..... 27

Virgin dipterocarp forest . IK)

General description : 80

Tree stories.... 31

Vines _ 84

Strangling figs 85

Monocotyledonous trees 35

Cauliflory 36

Ground covering.. .... 36

Epiphytes 37

Flowers ... 38

Seasonal changes. 40

General view 40

Bizarre plants 41

Description of plot .. 43

Culled dipterocarp forest 61

General discussion and description of plot 61

Succession in openings 75

MIDMOUNTAIN FOREST ..... 76

General description 76

Quercus-Neolitsea association 78

Transition from dipterocarp to midmountain forest. 82

Astronia rolfei association 88

Description of plot .... 84

Mossy Forest 98

General description 98

Description of plots.-. 104

Comparison of Vegetation at Different Elevations 110

Growth 116

General remarks on methods of measurement- 116

Growth of parang trees 125

Growth in dipterocarp forest 151

Growth in midmountain forest 161

Growth in mossy forest 167

Conclusions 169

Composition of Soil ;. 171

General Remarks on Records of Measurements 175

Temperature its

In parang 1T9

In dipterocarp forest 187

In midmountain forest 205

In mossy forest 211

Comparison of temperatures at different elevations 216

Calculation of mean temperatures. 222

Relation of temperature to vegetation 227

3

Department of Agriculture and Natural Resources

BUREAU OF SCIENCE

Manila

Publication No. 1 3

(Actual date of publication, November 15, 1919.)

CONTENTS

Page.

Illustrations 5

Introduction 13

Parang Vegetation 18

Dipterocarp Forest 27

Virgin dipterocarp forest 30

General description ; 30

Tree stories 31

Vines 34

Strangling figs 35

Monocotyledonous trees 35

Cauliflory 36

Ground covering 36

Epiphytes 37

Flowers 38

Seasonal changes 40

General view '. 40

Bizarre plants... . 41

Description of plot 43

Culled dipterocarp forest - 61

General discussion and description of plot 61

Succession in openings 75

Midmountain Forest 76

General description 76

Quercus-Neolitsea association 78

Transition from dipterocarp to midmountain forest 82

Astronia rolfei association 83

Description of plot 84

Mossy Forest _ 98

General description 98

Description of plots 104

Comparison of Vegetation at Different Elevations ... 110

Growth 116

General remarks on methods of measurement 116

Growth of parang trees 125

Growth in dipterocarp forest 151

Growth in midmountain forest 161

Growth in mossy forest 167

Conclusions 169

Composition of Soil . ;. 171

General Remarks on Records of Measurements 175

Temperature 178

In parang 179

In dipterocarp forest 187

In midmountain forest 205

In mossy forest 211

Comparison of temperatures at different elevations 216

Calculation of mean temperatures 222

Relation of temperature to vegetation 227

3

4 VEGETATION OF PHILIPPINE MOUNTAINS

Page.

Light Intensity 232

Method of measurement 232

Intensity at different elevations 232

Relation to vegetation 235

Rainfall 245

At base of mountain 249

At different elevations 249

Relation to vegetation . 257

Soil Moisture 260

Water-holding capacity and moisture equivalent . 260

Soil moisture in parang 266

Soil moisture in dipterocarp forest 267

Soil moisture in midmountain forest 268

Soil moisture in mossy forest 269

Relation to vegetation 270

Humidity 272

In parang 272

In dipterocarp forest 278

In midmountain forest 285

In mossy forest 291

Comparison at different elevations 294

Evaporation 296

In parang .. 297

In dipterocarp forest 324

In midmountain forest 335

In mossy forest 339

Comparison at different elevations 346

Comparison with rates in other localities 351

Relation to vegetation 357

Wind Velocity .... 3^3

Interrelation of Environmental Conditions 368

Seasonal Rates of Growth 370

In parang 370

In dipterocarp forest 375

Classification of Leaves 378

According to Raunkiaer's leaf sizes 378

According to length and breadth 379

According to whether compound or simple 388

According to character of margins ' 390

Mount Banahao 391

General description : 391

Vegetation 391

Measurements of environmental factors 394

Correlation of environment and vegetation.. 403

List of Species Considered 406

General Summary and Conclusions 414

Appendix 417

Index 423

ILLUSTRATIONS

Plate I

Frontispiece. A group of tree ferns (Cyathea) in a ravine in the mossy
forest near the top of Mount Maquiling. The feathery leaves
scattered through the picture belong to climbing palms (rattans) ;
they are particularly prominent under the tree fern to the right.

Plate II

Fig. 1. The northeastern slopes of Mount Maquiling as seen from the
grounds of the College of Agriculture. The peak on the left is
known as East Peak and is the summit on which measurements
of environmental conditions were taken.
2. The southwestern part of Mount Maquiling as seen from Santo
Tomas. The slope of the mountain on this side is much steeper
than on the opposite side, which is shown in fig. 1.

Plate III

Fig. 1. Section of volcanic tuff from near the base of Mount Maquiling at
an altitude of about 80 meters. Note the loose porous structure.
2. Growth of Saccharum spontaneum at an altitude of about 90
meters on Mount Maquiling.

Plate IV

Fig. 1. A specimen of Macaranga sp. This tree has about reached its
greatest height but not its greatest diameter.

2. Fieus nota, showing fruits on trunks. This is not an exceptional

amount of fruit for this species.

3. An old individual of Trema orientally. Note the open crown.

Plate V

View in dipterocarp forest, Mount Maquiling, at an altitude of about 500
meters. The large tree in the center is an individual of Para-
shorea malaanonan in the first story; the smaller trees on the right
are in the second story, while still smaller third-story species
are scattered throughout the picture. The feathery leaves of
the climbing palms (rattans) are the most conspicuous elements
in the undergrowth. The density of the vegetation is very
evident, the foliage of the undergrowth and lower stories being
so dense that most of the large trees are completely hidden.

Plate VI

lriG. 1. Interior of dipterocarp forest, Mount Maquiling, at an altitude
of about 500 meters. View from a slightly elevated point,

looking into the second and third stories. The large tree on

6 VEGETATION OF PHILIPPINE MOUNTAINS

the left is a Parashorea malaanonan. The leaves on the trunk
of this tree belong to an aroid vine, Pothos. Note the size of the
trees as compared with the man in the upper left center.
Fig. 2. Interior of dipterocarp forest on Mount Maquiling at an altitude
of about 300 meters. Note that the profusion of small trees
has almost completely hidden the larger ones. The conspicuous
leaves in the upper left-hand corner are of a climbing- bamboo.

Plate VII

View of dipterocarp forest at edge of a clearing at an altitude of 450
meters. The conspicuous palms in the foreground are Livistona
sp. These, as will be seen, are in the clearing and were left
when the rest of the forest was removed. The feathery leaves
near the ground at the edge of the forest belong to rattans.

Plate VIII

Fig. 1. Interior of a thinned dipterocarp forest on Mount Maquiling at
an altitude of about 300 meters. All of the small trees on this
area have been cut down by the College of Agriculture in order
to start a coffee plantation. Some trees more than 1 meter in
diameter were cut.
2. View of dipterocarp forest in a ravine on Mount Maquiling at
an altitude of about 300 meters. Note the small size of the
trees and the open condition of the forest. These features are
characteristic of dipterocarp forests in ravines.

Plate IX

A group of large dipter6carps in the forest in northern Negros. The small
trees have been largely removed from this area.

Plate X

Fig. 1. Interior of virgin dipterocarp forest in northern Negros. The
density of the stand does not permit an extended view. The
conspicuous leaves in the picture belong to climbing palms
(rattans).
2. Interior of virgin dipterocarp forest in Bataan Province, Luzon,
at an altitude of approximately 450 meters. The large trees
are Shor*ea polyspermia. Note the greater prominence of trees
than in the views of the forest on Mount Maquiling. The
Bataan forest is better developed than that on Maquiling and
consequently contains less undergrowth.

Plate XI

Fig. 1. A large strangling fig, Ficus dementis. This plant seems to have
started originally in the top of a large tree and sent its roots
down this and a neighboring tree; in dipterocarp forest, Mount
Maquiling, altitude about 300 meters.
2. Anastomosing aerial roots of a strangling fig; in dipterocarp
forest, Mount Maquiling, altitude about 450 meters.

ILLUSTRATIONS

Plate XII

Fig. 1. An old individual of a strangling fig. The trunk as seen from

the opposite side appears to have a fairly regular bole; in

dipterocarp forest, Mount Maquiling, altitude about 450 meters.

2. A tree with large planklike buttresses in dipterocarp forest, Mount

Maquiling, altitude about 300 meters.

Plate XIII

Fig. 1. A strangling fig on a large Parashorea; in dipterocarp forest,
Mount Maquiling, altitude about 500 meters.

2. A myrmecophilous Dischidia. This Dischidia is a vine, which in

this case is growing on a slender branch. Before taking the
picture alternating leaves were removed. Note that the leaves
are convex and that the edges are so close to the supporting
branch that the leaves inclose a space within which numerous
roots develop from the stem o*f the Dixehidia. These spaces
usually contain large numbers of ants. In dipterocarp forest,
Mount Maquiling.

3. Hydnophytum.

Plate XIV
Fig. 1. Myrmecodia.

2. Section of the base of Myrmecodia, showing cavities inhabited

by ants.

3. Section of base of Hydnophytum, showing cavities inhabited by

ants.

Plate XV

Fig. 1. A boiling mud spring on Mount Maquiling at an altitude of about
300 meters. Note the steam arising from the water and the
luxuriant vegetation in the immediate neighborhood. This spring
occurs at the highest point at which there is any evidence of
present volcanic activity on the northern side of the mountain.
It is an isolated case of volcanic activity, as most of the other
springs occur at the base of the mountain or even some little
distance from the mountain.
2. Rafflesia manillana in dipterocarp forest on Mount Maquiling at
an altitude of 450 meters. In this picture are shown six buds
and one open flower.

Plate XVI

View in midmountain forest, Mount Maquiling; altitude, about 700 meters.
Note the more open condition and the denser ground covering
than is seen in the dipterocarp forest. The two large trees
with cracked bark are Cratoxylon celebicum. The vine on the
one to the right is a Freycinetia. The conspicuous pinnate
leaves in the foreground are leaves of rattans. The numerous
leaves in the ground covering belong to species of Elatostcma.

Plate XVII

Undergrowth in midmountain forest at an altitude of 740 meters on Mount
Maquiling.

8 VEGETATION OF PHILIPPINE MOUNTAINS

Plate XVIII

Interior view of midmountain forest at an altitude of 740 meters on
Mount Maquiling. This view is taken along a trail, which is seen
in the center of the picture and in front of the man. The
conspicuous vines in the background belong to the genus Frey-
cinetia. The large tree on the right is a species of Ficus; note
the fruits on the trunk.

Plate XIX

Midmountain forest, Mount Maquiling, at an altitude of about 780 meters.
Note the small size of the trees, due apparently to the steepness
of the slope.

Plate XX

Fig. 1. View in midmountain forest, Mount Maquiling, at an altitude of
about 780 meters.
2. Exterior view of mossy forest on East Peak of Mount Maquiling.

Plate XXI

An average covering of epiphytes and vines on a tree trunk at the lower
edge of the mossy forest. The vine with the most prominent
leaves is Dichrotrichum chorisepalum.

Plate XXII

Aerial roots of an old tree in the mossy forest near the summit of Mount
Maquiling. Note the thick covering of mosses and mosslike
plants on the exposed part of the roots and their absence in the
interior where the light is greatly reduced.

Plate XXIII

Epiphytes, particularly mosses, on a branch of a tree in the mossy
forest. For convenience in photographing, this branch was cut
off. The lower cut end is seen in the lower left-hand corner of
the picture. The diameter of the cut end of the branch was
3 centimeters and the greatest diameter of the moss, 27 centi-
meters. Growing from the upper left-hand corner of the moss
is a conspicuous specimen of Rhododendron quadrasianum. This
plant occupies most of the upper left-hand corner of the picture.
Growing from the right of the moss is a grasslike orchid,
Dendrochilum glumaceum, while scattered here and there are
two species of ferns.

Plate XXIV

A specimen of the epiphytic Rhododendron quadrasianum. This individual
was about 2 meters tall. For convenience in photographing, the
branch on which it was growing was cut and one end placed
on the ground. The conspicuous small leaves in the foreground
in the upper part of the picture belong to this Rhododendron,
and in the lower part of the picture can be seen the base of the
Rhododendron and also its roots and the branch on which it was

ILLUSTRATIONS 9

growing. The roots were covered by a thick layer of mosses
which was on the branch. Before the picture was taken this
layer of moss was removed. The attachment of the roots shows
clearly in the lower center of the picture. Note the moss grow-
ing on the Rhododendron. This was naturally somewhat disturbed
in removing the plant from its original position.

Plate XXV

A covering consisting largely of Selaghiella miiquilieiisis and the filmy
fern Trichomanes proliferum, on a tree trunk in the mossy
forest near the summit of Mount Maquiling.

Plate XXVI

A covering of mosses, liverworts, and ferns on a tree trunk in the mossy
forest near the summit of Mount Maquiling. The conspicuous
filmy fern on the right is Trichomanes apiifolium.

Plate XXVII

A covering consisting largely of mosses and liverworts, on the small
aerial roots of a tree in the mossy forest near the summit of
Mount Maquiling.

Plate XXVIII

Interior view of the mossy forest on Mount Maquiling. In the left of
the picture and on the right of the man are tree trunks thickly
covered with mosses and mosslike epiphytes. The ground cover-
ing consists largely of selaginellas and ferns.

Plate XXIX

Festoons of mosses and mosslike epiphytes on the aerial roots of two trees
in the mossy forest near the summit of Mount Maquiling. The
roots to the left of the man are so densely covered as not to be
distinct in the picture.

Plate XXX

Fig. 1. Nepenthes alata in the mossy forest on Mount Maquiling.

2. Freycinetia wUliamsii on a tree in the mossy forest. Note the
mosses on the tree trunks.

Plate XXXI

Epiphytes on a branch of a tree in the mossy forest, The branch was
thickly covered with mosses, in which were growing considerable
numbers of Medinilla my rt if or mis, some M. venosa, one seedling
of each of two other tree species, two Polypodiaceae, several
medium-sized filmy ferns, and UtHcularia rosulata. The growth
of epiphytes is so dense that the branch of the tree cannot be
seen, but the mossy covering is evident in the lower left corner
of the picture.

Plate XXXII

Typical view in the mossy forest near the summit of Mount Maquiling.
The conspicuous vines are Freycinetia.

10 VEGETATION OF PHILIPPINE MOUNTAINS

Plate XXXIII

Ground covering of Selaginella in the mossy forest near the summit
of Mount Maquiling.

Plate XXXIV

Ravine in the lower portion of the mossy forest. Note the tree ferns and
the open character of the vegetation.

Plate XXXV

Vegetation on a level area near the lower limits of the mossy forest.
The vegetation here is very much denser than in the ravine
shown in Plate XXXIV.

Plate XXXVI

Side of ridge near the ravine shown in Plate XXXIV. Note the much
denser vegetation than is shown in Plate XXXIV.

Plate XXXVII

Fig. 1. Flowers of Melastoma polyanthum.

2. Begonia aequata on a branch of a tree in the mossy forest. The
size of the branch can be seen in the right of the picture.

Plate XXXVIII

Pine forest in Benguet mountains. The open parklike arrangement is
very typical.

Plate XXXIX

Fig. 1. A view in the forest near the top of Mount Banahao. The
prominent trees are Podocarpus imbricatus; note the slant of
the trees. Some epiphytes are seen on the trunks, but they are
much less prominent than is usual on mountain tops in the
Philippines.
2. Another view in the forest near the top of Mount Banahao. The
large trees are Podocarpus imbricatus. The undergrowth ap-
pears denser than it really is, due to the facts that the picture was
taken on a foggy day and that the perspective is poor.

Plate XL

Fig. 1. View in forest on Mount Banahao at an altitude of about 1,000

meters. Note' the thick undergrowth and the abundance of vines.

2. View in mossy forest in a shallow ravine on Mount Banahao at

an altitude of about 1,800 meters. The mossy covering shown

in this picture is much heavier than it is on the ridges.

Plate XLI

Map of Mount Maquiling. The contours are given in feet. The stations
where the instruments were placed are represented by circles
and the plots where exact counts of the vegetation were taken
by crosses. Drawn from a map by the Bureau of Forestry.

TEXT FIGURES

Pajjre.

Fig. 1. Rates of growth of second-growth trees at the base of Mount
Maquiling compared with the rates of growth of trees in
the United States 142

Fig.

16 (J

204

ILLUSTRATIONS \\

Rates of growth of trees in dipterocarp forest on Mount

Maquiling; altitude, 800 meters 157

3. Diameter growth of Parashorea at 800 meters', and of Astro-

glia pulchra at 740 meters', altitude 1^4

4. Rates of growth of Dillenia at altitudes of 800 and 740

meters

5. Rates of growth of second-growth trees on Mount Maquiling

at altitudes of 80 and 1,000 meters 1(58

6. Average weekly maximum and minimum temperatures in

dipterocarp forest on Mount Maquiling; altitude, 300
meters -j^-

7. Average weekly maximum and minimum temperatures in

dipterocarp forest on Mount Maquiling; altitude, 450
meters

8. Mean temperature under trees at different altitudes on Mount

Maquiling _ 219

9. Average daily maxima and minima and mean temperatures

under trees at different altitudes on Mount Maquiling 220

10. Average of weekly maximum and minimum temperatures

at different altitudes on Mount Maquiling 226

11. Average daily light intensity in top of dominant trees at

different altitudes on Mount Maquiling 234

12. Monthly rainfall at base of Mount Maquiling; altitude, 80

meters 250

13. Rainfall at different altitudes on Mount Maquiling 251

14. Average weekly percentage of soil moisture at different

altitudes on Mount Maquiling at a depth of 20 centimeters 265

15. Relative humidity under second-growth trees at base of

Mount Maquiling; altitude, 80 meters 277

16. Relative humidity in undergrowth in dipterocarp forest;

altitude, 300 meters 282

17. Relative humidity in midmountain forest; altitude, 740

meters _ 290

18. Mean relative humidity under forest at different altitudes

on Mount Maquiling 292

19. Average daily maxima and minima and mean relative humid-

ity at different altitudes on Mount Maquiling 294

20. Average daily evaporation in different situations near the

base of Mount Maquiling; altitude, about 100 meters 317

21. Average daily rate of evaporation in different situations in

the dipterocarp forest, Mount Maquiling; altitude, 300
meters 829

22. Average daily rate of evaporation in different situations in

the dipterocarp forest, Mount Maquiling; altitude, 450
meters 884

23. Average daily rate of evaporation in different situations in

the midmountain forest, Mount Maquiling; altitude, 740
meters 840

24. Average daily rate of evaporation in different situations in

mossy forest, Mount Maquiling; altitude, 1,050 meters 345

12 VEGETATION OF PHILIPPINE MOUNTAINS

Page.

Fig. 25. Average daily rate of evaporation in top of dominant trees

at different elevations on Mount Maquiling 346

26. Average daily rate of evaporation under the forest at differ-

ent altitudes on Mount Maquiling 347

27. Average daily wind velocity at the base of Mount Maquiling;

altitude, 80 meters 366

28. Seasonal diameter growth of Parashorea malaanonan (bag-

tican lauan) in open at the base of Mount Maquiling;
altitude, about 100 meters 372

29. Average seasonal diameter growth of 121 second-growth

trees near the base of Mount Maquiling; altitude, 80
meters 374

30. Seasonal rates of diameter growth of Parashorea malaano-

nan in dipterocarp forest; altitude, about 300 meters 375

VEGETATION OF PHILIPPINE MOUNTAINS

By William H. Brown
INTRODUCTION

The physical characteristics of the vegetation of a given region
are largely due to environmental factors, while the phyiogenetic
relationships depend to a great extent on past or present geo-
graphical connections or barriers. In most cases similar exter-
nal conditions appear to have produced associations of plants
whose f undamehtal physical characteristics are much alike. This
fact has made it possible for Warming,* in discussing the vege-
tation of the world, to formulate an extensive ecological classi-
fication based on habitat and physical characteristics rather
than on systematic composition. Schimper f likewise divides
the vegetation of the world according to habitat.

In preparing the present paper it has been assumed that the
distinctly different physical types of climax vegetation on
Mount Maquiling and Mount Banahao, Luzon, Philippine Is-
lands, are the result of environment. Working on this assump-
tion an attempt has been made to correlate periodical measure-
ments of environmental factors with the more obvious physical
characteristics.

Mount Maquiling is an exceptionally favorable locality for
such a study. The advantage of not having to deal with a cold
winter season is obvious. From the base to its summit a num-
ber of very distinct types of vegetation exist in exceptionally
close proximity, so that it is practicable to obtain weekly
readings in the more distinct ones. Perhaps of equal impor-
tance is the fact that the division of investigation of the Philip-
pine Bureau of Forestry, and the College of Agriculture of
the University of the Philippines, are located at the base of the
mountain, while the Bureau of Science, at Manila, can be reached
by train in about two and a half hours.

The different physical types of vegetation occurring on Mount

* Warming, E., Oecology of Plants. English edition by Groom and Bal-
four, Clarendon Press, Oxford (1909).

t Schimper, A. F. W., Plant Geography. English edition by Groom and
Balfour, Clarendon Press, Oxford (1903).

13

14 VEGETATION OF PHILIPPINE MOUNTAINS

Maquiling are similar to those natural on many, if not most,
mountain peaks rising from the lowlands in moist tropical re-
gions. On the lower slopes there is a lofty evergreen forest,
which type Schimper * has shown to be characteristic of moist
tropical lowlands. As higher altitudes are reached on Mount
Maquiling, shorter trees occur and epiphytes become more numer-
ous, until at an elevation of 1,000 meters there is an elfin forest
in which the trees are thickly covered with mosslike plants,
interspersed among which are many flowering individuals.
This condition is widespread in both hemispheres.

This characteristic gradation from a lofty evergreen forest
at low altitudes to a lower mossy one at high elevations, pecu-
liar to mountains in widely separated moist tropical regions,
certainly seems to show that the different types of vegetation
concerned are due to similar widespread environmental condi-
tions. However, the gradation is not equally characteristic on
all mountains and occurs at much lower elevations on some than
on others, depending on the geography of the mountain and the
region. On Mount Pauai, in the great mountain mass of central
Luzon, the mossy forest at an elevation of almost 2,500 meters
is taller than that on Mount Maquiling at 1,000 meters; while
the isolated cone of Mount Banahao, though more than twice
as high as Maquiling, is not so characteristically mossy anywhere
on its northern side (the only one the writer has visited) as is
the top of Maquiling. For comparison with Mount Maquiling
a short description of the vegetation and environment on Mount
Banahao is included in the present paper.

Whitford t has given a very comprehensive floristic analysis
of the vegetation at different elevations on Mount Mariveles,
including the number of individuals of each species on extensive
areas. The specific composition of the flora of Mariveles and
of Maquiling is very different, but many of the general prin-
ciples brought out by Whitford will apply not only to Maquiling
but also to a large part of the Philippines. For this reason it
has not been considered necessary to make a similar study of
Maquiling. The vegetation will, therefore, be treated with
special attention to measurements of individuals, and in a man-
ner suited primarily to the particular purposes of the present
paper. A general discussion will be given of the formations
occurring at different levels, with detailed descriptions of limited

* Schimper, A. F. W., Plant Geography. English edition by Groom and
Balfour, Clarendon Press, Oxford (1903).

f Whitford, H. N., The vegetation of the Lamao forest reserve, Phil.
Journ. Sci. (1906), 1, 373.

INTRODUCTION

15

areas in which the trees of each species have been counted
and the chief measurements of all individuals taken. These
measurements will serve as a basis for tables by means of which
the physical characteristics of the different formations may
be compared and studied in connection with the measurements
of the environmental factors.

The discussion of the vegetation of Mount Maquiling will be
confined to that on the eastern slope.

A list of the species considered, together with the authorities
and native names, is given at the end of this publication.

The writer wishes to express his thanks to Dr. F. W. Fox-
worthy and Mr. D. M. Matthews for facilities afforded him at
the division of investigation, Bureau of Forestry, at Los Banos;
and to Mr. E. D. Merrill, of the Bureau of Science, for assistance
in the identification of specimens.

MOUNT MAQUILING

Mount Maquiling is an isolated volcanic cone situated on
Luzon, midway between the eastern and western coasts, about
64 kilometers southeast of Manila, in latitude 14° 8' north and
longitude 121° 11/ east of Greenwich. Its geology has been dis-
cussed at some length by Abella.* Its main volcanic activity
has been long extinct, though still evident in many hot springs
and f umaroles ; these, however, do not affect the vegetation, ex-
cept locally. The position of the crater is not very perceptible,
but its rim may be traced in a series of individual peaks, while
the streams rising in the center have worn deep and wide chan-
nels that have obliterated the central depression. Ashes and
lava have disappeared ; and the whole mountain, except on very
steep slopes, is covered by a deep layer of soil. The vegetation,
where not disturbed by man, is apparently a climax type.

Most of the observations recorded in this paper were made on
the eastern slope. On this side the ascent of the lower slopes
is gradual, while near the top it is, for the greater part, much
steeper. This change is more or less gradual but is most pro-
nounced at an altitude of about 750 meters. Plate II, fig. 1,
shows this side of the mountain as seen from the College of Agri-
culture grounds. Plate II, fig. 2, is a view of the opposite side,
from Santo Tomas. The topography of the mountain is shown
by the map on Plate XLI. The topography of the lower slopes
may be described as a series of broad, radiating, well-drained
ridges separated by narrow valleys. Above 750 meters there

* Abella y Casariego, D. E., El Monte Maquiling. Madrid (1885).

16 VEGETATION OF PHILIPPINE MOUNTAINS

are flat places, and others with gradual slopes, but at these
higher elevations the slopes are usually fairly steep. On the
eastern side Mount Maquiling grades into the surrounding plain
at an altitude of about 50 meters, while the plain on the opposite
side is about 200 meters higher. The mountain is comparatively
lowr, the highest peak reaching an elevation of about 1,140
meters.

The climate of Maquiling and the surrounding country is
distinctly monsoon in character. On reaching the eastern coast
the northeastern monsoon, coming from the Pacific, strikes a
high plateau, which is the divide between Laguna de Bay and
the Pacific Ocean. This plateau reaches elevations of from 500
to 600 meters or more, and on it is deposited a large part of
the moisture carried by the northeastern monsoon. After pass-
ing over this plateau the monsoon reaches Maquiling as a drying
wind and produces a very distinct dry season, which is most
pronounced about March or April. This dry season is naturally
less severe on the eastern than on the western side of Maquiling.
At high elevations conditions are comparatively moist at all
times. The heaviest rainfall usually occurs between July and
September, during the season of cyclonic disturbances (ty-
phoons).

During the rainy season small springs occur high up on the
mountain; but, for the most part, the permanent streams rise
at elevations around 500 meters. It is very common in vol-
canic mountains in this region for the water to run underground
to such an extent that even on high mountains there are no per-
manent streams much above the base.

ENVIRONMENTAL CONDITIONS

As an understanding of the vegetation is dependent to a con-
siderable extent upon a knowledge of the environment, it seems
advisable to present here a brief summary of the environmental
conditions obtaining on Mount Maquiling.

The relative humidity in most parts of the Philippines is
comparatively high at all seasons of the year, and this is true
of the region in which Mount Maquiling is situated, and partic-
ularly so of that side of the mountain on which the present
study was made. As in the case of all mountains, the air which
is forced up from the lower regions becomes cooler and capable
of retaining less moisture. The result is that the relative hu-
midity increases as higher elevations are reached, and near the
summit the air under the forest is practically saturated the year

INTRODUCTION 17

round, while the top of the mountain is bathed in clouds during
a large part of the time. The hygrometer under the forest
recorded 100 per cent saturation for months at a time. This,
however, does not mean that the air was completely saturated,
as the instrument used was operated by the contraction and
expansion of hairs, which when wet by clouds would require
some time to dry before the instrument could record a lower
humidity.

Around the base of the mountain the wind is steady during
the entire dry season, and evaporation at this time is compara-
tively high. At other seasons it is much lower. With increas-
ing altitudes the velocity of the wind rises, but on account of
the greatly increased humidity the rate of evaporation decreases
and at the top is extremely low. For weeks at a time a non-rain-
absorbing atmometer under the forest showed no signs of evap-
oration.

Owing to increasing cloudiness near the top, the amount of
light received by the vegetation also decreases gradually as
high elevations are reached.

The decrease in evaporation and increase in relative humidity
would appear to be fairly independent of the amount of rainfall,
as the greatest rainfall occurs at middle altitudes, while the
rainfall at the top and at about 300 meters' elevation is prac-
tically the same.

The amount of moisture in the soil is always high in the
virgin forest but increases at higher elevations, although owing
to the contour of the ground the soil appears to be well drained
throughout.

The temperature gradually decreases with increasing alti-
tudes, but the range at any given elevation is small.

PARANG VEGETATION

The Tagalog word parang is a name applied to a mixture of
grassland and second-growth forest. Parang is found around
the base of Mount Maquiling. The grasses in the parang are
usually coarse and from 1 to 3 meters in height. The forest
occurs in patches of varying sizes and consists principally of
small trees about 6 to 10 meters high. Scattered individuals of
fair-sized trees are also found in the parang. This type of
vegetation is very common in the Philippines, as it occurs on
land from which the original forest has been removed. For a
general discussion of cleared areas see Brown and Matthews.*

With the exception of very limited dry areas, the whole of
the Philippines must originally have been covered by trees, as
environmental conditions throughout the Archipelago are favor-
able for forests. Both cultivated areas and grasslands quickly
return to forest if not disturbed by man and fires are excluded.
When land is cleared of forest and cultivated by primitive
methods, grasses and other weeds make their appearance.
These are frequently removed by burning, especially during the
dry season. Fires kill most of the dicotyledonous plants, but
do little harm to the rhizomes of the grasses. The result of
several successive fires is to leave the land in possession of the
grasses, especially Imperata exaltata (cogon) and Saccharum
spo?itaneum (talahib). After this, cultivation is usually aban-
doned. Plate III, fig. 2, showrs a stand of Saccharum spontaneum.

Dead leaves accumulate quickly in stands of Imperata or Sac-
charum, so that these grasses become very inflammable during
the dry season. At such times a grass area is usually burned
over completely, sometimes by accident, but as a rule, inten-
tionally. Burning is resorted to for various purposes; as, for
example, to make hunting less difficult, to obtain young growth
for forage, or to clear the land so that it can be easily traversed
or so that a part of it can be cultivated. When an area is burned
over regularly, the grasses form almost pure stands. With
primitive methods of agriculture the grasses get a good start
even without fires, as their rhizomes are much harder to eradi-
cate than are dicotyledonous plants; but it is only when other
plants are destroyed by fire that the grasses form extensive pure

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests.
Phil. Journ. Sci., Sec. A (1914), 9, 413-561.
18

PARANG VEGETATION \Q

stands. If the grass is not burned, it is quickly invaded
by second-growth trees. If no fire has occurred in an area for
two or three years, small patches of trees may appear; but an
area is rarely kept free from fire for a period sufficiently long
to allow trees to cover it. The part left in grass is usually
burned over with fair regularity. The fires may kill the trees
at the edge of the forest, or the occasional absence of fires may
cause the trees to encroach upon the grass. Thus the parang
persists for years, the trees at times gaining and at other times
losing ground. When they form a continuous forest, the land
is frequently cleared again and cultivated, as such areas are
much more easily put under cultivation than is grassland.

When ground is cultivated intensively, or with modern meth-
ods, the grasses do not take possession of it; but the shifting
system of cultivation just described has been so widespread in
the Philippines that, according to Whitford,* 40 per cent of the
land area of the Archipelago is occupied by grass, 16 H per cent
by second-growth forest, while only 10 per cent is cultivated.

PARANG ON MOUNT MAQUILING

The measurements, recorded in this paper, of environmental
factors for the cleared region at the base of Mount Maquiling
were made in the limited area between the College of Agriculture
and the lower edge of the forest. This area is typical parang.
In 1909, when the college was established, most of this land wras
covered by grasses, chiefly Imperata e.raltata (cogon) and Sac-
charum spontaneum (talahib).

The original vegetation of the country surrounding Mount
Maquiling and most of that on the mountain at elevations below
100 meters has been cleared away and the land put under cul-
tivation. Above this and up to an altitude of 200 meters the
forest has been so heavily logged that the main canopy has been
removed almost completely and replaced largely by other species.
From what is left in ravines and the seedlings found in them
and in the forest at elevations between 100 and 200 meters, as
well as by a comparison with the forest at higher elevations
and other forests occurring in similar situations, we can form
■;ome idea of the composition of the original forest of the plain
and slopes up to 200 meters. All these conditions would seem
to indicate quite clearly that it was, like that now occurring
at the next higher elevations, of a dipterocarp type. A diptero-

* Whitford, H. N., The Forests of the Philippines, Hull. P. J. Bnr. For.
'^11), No. 10.

20 MOUNT MAQUILING

carp forest is one in which the main story is dominated by
members of the family Dipterocarpaceae.

The number of seedlings at elevations between 100 and 200
meters and of small trees in the ravines at lower elevations is
sufficient to indicate that the main canopy of the original dip-
terocarp forest, now removed, consisted largely of Parashorea
malaanonan (plicata) (bagtican lauan), Shorea guiso (guijo),
and Pentacme contorta (white lauan). These are all large trees
and in this favorable locality probably formed a canopy about
40 meters high. Under this main story there must have been
two other stories besides the undergrowth, the whole form-
ing a tall, dense forest. When the area below 100 meters
was cleared and for how long a period it was cultivated are
uncertain.

The two grasses most prominent in the Maquiling area, Im-
perata exaltata (cogon) and Saccharum spontaneum (talahib),
have different characteristics and are suited to different hab-
itats. Imperata exaltata is the shorter, rarely reaching a
height of more than 1.5 meters. The erect stems grow from
rhizomes and are spread over the ground rather evenly, with
little tendency to form clumps. Imperata appears to be dis-
seminated more quickly than Saccharum and at first occupied
the larger part of the grass area at the base of Mount Maqui-
ling. Saccharum spontaneum is taller, being frequently more
than 3 meters high, and forms dense clumps. It succeeds Im-
perata in the more favorable localities, while the latter persists
in the drier places. Imperata will frequently be found on the
top of a small hill where the soil is shallow and comparatively
dry, while the slopes with deeper and moister soil will be
covered with Saccharum, Most of the land under discussion is
suitable for Saccharum, and this is now the more prominent
species.

The large grass areas in the Philippines are called cogonales.
All these areas appear to have a similar origin and possess
many characteristics in common. The species of grasses first
entering a cleared area depends to a considerable extent on the
proximity of seed-bearing plants; but, as the grass areas be-
come older, the distribution of many of the species will be
definitely determined by their habitats, as has been shown in
the case of Imperata exaltata (cogon) and Saccharum spontane-
um (talahib), and this distribution will apparently be permanent
so long as the area remains in grass. In old grass areas these

PARANG VEGETATION 21

two grasses do not form mixtures, but each in its special hab-
itat forms a practically pure stand.

In the grass areas there are usually individuals of a few
species other than grasses that, owing to large underground
structures, can withstand fire. In the region under consider-
ation the orchid Eulophia exaltata is one of the most wide-
spread, while Bliimea balsamifera (sambong), a shrub, occurs
in scattered patches. The fire-resisting trees Antidesma ghae-
sembilla (binayuyu), Bauhinia malabarica (alibangbang), and
Acacia farnesiana (aroma) occur as scattered individuals.
When these trees are young their shoots may be killed by fire,
but new ones readily spring up from the roots. As each succeed-
ing shoot is usually taller than the one preceding it, the trees
finally grow higher than the grass and, in the immediate neigh-
borhood, kill the latter by shading it. In this way the tree
may gradually become the center from which a small clump is
formed.

Besides the plants just mentioned, a small Selaginclla, S.
helangeri, and a species of Riccia were also common in the
Maquiling area during the wet season.

When fires are excluded from a grass area, it is invaded by
a large number of shrubs, vines, and small trees. The grasses
can stand but little shading and soon succumb, and in a few
years they are replaced by a second-growth forest of small,
rapidly growing trees.

Before the establishment of the College of Agriculture, in
1909, the area between it and the forest appears to have been
burned over regularly, and large parts of it were burned as late
as 1911; since then fires have been excluded.

Table I shows the composition of a plot 2 meters square in
an area of Imperata exaltata in 1912.

Table I. — Composition of plot of Imperata exaltata. Plot, 2 meters square.

IMPERATA EXALTATA (CO(JON). HEIGHT, 130 TO 140 CENTIMETERS.
Plants with —

One stalk 1,675

Two stalks 147

Three stalks 82

Four stalks 38

Five stalks 19

Six stalks 15

Total plants 1,976

Total stalks 2,552

22

MOUNT MAQUILING

MISCELLANEOUS SPECIES.

Species.

Herbs and shrubs:

blulophia exaltata

Biophytu m Mnsitivum . _

Sektfji n ella belangc ri

Mimosa pudira

Desmodium pulchellum ._

Comm.elina nudifiora

Compositae

Synedrella nodifiora

Sida javensix

Riccia. sp

Vines:

Streptocaulon baurnii

Opereulina turpethum

Merremia umbellata

Merremia haatata

Cissua trifolia

Ipomoea triloba

Total

Plants.

Greatest
height.

Average
height. J

Seed-
ling's.

cm .

cm.

|

1
{

5

6(1

35

1

7

4

3 !

2 I

16

3

2 1

68

18

1.5

43 !

122

27

21 |

84 1

7

4.5

3

i

23

6

4

23 !

10

21

8 !

8

1

5.5

5.5 ;

i ;

many

2

6

5.5 i

2

1

9

9

2

280

145 i

1

5

6

3

^

2

173

60

i 9

' 69

31 ■

4

1*1

An analysis of this plot shows a dense stand of Imperata.
With the exception of Imperata and five individuals of Eulophia,
which is fire-resistant, all the plants are small, the majority being
seedlings. All have invaded the area since the last fire. Mimosa
pudica, which grows about as tall as Imperata, and Desmodium
pulchellum, which is slightly taller, together with a few other
shrubs, are frequently conspicuous in grass areas. Table I
shows that the two just mentioned are present in sufficient
numbers to insure their prominence, unless killed by fire. Bio-
phytum sensitivum, Eulophia exaltata, and Commelina nudifiora
are small plants and will remain inconspicuous; while Syne-
drella nodi flora is an annual, and Sida javensis is a small shrub.
Owing to their length some of the vines will soon grow over
the grass and become prominent. This invasion of an Imperata
area by small shrubs and vines is typical. They grow along
with the grass, and while making the stand of grass less dense
they do not usually drive it out. This is done, however, by
trees that enter an area very quickly after fires are excluded.
The change from almost pure stands of grass to the first stages
of invasion by trees is usually accompanied by a change in the
composition of the grasses, Imperata exaltata and Saccharum
spontaneum being replaced by species forming taller but less-
dense stands.

PARANG VEGETATION 23

The tree species may invade either the relatively pure stands
of grass or those mixed with shrubs and vines. The invading
species are numerous, but most of them are alike in their chief
characteristics. They are usually small, 10 meters or less in
height, and are intolerant species with soft wood. They grow
rapidly, mature early, and decay quickly. There are some ex-
ceptions; as, for example, Bischofia javanica (tuai), a large
tree occasionally found in parang, and Psidium guajava (gua-
va), a small tree which has fairly hard wood. As the trees
grow up in the grass they shade the intolerant grasses, causing
them to disappear. The trees thus come to form patches of
second growth mixed with the grass.

In the area under discussion the second-growth forest has
already occupied much of the ground and, as fires will probably
be excluded permanently, it will continue to spread until the
grass has disappeared. Judging by the present rate of inva-
sion, this process should be completed in less than ten years.

The first trees to enter the grass were naturally those having
pronounced ability to resist fires; namely, Acacia farnesiana
(aroma), Antidesma ghaesembilla (binayuyu), and Bauhinia
malabarica (alibangbang). As soon as fires were excluded,
these were followed by a large number of others. The species
are so numerous, and the composition of the forest is so varied,
that it is difficult to tell which species are most prominent in
forming the young second-growth forest; but among them are
Melochia umbellata (labayo), Columbia serratifolia (anilao),
Litsea glutinosa (puso puso), Macaranga tanarius (binunga),
Macaranga bicolor (hamindang), Premna cumingiana (ma-
guili), Ficus nota (tibig), Ficus hauili (hauili), Ficus ulmi-
folia (isis), Mallotus philippensis (banato), Mallotus ricinoides
(hinlaumo), and Alstonia scholaris (dita). Some of the other
prominent species are Trema orientally (anabion), Cordia
myxa (anonang) , Canarium villosum (pagsahing) , Leucaena
glauca (ipil ipil), Piptiirus arborescent (dalunot), Voacanga
globosa (bayag-usa), Leea manillensis, Litsea perrottetii (ma-
rang), Psidium' guajava (guava), Eugenia cumiyii (duhat),
Mallotus moluccanus (alim), and Artocarpus cumingiana (anu-
bing). Plate IV, fig. 1, shows a tree of Macaranga; Plate
IV, fig. 2, Ficus nota; and Plate IV, fig. 3, an old individual of
Trema orientalis. The second-growth forest contains a great
many species besides those mentioned above, some of them being
possibly more prominent than a number of those listed.

The plants range in size from small, bushlike forms, such as

24 MOUNT MAQUILING

Tabernaemontana pandacaqui (pandacaqui) and Mussaenda
philippica (cahoy dalaga), to large trees, like Parkia javanica
(timoriana) (cupang) ; the last is occasionally found in both the
parang and the dipterocarp forests.

The distribution and the requirements of the different species
also vary considerably. Bischofia javanica (tuai), a large tree
frequently more than a meter in diameter, is represented in the
parang by a few individuals and also occurs in the dipterocarp
forest and even at elevations above the dipterocarp forest. Leea
manillensis, a small tree, is very common in the lowest tree story
in both the dipterocarp forest and the forest at the next higher
elevations; it is also a dominant tree in the parang. Tabernae-
montana pandacaqui is prominent as an undershrub in the dipte-
rocarp forest and is also a common weed in open ground. On
the other hand Trema orientalis (anabion), a very rapidly grow-
ing species, is extremely intolerant of shade. It produces large
numbers of small seeds, which are quickly and thoroughly scat-
tered by birds. Where the ground has been cleared, as by log-
ging, it frequently forms almost pure stands of great extent.*
On Maquiling it has taken possession of several clearings. The
writer made a clearing in the forest of Mount Maquiling at an
elevation of 450 meters. Trema invaded this so quickly and in
such large numbers that it soon formed an almost pure stand.
This is the more remarkable as the nearest seed plants observed
were at a considerable distance and about 200 meters lower in
elevation. The seeds of Trema are certainly well distributed;
and, if conditions are favorable, they come up in large numbers.
Trema does not, however, come up under other trees, and is
not so successful as are many others in invading grassland. It
seems not improbable that it usually gets its start in grass when
the latter has been temporarily disturbed by some external agency.

Since the trees forming the second-growth forest have such
decidedly different characteristics, it would seem that it ought
to be easy to subdivide it into smaller ecological units. Such,
however, is not the case. The larger trees play an inconspicuous
part in the early stages. The others form a heterogeneous mix-
ture in which certain ones are more prominent in some spots,
while others are more numerous elsewhere without there being
any very apparent reason.

The successions on cleared areas that are not cultivated are
much less complex than in grassland. In northern Negros Tre-

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests*
Phil. Journ. Sci.f Sec. A (1914), 9, 413-561.

PARANG VEGETATION 25

ma orientalis invades clearings and forms extensive, almost
pure stands, which can be measured in square kilometers and
are only limited in extent by the size of the clearings.* Like-
wise, there are places where, under different conditions, other
second-growth trees form almost pure stands on cleared land.
Another striking example is the extensive area covered by
Homalanthus populneus (balanti) on Mount Mariveles.f

The succession on grasslands is usually very complex, and
such a mixture as we find at the base of Maquiling is the rule
rather than an exception. In the area under discussion there
are certainly no clearly defined subdivisions, and for the pre-
sent it is probably best to regard the forest as a single type
and to apply to it Whitford's term "second-growth forest/'i

The individual species in this forest play different roles: as,
for example, the fire-resisting ones are the first invaders ; Trema
enters only in the early stages and has a very open crown ;
tolerant species close the canopy ; Macaranga enters early, grows
rapidly, and at the same time casts a fairly dense shade. Each
species thus has its individual peculiarities, which fact, together
with the favorable conditions of a tropical climate, probably
accounts for the great diversity of the forest.

Besides the trees there are many minor species, including
small grasses and other herbs, shrubs, and vines. The composi-
tion varies very greatly in different localities and is influenced
particularly by the density and age of the forest. The under-
growth is frequently dense, while vines are numerous. In the
earlier stages the most prominent vines are members of the
family Convolvulaceae.

The forest may perhaps be best described as one in which a
great variety of small trees, shrubs, and vines are grouped to-
gether in a dense, heterogeneous tangle.

The canopy of a second-growth forest is much less dense than
that of a dipterocarp forest, and the conditions within the
forest are much drier. This is especially true of young forests
like the one on Maquiling. The undergrowth is, therefore,
usually somewhat xerophytic. Epiphytes, other than small crus-
taceous lichens, are practically absent from the parang.

The second-growth forest will naturally pass over into the

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil Journ. Set., Sec. A (1914), 9, 451.

t Loc. cit.

t Whitford, H. N., The Forests of the Philippines, Bull. P. I. Bur. For.
(1911), No. 10.

26 MOUNT MAQUILING

dipterocarp type ; but, as this process can hardly be said to have
begun, it is impossible to describe the successions. It has al-
ready been shown that some species are common to both
the second-growth and the dipterocarp forests. As the second
growth becomes older, other species from the dipterocarp
forest will invade it, and the vegetation will become taller and
denser, until finally conditions will be moist enough for the
dipterocarps themselves to enter. At present there are on the
edges of ravines a few large individuals of Parashorea rnala-
anonan (bagtican lauan), which have been left from the original
forest. These scatter large quantities of seed over the parang;
but, as they do not produce seedlings, it is evident that con-
ditions are not yet favorable for Parashorea.

The above description of the parang at the base of Mount
Maquiling, between the College of Agriculture and the diptero-
carp forest, applies to conditions as they were observed from
1912 to 1915. Since that time they have been very materially
altered by cultivation.

No measurements of the stand were made in the second-
growth forest, as its composition is so varied and it changes so
greatly with age that it was not considered practical to obtain
representative plots.

DIPTEROCARP FOREST

Forests of the dipterocarp type are characteristic of situations
favorable for plant growth in the lowlands of the Philippines,
and according to Whitford * they cover 75 per cent of the
virgin forest area and contain 95 per cent of the standing
timber of the Archipelago. For an extensive account of Phil-
ippine dipterocarp forests see Brown and Matthews.f

The dipterocarp forest on Mount Maquiling begins at the
upper edge of the parang and extends up the slopes of the
mountain to an elevation of about 600 meters. This forest is
located in the center of a well-populated district and has been
subjected to a process of selective logging for many years;
naturally, the more accessible portions have been most heavily
logged. The cutting has been so severe at elevations below
200 meters that the forest has largely lost its dipterocarp
character. Between 200 and 400 meters' elevation there has
been less logging; and, although the trees most valuable for
commercial purposes have been largely removed, the general
character of the forest has probably not been greatly changed
at elevations above 300 meters. Above 400 meters logging has
not been carried on extensively.

In describing this forest it will be convenient to divide it
into a cut-over type and a natural one, and to make the 300-
meter contour the line of separation ; this division is, of course,
arbitrary. The upper and lower portions differ, however, not
only in the extent to which they have been logged, but also
probably in original composition.

The dominant dipterocarps of this forest are Parashorea ma-
laanonan (plicata) (bagtican lauan), Shorea guiso (guijo), and
Pentacme contorta (white lauan). The last mentioned two are
very valuable timber trees, while Parashorea is much less
highly prized and is far more prominent over the whole area
than are the other two.

A study of the present distribution of seedlings and saplings
of the dipterocarps throws much light on their past distribution.

* Whitford, H. N., The Forests of the Philippines, Bull. P. L Bur. For.
(1911), No. 10.

f Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil. Journ. Scl, Sec. A (1914), 9, 413-561.

27

oo MOUNT MAQUILING

In the region between 200 and 300 meters' elevation large in-
dividual* of Shorea guiso and Pentacme contorta have been
almost entirely removed, but there are present large numbers
of seedlings and saplings of these species. This would indicate
that Shorea and Pentacme were fomerly prominent in the area.
Parashorea has been removed to only a slight extent at elevations
above 200 meters and probably not at all above 250 meters. A
comparison between the ratio of small to large trees of this species
and similar ratios of Shorea and Pentacme will, therefore, indicate
the extent to which the last two have been removed at higher
elevations Such a comparison does not show that Pentacme
has been removed at all at elevations of about 300 meters,
while the large specimens of Shorea in the same region have
for the most part disappeared. Here there are perhaps eight
small individuals of Parashorea to one of Shorea. At an eleva-
tion of about 450 meters Shorea has apparently not been removed
to any considerable extent. At elevations above 300 meters
there are many times as many individuals of Parashorea as of
Pentacme, although the latter does not appear to have been
logged at this elevation and there have probably always been
seven or eight of Parashorea to one of Shorea. This would
indicate that in the virgin condition of this area Parashorea
was dominant and that, as stated above, the dipterocarp char-
acter of the forest above the 300-meter contour has not been
greatly changed.

It is not practicable for one man to obtain exact figures in
dealing with the composition of so large and dense an area
as this dipterocarp forest. The figures given here are, how-
ever, probably correct in the main, for they include numerous
observations over a long period and are confirmed in a number
of cases by extensive measurements taken by Dr. F. W.
Foxworthy and his class in dendrology — particularly by a
classification made by them in 1915 of all individuals' of tree
species on one square kilometer. We can only guess at the
ratio that formerly existed on the lower slopes, but Shorea and
Pentacme were probably much more prominent there than at
altitudes above 300 meters.

The dipterocarps are by no means the only species that have
been cut, as there are many others, such as Koodersiodendron
pinnatum (amugis), Strombosia philippinensis (tamayuan), and
Dillenia philippinensis (catmon) , that are valuable. These, how-
ever, like the dipterocarps, have been removed to a much greater
extent at lower than at higher elevations.

Environmental conditions in the forest have probably not

DIPTEROCARP FOREST 29

undergone marked change above the 300-meter contour. One
important reason for this is that the forest consists of a mixture
of a great many species, many of which are not valuable for
local use. This is true of Parashorea malaanonan and Celtis
philippensis (malaicmo), the two trees that are far more nu-
merous than any others in the dominant story, and also of
Diplodiscus paniculatus (balobo) , a second-story tree, represented
by about three times as many individuals as any other except
the two just mentioned.

Cutting may change the value of the stand considerably, even
though it may not affect the environment within the forest.
When the valuable trees are cut their places are naturally taken
by others, and as growth within the forest is slow much time
may elapse before the valuable species occur again as large
individuals. Many of the trees form soft and medium-hard
woods valuable in temperate countries for construction timbers ;
but these are quickly destroyed by termites and fungi in the
Philippines and, therefore, are not sought by loggers who, like
those who have worked on Maquiling, use animals to haul their
lumber. Other trees have wood that is very hard to work. For
these reasons trees that would be used by a sawmill have been
left even on the lower slopes of Maquiling. Brown and Mat-
thews * have given a short description of this forest and discussed
the forestry problems connected with it.

Not only has the forest above the 300-meter contour undergone
comparatively little change so far as environment is concerned,
but the number of individuals of each species has also been
changed much less than might be supposed. Each species is
usually represented by more small individuals than large ones;
and, as only a portion of the latter have been removed, a count of
those present gives a fairly good idea of the original composition.
From the standpoint of the present paper we would appear to
be justified in treating the forest above an elevation of 300
meters as a natural climax one. However, the plot used for
detailed measurements was located at an elevation of about
450 meters and in an area where there has been little logging.
There was no evidence of trees having been removed from the
plot.

For convenience the more nearly virgin forest (that above the
300-meter contour) will be discussed first, as the cut-over forest
will then be more easily understood.

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil. Journ. Sci.t Sec. A (1914), 9, 413-561.

30 MOUNT MAQUILING

VIRGIN DIPTEROCARP FOREST

The virgin dipterocarp forest, which we have considered as
extending from the 300-meter contour to an elevation of ap-
proximately 600 meters, is decidedly a lowland, moist-tropical
forest formation. In the Philippines dipterocarp forests are
characteristic of the moist plains and lower slopes of mountains,
giving way to other types in drier situations, and usually at an
altitude of 800 meters or less. From the standpoint of the
physical characteristics of the vegetation the dipterocarp forest
on Maquiling is a lofty, evergreen, three-storied forest formation.

The regular occurrence of lofty, evergreen forest in lowland,
moist-tropical regions would certainly seem to justify the use
of the term lowland, moist-tropical forest formation.

The dipterocarp forest of Maquiling not only represents a
single formation, but except for the tension zone at its upper
limits also belongs to a single well-defined association, which
from its composition should be called the Parashorea-Diplodisciis
association. This forest, like the dipterocarp types described by
Whitford * from Mount Mariveles, contains a great mixture of
species. There are probably at least three hundred fifty tree
species in the dipterocarp forest of Mount Maquiling.

Some species are more prominent at lower than at higher
altitudes, while with others the reverse is the case. Again,
certain species will be more numerous in limited areas than else-
where, or species that occur in fairly large numbers in one
locality may not be represented in a neighboring one. The
reasons for some of these differences are more or less obvious ;
as, for example, certain species do best in the valleys and others
on the ridges. In general, however, the composition is fairly
uniform, the slight differences being confined largely to the less
conspicuous elements of the vegetation.

The development of the trees varies somewhat according to
the topography. Large trees are scarce in ravines and narrowr
valleys, while on the tops of sharp ridges the individuals may
have large diameters but are usually shorter than on gentle
slopes. In ravines the light is poor, while on sharp ridges the
trees do not have to grow particularly tall to enable them to
reach the light. Therefore, it would seem that light is the
factor determining their development. In ravines the under-
growth also is more open than on the ridges. The small size of
the trees in a ravine is shown in Plate VIII,- fig. 2.

* Whitford, H. N., The vegetation of the Lamao forest reserve, Phil
Johm. Sci. (190(i), 1, 37.°,.

DIPTEROCARP FOREST 31

The trees are arranged in three rather definite stories. The
first, or dominant, story forms a complete canopy; under this
there is another story of large trees, which also forms a complete
canopy. Still lower there is a story of small scattered trees.

Plate V is a view in the virgin dipterocarp forest at an altitude
of about 500 meters. The large tree in the center is a Para-
shorea malaanonan. On the right are two second-story trees,
while in the center at the left a third-story tree can be seen
very plainly. Plate VI, fig. 1, is another view at about the same
altitude. A view of this forest at the edge of a recent clearing
is shown in Plate VII. In making the clearing several specimens
of the palm Livistona sp. were left standing; these are seen in
the foreground.

FIRST, OR DOMINANT, STORY

The Maquiling region has a too pronounced dry season for the
best development of a dipterocarp forest; and, moreover, this
type is usually much poorer near its upper limits than at lower
elevations. It is not surprising, therefore, that the first, or
dominant, story is not so well developed nor so distinctly dip-
terocarp as is that of forests in more favorable situations. The
first story is irregular and, while usually continuous, is not very
dense.

The most prominent tree is Parashorea malaanonan (bagtican
lauan), which reaches a height of 35 to 40 meters and is fre-
quently considerably more than a meter in diameter. Over large
areas there are more than twice as many individuals of this
species having a diameter of a meter or more as of all other
species together. This does not take into account the strangling
figs with their irregular and hollow trunks; these occur in the
proportion of one large individual of Fiats to about three of
Parashorea. Parashorea, like the other dominant dipterocarps,
is taller than most trees of the first story. Its crown is flat
and spreading and has a tendency to grow out over the neigh-
boring trees. Other species, such as Canarium luzoniciim (pili)
or Eugenia spp., are represented by large individuals that, like
Parashorea, tower over the surrounding trees; however, they
seldom dominate their surroundings as do the dipterocarps.

Celtis philippensis (malaicmo) is a good example of another
class of trees in the first story. It is represented by probably
about two-thirds as many individuals as Parashorea, and next
to it is decidedly the most numerous tree in the first story.
It is a smaller and shorter tree than Parashorea; and, while it

g2 MOUNT MAQUILING

may reach the upper surface of the canopy, it is usually somewhat
shaded by taller individuals like Parashorea. Celtis phihppensis
is one of the species that are more numerous at lower than at
higher altitudes. Among the more prominent of the remaining
species are Shorea guiso and members of the genera Eugenia,
Canarium, and Palaquium.

Under the first story there are two other stories, each com-
posed of different species, and a ground covering. The presence
of the three stories of different trees is not evident on casual
observation, for the composition of all the stories is very complex
and few of the trees present any striking peculiarities, while
smaller trees of a higher story always occur in a lower story and
between the different stories.

SECOND STORY

The second, or middle, story is composed of fair-sized trees,
which spread their leaves under the branches of those of the top
story. The trees of this story, like those of the first, vary
greatly in height. There is, of course, no sharp line separating
the different stories ; but the second story may be regarded as
having an average height of about 18 meters, although many
individuals will grow as tall as 20 meters or even taller. Oc-
casionally, under favorable circumstances, a tree of the second
story may make exceptional growth and take a place in the
dominant canopy ; but usually they remain under the first story,
except in cases where, by the falling of an old tree, they are
temporarily exposed to full sunlight. Most of the second-story
species grow to more than 50 centimeters in diameter, and
some of them attain diameters of a meter or more. In this story
there are many individuals with diameters of from 50 to 80
centimeters.

The second-story trees have much smaller crowns than do
those of the dominant story, and they are much more numerous
than the latter. This story also contains a greater number of
species than either the first or the third and probably as many
as both.

The most prominent species is Diplodiscus paniculatiis (balo-
bo), represented by many more trees than any other species
in the forest, and probably about four times as numerous
as any other second-story species. The next most prominent
species are probably Diospyros ahernii (anang) , Dillenia philip-
pinensis (catmon), and Nephelium mutabile (bulala). Among
the other important ones are Diospyros discolor (camagon),

DIPTEROCARP FOREST 33

Strombosia philippinensis (tamayuan), and members of the
genera Aglaia and Chisocheton.

THIRD STORY

The third story, like the other two, is composed of species
attaining different heights. The average height of this story is
probably about 10 meters. Comparatively few of the trees are
more than 30 centimeters in diameter, and most of them are
much smaller. The foliage is usually not dense, and the crowns
are small. There are fewer species than in the second story,
and in a given area of forest there will be about half as many
individuals of third-story species as there are of second-story
ones. This is probably due partly to the situation of this story
and partly to competition with smaller individuals of the other
stories. There are several times as many trees in the third as
in the second story, but most of them are small individuals of the
taller stories.

Some of the species are not evenly distributed throughout the
area, and the composition of the third story is probably not so
uniform at low and high altitudes as is that of the other stories.
Among the most prominent and widely distributed are Thea
montana, Garcinia spp., Laportea subclausa (lipa), and Leea
manillensis.

Whitford,* in discussing the vegetation of the Lamao forest
reserve, describes a dipterocarp type which he calls the Anisop-
tera-Strombosia formation, and in which he says a two-story
vegetation prevails. This forest has a storied arrangement very
similar to that in the Parashorea-Diplodiscus association on
Mount Maquiling. Whitford evidently includes in the second
story or in the undergrowth those plants which in this paper are
regarded as forming the third story.

Brown and Matthews f describe the Philippine dipterocarp
forest as composed of three stories. Any division into stories
is more or less arbitrary; but there are certainly three very
distinct classes of trees in the dipterocarp forests, and it is
convenient to divide the vegetation into three stories.

Wallace, J in discussing the general character of the forests

* Whitford, H. N., The vegetation of the Lamao forest reserve, Phil.
Joum. Sci. (1906), 1, 373.

f Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil. Joum. Sci., Sec. A (1914), 9, 413-561.

% Wallace, A. R., Natural Selection and Tropical Nature. London
(1895), 240-244.

159549 3

34 MOUNT MAQUILING

in the equatorial belt, describes them as composed of three
stories of trees, as will be seen from the following quotation:

The observer new to the scene would perhaps be first struck by the
varied yet symmetrical trunks, which rise up with perfect straightness to
a great height without a branch, and which, being placed at a considerable
average distance apart, give an impression similar to that produced by
the columns of some enormous building. Overhead, at a height, perhaps,
of a hundred and fifty feet, is an almost unbroken canopy of foliage formed
by the meeting together of these great trees and their interlacing branches ;

* * *. The great trees we have hitherto been describing form, however,
but a portion of the forest. Beneath their lofty canopy there often exists
a second forest of moderate-sized trees, whose crowns, perhaps forty or
fifty feet high, do not touch the lower-most branches of those above them.

* * * Yet beneath this second set of medium-sized forest trees there is
often a third undergrowth of small trees, from six to ten feet high, of
dwarf palms, of tree-ferns, and of gigantic herbaceous ferns. Yet lower,
on the surface of the ground itself, we find much variety.

VINES

Vines are very numerous in the Parashorea-Diplodiscus asso-
ciation. These are very evident in Plate V and in Plate VI,
fig. 1. The most conspicuous are species of the climbing palms
Calamus and Daemonorops (rattans) , which in their early stages
are also the most noticeable element in the ground covering.
The rattan plant forms a rosette when young, and maintains
this form until the spiny, pinnate leaves are 2 to 3 meters long.
After this it sends out a climbing stem with long internodes.
This scrambles up among the trees, sometimes attaining a
length of more than 100 meters. The midribs are armed with
strong recurved spines, besides which there is a lashlike struc-
ture (in some species an extension of the midrib and in others
growing directly from the stem), also covered with recurved
spines. These spines enable the plant to climb, while other
smaller ones, scattered over the leaves and long leaf -bases, help
to protect it from being eaten by animals. These rattans are
very numerous, and their feathery leaves are exceedingly prom-
inent in giving character to the appearance of the vegetation.
The feathery leaves of the rattan are very conspicuous in the
undergrowth in Plate V.

Climbing bamboos, especially Schizostachyum diffusum, are
very abundant and conspicuous. The leaves of a climbing bam-
boo are shown at the left of Plate VI, fig. 2. Besides these
there are other prominent monocotyledonous vines, particularly
members of the families Pandanaceae and Araceae, the genera
Freycinetia and Pathos being very prominent. Large dicotyle-
donous vines are also numerous, especially on the trunks of

c

DIPTEROCARP FOREST 35

the larger trees. The long spirally arranged leaves of Freycine-
tia, a genus of the Pandanaceae, are crowded together over
considerable lengths of stem and make these plants conspicuous,
while the dicotyledonous vines are chiefly noticeable, except
when in flower, as large cords extending from the ground to the
crowns of the trees. A conspicuous development of Freycinetia
is shown on Plate XXX. Symphorema luzonicum appears to
be the most numerous of the dicotyledonous vines, possibly be-
cause of its showy flowers. The vines, naturally, increase the
density of the vegetation.

STRANGLING FIGS

A very striking appearance is presented by the strangling
figs, species of Ficus. They start as epiphytes in the tops of
the trees and send down roots that reach the ground (Plate
XIII, fig. 1). Branches from these roots grow around the tree
and coalesce either with each other or with the main root, until
the trunk of the tree is usually enclosed by a network (Plate
XI, fig. 2). As this grows and coalesces, it interferes with the
growth of the tree, the fig leaves shade the tree, and the roots
of the fig interfere with those of the tree. This combination
usually results in the death of the tree on which the fig is grow-
ing. The meshlike support of the fig continues to grow until
it may finally have the appearance of a solid trunk. Usually,
however, some of the meshes persist (Plate XII, fig. 1). The
final appearance of these figs is greatly influenced by the form
and height of the trees on which they start. When they grow
on slanting or peculiarly shaped trees, they sometimes assume
very fantastic shapes.

Plate XI, fig. 1, shows a very large strangling fig, which
apparently developed on one tree and then sent roots down a
neighboring tree. The result is a conspicuous harplike appear-
ance. The large size of the tree can be seen plainly by compar-
ing it with the man in the picture. These strangling figs are
very numerous and often give a picturesque appearance to the
vegetation. Old individuals are properly considered trees.

MONOCOTYLEDONOUS TREES

Erect palms are very scarce as compared with rattans or
dicotyledonous trees, but are present in sufficient numbers to
ornament the forest. Their bulk is inconsiderable, and they
have almost no influence on the other elements of the vegetation.
Their crowns frequently reach into the second story. The most
prominent is Livistona sp. (anahau), a fan-leaf palm. A large

36 MOUNT MAQUILING

specimen of this palm is seen in the center of Plate V and a
small individual in the lower right. Several large specimens
are shown on Plate VII. The other species have pinnate leaves.
Pinanga insignis and Caryota cumingii occur in considerable
numbers, Heterospathe elata is less numerous, while Arenga
pinnata (sugar palm) is conspicuous at lower elevations.

Wallace,* in discussing the occurrence of palms in the equa-
torial belt, says:

They are, however, by no means generally present, and we may pass
through miles of forest without even seeing a palm. In other parts they
abound; either forming a lower growth in the lofty forest, or in swamps
and on hillsides sometimes rising up above the other trees.

Monocotyledonous trees are also represented in the diptero-
carp forest by a few scattered specimens of Pandanus luzonensis
and P. gracilis, which belong to the third story.

BUTTRESSES

In this, as in many other tropical forests, buttresses f and
cauliflory are characteristic of a number of species. A consider-
able proportion of the tall trees have large planklike buttresses,
#which in extreme cases may extend several meters from the
tree and probably help to support it (Plate XII, fig. 2). Whit-
ford t has discussed the occurrence of these in the Lamao forest.

CAULIFLORY

Cauliflory occurs in a number of species, particularly in the
genus Ficus. This character is not found in the largest species,
and the number of individuals possessing it is insignificant when
compared wth the total number of trees present.

GROUND COVERING

Rattans in the rosette stage are the most prominent element
in giving character to the appearance of the ground covering
throughout the forest. The other elements vary according to
the locality. Small individuals of tree species are the most
numerous plants on the ridges at the lower elevations. In these
localities succulent herbs are rare and ferns are represented by
very few individuals. In the wet ravines succulent herbs are

* Wallace, A. R., Natural Selection and Tropical Nature. London
(1895), 248.

t Schimper, A. F. W., Plant Geography. English edition by Groom and
Balfour, Clarendon Press, Oxford (1903).

JWhitford, H. N., The vegetation of the Lamao forest reserve, Phil.
Journ. Sci. (1906), 1, 373.

DIPTEROCARP FOREST 37

conspicuous ; species of Elatostema, small shallow-rooting herbs,
are present in large numbers, while ferns are numerous. The
latter are usually fairly small species; but Angiopteris angusti-
folia, with fronds from 3 to 5 meters in length, is fairly
common and very showy. At the higher elevations, about 500
meters or more, succulent herbs, especially Elatostema, are con-
spicuous and cover large patches of ground even on the ridges.
The environment here is moister, and ferns are a very noticeable
element in the undergrowth.

Except at high elevations and in spots along the streams, the
ground is not carpeted with vegetation. The undergrowth is
dense as one looks through the forest, but the soil itself is bare.

EPIPHYTES

Epiphytic vegetation is scarce, being confined chiefly to the
large branches of the tallest trees. Here they form veritable
aerial gardens. The chief components are ferns (particularly
the humus-gathering Drynaria quercifolia) , orchids, and species
of Hoya. All of these are pronounced xerophytes and usually
have well-developed water-storing tissue. Drynaria has large
fleshy stems which store water, while certain of the leaves are
modified and form cups for collecting humus. These gather soil
for the Drynaria, but also produce a substratum in which many
other plants take root. The epiphytes forming these aerial gar-
dens are in an advantageous situation for collecting water and
for making full use of the sunlight.

Mosses and hepatics, on the trunks of the trees, are very
rare. Other epiphytes on the trunks or even in the crowns of
the small trees are also scarce, and with the exception of Asple-
nium nidus (bird's-nest fern) are for the most part incon-
spicuous. The bird's-nest fern, on the other hand, with its many
entire fronds a meter or more in length, is the most striking
epiphyte in the forest. This plant grows either in the crotches
of the trees, on the lower branches, or along the trunks. When
so situated that its fronds can grow freely, these radiate from
the center in all directions, from which habit it derives its name.
It does best in the moister situations and is not present on the
drier ridges.

The largest epiphytes, other than young strangling figs, are
members of the genus Schefflera, These are vines with pal-
mately divided xerophytic leaves, and woody stems several centi-
meters in diameter. They usually start in hollows in the trees,
in crotches, or in other places where a quantity of debris has
accumulated.

38 MOUNT MAQUILING

Phalaenopsis amabilis, a handsome orchid, grows high up on
the trunks of trees and is collected by orchid hunters, but is
rarely seen by anyone else. This is an example of a number
of plants, usually less showy, which are small and occur in such
limited numbers that they do not influence even the appearance
of the vegetation. The Philippine flora is very rich in Orchida-
ceae, there being about seven hundred fifty species, many more
than there are in any other family. Most of these have small
inconspicuous flowers, but a number are showy and are highly
prized by orchid collectors. However, in the tall forests showy
individuals are rare and, as noted above, are usually hidden by
the foliage.

Wallace,* in discussing the orchids in the equatorial belt, says:

Yet notwithstanding the abundance and variety of orchids in the equa-
torial forests, they seldom produce much effect by their flowers. This is
due partly to the very large proportion of the species having quite in-
conspicuous flowers; and partly to the fact that the flowering season for
each kind lasts but a few weeks, while different species flower almost every
month in the year. It is also due to the manner of growth of orchids,
generally in single plants or clumps, which are seldom large or conspicu-
ous as compared with the great mass of vegetation around them. It is
only at long intervals that the traveller meets with anything which re-
calls the splendour of our orchid-houses and flower shows.

FLOWERS

Showy flowers are not so conspicuous in the Parashorea-Diplo-
discus association as in deciduous temperate forests. This is not
due so much to scarcity of flowers as to a lack of a definite bloom-
ing period when the trees are leafless, and to the absence of a
ground covering of herbs that in temperate countries have a
striking display of flowers in the spring. A very large propor-
tion of the flowers in the dipterocarp forest are in the tops of
the tall trees and so are completely hidden by the foliage. The
flowers of Planchonia spectabilis are large and very handsome,
but are only seen as scattered specimens that have fallen
to the ground. Parashorea malaanonan has yellow flowers
tinged with pink, which fall in such numbers as almost to cover
the ground under the large flowering trees. These flowers
would be very conspicuous if they were borne in like quantity
on short leafless trees. The Parashorea-Diplodiscus associa-
tion is, however, like the temperate deciduous forests in that
the majority of the trees have small and inconspicuous flowers.

* Wallace, A. R., Natural Selection and Tropical Nature. London
(1895), 25fi.

DIPTEROCARP FOREST 39

Showy flowers are not confined to the dominant canopy, as a
few of the under-story trees have displays which are readily
seen from the ground. Dillenia philippinensis, a common sec-
ond-story tree, has very handsome, large, white flowers, but
usually only a few are open at one time. The purple clusters
of Clerodendron quadriloculare, a third-story species, are pretty
but not conspicuous at a distance.

The flowers of most of the vines are produced in the crowns
of the tall trees. Symphorema luzonicum is very common, and
has flowers with large lilac-colored bracts. These are produced
in great numbers and are very showy, particularly in the culled
forest. Perhaps the most striking flowers in the Parashorea-
Diplodiscus association are those of the leguminous vine Strongy-
lodon macrobotrys. These are large and bluish green and are
crowded together on pendent racemes, which may be a meter
in length. These racemes are not seen very frequently. At the
higher altitudes in the dipterocarp forest climbing begonias
sometimes produce very handsome displays.

The flowers in the undergrowth are not conspicuous as they
are usually small and scattered.

The above list includes some of the most striking flowers in
the forest, but only a small proportion of those that could be
considered as showy. The flowers have, however, little influence
on the appearance of the vegetation, as they are usually either
borne at a great height or so few of them are produced at any
one time that they are not conspicuous from the ground.

In a temperate-zone forest the dominant tree species are
usually few in number, and so are favorably situated for wind
pollenation. The majority of trees in such forests are thus
pollenated, while showy flowers are confined largely to scattered
and minor elements. The mixed dipterocarp forest contains
very few wind-pollenated species. On the plot in the virgin
dipterocarp forest there were ninety -two species of erect woody
plants more than 2 meters in height. In many of these pollena-
tion has not been observed, but with the exception of the palm Li-
vistona sp. all appear to be adapted for insect pollenation. The
method of pollenation in Livistona sp. is not known. The scarcity
of wind-pollenated trees in the dipterocarp forest appears to be
associated with the mixed composition of the forest. It seems
surprising, therefore, that the small scattered species usually
have inconspicuous flowers, while the gregarious, dominant
dipterocarps frequently have showy displays.

40 MOUNT MAQUILING

SEASONAL CHANGES

The appearance of the vegetation varies slightly according to
the season. During the dry season the shedding of leaves by the
trees is conspicuous. At such times the ground is usually cov-
ered with leaves, and the view in the forest is more open than
in more favorable weather. The trees are, however, by no means
deciduous, and this difference in the density of the foliage would
only be noticed by one familiar with the forest. A few minor
changes occur with the seasons; as, for example, a species of
Selaginella is very common in the wet season on cuts in the
banks, but it disappears during the dry period.

GENERAL VIEW

We have seen that the ParasJiorea-Diplodiscus association on
Maquiling is essentially a forest of large and medium-sized trees
and that these compose the great bulk of the vegetation. Ex-
cept for the arrangement in stories, with accompanying greater
density of foliage, most of these trees are not very different in
appearance from those in dicotyledonous forests in temperate
countries.

The view of the large trees is, however, frequently obscured
by the great development of small trees and vines, particularly
rattans and climbing bamboos. Owing to this fact, it is the
great development of foliage that gives character to the appear-
ance of the vegetation rather than the trunks of the large trees.
Plate VI, fig. 2, shows this characteristic very plainly. A
striking contrast is afforded by Plate VIII, fig. 1, which represents
the forest at an elevation of about 300 meters. All of the small
trees and some even more than a meter in diameter were re-
moved from this area in preparation for a coffee plantation.
The number of large trees in this area is probably not greater
than in that represented in Plate VI, fig. 2. Except when one
looks up at the canopy, the view in the dipterocarp forest is
usually that of a dense tangle of small trees and vines rather
than* of a forest of big trees. In better-developed dipterocarp
forests the large trees are relatively very much more prominent,*
while small trees and vines are less developed; see Plates IX
and X.

If we were to sum up the impression made upon one in passing
through the dipterocarp forest, it would be something like this :
A tall, dense forest, in which large and small trees are crowded

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil. Journ. ScL, Sec. A (1914), 9, 413-561.

DIPTEROCARP FOREST 41

together until their leaves very fully occupy all the available
space, while the ground is covered with a dense undergrowth
consisting largely of feathery rattans, some of which reach up
among the trees. Scattered here and there are tall palms, while
now and then the eye is caught by a large tree with gigantic
buttresses, the bizarre form of a strangling fig, the long leaves
of the epiphytic bird's-nest fern, or a tree trunk covered with
fruit.

BIZARRE PLANTS

The tropical forest is usually considered the special habitat
of bizarre plants. Such plants occur in the forest under dis-
cussion, but with the exception of the strangling figs are not
prominent.

In spots Rafflesia manillana is rather showy. Scattered
through the forest are places several meters square where the
roots of Cissus are either near or on the surface of the ground.
Such roots may be thickly infested with Rafflesia.* Usually only
a few flowers will be open at a time, but the buds are frequently
numerous (Plate XV, fig. 2). When several of the flowers,
which spring directly from the root of the host and are from
15 to 20 centimeters in diameter, are open at once, they are
rather striking; but the patches are widely separated and affect
the appearance of the forest so little that people usually become
very familiar with it without noticing the Rafflesia.

Several interesting myrmecophilous plants are present but are
rarely seen, as they are not abundant and are usually confined
to the tops of the tall trees. Hydnophytum and Myrmecodia
(Plates XIII, fig. 3, and XIV), with their large bulbous bases
containing labyrinthian cavities, are occasionally found on fallen
trees; while Polypodium sinuatum, with its enlarged, hollow
stems, has been observed once. Probably more abundant than
the above-mentioned species is Dischidia purpurea, a vine grow-
ing in close contact with the surface of the bark of a tree
(Plate XIII, fig. 2). The edges of a leaf touch the bark while
the center is raised, forming a cavity in which roots grow and
which is inhabited by ants.

The leafless orchid Taeniophyllum philippinense, with its pho-
tosynthetic roots, is occasionally found on the trunks of trees ;
this is a small and very inconspicuous plant. Galeola hydra,
a rare but conspicuous saprophytic orchid, is a vine, which may
grow to be about 10 meters in length, and which has rather

* Brown, W. H., The relation of Rafflesia manillana to its host, Phil.
Journ. Sci., Sec. C (1912), 7, 209-226.

42 MOUNT MAQUILING

large clusters of yellow flowers. Other saprophytes and para-
sites occur in this forest, but for the most part they are small
and not striking- in appearance. The previously mentioned
humus-gathering ferns, Drynaria quercifolia and Asplenium
nidus, are much more in evidence than the plants just mentioned.

In discussing the bizarre plants their scarcity has been em-
phasized. This feature is not peculiar to the dipterocarp forest
of Mount Maquiling, but is characteristic of the tall forests
of the Philippines. Most of the unusual forms of plants found
in the Indo-Malayan region occur in the Philippines, and many
of them are widely distributed, but they are usually of local
occurrence. Bizarre plants, when they occur in more open and
lower types of forest at high elevations, are frequently more
evident than in the dipterocarp forest. It is from high-
mountain forests that many of the current impressions of trop-
ical forests have been obtained, as frequently the tall lowland
forests have been removed for cultivation, while only the more
inaccessible mountain forests have retained their virgin char-
acter. Most botanists in describing tropical forests mention
only or chiefly peculiar characters which are of particular in-
terest to botanists, and thus unintentionally give the impression
that striking and bizarre plants are much more prominent than
is the case.

In considering the question of peculiar plants it is well to
bear in mind that people are apt to regard the things to which
they are accustomed as usual and those to which they are
unaccustomed as unusual. Thus one raised in a temperate
country will think of the deciduous broad-leaved forest as a
usual one, and of the tropical forest as strange and bizarre. On
the other hand, the inhabitants of moist tropics look upon
the deciduous forests in temperate regions as very strange.
It is certainly reasonable to regard the broad-leaved, evergreen
forests of the tropics as a generalized type; and the deciduous
forest of temperate regions as fitted to adverse winter con-
ditions, just as the thorny vegetation of desert regions is suited
to a dry climate. Nor is there any reason to regard the presence
of palms, tree ferns, and epiphytes as more peculiar than their
absence, particularly as their absence is connected with adverse
rather than favorable conditions. Likewise, a dense forest
composed of many species should not be regarded as more pe-
culiar than a more open one composed of a few species. Again,
it may be pointed out that annual growth rings; winter pro-
tective bud-coverings; early spring bloomers; biennials; and
many other features connected with the presence of a cold sea-

DIPTEROCARP FOREST 43

son are special adaptations. It seems well to emphasize the
above points, as botanists from temperate regions are too apt
to regard temperate vegetation as a generalized type and trop-
ical vegetation as a specialized one, whereas there certainly are
many reasons for considering the reverse as the more nearly
correct view. Although all the fundamental features of botany
are similar in tropical and temperate zones, elementary text-
books prepared for temperate countries are not suitable for the
tropics, because conditions connected with the winter season
are treated as though they were not only the usual but also the
generalized conditions. This method is natural and may be
valuable in view of the use for which the books are prepared,
but it would seem to have a tendency to leave an incorrect
impression.

DESCRIPTION OF PLOT

In order to compare the physical characteristics of different
types of vegetation, accurate measurements of the component
parts are necessary. Such measurements are obtained only with
difficulty in lofty forests that have the density and diversity
found in the dipterocarp type, and the methods that ecologists
have usually used in describing vegetation are not suitable for
these forests.

Owing to the density of the stand and the size of the trees,
it is impossible to measure the heights of the individuals in
situ. Accurate measurements over extensive areas are there-
fore impracticable, while data from small plots do not give an
adequate idea of the composition of the stand. For these reasons
it seemed best to select a single fair-sized plot in each of the
tall types of vegetation, particularly as the purpose of the
present paper is to compare different formations rather than
minor variations within a formation. The different plots used
had similar slopes and exposures. Each of the three lower ones
comprised an area 50 meters square. All of the plants on these
plots were cut and removed, which made it possible to measure
the individuals accurately and to utilize the plots for further
experiments.

The plot in the virgin dipterocarp forest was at an altitude
of approximately 450 meters, situated on the gently sloping side
of a ridge, and fully exposed to sun and wind. All the plants
were cut down, and each individual more than 2 meters in
height was measured with a tape to ascertain its height and
diameter. The clear length of trunk was also measured of all
trees that were large enough to have trunks free from branches.

44

MOUNT MAQUILING

Buttresses were not included in the measurements of the diam-
eters. The results of the measurements for the plot in the
dipterocarp forest are given in Tables II to IX.

Table II. — Stand of trees over 2 meters in height on 0.25 hectare in
dipterocarp forest on Mount Maquiling ; altitude, U50 meters.

Species.

FIRST-STORY SPECIES.

Dipterocarps:

Hopea acuminata (daling-

dirigan)

Parashorea malaanonan (bag-

tican lauan)

Shorea guiso (gui jo)

Miscellaneous species:

Bischojia javanica (tuai)

Canarium luzonicum (pili) . . ..

Canarium villosum

Canarium sp. (pagsahing)

Canarium- sp

Celtis philippensis (malaicmo)
Eugenia, luzonenais (malaru-

hat puti)

Eugenia mananquil

Eugenia similis (malar u h at) -.

Eugenia sp

Meliosma macrophylla

Neonauclea sp

Palaquium tenuipetiolatum

(palac palac)

Palaquium sp

Palaquium sp

Planchonia spectabilis (lamog)

Pterocymbium tinctorium

Sterculia sp. (lapnit)

Turpinia pomifera

Indi-
vid-
uals.

SECOND-STORY SPECIES. j

Aglaia diffusa (salaquin pula) .J

Aglaia sp (malasaging) j

Alangium meyeri (putian) |

Amoora sp

Ardisia boissieri (tagpo)

Ardisia perrottetiana

Ardisia sp

Chisocheton cumingianus (sala-

quin-puti)

Chisocheton pentandrus (salaquin

pula)

: Great- iG-f"
est I ,?st

»>*«** i *!£-

onplot-!onplot.

Volume of trees. a

29 35.95 j 96.0
4 10.50 i 15.0

21.00
23.60

5.80 j
10.10 |

4.90 |
18.35 |

6.85 |

3.00

26.00

2.30

21.25

28.40

22.65
4.30
2.00

28.30
2.50

32.10

17.55

2.10
17.10
13.55

6.00
14.15

9.20

2.70

11.65
2.00

72.0
58.0

6.0
17.0

5.0
15.0

13.0
2.5

95.0
2.5

25.0

50.0

20.0
3.0
2.0

75.0
1.5

83.0

25.0

1.5
30.0
14.0

8.0
25.0

8.0

2.0

15.0
2.0

Total.
cu. m.

In third
story

(2 to 12
m. in

height)

cu. m.

In sec-
ond

story
(12 to 22

m in
height)

cu. m.

In first
story

(22 to 38
m. in

height)

cu. m.

18.47

0. 09 0. 09

2.25

16.22

4.31
3.04

4.31

3.04

0.07
0.14
0.05

0.07
0. 05

0.14

8.92

.. .

8.92

j

0.46
5.38

0.22

1 0.20

1.01

0.04 j

0.26
4.37

0.18

!

7.87

!

7.87

I

6.35

!

6.35

0.36

°-05 0.31

J

0.38
0.03

. ...

0.09

0.29
0.03

0.39

0.11

0.28

i

0.05

0.05

DIPTEROCARP FOREST

45

Table II. — Stand of trees over 2 meters in height on 0.25 hectare in
dipterocarp forest on Mount Maquiling ; altitude, 1>50 meters— Continued.

Species.

SECOND-STORY SPECIES"

Indt

Cinnamomum. mercadoi (calingag)
Cryptocarya lateriflora

Cyclostemon sp

Dillenia philippinensis (catmon) _
Dillenia reifferscheidia, (catmon) _

Diospyros discolor (camagon)

Diplodiscus paniculatus (balobo) -

Dysoxylum sp

FJuonym.ua javanica

Euphoria cinerea (alupag)

FJvodia sp

FicuR barnesii

FXcux ribeti (auymit)

Ficus variegata (tangisang bia-

uac)

FXcus sp

Garcinia binucao (binucao)

Garcinia venulosa (gatasan)

Gymnacranthera paniculata (tam-

bulao)

Litsea garciae

Livistona sp. (anahau)

Lophopetalum f.oxicum (calatum-

bago)

Mastixia philippinensis (tapulao) .
Memecylon paniculatum (culis)...

Nauclea junghuhnii (mam bog)

Neonauclea calycina

Neonauclea media

Nephelium mutabile (bulala)

Pisonia umbellifera (anuling)

Papualthia lanceolata (lanutan) _ . .
Sem.eearpus gigantifolia (ligas) .
Strombosia philippinensis (tama-

y uan)

Symplocos sp

Terminalia pellucida (calumpit) ._

THIRDSTORY SPECIES.

F'icus minahassae (hagimit)

Flacourtia sp

Garcinia rubra

Glochidion lancifolium

Glochidion ap

Goniothalamus elmeri

Grewia stylocarpa (susumbic)

Jxora longistipula

Indi-
vid-
uals.

Great-
est
height
on plot.

tn.

17.40

20.00

5.60

4.17

17.00

14.20

22.00

19.20

2.80

2.45

2.10

16.55

13.14

12.50

20. 35

20. 15

2. 95

9.80

3

3
2
4
3
1
10
1
3
1

1

1 |

i !

10.05 !

2.40 j

7.00 i
3.07 |
4.06 !
4.40 |
10.72 I
2.20 I

Volume of trees. '

Total.

0.21
0.51

Great-
est
diam-
eter,
on plot.

cm.

25.0
30.0
4.5
4.5
55. 0
45.0
50.0
38.0
3.0
2.0
2.0
25.0
20.0
15.0 j

35.0 I 1.60

38.0 j 0.98

2. 5 I

16.0 | 0.07

In third
story
(2 to 12
m. in

height)

2 I 3.10 4.0

3 17.50 ! 35.0 j
13 18.00 21.0 ;

30.0 I
3.0 j

In sec-
ond
story

In first
story

(l2to22(22to.38
m. in !,m: "?,'
height), he,*ht)

I

I -

cu. m. \ cu. m.

0.21 j ,

0.43 ! :

_

5. 36

0.68

4.68 ;

0.78

0.78 j

3.21

3.21 !

1.37

0. 25

1.12
|

0.33

0.33

0.05

0.05 !

0.16

0.13

0.03 !

i
i

60 j.

0.07 I

0.06

0. 48 i 0. 57

2.5

25.0

0. 38

0. 04

0,34

21.0

0.06

0. 06

8.0 .

42.0 ;

1.69

0. 08

0.44

1.17

8.0 .

11.0 .

30.0 ;

0.43

0.43

3.0 :

3.5 i

8.0

3.0 !.

2.0 |.

7.0 j.

3.0 |

6.0 j.

I

5.0 1

17.0

0.01

0.01

!

2.0 L

i

46

MOUNT MAQUILING

Table II. — Stand of trees over 2 meters in height on 0.25 hectare in
dipterocarp forest on Mount Maquiling; altitude, J>50 meters — Continued.

Species.

I THIRD-STORY species— continued.

I Ixora macrophylla

! Laportea, subclausa (lipa)

Leea aculeata

Leea manillensis

Leea philippinensis

Leucosyke capitellafa (lagasi)

Macaranga bicolor (hamindang) -
Macaranga grandi folia (taquip

asin)

Mallotus ricinoides (hinlaumo)

Neolitsea villoaa

Neotrewia cumingii (batobato)

Oreocnide trinervis (malatuba)

Sambucus javanica

Saurauia latebraeteata

Saurauia sp ..

UNDERGROWTH SPECIES.

Callicarpa erioclona

Clerodendron quadrilocida re

Tabernaemontana p a n d a caqu i

(pandacaqui)

Wickstroemia meyeniana

Total .

Indi-
vid-
uals.

Volume of trees. !

I Great-

I est
I height
Jon plot.

Great- |

est |

diam- j

eter

on plot.!

353

!

2

6.15

12

10.20

3

2.90

15

11.20

2

10.90

1

3.30

1

11.60

3

12. 40

1

2.50

2

8.95

3

5.00

9

8.25

1

2.00

2

10.20

2

6.60

2.10
3.70

4. 50
2.08

cm.

6.0
10.0

3.0

8.0
10.0

3.0
12.0

15.0

2.0
10.0

7.0
12.0

1.5
25.0

7.0

1.0
2.0

5.5
1.5

Total.

!

In third

story

(2 to 12

m. in

height)

In sec-
ond

story
(12 to 22

m. in
height)

In first
story

(22 to 3
m. in

height)

0.02

0.03

0.03

0.17

25.11 j 48.95

R The volume of trees less than 10 centimeters in diameter is omitted.

Table III. — Summary of composition of volume a of different stories on
0/25 hectare in dipterocarp forest on Mount Maquiling; altitude, 450
meters.

Story to which species belong when the
individuals mature.

First-story species. .
Second-story species..
Third-story species
Undergrowth species .

Stories in which the indi-
viduals present were found.

Total .

First
story

Second
story.

(Height, : (Height,

22 to
38 m.)

47.21
1.74

12 to
22 m.)

8.22 !
16.89 i

| Third

story.

(Height,

2 to

12 m.)

0. 30
1.64 :
0.35 j

Total.

55.73
20.27
0.35 |

73.0

26.5

0.5

48.95 I

76.35 i 100.0

• The volume of trees less than 10 centimeters in diameter is omitted.

DIPTEROCARP FOREST 47

In Table II the species are arranged according to the stories
in which the mature individuals occur. This classification is
necessarily inexact, as not all specimens of a single species attain
the same size or form. Individuals of species usually occurring
in the second or third story may be in an exceptionally favor-
able situation and attain a height sufficient to place them in
the story next higher than that in which they are usually found.
On the other hand, individuals of species that are usually large
may be dwarfed and never reach the story to which the species
properly belongs. The species are placed in the story in which
mature specimens have usually been found. The species in a
story vary considerably in size, some being nearer than others
to the border line between the stories.

Some of the species occur only as very scattered individuals,
and a few may be placed in the wrong story owing to a lack
of thorough acquaintance with the species. In Table II are listed
nineteen which are identified only as to the genus and one
unidentified species. Many of them are better known than this
would indicate, and in most cases the species can be readily
assigned to the proper story. In a few instances this could
not be done with certainty, but probably few if any of the
species are placed in the wrong story.

In preparing a table it is convenient to adopt arbitrary limits
for the different stories. In Table II trees from 22 to 38 meters
in height are regarded as being in the first story; those from
12 to 22 meters, as composing the second story ; and those from
2 to 12 meters high, as forming the third. In most cases this
arbitrary classification throws the trees into the stories in
which they properly belong. Some of the individuals whose
tops are near the border line between two stories may be
thrown into a story that contains only a small part of the crown ;
but this error is not serious, as such individuals can usually be
regarded as belonging to either story.

In Table II is given the number of individuals of each species
on the plot, as well as the greatest height and largest diameter
attained by each species, and the volume arranged according to
the story in which the individuals were found.

There were in all 92 species and 353 individuals of erect
woody plants more than 2 meters in height on this plot. Thirty-
two, or more than one-third of the species, were represented
by only one individual. This would indicate that, had the plot
been larger, the number of species would have been greater.
An examination of the surrounding vegetation showed this to
be true.

48

MOUNT MAQUILING

There were on the plot 22 first-story species, 43 second-story,
and 23 third-story species. The second-story species are smaller
than those in the first, and there are naturally more individuals
present in the story containing the smaller species. This fact
may account to some extent for the presence of about twice
as many species of second- as of first-story trees. The third-
story species are small, but there is only one more of these
species than there are of the first story. The former have the
disadvantage of being heavily shaded ancl of having to com-
pete with small individuals of the higher stories. In the general
discussion it was pointed out that there are many more species
of second-story trees in the Parashorea-Diplodiscus association
than there are of either first- or third-story species.

In Table IV are given the heights of all individuals more than
2 meters tall. The results of this table are summarized in
Table V. An examination of Table V shows that the individuals
of first-, second-, and third-story species are present in about
the same proportion as the species themselves. That is, the
number of individuals belonging to first-story species is not very
different from the number belonging to third-story species, while
the individuals of second-story species are about as numerous
as those of both of the other stories together. The number of
species of second-story trees is 96 per cent of that of both
first- and third-story species, while the number of individuals
of second-story trees is 109 per cent as great as that of in-
dividuals of both first- and third-story species.

Table IV. — Height of all trees over °2 meters high on 0.25 hectare in
dipterocarp forest on Mount Maquiling; altitude, £50 meters.

[Figures represent numbers

of individuals.]

Height in meters.

No.

Species.

2 I 6 I 10
to 6. I to 10. | to 12.

12 i 14
to 14. 1 to 18.

18 22 i 26
to 22. ! to 26. i to 30.

1

30
to 34.

34
to 38.

FIRST-STORY SPECIES. j

1 "]

!

Dipterocarps: i 1

1

IJopea acuminata (da- 1 j

lingdingan) , . 1 ! 1 ! .1

2

Pa rash or ea malaanovan i I

i

(bagtiean lauan)
Shorea fjuiso (guijo)

20 j 1 1 1 ;

2 ■ 3

2

3

2 i 1 ! 1

Miscellaneous species: i |

: i

4

Bischofia javanica, (tuai) J __.| ! __ _j ' 1

5

Canarium luzoni cum | ' 1

(pili)

1 : 1 ; i

j i :

6

Canarium villosum

: |

(pagsahing) , 1 ! | j >

DIPTEROCARP FOREST

49

Table IV. — Height of all trees over 2 meters high on 0:25 hectare in
dipterocarp forest on Mount Maquiling ; altitude, 450 meters — Continued.

Species.

Height in meters.

2 J f» I 10 ! 12 14 I 18 ! 22 ! 26 I 30

to 6. ; to 10. u> 12. to 14. to 18. to 22.to 26. to 30. to 34.

34
to 38.

FIRST-STORY SPECIES— COnt.

|

Miscellaneous species Cont. !

Canarium sp. (pag-
sahinpr)

Caiutri um sp .. _

Ccllis philip-pcnsis (ma-
laicmo) ,

Kugcnia Inzancn sis (ma-
lar u hat p u ti )

Kugcnia, ma nan qui! ..

/Eugenia, fii.mil is (mala- !
ruhat) ......

Kugcnia sp '

Mcliasma. marrophylta .'■

Neanauclca sp

Palaquium tcnuipctiala- i
turn (palac palac)

Palaquium sp .

Palaquium sp

Planchonia spcctabilis
(lamog-)

Pterocymbium tincf avi-
um (taluto)

Sterculia sp. (lapnit)

Turpivia pomifera (ma-
lahago) ..-

SECOND-STORY SPECIES. |

I

Afflaia diffusa (salaquin pula);
Aglaia sp. (malasaging) .J
Alangium mcycri (putian)

Anioor a, sp - . . j

Ardisia boissicri (tag-po) '

Ardisia pcrratt.ctia.-ti a . ,j

Ardisia sp _ . - - ;

( yh i sac he 1 an r.u m it) gia ti us ( sa- j

laquin-puti) I

Chisochctan pen-land run (sa-
laquin pula). ~ '

Indt

Cinna.mam nni mcrcadai (ca-

lingag) !

Cryptacarya lanrijlora -... - :

Cyclastcman sp !

Dillcnia phili ppineusis (cat-

mon ) . .

Dillenia rcijfcrscheidia (cat-'

mon) . -

Diaspyras di scalar (camag-on)
Dipladiscus paniculatus (ba-

lobo)

159549 4

2
1

6

3
3

1
2

1

2

2

.

2

20

50

MOUNT MAQUILING

Table IV. — Height of all trees over 2 meters high on 0.25 hectare in
dipterocarp forest on Mount Maquiling ; altitude, U50 meters — Continued.

No.

Height in meters.

Species.

2
to 6.

4
3
1

6
to 10.

10
to 12.

12
to 14.

14
to 18.

18
to 22.

22
to 26.

26
to 30.

30
to 34.

34
to 38.

SECOND-STORY SPECIES— COnt.
Dysoxylum sp___ ...

Euonymus javanica _ _

Euphoria einerea (alupag)

Evodia sp

1

Ficus barnesii _____

1
1

Ficus ribes (auymit) _ _ _

1
2

3
2

1

i

Ficus variegata (tangisang

biauac) __ __.

1
1

1
1

Ficus sp _ _ _ _ _

Garcinia binucao

1
1

2

Garcinia venulosa (gatasan)

1

i

Gymnacranthera paniculata
(tambulao)__ __

Litsea qarciae

2
2

1
3

Livistona sp. (anahau)

3

3
1

2

Lophopetalum toxicum (cala-
tumbago) _____

1

1

Mastixia philippinensis (ta-
pulao) __. __ ___ .

3

Memeeylon paniculatum (cu-
lis)

2
2

i
|

Nauclea junghuhnii (mam-
bog)

i

Neonauclea calycina

2
1
6

1

1

Neonauclea media .

|

Nephelium mutabile (bulala)

2

1

1

Pisonia umbellifera (anuling)

1

1

Papualthia lanceolata (lanu-
tan) _

2

1

Semecarpus gigantifolia (li-
gas) _ _ _ _ . .

1

Strombosia phi I i p p in en s is
(tamayuan) __

1
1

Symplocos sp

Terminalia pellucida (calum-
pit)

1

THIRD-STORY SPECIES.
Ficus minahassae (hagimit)

1

Flacourtia sp ___

2

Garcinia rubra . _

1

Glochidion lancifolium

1
2
3
7
1
1

11
3
9

Glochidion sp

Goniothalamus elmeri

Grewiastylocarpa (susumbic)

1

1

Ixora longistipida . _ _

Ixora macrophylla

1

Laportea subclausa (lipa)__

1

Leea aculeata

Leea manillensis

5

1

DIPTEROCARP FOREST

51

Table IV. — Height of all trees over 2 meters high on 0.25 hectare in
dipterocarp forest on Mount Maquiling ; altitude, 1*50 meters— Continued.

Species.

THIRD-STORY SPECIES— COnt.

Leea philippinensis

Leucosyke eapitellata

(lagasi)

Macaranga bicolor (ha-

mindang)

Macaranga grandifolia (ta-

quip asin)

Mallotus ricinoides (hin-

laumo)

Neolitsea villosa

Neotrewia cumingii (ba-

tobato)

Oreocnide trinervis

Sambucus javanica

Saurauia latebracteata

Saurauia sp

Height in meters.

2 ! 6

12

14

18 22

26 | 30

34

to 6. to 10. to 12. to 14. to 18. to 22. to 26. to 30. to 34. to 38

UNDERGROWTH SPECIES.

Callicarpa erioclona

Clerodendron qua driloculare
Tabernaemontana panda-

caqui (pandacaqui)

Wickstroemia meyeniana j

Total J

1

2

1

1

1

!

1

j

2

| L_ j :

1

1 --■,---•-

.___ L. i ! !

i

! ! j 1

19

20

--"

2

54

23

15

9

4

1

Table V. — Summary of the composition of different stories in the dip-
terocarp forest on Mount Maquiling; altitude , £50 meters.

[Figures represent numbers of individuals.]

I Stories in which the individ-
uals present were found.

Story to which species belong- when the individuals
are mature.

First- story __
Second-story ,
Third-story ___
Undergrowth.

First j Second
j story; j story;
j height, j height,
22 to 38 m.1 12 to 22 m.

Third

story;

height,

2 to 12 m.

62

137

78

6

Total .

Total.

87

181

79

6

The total number of individuals in the first story was 16.
Owing to their size these formed a practically closed canopy.
The second-story trees were smaller, and there were 54 present
in the second story, or 3.4 times as many individuals as in the

52 MOUNT MAQUILING

first story. In the third story there were 283 individuals, or
5.2 times as many as in the second story and 17.7 times as
many as in the first story. The large number present in the
third story is evidently connected with the small size of the
trees. The third story consists largely of individuals belonging
to stories other than the third, the latter species composing
only 27.6 per cent of the total number of individuals present,
while the second-story species are represented by 48.4 per cent.
In the second story 77.8 per cent of the trees belong to sec-
ond-story species.

An examination of Table IV shows that most of the trees of
any story reach only to the lower portions of the story. This
is particularly true of the third story. The individuals between
2 and 6 meters in height form 72.8 per cent of the total number
of those in the third story and 58.4 per cent of all erect woody
plants more than 2 meters high that were on the plot.

Table II shows that Parashorea malaanonan and Diplocliscus
panieulatus were by far the most numerous species on the plot,
while from Table IV it will be seen that Parashorea is repre-
sented by more large trees than is any other species.

In Table II are given the volume of each species in the differ-
ent stories and the total for each species. The figures repre-
sent the volume in cubic meters of the part of the trunk that
was clear of branches. The volume of trees less than 10 centi-
meters in diameter was very small and was omitted from the
tables. The total volume was 76.35 cubic meters. The volume
of Parashorea was 2.1 times as great as that of any other spe-
cies and was 24.2 per cent of the total volume on the plot.
Parashorea composed a larger proportion, 33.1 per cent, of the
volume of the first story than of the volume as a whole.

The volume shown in Table II is not large for a dipterocarp
forest, and the percentage of dipterocarp timber by volume is
low. Measurements made by Everett and Whitf ord * in the
forest of northern Negros showed a volume of 519.58 cubic
meters to the hectare, and more than 95 per cent of this be-
longed to members of the family Dipterocarpaceae. Plate IX
and Plate X, fig. 1, show views in this forest.

Table III gives a summary of the volume of the different
stories in the Maquiling forest. Of the total volume of 76.35
cubic meters 55.73, or 73 per cent, belong to first-story species ;

* Everett, H. D., and Whitford, H. N., A Preliminary Working Plan
for the Public Forest Tract of the Insular Lumber Company, Occidental
Negros, P. I., Bull. P. I. Bur. For. (1906), No. 5. Brown, W. H., and Mat-
thews, D. M., Philippine dipterocarp forests, Phil. Journ. Sci., Sec. A (1914),
9, 413-561.

D1PTER0CARP FOREST

53

20.27 cubic meters, or 26.5 per cent, to second-story species;
while third-story species are represented by only 0.35 cubic
meter, or 0.5 per cent. The volume is not only concentrated in
first-story species, but 47.21 cubic meters, or 61.8 per cent of
the total volume, are of these species within the first story.

The first story contained 48.95 cubic meters, or 64.1 per cent
of the total; the second story 25.11 cubic meters, or 32.9 per
cent; and the third story 2.29 cubic meters, or 3 per cent.
These figures, considered in connection with the number of trees
in the various stories, show a very striking difference in the
size of the individuals composing them. In the first story there
were 16 trees containing 48.95 cubic meters of timber, an aver-
age of 3.1 cubic meters to a tree. The second story contained
54 individuals with an average volume of 0.46 cubic meter.
The volume of third-story trees less than 10 centimeters in
diameter is not included in the table. The 2.29 cubic meters in
this story were, therefore, in the 37 individuals more than 10
centimeters in diameter, the average per tree being 0.062 cubic
meter. The figure would, of course, have been very much
smaller had it been based on the 283 trees comprising the
third story.

Table VI gives the diameter classes of all trees over 10 centi-
meters in diameter on the plot. The largest number belonging
to any one species was 13, of Dillenia philippinensis, a second-
story species. Parashorea malaanonan and Livistona sp., the
latter a palm, were represented by 8 individuals each. The
specimens of Livistona were relatively small while, as in pre-
vious tables, Parashorea was the most conspicuous large tree.
In all there were 107 trees more than 10 centimeters in dia-
meter, distributed in 36 genera and 43 species.

Table VI. — Diameter classes of all trees over 10 centimeters in diameter
on 0.25 hectare in dipterocarp forest on Mount Maquiling? altitude,
U50 meters.

[Figures* represent numbers of individuals.]

No.

Species.

Diameter class in centimeters.

FIRST-STORY SPECIES.

Dipterocarps:

1 Parashorea malaanonan

(bagtican lauan)

2 j Shorea guiso (guijo)

j Miscellaneous species:

3 ! Bischofia javanica (tuax) J

10 to
20.

20 to

30.

30 to
40.

40 to
50.

50 to 1 60 to
60. 70.

70 to
80.

80 to I 90 to
90. | 100.

|

1

1

4

1 i

j 1

1

Total.

54

MOUNT .MAQUILING

Table VI. — Diameter classes of all trees over 10 centimeters in diameter
on 0S5 hectare in dipterocarp forest on Mount Maquiling ; altitude,
450 meters — Continued.

Total

Species.

Diameter class in centimeters.

No.

10 to
20.

20 to
30.

30 to

40.

40 to
50.

60 to
60.

60 to
70.

70 to

80.

80 to
90.

90 to
100.

4

FIRST-STORY SPECIES— COllt.

Miscellaneous species — Cont.

Can avium luzonicum

(pili)

1

5

Canarium sp. (pagsa-
hing)

2
3
1

6

Celtis philippensis
(malaicmo)

7

Eugenia luzonensis (ma-
laruhat puti)

8

Eugenia similis (malaru-
hat)._ -

1

9

Meliosma macrophylla 1

Neonauclea sp '

1

10

2

2

11

Palaquium tenuipetiola-

, turn (palac palac)

Planckonia apectabilis
(lamog)

2

12

1

1

13

Sterculia sp. (lapnit)

1

14

Turpinia pomifera

SECOND-STORY SPECIES.

Aglaia sp. (malasaging)

Alangium meyeri (putian) __

Ardisia boisaieri (tagpo)

Chisocheton cumingianus
(salaquin-puti) -_

2

2
1
2

2

1
1

15

16

17

1

18

19

Indt

1
1
4

20

Cinnamomum mercadoi (ca-
lingag)

1
2

21

LHUenia philippinensis (cat>
mon) _ __

4

2
1
1

1

22

Dillenia reifferscheidia (cat-
mon)

23

Dioapyros discolor (cama-
g-on) _

1

1

1

1
1

1
2

24

LHplodiscus paniculatua (ba-

lobo)

25

Evodia sp. _

26

Ficus barnesii __

1
4

1

|

27

Ficus ribea (auymit)

Ficus variegata (tangisang
biauac)

I

28

1

2
1

29

Ficus sp — _

!

30

Garcinia venulosa (gatasan) _
L/itsea garciae _ _.

1
2

7
1

1

81

1
2

1
1

1

J

32

Liviatona sp. (anahau)

Lophopetalwm toxicwmJjk

Nauclea junghuhnii (mam-
bog)

33

34

35

Neonauclea calycina

DIPTEROCARP FOREST

55

Table VI. — Diameter classes of all trees over 10 centimeters in diameter
on 0.25 hectare in dipterocarp forest on Mount Maquiling; altitude,
450 meters — Continued.

No.

Species.

i Diameter class in centimeters.

Total.

10 to
20.

20 to

30.

30 to
40.

40 to
50.

50 to
60.

60 to

70.

70 to
80.

80 to
90.

90 to
100.

36
37

38

39
40
41
42
43

SECOND-STORY SPECIES— COllt.

Nepkelium mutabile (bulala)

Papualthia lanceolata (lanu-

tan)__

1
1

1

1

3
1
1

2

1

2

1
1

Semecarpu8 gigantifolia (li-
gas) __-

1

THIRD-STORY SPECIES.

Grewia stylocarpa (susum-
bic)

2
1
2
1

Macaranga bicolor (hamin-
dang)

Macaranga grandifolia (ta-
quip asin) J.

Oreocnide trinervis (mala-
tuba)

Saurauia latebracteata

1

Total _

51

23

17

8

3

0

2

1

2

107

In Table VII are given the diameter classes of the same 107
trees distributed according to the story in which they occurred,
and not according to that to which the species usually belong

Table VII. — Diameter classes of trees over 10 centimeters in diameter in the
different stories on 0.25 hectare in dipterocarp forest, Mount Maquiling ;
altitude, 450 meters.

[Figures represent numbers of individuals.]

Diameter class in centimeters.

Total.

Aver
age
diam-
eter.*

cm.
52.9
28.4
15.6

Story. •

10 to
20.

20 to
30.

30 to
40. '

40 to
50.

50 to
60.

2
1

60 to i 70 to
70. 1 80.

|
1

80 to
90.

90 to
100.

First story _

1

17
33

2

18
3

3
13
1

4
4

1

2

16
54
37

Second story. .

1

Third story

Total

51

23

17

8

3

2

1

2

107

a The average diameters were calculated from the exact measurements and not from the
figures in this table.

56 MOUNT MAQUILING

when mature. The range of diameter classes for the first and
second stories is not so different as might have been expected.
Both stories have trees in the 10- to 20-centimeter class. The
only first-story tree in this class, however, was just small enough
to be included, as it was 20 centimeters in diameter. The
largest diameters of first-story trees were between 90 and 100
centimeters, while a second-story tree is included in the 70- to
80-centimeter class. The latter was an old individual of Bis-
chofta javanica, a first-story species. It is probable that this
tree formerly reached into the first story.

The average diameter of trees in the three stories is very dif-
ferent, that of the first story being 52.9 centimeters, the second
28.4, while that of the third-story trees that were more than 10
centimeters in diameter was 15.6 centimeters. The average dia-
meter of all individuals of first-story species in the first story
was 55.4 centimeters; of second-story species in the second
story, 28.9 centimeters; and of third-stor,y species in the third
story, 16 centimeters. These averages are very similar to those
just given for all of the trees in the different stories. Table
VII shows that there are comparatively few second-story trees
more than 40 centimeters in diameter, while most of the third-
story individuals are less than 20. The third story contained
246 individuals less than 10 centimeters in diameter, which were
not included in Tables VI and VII.

The average height of all first-story trees was 27.2 meters;
of second-story individuals, 16.4 meters; while the third-story
trees more than 10 centimeters in diameter averaged 9.8 meters.
If these figures are compared with the average diameters of
trees in the different stories it will be seen that, as a higher
story is reached, the percentage of increase is greater for the
diameters than for the heights. First-story trees have an aver-
age height that is fifty-one times as great as the average diam-
eter; in the second story the average height is fifty-eight
times as great as the average diameter; while third-story trees
more than 10 centimeters in diameter have an average height
sixty-three times as great as the average diameter.

DIPTEROCARP FOREST

57

Table VIII. — Clear lengths of first-story trees 22 to 38 meters in height
on 0.25 hectare in dipterocarp forest on Mount Maquiling; altitude,
4.50 meters.

[Figures represent numbers of individuals.]

No.

Species.

Parashorea malaanonan (bag-

tican lauan)

Canarium luzonicum (pili)

Eugenia similis imalaruhat)

Neonauclea sp

Palaquium tenuipetiolatum (palac

palac)

Planchonia spectabilis (lamog)

Sterculia sp. (lapnit)

Total

Clear length in meters.

Total.

10 to 12. 12 to 14. 14 to 16. 16 to 18. 18 to 20.120 to 22.

1

Table VIII gives the clear lengths of the trunks of all first-
story trees in the first story, and Table IX of all second-story
trees in the second story. From Table VIII it will be seen that
no first-story tree had a clear length of more than 22 meters, or
in other words part of the crown of all the individuals was in
the space considered as being occupied by the second story. The
average clear length of all the trees was 14.1 meters. If this
figure is compared with the heights of the same individuals, it
will be seen that a larger part of the length of the average crown
is below rather than above a height of 22 meters. From Table
VIII it will be seen that two of the first-story trees have
branches below 12 meters, or within the third story. These
figures show that there is no sharp dividing line between the
crowns of the first and second stories, but that the higher
branches of the second-story trees reach up among the lower
branches of the first story. In a forest the lower leaves of a
tree are frequently at a much greater height than the origin
of the first branches, so that there is not as much overlapping
of canopy as of branches in first- and second-story trees. It is,
however, natural that there should be considerable interming-
ling of the lower part of the canopy of the first story and the
upper part of that of the second story.

58

MOUNT MAQUILING

Table IX. — Clear length of second-story trees 12 to 2U meters in height
on 0.25 hectare in dipterocarp forest on Mount Maquiling ; altitude,
U50 meters.a

[Figures represent numbers of individuals.]

No.

Species.

Clear lengths in meters.

2 to 4.

4 to 6.

1
1

6 to 8.

8 to 10.

10 to 12.

12 to 14.

1

2

3

1

4

Indt

1

5

1

4

|

6
7
8
9

10
11
12
13
14
15
16

17
18
19
20

Dillenia philippinensis (catmon) _
Dillenia reifferscheidia (catmon) .

2

1

1 1 ' 1

1

Diospyro8 discolor (camagon) i

1
1

! 2 ! i

i

Diplodiscus paniculatus (balobo)J 1 1

i :..

1

Ficus ribes (auymit)

Ficus variegata (tangisang biauac)
Ficus sp

1

i

1 1

I

i! i
i

2

1
1

1

- --

Lophopetalum toxicum (calatum-

Nauclea junghuhnii (mambog) . _ _

1

Nephelium mutabile (bulala)

1

Semecarpus gigantifolia (ligas) .

1
10

Total

5

8

7

5

2

Total.

« Livletona sp., a palm, is not included in this table.

Table IX shows that out of 37 second-story species in the
second story 35 had clear trunks less ^ than 12 meters in length.
The average clear length of all trees was 8 meters. These fig-
ures show that there was an intermingling of branches between
the second and third stories similar to that described for the
first and second stories.

GROUND COVERING OP PLOT

In clearing the plot just described an area 10 meters square
was selected, and an enumeration was made of all terrestrial
plants growing on it; the results are given in Table X. The

DIPTEROCARP FOREST

59

Table X.—€omposition of plot 10 meters square in dipterocarp forest
on Mount Maquiling; altitude, 450 meters.

[Figures represent numbers of individuals.]

No.

Species.

Otol.

j

9

Height in meters.

22 to 38.

|

i

lto2.

2 to 12.

12 to 22.

Total.

1

TREES.

Aglaiasp. (malasaging-)

Alangium meyeri (putian)

1

10

2

1

1
1
1
1
1

3

Ardisia boissieri (tagpo)

1

| —

4

Ardisia perrottetiana

1

i 5

Ardisia sp

1

6

Canarium luzonicum (pili)

1
3

i 7

Candrium sp 1

3

1

! 8

Celtis philippensis (malaicmo)

Cinnamomum mercadoi (calingag)

Clerodendron quadriloculare

! 2

1

9

2

I io

1

I

11

Cryptocarya lateriflora

8
1

1
1

9
2

; 12

Dillenia philippinensis (catmon)

1

13

Dimorphocalyx luzoniensis

1
1
56
1
1
1
3

2

1
1

14

Diospyros discolor

1

51

1

15

Diplodiscus paniculatus (balobo)

2

2

1

16

Dysoxylum sp

17

Eugenia saligna

1
1
1

18

Eugenia sp „

19

Eugenia sp

2
2

20

Euonymus javanica

21

Ficus ribes (auy mi t)

1

22

Garcin ia binucao (binucao)

1

23

Grewia stylocarpa (susumbic)

2
1
3
3

2

24

Ixora longistipula

1
3

25

Knema glomerata (tambalao) __

26

Laportea subclausa (lipa) ._

1
1

4

27

Leea aculeata

1

28

Leea manillensis

1
1

7

7

g

29

Livistona sp _ _ .

1
1
g

30

Neolitsea sp . . .

31

Palaquium sp

1

82

Parashorea malaanonan (bagrtican lauan).
Pinanga sp _

1

I

33

15
7
2

15

7

34

Planchonia spectabilis (lamog)

Pterocymbium tinctorium (taluto)
Radermachera sp _. _

35

2
1

4

36

I

37

Semecarpus sp

1

28

I

38

Miscellaneous indt

28

Total

9A

151

11

4

| 187

SHRUB.

Tabernaemontana pandacaqui (pandaca-
qui) _

39

1

1
1
1

1
- ! 1 1

60

MOUNT MAQUILING

TABLE X. — Composition of plot 10 meters square in dipterocarp forest
on Mount Maquiling ; altitude, 450 meters — Continued.

No.

Species.

Alpinia brevilabris

Chlorantkus officinalis.

Donax cannaeformis

Hemigraphis strigosa __

Phacelophrynium sp

Pteris quadriaurita

Rungia sp

Tectaria sp

Total .

I

Agelaea sp

Alyxia monilifera

Araceae

Calamus and Daemonorops spp _

Freycinetia williamsii

Lygodium circinnatum

Pothos sp

Schizostachyutn diffusion

Miscellaneous indt

Total-

Total of all plants.

Height in meters.

Total.

Otol.

1 to 2.

2 to 12.

12 to 22.

22 to 28.

1

1
13
19

7
10

1
14

1

13

19

7

10

1

14

1

.-._...

|

66

. . i

66

1

53

53
1
1

82
4
3
3
2

89

238

1

1

53
4

15

13

1

3

3

2

89

209

15

13

1 |

427

26

34

5

492

total number of plants was 492. Of these, 427 were less than
1 meter high; 26 were between 1 and 2 meters; and 39 were
more than 2 meters in height. There were 238 vines, 187 plants
of tree species, 66 herbs, and 1 shrub. Of plants less than 1
meter high 209 were vines, 151 were tree species, 66 were herbs,
and 1 was a shrub. With the exception of some of the herbs,
most of these were seedlings, and only a small percentage of
them stood any chance of reaching maturity. In the case of
the tree species this is evident when it is considered that there
were 151 individuals less than a meter in height on 100 square
meters, and only 353 that were more than 2 meters high on 2,500
square meters. In the first case there were 1.51 seedlings and
in the second 0.14 tree to the square meter.

Herbs were represented by 8 species. These are, perhaps,
best described as mesophytes ; certainly not one of them is a hy-
drophyte. Alpinia brevilabris, Chloi*anthus officinalis, and Donax
cannaeformis are among the commonest herbs in the forest.
The herbs, including seedlings, were scattered over the plot at
the rate of one to every 1.5 square meters. It is evident from
this that the herbs were not a prominent part of the vegetation.

DIPTEROCARP FOREST 61

The most conspicuous vines were the rattans Calamus and
Daemonorops, of which there were 82 specimens. Of these there
were 15 between 1 and 2 meters high, 13 between 2 and 12
meters, and 1 that was 15.3 meters in length. This number of
young rattans is not unusually large. Their long leaves are
the most striking feature of the undergrowth.

There were on the plot 427 plants less than 1 meter in height,
or 4.27 to the square meter. This shows that the ground it-
self is not covered by a carpet of vegetation. Density is char-
acteristic of the undergrowth rather than the ground covering,
the soil being usually visible, except when covered with leaves,
as is frequently the case in the dry season.

The unidentified specimens of vines and tree seedlings, shown
in Table X, represented a number of species. On this plot, 10
meters square, there were certainly more than 75 species of
terrestrial plants.

CULLED DIPTEROCARP FOREST

We have noted that the composition of the dipterocarp forest
at elevations below 300 meters has been changed from its orig-
inal condition by a system of selective logging. Naturally, the
results are most marked near the lower edge of the forest and
much less evident as higher elevations are reached. At about
300 meters' altitude many of the trees most valuable for com-
mercial purposes have been removed; however, only the best
specimens of the most highly prized species have been logged,
and the physical character of the forest as a whole has probably
not been greatly changed. Near the lower edge of the forest
almost all good specimens of the valuable species and many of
the better individuals of poorer ones have been removed.

At elevations of about 200 meters the original forest must
have been much more largely dipterocarp than that now existing
at elevations above 300 meters. Brown and Matthews * have
shown that in the Philippines dipterocarp forests are better
developed at' lower elevations than at higher. That this is true
of the forest on Maquiling also is indicated by the present dis-
tribution of seedlings and small trees. At an altitude of about
200 meters there are now present sufficiently large numbers
of seedlings and small individuals of the valuable dipterocarps
Pentacme contorta (white lauan) and Shorea guiso (guijo) to
make it probable that these species were nearly as prominent in
this area as Parashorea malaanonan (bagtican lauan) . It seems
likely, therefore, that the dipterocarps formed most of the first

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil. Journ. Sci., Sec. A (1914), 9, 413-561.

62 MOUNT MAQUILING

story and that this was more regular and had a higher average
height than the virgin forest which has already been discussed.

This culled forest is not so directly connected with the present
problem as is the more virgin forest at higher elevations; but
a study of it will be of help in understanding the latter and, by
giving an idea of the original composition, will aid in tracing the
changes which naturally occur in the physical type of vegetation
from the base to the summit of the mountain. The problem of
how this culled forest can be restored to its original condition
is a very practical one and has been discussed by Brown and
Matthews.*

If the culled forest were to be placed in a formation named
from the first- and second-story species most prominent in their
respective stories, it would be in the Pa/rashorea-Diplodiscus
association. The wood of Parashorea malaanonan (bagtican la-
uan) is not resistant enough to termite and fungus attacks to be
considered valuable in the Philippines ; and, as the large trees of
this species are difficult to handle with the primitive methods
of logging that have been used on Mount Maquiling, Parashorea
is very conspicuously the commonest of the very large trees
found in the culled forest. Likewise the wood of Diplodiscus
paniculatus (balobo) is not regarded as being of good quality,
and this species is probably even more prominent in the second
story of the culled than of the virgin forest.

It would seem certain that both of these species were originally
very numerous in the area ; but, as will be shown later, possibly
others were equally prominent. However, as the latter possibi-
lity is only a speculation, the culled forest will, for convenience,
be placed in the Parashorea-Diplodiscus association. To avoid
confusion "dipterocarp forest" or "Parashorea-Diplodiscus as-
sociation" will be used only for the virgin portion of the forest,
except where the names are modified by "culled" or an equiv-
alent adjective.

The present composition of this forest can be best explained
by describing in detail the composition of a selected area. The
plot on which measurements were made was at an elevation of
about 200 meters and was 50 meters square. It was thus the
same size as the plot described in the virgin dipterocarp forest,
and its slope and exposure were similar.

In Table XI are given the heights of all erect woody plants
on the plot that were more than 1 meter in height. Two, Anax-
agorea luzonensis and Tabernaemontana pandacaqui, are small
undergrowth shrubs; while another, Schizostachyum sp., is an

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil J ovum. Sci., Sec. A (1914), 9, 413-561.

DIPTEROCARP FOREST

63

erect bamboo, which in this case formed a clump of thirty-five
stalks. The remainder may be considered as trees, although a
few might properly be classified as large shrubs.
Table XL — Heights of all trees over 1 meter in height on 0.25 hectare in
culled dipterocarp forest on Mount Maquiling ; altitude, 200 meters.

[Figures represent numbers of individuals.]

No.

Species.

Height

in meters.

Total.

13

43

25
2

lto2.

2 to 6.

6 to
10.

10 to 12 to
12. | 14.

i

i 1

i

14 to
18.

1

| !

18 to 22 to 26 to

22. 26. 30.

1

I

30 to 34 to
34. 38.

1
2

3

4
5

6

7

8
9

10
11

12
13
14

15
16
17
18

19
20

21

22

23

24

FIRST-STORY SPECIES.

Dipterocarp s:

Shorea guiso (gui jo)
Parashorea mala-
anonan (bagtican
lauan) _ _

1

26
4
1
1

9

12

12

1

1
1

109

1

2
4

i
1 I.

2

Pentacme contorta

(white lauan)

Miscellaneous species:

Alphonsea arbor ea

Canarium luzoni-
cum (pili) _

4

1

! !

2

Canarium sp

I |

j

1

Celtis philippensis
(malaicmo)

69

23

3 ! 3 1 2

1 '

! 1

i
1 i

211
1

2

Cryptocarya sp

1 i

Dracontomelum dao
(dao)

Eugenia longifiora ._

Eugenia luzonensis
(malaruhat puti) . _ _

Eugenia sp

2
1

1

1

1

1

2

1 !.

1

1

Eicus nervosa

Koodersi odendron

pinnatum (amugis)

Meliosma sylvatica

2
1

4

1
1

1 i

: i

7

|

1

i j

2

-—

~—

--f-

| i

1

Octomeles sumatrana.
Palaquium merrillii .
Palaquium tenuipe-

tiolatum (p a 1 a c

palac)

1 1 1

1 j

i !

2

4

2

3
1

1

1

1

1

|

i

!

1 1

„-.

3

Palaquium sp

Planchonia spectabi-

1

! ' ';

2

1

Mm

2

Pometia pinnata
(malugay) .

1
!

1 ■

1

! i ! i

! i !

2

Pterocymbium tine-
torium (taluto)

2 i 2 2

...._..;„....

i L ..

j

7

Sterculia crassira-

mea . .

2

i

I

j )

:

2

Terminalia edulis
(calumpit)

i
l

| 1

2

25

1

1

L.

i

26

Urandra luzoniensis
(tapulao)

i|i 1

.... L....S .. ! i

i

64

MOUNT MAQUILING

Table XI. — Heights of all trees over 1 meter in height on 0.25 hectare in
culled dipterocarp forest on Mount Maquiling; altitude , 200 meters — Ctd.

No.

Height in meters.

Total.

Species.

1 to 2. 2 to 6.

I

6 to
10.

10 to
12.

12 to
14.

14 to
18.

18 to 22 to 26 to
22. 26. j 30.

30 to
34.

34 to
38.

SECOND-STORY SPECIES.

Aglaia diffusa (salaquin

7
2

1

1

10
9

8

5
21
14

2

2

1

3

1
1
4
4
2

4

8

2

2
1

4

1

4

2
1

6 '

Aglaia harmsiana (ma-

2
2

3
1

7

2

„_._

; 1

I

1

2

1

1

Alangium meyeri (pu- i

tian) l 1

2

Allophylus grossedenta- j

1

Amoora cumingiana '

1
3
1
1

2

1

1

1

3
1

1

Ardisia serrata..

Arenga pinnata (cabo

2

Artocarpus rubrovenia
(anubing)

1

1

Barringtonia sp . ,

1

Bridelia minutiflora

1

Buchanania arbores-
cens (baling'hasay)

1

Canarium ahernianuni--

1

1

Caryota sp. (pugrahan) _ -

1

Chisocheton sp. (sala-

1

3
2

2

1

1

Cratoxylon celebicum,

Cyclo8temon maquiling-

2

Cyclostemon sp

1

Dillenia philippinensis
(catmon) __

2

1

1

Dillenia reifferscheidia
(catmon) _.

1
1

1

2

1
1

Dimorphocalyx luzoni-
ensis

Diospyros ahernii
(ananj?)

1

Diospyros pilosanthera
(bolongreta)

2

14
2
2
1

2

28
4
1
2

2
11

Diplodiscus paniculatus
(balobo) _

1

2 2

2

60 !

Dysoxylum pauciflorum .

J

6 !

Dysoxylum rubrum

|

1

3 ;

Euonymus javanica

1

j

3 !

DIPTEROCARP FOREST

65

Table XI. — Heights of all trees over 1 meter in height on 0.25 hectare in
culled dipterocarp forest on Mount MaquUing; altitude, 200 meters — Ctd.

Species.

lto2.

Height in meters.

Total.

1

2
2
4
3
6
1

1
1
2
1

3
1
1
5

38

1

2

13

1
9
7

2
4
11

43
2

1
1

1
1

1

4

1

' No.

2 to 6.

1

1
1

6 to
10.

10 to
12.

12 to
14.

14 to
18.

!

18 to 22 to

22. j 26.

26 to

30.

30 to
34.

34 to
38.

63

SECOND-STORY SPECIES—

continued.

Euonymus viburnifolia..

Euphoria cinerea (alu-

pag) _ __.

64

1

|

65

Evodia glabra

1

66

Evodia villamilii

4

67

Ficu8 ampelos (malaisis)
Ficus barnesii

5

2

1

68

1

69

Ficus linearifolia

1

70

Ficus minahassae (hagi-
mit)

~ V"

1

71

72

Ficus satterthwaitei

1

Ficus sp

1

1

73

Ficus sp

1

74

Garcinia venulosa (ga-
tasan)

2

1
1

75

Goniothalamus amuyon __

76

Goniothalamus elmeri

1

77

Indt ...

4
20

1

78

Knema glomerata (tam-

balao)

15

3

79

Mallotus ricinoides (hin-
laumo)

1

80

Myristica philippensis
(duguan)

1 i

1

!

81
82

Nephelium mutabile (bu-
lala)..__

11

1

1
6
1

1
1

7

9
1

1
1

1

1

Oroxylum indicum (pin-
capincahan)

83

2

1
1

1

84

Osmelia philippinensis

1

3

1

85

Pisonia umbellifera (an-
uling) .

j

i

86

Polyalthia cumingiana . _ _

3

4

20

87

88

Pterospermum diversifo-
lium (boyek) _ _ .

5

1

4

3

2

89

Pygeum preslii (uto-uto) _

Quercus soleriana (cata-

ban)

90

91

Quercus sp

92

Nauclea orientalis (ban-
cal)

93

Schizostachyum sp (boho)
Semecarpus philippinen-
sis (ligas)...

1

94

1

i

95

Sideroxylon sp. (white
nato) _ _

?

1 1

!

96

Sterculia oblongata (ma-
lacacao) ...

j

i i

159549^ 6

66

MOUNT MAQUILING

Table XI. — Heights of all trees over 1 meter in height on 0.25 hectare in
culled dipterocarp forest on Mount MaquUing; altitude, 200 meters — Ctd.

1

No.

97

98
99

100

101

102
103
104
105

106
107
108

109
110
111
112

113
114
115
116
117
118
119

120

121

122

123
124
125
126
127

128
129

Species.

Height

in meters.

Total.

74
1
1

13
1

1 to 2.

2 to 6.

6 to
10.

2

10 to
12.

1

12 to1 14 to

14. 18.

18 to
22.

! |

22 to 26 to 30 to
26. 30. | 34.

34 to
38.

SECOND-STORY SPECIES—

continued.

Strombosia philippinen-
sis (tamayuan)

36

35
1

1

I
I

1

.„ L

1

THIRD-STORY SPECIES.

Callicarpa erioclona (pa-

lis) —

2

11
1

;

Canarium villosum (pag-
sahing)

•

Casearia sp. (malatapai).
Citrus hystrix (cabuyao) .

11
2

11

1

1
1
1

2
2
1

1

!

3
1

2
1
2

2

.. ! 1

Clerodendron quadrilo-
culare

1

— i — | —

I

1 1

Ficus manilensis (isis)_.

l

Glochidion album (mag-
na)

Glochidion philippicum. _

o

Glochidion reticulaium,-.

1

1
1

3
3

Glochidion sp

1
1

Grewia stylocarpa (su-
sumbic)

1
3
1
1
2

1

_-._L—

Ixora longistipula

Leea manillensis

5
1

1

7

Leea philippinensis

Lepisanthes schizolepis _ .

2
2
1
1

Leucosyke capitellata

i

Litsea luzonica __

1
1

Macaranga bicolor (ha-
mindang)

1

3

- — -

i

,

Macaranga grandifolia
(taquip asin)

3

Neotrewia cumingii (ba-
tobato).

4
12

3
1

2

9

Papualthia lanceolata
(lanutan)

i

13

Pithecolobium subacutum
Psychotria sp

i

1

1
1
1

2

12

1

1
1

2

Siphonodon celastrineus _

Sterculia cuneata

Voacanga globosa (bayag-
usa)

2

1

1

1

3 1

UNDERGROWTH SPECIES.

Anaxagorea luzonensis __

Tabernaemontana pan-

dacaqui (pandacaqui)..

Total

12 :

1

n

15

16

2

1

0

2

332

379 1 84

83

23

887

DIPTEROCARP FOREST @7

In the table are listed 129 species. Of these only 29 are found
in the table for the plot in the virgin dipterocarp forest. This
difference in specific composition was due partly to differences
in elevation, some species in the dipterocarp forest being charac-
teristic of higher and others of lower elevations.

The removal by logging of a large part of the main canopy
favored the development of certain species, but did not cause the
appearance of any that do not normally occur in the dipterocarp
forest. Species that are aided by logging are more likely to be
found on a limited plot in a culled than in a virgin forest, while
the reverse is the case with species upon which the effect of
cutting is injurious. The disappearance of most of the large
trees resulted in the presence of a much larger number of small
individuals and very likely an accompanying greater number of
species. It is thus probable that logging caused a considerable
change in the species on the plot, but it would seem that its
greatest effect was to increase the number of species on a limited
area and not to add new ones to the forest.

The differences in the lists of species for the plots in the
culled and in the virgin forest are due to a considerable extent
to the small size of the plots, and they emphasize the great di-
versity of species found in the dipterocarp forest. In each case
many species are represented by only one individual, and so it
is not surprising to find that enlarging the size of the plot would
greatly increase the number of species. It is not unusual to find
that a species which is fairly numerous in a given area is not
represented on a plot as small as those from which the lists were
prepared. In classifying the species according to stories, the
same heights have been used as in the case of the virgin forest.
Most of them belong to the same story in both areas, but a
few appear to reach different heights in the two regions. This
is probably due to changed conditions in the lower forest.

There were 50 individuals of dipterocarps more than 2 meters
in height on the plot in the culled forest, and only 34 on that in
the virgin forest. In the culled forest there were 81 dipterocarps
over 1 meter high ; of these 43 were of Parashorea malaanonan
(bagtican lauan), 25 of Pentacme contorta (white lauan), and
13 of Shorea guiso (guijo). The largest trees on the plot were
2 specimens of Parashorea, which were more than 37 meters in
height. Neither Shorea nor Pentacme was represented by large
individuals, either on the plot or in the general neighborhood;
but in both cases there were enough small and medium-sized
trees present to indicate that specimens comparable in size with
the large ones of Parashorea formerly existed on the plot.

After the two large individuals of Parashorea the tallest tree

68 MOUNT MAQUILING

on the plot was a Celtis philippensis (malaicmo), 26.64 meters
in height. Celtis philippensis is a much shorter and smaller
species than Parashorea malaanonan, and in a virgin forest its
crown is usually shaded by such species as the latter. Celtis was
the most numerous species on the plot, but most of the individuals
were very small, only one being tall enough to be in the first
story of a virgin forest. Logging has probably made this
species more prominent than it was originally, as its wood is con-
sidered of very poor quality, and it is one of the last trees to be
removed. Owing to its smaller size it is not nearly so prominent
as Parashorea. An examination of Table XI will show that
Celtis philippensis is the only first-story species that can compare
in numbers with the dipterocarps Parashorea malaanonan and
Pentacme contorta.

Diplodiscus paniculatus (balobo) was the most numerous spe-
cies within the limits of the second story and was represented
by more large individuals than any other species of this story.
The most numerous second-story species was Strombosia philip-
pinensis (tamayuan), but most of the individuals were small.
Strombosia has a very durable wood and is much used for posts
of houses, so that even medium-sized trees are logged. Diplo-
discus is of little value and is not removed until the culling is in
its last stages. There were 74 individuals of Strombosia and
60 of Diplodiscus, so that it seems not impossible that originally
Strombosia was nearly as prominent as Diplodiscus, if not equal-
ly so. Whitford * found that Strombosia philippinensis was the
principal second-story tree in the dipterocarp forest occurring
at the lowTest altitude on Mount Mariveles. This forest, which
Whitford called the Anisoptera-Strombosia formation, has a
composition very different from anything on Mount Maquiling.

Table XI shows that none of the third-story species were
numerous on the plot in the culled forest.

The figures in Table XI are summarized in Table XII. In this
table the different stories are regarded as being of the same
heights as in the virgin forest. Since a large part of the main
canopy has been removed, this classification places in the second
story many trees that are exposed to full sunlight. There were
5 trees in the first story, 54 in the second, and 496 in the third.

* Whitford, H. N., The vegetation of the Lamao forest reserve, Phil
Journ. Set. (1906), 1, 403.

DIPTEROCAKP FOREST

69

Table XII. — Summary of the composition of different stories in the culled
dipterocarp forest on Mount Maquiling ; altitude, 200 meters.

[Figures represent numbers of individuals.]

Story to which species belong when the individuals
are mature.

First story

Second story _
Third story. ..
Undergrowth

Stories in which the indi-
viduals present were found.

First

Second

Third

story ;

story;

story;

height,

height,

; height,

22 to 38

12 to 22

2 to 12

meters.

meters.

i meters.

Total .

15

35 ;
4 !

207 -

243

46

227

278

50

The number of trees in the second story was exactly the
same as that in the second story on the plot in the virgin forest.
The number of individuals in the first and the third stories is
very different in the two cases. That a large portion of the
first story had been removed from the plot in the culled forest
is shown by the fact that there were only 5 trees in this story,
while there were 16 in the same story in the virgin-forest ptet.
The disappearance of a large portion of the first story resulted
in the entrance of a greater amount of light into the other stories.
The effect of this was to increase the number of individuals in
the third story. This story contained 496 trees in the culled
forest and 283 in the virgin forest. The large number of indi-
viduals in the third story is due to an increase in the number
of trees of first- and second-story species in this story, as there
are fewer individuals of third-story species in the third story
of the culled than of the virgin forest. In the latter there were
78 specimens of third-story species, while there were only 46
in the same story in the culled forest. This would indicate that
the trees of third-story species could not stand the drier condi-
tions caused by the removal of the first story so well as could
those of first- and second-story species. Small individuals of
the latter appear to be benefited by having a greater amount of
light than they would normally have in a virgin forest. This
is in agreement with the conclusions of Brown and Matthews,*
who found that dipterocarps in a virgin forest passed through
a very long suppression period, during which growth was ex-
tremely slow.

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil. Journ. Scl, Sec. A (1914), 9, 413-561.

70

MOUNT MAQUILING

The decrease in the number of trees of third-story species
in the culled forest is the more striking when we consider that
eleven of the twenty-three third-story species on the plot also
occur in open country, and that five of them are common in
second-growth forests. These species occur normally in a dip-
terocarp forest. They have not entered the forest on account
of the changed conditions. On the plot in the virgin forest
there were in the third story eight third-story and two under-
growth species, which are also found in the open country at
the base of the mountain.

Table XIII gives the diameter classes of all trees more than
10 centimeters in diameter on the plot in the culled forest.
The prominence of Parashorea malaanonan and Diplodiscus pa-
niculatus is even more pronounced in this table than in Table
XI. The largest tree was a Parashorea with a diameter of
139 centimeters. No other species showed diameters half as
large as this Parashorea. The diameters were for the most
part small, and medium-sized diameters occurred only in trees
that were not valuable for lumber.

Table XIII. — Diameter classes of all trees more than 10 centimeters %n
diameter on 0.25 hectare in culled dipterocarp forest on Mount M#-
quiling; altitude, 200 meters.

[Figures represent numbers of individuals.]

No.

Species.

FIRST-STORY SPECIES.

Dipterocarps:

Shorea guiso (guijo)

Parashorea malaanonan (bagtican

lauan)

Pentacme contorta (white lauan)

Miscellaneous species:

Celtis philippensis (malai cmo)

Cryptocarya sp

Eugenia sp

Ficus nervosa (agusua)

Octomeles sumatrana

Palaquium merrillii

Pterocymbium tinctorium (taluto)

Diameter class in centimeters.

10 to
20.

30 to 40 to
40. 50.

50 to
60.

70 to 130 to
80. 140.

Total.!

DIPTEROCARP FOREST

71

Table XIII. — Diameter classes of all trees more than 10 centimeters in
diameter on 0.25 hectare in culled dipterocarp forest on Mount Ma-
quiling; altitude, 200 meters — Continued.

No.

Diameter class in centimeters.

Species.

SECOND-STORY SPECIES.

Aglaia llanosiana (alupag)

Alangium longiflorum

Allophylus grossedentat us

Artocarpus woodii

Caryota sp. (pugahan)

Chisocheton sp. (salaquing: pula)

Cyclostemon sp

Dillenia philippinensis (catmon)

Diospyros pilosanthera (bolong-eta)

Diplodiscus paniculatus (balobo)

Evodia glabra

Evodia villamilii

Ficus ampelos (malaisis)

Ficus barnesii

Ficus minahassae (hagimit)

Ficus sp

Ficus satterthwaitei

Goniothalamus clmcri

Indt

Mallotus ricinoides (hinlaumo)

Myristica philippensis (duguan) .

Nephelium mutabile (bulala)

Osmelia confer t a (malatapai)

Osmelia philippinensis

Pisonia umbellifera (anuling)

Pterospermum diver sifolium (boyek) - ..

Sideroxylon sp. (white nato)

Strombosia philippinensis (tamayuan) -

10 to
I 20.

20 to
30.

THIRD-STORY SPECIES.

Ficus manilensis (isis)

Leucosyke capitell ata

Macaranga bicolor (hamindang)
Pithecolobium subacutum

30 to
40.

40 to
50.

Total.!

50 to ! 70 to !130 to
60. ! 80. I 140.

Total .

75

Table XIV gives the volume of all trees more than 10 centi-
meters in diameter. Parashorea malaanonan is more promi-
nent in this than in the preceding tables. This species contained
31.79 cubic meters out of a total volume of 47.72 cubic meters.
Table XIV also emphasizes the small size of the other trees,
the species next in volume being Celtis philippensis, which
contained only 2.45 cubic meters, distributed among five
individuals.

72

MOUNT MAQUILING

Table XIV. — Volume of all trees more than 10 centimeters in diameter on
0.25 hectare in culled dipterocarp forest on Mount Maquiling;
altitude, 200 meters.

No.

Species.

FIRST-STORY SPECIES.

Dipterocarps:

Shorea guiso (guijo)

Parashorea malaanonan (bagtican lauan) _
Pentacme contorta (white lauan)

Miscellaneous species:

Celtis philippensis

Cryptocarya sp

Eugenia sp

Ficus nervosa (agusus)

Octomeles sumatrana

Palaquium merrillii

Pterocymbium tinctorium (taluto)

Volume in cubic meters.

First
story.

31.12

1.43
1.29

0.21

SECOND-STORY SPECIES.

Aglaia llanosiana (alupag)

Allophylus grossedentatus

Artocarpus woodii

Chisocheton sp. (salaquing pula)

Dillenia philippinensis (catmon)

Diospyros pilosanthera (bolongeta) . _.

LHplodiscus paniculatus (balobo)

Evodia glabra

Evodia villamilii

Ficus ampelos

Ficus barnesii

Ficus minahassae (h agimit) _ _ __.

Ficus satterthwaitei

Ficus sp .-

Goniothalamus elmeri

Indt _

Mallotus ricinoides (hinlaumo)

Myristica philippensis (duguan)

Nephelium mutabile (bulala)

Osmelia conferta (malatapai)

Osmelia philippinensis __

Pisonia umbellifera (anuling)

Pterospermum diver&ifolium (boyek)___

Sideroxylon sp. (white nato)

Strombosia philippinensis (tamayuan) .

THIRD-STORY SPECIES.

Ficus manilensis (isis)

Leucosyke capitellata

Macaranga bicolor (hamindanj?)

Pithecolobium subacutum . ..

Total.

34.05

Second
story.

0.47
0.67
0.07

,0.96

0.41
0.35
0.19
0.08
0.10

0.05

0.02
0.39
0.12

2.30
0.11
1.57

0.06
1.25

0.52
0.49
0.27
0.16

0.11
0.03
0.07
0.19
0.24
0.06
0.37

0.57
0.15
0.03
0.01

12.44 I

Third
story.

0.06

0.09

0.03

0.07
0.39
0.03

0.06

0.19

0.12

0.15

1.23

Total.

0.47

31. 79

0.11

2.45
1.29
0.41
0.35
0.40
0.08
0.19

0.05
0.03
0.02
0.39
0.19
0.39
2.33
0.11
1.57
0.06
0.06
1.25
0.19
0.52
0.49
0.27
0.16
0.12
0.11
0.03
0.22
0.19
0.24
0.06
0.37

0.57
0.15
0.03
0.01

47.72

DIPTEROCARP FOREST

73

The results given in Table XIV are summarized according to
stories in Table XV. Owing to the huge bulk of the large
individuals of Parashorea a great part of the volume was in
the first-story species in the first story. The volume of the
first story was only 38 per cent lower than that of the same
story in the virgin forest. The comparatively high volume of
the culled forest was due to the presence of a single, very large
Parashorea. The second and third stories in the culled forest
showed relatively greater decreases in volume than the first
story. The loss in the second story was probably due to the
logging of the more valuable specimens, while that in the third
was incidental to the removal of large trees or was the result
of changed conditions.

Table XV. — Summary of composition by volume of the different stories
in culled dipterocarp forest on Mount Maquiling; altitude, 200 meters.

Stories in which individuals
I present were found.

Stories to which species belong when the individuals
are mature.

! First

I story;

I height,

J 22 to 38

j meters.

First story ._.
Second story .
Third story. ..

Total

34.05

Second
story;
height,
12 to 22
meters.

MO

Third
story;

height,
2 to 12

meters.

0.19
1.04

Total.

37. 54
9.42
0.76

12.44

1.23 47.72

The plot just discussed is evidently a reduction product from
a typical dipterocarp forest. The same species are present,
but the individuals are smaller and more numerous. Probably
the chief difference in specific composition, which has resulted
from culling, is that the removal of the best individuals of
the most valuable species has favored the less valuable ones.

In the plot just described an area 10 meters square was se-
lected before it had been disturbed, and all plants less than
a meter in height were counted, the results being given in Table
XVI. There were 112 plants less than a meter in height on
the plot. The majority of them, 62, were of tree species, 46
were herbs, and 4 were vines. The total number was small
when compared with the 427 on the similar plot in the virgin
forest.

74

MOUNT MAQUILING

Table XVI. — Plants less than 1 meter in height on plot 10 meters square in
culled dipterocarp forest on Mount Maquiling; altitude, 200 meters.

No.

10

[li

12
13

Species.

TREES.

Aglaia iloilo..

Aglaia diffusa _.

Casearia sp

Celtis philippensis

Cyclostemon maquilingensis

Dysoxylum sp

Euonymos javanica

Ficus lin earifolia

Indt

Lepisanthes schizolepis

Palaquium sp

Papualthia lanceolata

Pa rash orea malaanonan

Num-
ber of
plants.

No.

Species.

Pentacme contorta

Pithecolobium subacutum ,

Polvalthia sp

Sterculia crassiramea

Strombosia philippinensis.

Symplocos sp

Terminalia nitens

Num-
ber of
plants.

HERBS.

Alpinia brevilabris

Chloranthus officinalis .
Donax cannaeformis^^.

2
15

2

1
11

1

11
23
12

Calamus and Daemonorops .
Total

112

Vines are very prominent in the culled forest. The most
conspicuous are climbing bamboos, especially Schizostachyum
diffusum. Besides these there are climbing palms (rattans)
and a large number of dicotyledonous vines. The increase in
light in the lower stories, due to the removal of the large trees,
causes such an increased development of climbing bamboos
that they are very important factors in giving character to
the appearance of the vegetation. Owing to the small size of
most of the trees and the great development of vines, the culled
forest presents the appearance of a low dense tangle.

The ground covering consists largely of woody plants, for the
most part seedlings of trees and vines. Among the commonest
shrubs are Anaxagorea luzonensis and Tabernaemontana pan-
dacaqui. Except in ravines herbaceous species are scarce, and
those that do occur on the ridges are adapted to withstand fairly
dry conditions.

Having considered the present composition of the culled for-
est, we are now in a position to form an idea of thue type of
forest that originally occurred on the lower slopes of Mount Ma-
quiling. Judging from the size of the large individuals of Para-
shorea malaanonan that are left and the number of seedlings and
small specimens of other dipterocarps, the original forest at
elevations of about 200 meters must have been pronouncedly
dipterocarp. Its average height must also have been greater
than that of the more nearly virgin dipterocarp forest at higher
elevations.

DIPTEROCARP FOREST 75

This forest probably extended below the region in which
we now find the grassland and the second-growth forest pre-
viously described. At these elevations occasional large indi-
viduals of Parashorea malaanonan and smaller trees of other
dipterocarp species occur along the streams.

OPENINGS IN DIPTEROCARP FOREST

The first stages of the successions that occur in openings
appear to be quite uniform. If the opening is a small one,
such as is caused by the fall of a large tree, the first tree
species to enter is usually Macaranga bicolor. Accompanying
it at low elevations is an herbaceous vine, Trichosanthes quinr
quangulata, and at higher altitudes a raspberry, Rubies fraxini-
folius. These plants grow rapidly, and rattans quickly enter the
area, so that the opening is soon filled.

The plot in the virgin forest at an altitude of 450 meters was
divided into two parts, after the vegetation had been removed.
One part was used for planting experiments, and the other was
left bare. The latter part soon became covered with a thick
growth consisting almost entirely of the second-growth tree
Trema orientalis.

Clearings have been made in the forest at low altitudes and
then abandoned after little or no cultivation. The early stages of
these were not observed, but after four or five years they were
covered with second-growth forest composed very largely of
Trema orientalis, Trema appears, therefore, to be the first in-
vader in cleared areas.

On the plot at an elevation of 450 meters Trema was not
preceded by herbaceous vegetation. A few scattered annuals
appeared about the same time as Trema, but they were small
and not numerous enough to influence the successions and soon
disappeared. Brown and Matthews * found that when the dip-
terocarp forest of northern Negros was removed the ground
became covered very quickly with an almost pure stand of
Trema orientalis. Usually areas from which dipterocarp for-
ests have been removed are invaded by second-growth forests
consisting of almost pure stands of a single species, but the
species varies in different cases. If the ground is cultivated,
the successions are quite different, as has been previously shown.

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil Journ. Scl, Sec. A (1914), 9, 413-561.

MIDMOUNTAIN FOREST

The formation above the dipterocarp forest, which from its
habitat may be called the midmountain moist-tropical for-
mation, differs from the former not only in composition but also
in physical type. It is much less dense than the dipterocarp
forest and has only two stories of trees, the taller being about
the same height as the second story in the Parashorea-Diplo-
discus association. From its physical type it may be called an
evergreen two-story forest formation.

Its two-story character, rather than its specific composition,
has been used as a criterion for determining the limits of the
distribution of this formation. It may be regarded as extend-
ing from about the 600-meter contour up to an elevation of ap-
proximately 900 meters. The most prominent physical charac-
teristics remain fairly constant throughout this area, but the
specific composition changes considerably. For convenience the
present discussion will be confined to the ridge on which the
main trail is located, and where all measurements of environ-
mental factors were made. Neighboring ridges would, of
course, be much like the one to be described. As the trees of
this formation are small and the region is inaccessible, the forest
has remained in practically a virgin condition. Plates XVI to
XX, fig. 1, show views in this forest.

The midmountain formation, like the dipterocarp forest, con-
tains many species and is such a mixed type that it is difficult
to tell which species predominate, even in a limited area, with-
out making actual counts and measurements of the individuals
present.

The main canopy is usually continuous, but is fairly open —
much more so than is that of the dipterocarp forest. The height
of the canopy varies slightly at different elevations, becoming
lower as higher altitudes are reached. At 700 meters it is
approximately 18 meters in height, although some of the species
are taller than this and some shorter.

The second story is well developed at lower elevations, but
less prominent at higher. The species composing it vary con-
siderably in height. Some of them have a maximum height of
about 6 meters, while others frequently reach 12 meters or
more. The average for this story is probably about 8 meters.

76

MIDMOUNTAIN FOREST 77

Between elevations of about 600 and 700 meters there is a
considerable development of rattans, which are tangled with
the second story and the undergrowth. In places this gives
the forest a dense appearance. Rattans occur at higher ele-
vations, but they are not a prominent part of the vegetation.

The undergrowth is much less dense than in the dipterocarp
forest (see Plates XVI to XVIII) . The ground covering consists
largely of ferns and other herbaceous plants. The commonest
tall herb is Strobilanthes pluriformis, while the most numerous
small ones are species of Elatostema. These frequently form a
thick carpet over the ground. Ferns are also prominent.

The most conspicuous change that takes place within the
confines of the midmountain formation is an increase in the
amount of epiphytic vegetation. At lower elevations in this
formation, as jin the dipterocarp forest, epiphytes are scarce,
except in the crowns of the taller trees. Ferns and mosses
on the tree trunks are, however, slightly more numerous
than in the dipterocarp forest. In the lower half of the for-
mation, mosses on the trunks of the trees never form more than
a thin covering, and this development is reached on only a
small proportion of the trees. In the same region orchids also
occur to some extent on the trunks of the trees, and at an ele-
vation of about 750 meters they are numerous enough to be
rather showy. Here, however, it is the bark of the trees that
is prominent in giving character to the appearance of the for-
est, and not the epiphytic vegetation.

In the upper portion of this formation epiphytic and climb-
ing vegetation is very much more abundant. At elevations
greater than 900 meters the trees are so thickly covered with
these epiphytic and climbing plants that the bark is largely hid-
den, and the branches of the trees are frequently loaded with
epiphytes. Orchids are numerous, both on the trunks and in
the branches. Vines, more particularly species of Freycinetia,
are very prominent. Not only scandent but also epiphytic vines
are conspicuous. Among the latter may be mentioned Dichro-
trichum chorisepalum, which is very numerous and owing to
its long flowering season and showy blooms is very conspicuous.
The other most prominent epiphytic vine is Trichosporum phiU
ippinense. Plate XXI represents the average covering of the tree
trunks at an altitude of about 900 meters. The long leaves on
the left belong to a Freycinetia; the numerous elliptic, serrate
°nes in the center and on the right are the leaves of Dichro-
trichum chorisepalum. The vine with smaller, opposite, entire
leaves is Trichosporum philippinense. Besides the above, there

78 MOUNT MAQU1LING

are several species of ferns, a Selaginella, a species of Piper,
and a number of other plants. Between and among the larger
plants is a covering of mosses.

The increased amount of epiphytic vegetation at this altitude
represents a transition from the condition in this formation at
lower elevations to that in the mossy forest at higher elevations.
In the latter situation the trees are, for the most part, densely
covered by a growth of mosses and mosslike plants in which
grow a great variety of larger epiphytes.

From the above discussion it will be seen that the midmoun-
tain forest formation is an evergreen, two-story, rather open
forest composed of medium-sized trees representing many spe-
cies. Between elevations of approximately 600 and 850 meters
there • appear to be two distinct associations. Changes in en-
vironment between the upper and lower limits of this formation
are much greater than in the same range of altitude in the dip-
terocarp forest. This is largely due to the increased cloudiness
near the top of the mountain, the lower part of the formation
being frequently in the sunlight while the upper part is bathed
in clouds.

The midmountain forest is in most places a very greatly
mixed type in which no species dominates in any such manner
as does Parashorea in the dipterocarp forest. It is, therefore,
difficult to define the associations. Counts and measurements of
all trees over large areas will very likely show other associations
than those described from the ridge under discussion.

QUERCUS-NEOLITSEA ASSOCIATION

Between elevations of approximately 600 and 750 meters there
appears to be a single type, to which the name Quercus-Neo-
litsea association has been applied. Quercus soleriana (cata-
ban) is apparently represented by more individuals than any
of the other larger species of dominant trees, while additional
species of Quercus are also present in considerable numbers.
Cratoxylon celebicum, another first-story tree, is probably pres-
ent in greater numbers than Quercus; but it is usually smaller,
being slightly shorter and having a smaller crown, so that the
individuals are not so conspicuously dominant. The three large
trees shown in Plate XVI are of this species. Among the other
more prominent first-story species are Neonauclea calycina
(uisac), Palaquium philippense (palac palac), Weinmannia lu~
zoniensis, and species of Ficus.

The canopy of the first story has an average height of about
18 meters. The trees composing it are smaller than in the first

MIDMOUNTAIN FOREST 79

story of the dipterocarp forest, and consequently much more
numerous (see Plates XVI and XVIII). In limited areas, such
as a fourth of a hectare, there are also more species in the first
story of the Quercus-Neolitsea association than in the same story
in the dipterocarp forest.

Most of the tree species in the Quercus-Neolitsea association
are also found in the dipterocarp forest. The species common
to the two associations and which occur as first-story trees in
the Quercus-Neolitsea association are usually second-story
species in the dipterocarp forest.

The occurrence of these species in the first story in the mid-
mountain forest is probably connected with the smaller amount
of light at the higher elevations. These first-story trees are not
very different in size from those of the second story in the
Parashorea-Diplodiscus association. Large specimens frequent-
ly grow to be between 20 and 22 meters in height and have
diameters of more than 50 centimeters. When species belong-
ing to the first story in the dipterocarp forest are found in the
Quercus-Neolitsea association, they are much smaller at maturity
in the latter than in the former forest.

The second story is composed of numerous small trees be-
longing to many species. The average height of this story is
about 7 meters. Occasional specimens may be more than 14
meters in height, but most of the species are rarely more than
10 and some, such as Saurauia luzoniensis, reach a maximum
height of about 6 meters. The method of growth of many of
the species is quite irregular. Some of the individuals will form
straight trees with clear trunks, while others of the same species
will branch near the ground, or in other ways form irregular
specimens. In Table XVII the height of the tallest individual
of Neolitsea villosa on a quarter of a hectare is given as 18.55
meters. The main part of the crown of this tree was well with-
in the second story, while a small, slender branch had shot up
and entered the first story. Most of the trees are not only short
but also slender. In some species, however, individuals with
diameters of 30 centimeters or more are not rare.

The most numerous tree species in the association belong to
this story. These are Oreocnide trinervis (malatuba), Neolit-
sea villosa, and Saurauia luzoniensis. Oreocnide trinervis (ma-
latuba) is, apparently, the most numerous in the central part
of the association, while near the upper limits it is almost en-
tirely absent. This is a small species, which reaches a height of
about 8 or 9 meters and is quite irregular in its branching. It

80 MOUNT MAQUILING

is comparatively seldom that it has a definite clear trunk. Neo-
litsea is a larger species with a more regular tree form. Indi-
viduals with a height of 10 or 12 meters are fairly numerous.
The leaves are covered with silky hairs, which give them a
striking appearance. Owing to the size and number of the trees
and the character of the leaves, this species is the most conspic-
uous of the tree forms in the association. Saurauia luzoniensis
is one of the smallest second-story trees and is less prominent
than Oreocnide or Neolitsea. Its maximum height is about 6
meters, and its greatest diameter is about 7 centimeters.

Erect palms are much less numerous than in the Parashorea-
Diplodiscus association and are represented chiefly by scattered
specimens of Pinanga barnesii.

Tree ferns, Cyathea, are much more prominent. Scattered
individuals occur in the upper part of the dipterocarp forest.
From this point they gradually increase in numbers as higher
elevations are reached, until near the top of the mountain they
are more numerous than any other tree species. In the Quercus-
Neolitsea association they occupy about the same position that
erect palms do in the dipterocarp forest. They occur as scat-
tered individuals, which have little effect on the forest except
as ornaments.

Dicotyledonous vines are much less prominent than in the
Parashorea-Diplodisciis association. Climbing palms (rattans)
are numerous ; and, as the forest is so low that they cannot reach
great heights, they are very conspicuous. Their bulk, however,
is probably much less than in the dipterocarp forest. They are
much more prominent in some spots than in others. Where they
are relatively scarce, the main canopy is frequently well devel-
oped and the undergrowth very open. When they are numerous,
the forest appears to be very dense; but in such places the tree
growth is usually much less developed than in spots where they
are not conspicuous. The rattans, apparently, grow quickly
into the more open places where the main canopy has been dis-
turbed, and are afterwards put at a great disadvantage, as the
trees reach large size.

Next to the rattans species of Freycinetia (Pandanaeeae) are
the most conspicuous vines. In many places their long spirally
arranged leaves give a characteristic appearance to the vegeta-
tion. In Plate XVIII they can be seen very plainly on the trunks
of the trees. The trunks and branches of old trees are some-
times almost completely covered with them.

MIDMOUNTAIN FOREST g\

With the exception of small rattans, the ground covering is
largely herbaceous. Strobilanthes pluriformis, which is fre-
quently from 1 to 2 meters high and occasionally reaches about
4 meters, occurs in large numbers.

Among the smaller herbs Elatostema viridescens and E. carinoi
are the most prominent. These are succulents that in places
form a thick carpet over the ground. Ferns are much less
numerous, but they are rather conspicuous. Strobilanthes and
Elatostema- are alike in having very shallow root systems (see
Plates XVI and XVII).

The density of the undergrowth, except where rattans form
tangles, is very much less than in the dipterocarp forest, while
the ground covering is much better developed. The character
of the ground covering is shown in Plates XVI and XVII. The
open character of the undergrowth is apparently connected with
the decreased light intensity at the higher elevations, and the
more prominent ground covering of succulent herbs with moister
conditions.

In wet ravines Hymenophyllaceae may be fairly numerous;
the most prominent species is Trichomanes apiifolium.

Not only are epiphytes more numerous than in the dipterocarp
forest, but owing to the smaller size of the trees those in the
crowns are decidedly more in evidence. The most striking are
species of ferns and orchids large enough to render the indi-
vidual plants conspicuous. Those in the tops of the trees have
a xerophytic appearance, while the species in more-protected
situations are sometimes more mesophytic.

Species of ferns are more numerous than in the dipterocarp
forest. The most prominent are humus-gathering ones, particu-
larly Asplenium nidus (the bird's-nest fern) and Aglaomorpha
meyeniana. Aglaomorpha has fleshy stems, while the bases of
the leaves are modified into humus-gathering pockets. The
leaves are large, frequently more than a meter in length, pinnate,
and very handsome. Asplenium nidus is considerably smaller
in the midmountain than in the dipterocarp forest.

Orchids are frequently found on the trunks of the trees.
Probably the commonest is Dendrochilum glumaceum. The
flowers of this species are small, but are crowded in the racemes,
which are fairly striking. Showy orchids are very scarce in the
midmountain forest.

Dicotyledonous epiphytes are also present; among the most
Prominent are the vine Schefflera and the myrmecophilous genera

159549 6

82 MOUNT MAQUILING

Hydnophytum and Myrmecodia. These are not conspicuous
from the ground, but owing probably to the small size of the
trees are more in evidence than in the dipterocarp forest.

Mosses and various mosslike plants are frequently numerous
on the trunks of the trees, and these sometimes form a thin
layer over considerable areas of bark. Hepatics are often found
as epiphytes on leaves in ravines.

Strangling figs occur in this forest, but they are rare. Bizarre
plants are not so numerous as in the dipterocarp forest. The
saprophytic phanerogams are small and inconspicuous. The
most numerous are Epirixanthes cylindrica (Polygalaceae) and
the blue-flowered Cotylanthera tenuis (Gentianaceae). The root
parasite Christisonia wightii (Orobanchaceae) is slightly larger
and grows in small clumps. All of these plants are rare.

At an elevation of approximately 740 meters the ridge to
which this description applies is narrow and flat for a short dis-
tance. Just beyond this there is a steep ascent. The forest
on the flat is well developed and has relatively little undergrowth.
A large proportion of the dominant trees belongs to one species,
Astronia pulchra, which is represented by only a few individuals
on other parts of the ridge. The flat is, therefore, quite distinct
in composition from the remainder of the Quercus-N eolitsea as-
sociation. It has been included in the latter, however, as the
flat is small and the physical character of the vegetation is very
similar to that of the well-developed parts of the association.

TRANSITION FROM DIPTEROCARP TO MIDMOUNTAIN FOREST

The change from one association to another is usually gradual
and is marked by intermediate conditions. This is likely to be
particularly true of such complex associations as those on Mount
Maquiling. We have seen that the chief difference between the
dipterocarp forest ai^d the Quercus-Neolitsea association is that
the latter lacks the first story of the former. The first story
of the Quercus-Neolitsea association is approximately the same
height and is composed largely of the same species as the second
story in the dipterocarp forest. The disappearance of the first
story of the Parashorea-Diplodiscus association, as this forest
changes into the midmountain type, is gradual. In the well-
developed dipterocarp forest it forms a continuous canopy. This
gradually becomes more and more open, until these first-story
trees occur as scattered individuals only and finally disappear.

No marked change in the composition of the minor elements
occurs in this transition zone. In most of the dipterocarp forest
the ground is bare and herbs are scarce. In the Quercm-

MIDMOUNTAIN FOREST 83

Neolitsea association there is in most places a well-developed
ground covering of herbs, of which Elatostema carinoi and E.
viridescens are the most prominent. The change takes place,
not in the tension zone between the two associations, but in the
upper part of the dipterocarp forest. Elatostema begins to be
abundant at altitudes of 500 to 550 meters, and frequently covers
large areas just as it does in the Quercus-N eolitsea association.

Rattans, conspicuous as vines and in the undergrowth in the
dipterocarp forest, are very numerous in the lower part of the
Quercus-N eolitsea association ; but they are not prominent in the
upper part of this area or at higher elevations. The next most
conspicuous vines in both the upper part of the dipterocarp forest
and the lower part of the midmountain forest are the same
species of Freycinetia that are the most prominent vines in the
remainder of the midmountain forest.

The development of epiphytes is greater in the Quercus-
Neolitsea association than in the dipterocarp forest. This is due
to the general complex of conditions that causes increased
epiphytic vegetation as higher elevations are reached; there is
no marked change, either in amount or composition of this
vegetation, on the border between the two associations.

The midmountain forest is more open than the dipterocarp
forest. This change is also a gradual one and begins in the
upper part of the dipterocarp forest.

ASTRONIA ROLFEI ASSOCIATION

The ascent of the ridge, above an elevation of approximately
750 meters, is very steep for a height of about 100 meters. The
difference in slope is probably connected with the change that
takes place in the type of vegetation at this point. The trees
are usually much smaller than in the Quercus-N eolitsea associa-
tion, although some reach about the same heights. Many of
them have a tendency to assume a down -hill inclination (see
Plate XIX and Plate XX, fig. 1).

The small size of the trees is not due entirely to the general
complex of conditions that causes the vegetation to become more
and more dwarfed as higher elevations are reached. This is
*hown by the fact that on more gentle slopes at elevations just
above this steep region the trees are larger and the forest has
an appearance more like that of the Quercus-N eolitsea associa-
tion. The smaller sfze of the trees on the steep slopes would
s«em to be due to the unstable condition of the soil and to the
11 Perception by the mountain of a part of the light that would
feach vegetation on more even ground. The slanting of the

84 MOUNT MAQUILING

trees is likewise apparently connected with the effects of erosion
combined with a tendency to grow toward the light.

The most numerous trees are species of Astronia, particularly
Astronia rolfeL The forest is, however, a very mixed type.
The two-storied arrangement is not as well developed as in the
Quercits-NeoKtsea association. Most of the trees would belong
to the second story in the latter. The first story is well repre-
sented in patches, but in general is not continuous.

Rattans are not prominent and are usually small. The most
conspicuous vines are species of Freycinetia.

The forest is an open one. Palms are almost entirely ab-
sent; while tree ferns, particularly Cyathea caudata, are fairly
numerous. The ground covering is herbaceous and very similar
to that in the Quercus-Neolitsea association. Epiphytes are
more numerous. At this and higher elevations the pitcher plant
Nepenthes alata grows as an epiphytic vine in the crowns of the
trees. The insect-catching pitchers of this plant are striking
when seen at close range, but it is very difficult to find them
among the foliage usually surrounding them.

DESCRIPTION OF PLOT

The plot used for detailed measurements in the midmountain
forest was at an elevation of approximately 700 meters. It
was the same size, 50 meters square, as the plots in the diptero-
carp forest and had a similar slope and exposure. As in the
other cases the trees were cut, measured with a tape, and then
removed. The results are given in Tables XVII to XXII. In
these tables the first story is regarded as being from 14 to 22
meters in height, and the second as being from 2 to 14. This
arbitrary division has the advantages and disadvantages that
were mentioned in the discussion of the tables for the virgin
dipterocarp forest. As in the former case the division is ap-
proximately correct.

Table XVII gives the heights of all erect woody plants more
than 1 meter high. The total number was 578, distributed in 48
genera and 72 species. Besides these there were 255 erect
herbs more than a meter in height. Twelve were of the arbores-
cent aroid Alocasva macrorrhiza, and the remainder were Stro-
bilanthes pluriformis. The tallest of the latter was 3.85 meters
high, while 201 of them were between 1 and 2 meters in height.

MIDMOUNTAIN FOREST

85

Table XVII. — Height of all erect plants over 1 meter high on 0.25 hectare
in midmountain forest (Quercus-Neolitsea association) on Mount Ma-
quiling ; altitude, 700 meters.

[** Indicate that the species is also found in the dipterocarp forest; * that the genus but not
the species is found in the dipterocarp forest.]

[Figures represent numbers of individuals.]

Species.

FIRST-STORY SPECIES.

Aglaia harmsiana (malasaging)

lto2.

1
1

Height in meters
2 to 6. 6 to 10. 10 to 14.

2 !

14 to 18.

18 to 22.

Amoora cumingiana _

1

1

Antidesma pleuricum

1
2

Ardisia boissieri (tagpo)

1
1

1

Ardisia sp

Bischojia javanica (tuai)

1

i !

Ca narium sp. (isarigjuac)

1

Chisocheton cumingianus (sa-
laquin-puti)

3
1

Cinnamomum mercadoi (ca-
lingag)

;
i ;

Cratoxylon blancoi .

2

8

Cratoxylon celebicum (guyong-
guyong)

„

1

13
1

3

Croton leiophyllus .

1
1

Dysoxylum turczaninowii -

. _

Elaeocarpus calomala J .

1

1

Eugenia arcuatinervia

Eugenia luzonensis (malaru- j

hat puti)

3
1

1

Eugenia sp. (malabayabas) ] -

1

1

2

1

I

Ficus garciae _ _ j_ .

1
3

Ficus paucinervia (tangisang j

biauac) _J

1

Ficus variegata (tangisang

biauac)

1
4
1

1

i j____

j i

___ i

Grewia stylocarpa (susumbic)-!

Litsea garciae j

Mastixia philippinensis (ta- j

pulao) . . 1

1

| j

Nauclea junghuhnii (mambog) ,

Neonauclea calycina (uisac)

Palaquium philippense

(palac palac)

Planchonia spectabilis (lamog)

3

4

; 3

1

1

3
1
1

j
1 1

3 ! 1

- 2

; i

Polyalthia sp

::' ::;:i::::::::

I

!

1

2
■2

1

Quercus soleriana (cataban) _

—

2

2 1 4

2

Saurauia whitfordii

1

Symplocos ahernii

1

2

Terminalia pellucida (talisay-
gubat) ._ ._

1

! |

• !

1 '

Weinmannia luzoniensis ' __.

1 ! 1

11 11 2 1 3

86

MOUNT MAQUILING

TABLE XVII. — Height of all erect plants over 1 meter high on 0.25 hectare
in mid/mountain forest (Quercus-Neofitsea association) on Mount Ma-
quiling; altitude, 700 meters — Continued.

No.

72

Species.

Height in meters.

1 to 2. I 2 to 6. I 6 to 10. 10 to 14. 14 to 18.J18 to 22.

Total.

SECOND-STORY SPECIES.

2

3

11

1 ' i 1 •

3 6 l! 12

** Astronia williamsii (dungao) - .

2

1

1

4

i

13

3

2

3

** Dillenia philippinensis (cat-

3

!

5

2
1
3

** Dillenia reifferscheidia (cat-

2

1
2

15

1

** Eugenia crassipes (calubcob) .__

12

27

1

1

1
5

1

2

1

8

1
1

1

1
6
3
1

1
8
1
2

5
3

;

..

. j

1

i

** Glochidion trichogynum (bog-

1

I

3
1
1
3

19
5

15

5

Indt , - —

*•* Laportea subclausa (lipa)

1

3

1

2
1

22

6

15

1

J

1

1

5
6
2
5
52
88
2

49
8
3

6

;

6

2

** Memecylonpaniculatum (culia)

1
3
5

2

24
23

8

7

l ! l

88

** Oreocnide trinervis (malatuba) _

116

2

6
1

!

55

1
1

|

10

1

4

2

1

2

SHRUBS.

1

j

1

j _

Total .

39

352

94

41

36 | 16

578

HERBS.

Alocasia macrorrhiza _.

12
42

12

201

243

Grand total.-.

240

406

94

41

36

16

833

MIDMOUNTAIN FOREST g7

In Table XVII there are listed 35 first-story species and 36
second-story ones. The total number of species of erect woody
plants more than 2 meters high was 70, whereas there were 92
on the plot of equal size in the virgin dipterocarp forest. The
smaller number would seem to be the natural result of the
adverse conditions that caused the disappearance of the first
story of the dipterocarp forest.

The species mentioned in Table XVII that also occur in the
dipterocarp forest are marked with two stars; where the genus
but not the species has been found in the dipterocarp forest,
one star is used.

Many of the species in both types occur only as scattered
individuals, so that it is very difficult to determine their distri-
bution. Moreover, only a small proportion of the species is
in flower at any one time, so that it is frequently impossible to
identify the trees as to the species. Among the ninety-two
species on the quarter of a hectare in the dipterocarp forest
were one unidentified tree and nineteen others which could not
be determined as to the species. This was due in part to the
similarity of related species and in part to the present state of
our knowledge of many Philippine genera. In such a mixed
forest as that on Mount Maquiling it is natural that species new
to the mountain are frequently found. Only an intensive study
of the flora of Maquiling would make it possible to give anything
like an exact discussion of the distribution of the component
species. Such a study would be an extensive undertaking and
is beyond the limits of the present paper.

Among the first-story species there were 28 that also occur
in the dipterocarp forest. There were 4 species that could be
identified only as to the genus. All of these genera are repre-
sented by a number of species in the dipterocarp forest; and it
is probable that these 4 species would have been found to occur
in this forest, if they could have been identified as to the species.
The remaining 3 species were not seen in the dipterocarp forest,
but belong to genera that occur in this formation. These 3
species are relatively rare on Mount Maquiling, but it is prob-
able that one of them, at any rate, Cratoxylon blancoi, will be
found in the dipterocarp forest. Most of the 28 species known
from the dipterocarp forest are common in that formation.
There were 13 of them on the plot in the virgin dipterocarp
forest and 9 on that in the culled forest. Nineteen of the species
were on one of the two plots. The number of species common
to the plots in both formations is large, when compared with
the number found on both plots in the dipterocarp forest. On

88 MOUNT MAQUILING

the plot in the culled dipterocarp forest there were 129 species,
only 29 of which were identified on the plot in the virgin forest.

Of the 28 species found in the first story on the plot in the
midmountain forest and which also occur in the dipterocarp
forest, 24 are second-story species in the latter formation, while
4 belong to the first story. The latter are Bischofta javanica,
Eugenia luzonensis, Pometia pinnata, and Planchonia spectabilis.

Table XVII shows that there were 36 second-story species
on the plot in the midmountain forest, of which 27 occur in
the dipterocarp forest. Seven of the identified species and one
of the genera were not observed in the latter formation. One of
the remaining species could not be identified, while the other
was determined only as to the genus. Of the 27 second-story
species that occur also in the dipterocarp forest, 22 are third-
story trees in the latter formation, while 5 belong in the second
story. These are Dillenia philippinensis, Dillenia reifferschei-
dia, Ficus linearifolia, Ficus vibes, and Memecylon paniculatum.

The above figures show that of the identified species on the
plot, 90 per cent of the first-story species and 81 per cent of
those in the second story occur in the dipterocarp forest. From
this it will be seen that the Quercus-Neolitsea association is
made up largely of species that occur in the dipterocarp forest.
Many of the species in the various stories of the latter, however,
are not found in the midmountain formation. Moreover, the
abundance of a species in the dipterocarp forest apparently
affords little indication as to whether or not it will be found at
higher elevations. Parashorea malaanonan and Celtis philip-
pensis, the most numerous species in the first story of the
dipterocarp forest, do not occur in the Quercus-Neolitsea associa-
tion. However, Bischofia javanica, Eugenia luzonensis, and
Planchonia spectabilis are common species in the first story of
the dipterocarp forest and are also in the Quercus-Neolitsea as-
sociation. Dillenia philippinensis, probably the third most
numerous species in the second story of the dipterocarp forest,
is represented by five individuals on the plot in the midmountain
forest and is common throughout this formation, while many
other numerous second-story species in the dipterocarp forest
do not occur at higher elevations.

The species that occur as first-story trees in both the dip-
terocarp and midmountain forests have a very different size in
the two situations. This change in physical type is evidently
due to the environmental conditions that have caused the mid-
mountain formation to be a small forest. What has just been
said apparently applies also to the species common to the second

MIDMOUNTAIN" FOREST

89

story of both the dipterocarp forest and the Quercus-Neolitsea
association.

In Table XVIII are shown the greatest heights and diameters
attained on the plot by each species, the total volume of each
species, and the volume of trees more than 14 meters in height
(in the first story) and of trees less than 14 meters in height
(in the second story) . The figures represent the volume of that
part of the trunk that was free from branches. The volume
of individuals less than 10 centimeters in diameter was very
small and so has been omitted from the table.

Table XVIII.— Stand of erect plants over 1 meter in height on 0. 25 hectare
in midmountain forest (Quercus-Neolitsea association) on Mount Ma-
quiling; altitude, 700 meters.

Species.

FIRST-STORY SPECIES.

Aglaia harmsiana (malasaging)

Amoora cumingiana

Antidesma pleuricum .- __

Ardisia boissieri (tagpo) _ ...

Ardisia sp ._

Bischofia javanica (tuai) -_

Canarium sp. (isangjuac) ...

Chisochetoncumingianus (salaquin-puti) _

Cinnamomum mercadoi (cali ngag)

Cratoxylon blancoi

Cratoxylon celebicum (guyong-guyong) _ .

Croton leiophyllus

Dysoxylum turczaninowii

Elaeocarpus calomala

Eugenia arcuatinervia

Eugenia luzonensis (malaruhat puti)

Eugenia sp. (malabayabas) ._.

Fieus garciae _

Ficu8 paucinervia (tangisang biauac)

Ficus variegata (tangisang biauac)

Grewia stylocarpa (susumbic) _._

Litsea garciae

Mastixia philippinensis (tapulao)

Nauclea junghuhnii (mambog) . _

Neonauclea calycina (uisac) _..

Palaquium philippense (palac palac)

Planchonia spectabilis (lamog )._. _

Polyalthia sp

Pometia pinnata _ _.

Quercus robinsonii (oayan)

Quercus soleriana (cataban) _.

Saurauia whitfordii

Symploeoa ahernii _

l Num-
ber
of
i indivi-
i duals.

Great-
est

height

on

plot.

m.

4.30

5.30

9.56

10.95

7.32

21.76

17.70

5.74

2.45

13.33

20.76

15.00

2.70

19.14

6.24

5.06

15.70

21.55

20.03

18.55

15.00

2.32

1

3.80

5

13.78

9

14.85 j

8

16.30

2

16.97

1

7.08

1

21.80

2

2.65

L2

21.68

1

14.25

3

8.27

Great-
est
diam-
eter
on
plot.

cm.

3.0

6.0

20.0

11.0

14.0

85.0

32.5

9.0

2.5

26.0

58.0

22.0

2.0

45.0

6.0

6.0

45.0

45.0

53.0

28.0

25.0

2.0

2.5

27.0

17.0

32.5

32.0

14.0

62.0

2.0

56.0

45.0

9.0

Volume.8

I
i

1 Trees

4 to 14

Total, meters

in

height.

Trees j
14 to 22;
meters

in
height.

cu. m.

cu. m.

cu. m.

0.06

0.06

0.06

0.06

|

0.06

0.06

|

6.02

0.14

5.88

0.49

0.49

0.36

0.36

7.03

0.63

6.40

0.13

0.13

1.84 j'

1.84

1.02

1.02

1.98

1.98

3.63

3.63

0.39

0.05

0.34

1 0.19

i

0.19

j

1 0.34

0.34

j 0.26

0.17

0.09

i 0.51

0.51

0.55

0.03

0.52

0.04

0.04

1.48

1.48

6.22

1.47

4.75

0.44

0.44

90

MOUNT MAQUILING

Table XVIII. — Stand of erect plants over 1 meter in height on 0.25 hectare
in midmountain forest (Quercus-N eolitsea association) on Mount Ma-
quiling; altitude, 700 meters— Continued.

37

38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
63
67
68
69
70
71

72

Species.

j Num-
ber

I of
! indivi-
! duals.

first-story species— continued.
Terminalia pellucida (talisay-gubat)

Weinmannia luzoniensis

SECOND-STORY SPECIES.

Astro7iia rolfei (dungao)

Astronia williamsii (dungao)

Cyathea caudata ..

Decaspermum paniculatum

Dillenia philippinensis (catmon)

Dillenia reifferscheidia (catmon carabao)

Eugenia astronioides

Eugenia calubcob (calubcob) - - -

Eugenia crassipes (calubcob)

Ficus linearifolia (auymit) -

Ficus nota (tibig)

Ficus ribes (auymit)

Ficus sp

Glochidion album (magna) —

Glochidion lancifolium

Glochidion merrillii

Glochidion trichogynum (bogna)

Homalanthus fastuosus

Indt —

Laportea subclausa (lipa)

Leea aculeata .--

Leea manillensis

Leea philippinensis

Leea auadrifida -

Leucosyke capitellata (lagasi)

Medinilla astronioides

Medinilla venosa

Meliosma sylvatica

Memecylon paniculatum (culis) .

Neohtsea villosa

Oreocnide trinervis (malatuba) _

Pinanga barnesii

Saurauia luzoniensis .

Thea montana .._

Urophyllum banahaense

Vernonia lancifolia

SHRUBS.

Cyrtandra incisa

TotaL---

HERBS.

Alocasia macrorrhiza

Strobilanthes j)luriformis .

Total erect plants over 1 meter high.-

116
2
55
10
4
2

Great-
est

height

on

plot.

Great-
est

diam-
eter
on

plot.

14.10
19.00

15.11

7.38
5.45

13.40

11.40
8.90
3.00
8.00
4.27
7.03
2.90
7.37 |
6.30
6.14
2.65
7.31
1.07
9.56
3.30
1.80
4.80
6.15
7.10
5.10
7.01
3.82
3.82
5.42
6.65

18.55
8.60
5.80
5.40
6.27 |
6.72 j

12.36 i

1.10

Total.

Volume, a

Trees
4 to 14

meters
in

height.

8.0
3.5
3.0
4.0
9.0

12.5
7.0

14.0
6.0
6.0
4.5
9.0

30.0

18.0
6.0
8.0

17.0
8.0

41.0

1.5

12

243 j

833 i

2.60
3.85

17.0
3.0

0.21
0.32
0.30

cm. cu. m.
19. 07 0. 12
53. 5 2. 77

30.0

8.0

11.0

18.0

20.0

33.0

2.0

13.0

5.5

15.0

4.0

19.0

12.0

6.4

3.0

5.0

0.12

0.21
0.32
0.30

0.02

1.87
0.05

0.09

41.13

1.32
0.05

0.09
0.80

7.85 33.28

* Volume of trees less than 10 centimeters in diameter is omitted.

MIDMOUNTAIN FOREST

91

Table XIX gives a summary of the data presented in Tables
XVII and XVIII. From this table it will be seen that there
were 52 individuals in the first story, whereas in the second story
of the dipterocarp forest there were 54 individuals. This em-
phasizes the similarity of the first story in the midmountain
forest and the second story in the dipterocarp forest. On the
plot in the midmountain forest there were 539 individuals more
than 2 meters in height as against 353 in the dipterocarp forest.

Table XIX. — Summary of composition of different stories on 0.25 hectare
in midmountain forest (Quercus-Neolitsea association) on Mount Ma-
quiling; altitude, 700 meters.

Story to which species belong when the indi-
viduals are mature.

First

Second -.

Total

Stories in which individuals
present were found.

First story;

height, 14 to

22 m.

Trees. !

cu. m.
49 I 32.46
3 | 0.82

52 ! 33.28

-

Total.

Second story;

height, 2 to

14 m.

Trees.

Vol-
ume.

cu. m.

Trees.

Vol-
ume.

cu. m.

77

3.53

126

35.99

410

4.32

413

5.14

. 487

7.85

539

41.13

The larger number in the midmountain forest is apparently con-
nected with the fact that the tall dominant story of the dipter-
ocarp forest is lacking, so that the lowest story receives more
light. In the first story there are 3 individuals belonging to
second-story species. One of these is an individual of Astronia
rolfei, which an examination of Table XVIII shows was just
within the limits of the first story. Two were individuals of
Neolitsea villosa, one of which was also just within the limits
of the first story; while the other, which was 18.55 meters in
height, had all of its branches except a single, tall, slender one
well within the second story. The number of individuals in the
second story was 487, or 9.4 times as many as in the first story.
In the second story there were 410 individuals of second-story
species and 77 of the first story, showing that the second story
is made up very largely of second-story species. This condition
is very different from that found in the third story on the plot
in the dipterocarp forest, where only 27.6 per cent of the total
number of individuals in the third story were of third-story
species.

An examination of Table XVII shows that the most numerous
first-story species was Cratoxylon celebicum (guyong-guyong) ,

92 MOUNT MAQUILING

with 25 individuals, while the next most numerous was Quercus
soleriana (cataban), with 12 individuals. The most numerous
second-story species was Oreocnide trinervis (malatuba), with
116 individuals; the next, Neolitsea villosa, with 88 individuals;
and the third, Saurauia luzoniensis, with 55 individuals. These
last three species together were represented by 259 individuals,
which were 45 per cent of all erect woody plants more than 1
meter in height. Each of these three species was much more
numerous on the plot in the midmountain forest than any species
on the plot in the dipterocarp forest. The most numerous species
in the latter case was Parashorea, malaanonan, with 29 individ-
uals more than 2 meters in height; whereas on the plot in the
midmountain forest Oreocnide trinervis was represented by 111
individuals more than 2 meters in height; Neolitsea villosa, by
85; and Saurauia luzoniensis, by 49.

Table XIX shows that the total volume on the plot in the
midmountain forest was 41.13 cubic meters. As was to be ex-
pected this is much smaller than that on the plot in the dipter-
ocarp forest, which was 76.35 cubic meters. The trees showing
the greatest volume were Cratoxylon celebicurri, with 7.3 cubic
meters ; and Quercus soleriana, with 6.22. The total volume of
all trees in the first story was 33.28 cubic meters, and in the
second story, 7.85 cubic meters. The volume of first-story trees
in the first and second stories is 35.99 cubic meters, and of
second-story trees, 5.14 cubic meters. A large portion of the
volume was of first-story trees in the first story, this being 32.46
cubic meters, or 79 per cent of the total. The average volume
of all trees in the first story was 0.64 cubic meter, and of all
in the second story more than 10 centimeters in diameter, 0.09
cubic meter. The average volume of trees in the first story is
much less than that of first-story trees in the dipterocarp forest,
which have an average volume of 3.1 cubic meters, but consider-
ably greater than the average volume of second-story trees in
the dipterocarp forest, these having an average volume of 0.46
cubic meter. The average volume of all trees more than 10
centimeters in diameter in the second story is more than three
times that of all third-story trees more than 10 centimeters in
diameter in the dipterocarp forest. The average volume of first-
story trees in the first story was 0.66 cubic meter; of all first-
story trees more than 10 centimeters in diameter in the second
story, 0.13 cubic meter; and of all second-story trees more than
10 centimeters in diameter in the second story, 0.07 cubic meter.
These figures emphasize the difference in the size of trees in
the different stories.

MIDMOUNTAIN POEEST

93

Table XX. — Diameter classes of all trees over 10 centimeters in diameter
on 0.25 hectare in midmountain forest (Quercus-Neolitsea association)
on Mount Maquiling ; altitude, 700 meters.

[Figures represent numbers of individuals.]

No.

1
2
3
4
5
6
7
8
9
10
11
12

13
14
15

16

17

18
19
20
21
22
23

Species.

FIRST-STORY SPECIES.

Antidesma pleuricum

Ardisia boissieri (tagpo)

Ardisia sp

Bischofia javanica (tuai)

Canarium sp. (isangjuac)

Cratoxylon blancoi

Cratoxylon celebicum

Croton leiophyllus-

Elaeocarpus calomala

Eugenia sp. (malabayabas)

Ficus garciae

Ficus paucinervia (tangisang bia-

uac)

Ficus variegata (tangisangbiauac)

Grewia stylocarpa (susumbic)

Nauclea junghuhnii (mambog)

Neonauclea calycina (uisac)

Palaquium philippense (palac pa-
lac)

Planchonia spectabilis (lamog)

Polyalthia sp

Pometia pinnata,

Quercus soleriana (cataban)

Saurauia whitfordii

Terminalia pellucida (talisay-gu-

bat)

Weinmannia luzoniensis

Diameter class in centimeters.

10 to j 20 to ! 30 to I 40 to l 50 to
20. 30. | 40. I 50. ! 60.

SECOND-STORY SPECIES.

Astronia rolfei (auymit) ___ _.

Decaspermum paniculatum

Dillenia philippinensis (catmon) _
Dillenia reifferscheidia (catmon ca-

rabao) _.

Eugenia calubcob (calubcob)

Ficus linearifolia (auymit)

Ficus ribes (auymit)

Ficus sp._

Leea philippinensis

Leucosyke capitellata

Neolitsea villosa

Oreocnide trinervis (malatuba) ___

Thea montana

| Vernonia lancifolia

Total

l !
11 !

i !
i

60 to , 70 to

70. j 80.

80 to
90.

1 j

1 I-

1 ].

To-
tal.

1
1
1
2
1
2
24
1
2
1
2

5
2

1
1
4

2
2

1
1
8
1

2

7

10
3
4

1
24
10
2
2

1 138

94

MOUNT MAQUILING

In Table XX is shown the distribution according to diameter
classes of 10 centimeters of all trees more than 10 centimeters
in diameter. The total number was 138, or 24 per cent of the
total of all trees more than 1 meter in height on the plot. These
were distributed in 29 genera and 38 species. Seventy-two, or
52 per cent, were between 10 and 20 centimeters in diameter,
while only 7, or 5 per cent, were more than 50 centimeters in
diameter. These 7 individuals were all first-story species.
Only 2 individuals of second-story species were more than 30
centimeters in diameter, while 26 individuals of first-story spe-
cies had a diameter greater than 30 centimeters. This again
shows the difference in size of first- and second-story species.

Table XXI. — Diameter classes of trees more than 10 centimeters in dia-
meter in the different stories on 0.25 hectare in midmountain forest
(Quercus-N eolitsea association) on Mount Maquiling; altitude, 700
meters.

[Figures represent numbers of individuals.]

Diameter class in centimeters.

Story.

10 to 20.

3

69

72

20 to 30.

30 to 40. 40 to 50.

50 to 60.

60 to 70.

70 to 80.

80 to 90.

Arer-

age.a

First

Second

23
15

38

9 ; 10
1 1 1

4
1

1 1 — -j 1

.L_ _

34.3
17.7

Total

10 11 5

i

1

a The average diameters were calculated from the exact measurements and not from the
figures in this table.

In Table XXI is shown the distribution of the diameter classes
in the two stories. It will be seen that 69 out of 72 trees between
10 and 20 centimeters in diameter were in the second story.
The larger size of the first-story trees is very evident from the
figures in the table. The average diameter of the first-story
trees was 34.3 centimeters ; and of the second, 17.7 centimeters.

Table XXII gives the clear length of all first-story trees in
the first story ; that is, those between 14 and 22 meters in height.
There were 49 of these, and they were distributed in 16 genera
and 18 species. Only 2 individuals had clear lengths greater
than 14 meters, while 4 had clear lengths of less than 4 meters.
This shows very clearly that most of the first-story trees pos-
sessed branches that were within the region regarded as belong-
ing to the second story, and that there was consequently a
considerable overlapping of stories. This overlapping was, how-
ever, not so great as is indicated in the table, as the lowest
foliage of the tree is frequently much higher than the origin
of the first branches.

MIDMOUNTAIN FOREST

95

Table XXII. — Clear length of first-story trees 1U to 22 meters in height
on 0,25 hectare in midmountain forest (Quercus-Neolitsea association) ,
on Mount Maquiling ; altitude, 700 meters.

[Figures represent numbers of individuals.]

No.

! 1

Clear length in

meters.

Bischofia javanica (tuai) .

2 to 4.

4 to 6.

6 to 8.

8 to 10.

10tol2.

12tol4..14tol6.

i

1 !

1 2

Canarium sp. (isarigjuac)

1
4

1

! 3

Cratoxylon celebicum (guyong-gu-
yong)

i

4
1

5

2

|

! 4

Croton leiophyllus __ ._

J

5

Elaeocarpus calomala.^

1

1

6

l'

!

7

Ficus parciae __ |__ __ .

1
1

1

- J 1

8
9
10

Ficus paucinervia (tangisang bia- i

uac) ] 1

Ficus variegata (tangisang bia- i

uac) .__

1

1

I

i !

Grewia stylocarpa (susumbic) - _.

1
1

1

11

Neonauclea calycina (uisac)

1 :

12

Palaquium philippense (palac pa-
lac)

1
1

J

13

14

Planchonia spectabilis (lamog).. J

1

Pometia pinnata

1
1
1

i !

15

Quercus soleriana (cataban)

1

v3

";i:::::::l::::::::

16

Saurauia whitfordii

17

Terminalia pellucida (tali say -
gubat)

1
1

12

" i '

18

Weinmannia luzoniensis . _

2

4

2
13

Total

11

. . |

5

2 2

1
!

In order to determine the character of the ground covering, a
plot 10 meters square was selected within the limits of the plot
of 2,500 square meters, and all terrestrial plants on it measured.
The ground covering on this plot was approximately average for
the forest. The results are given in Table XXIII. The total
number of terrestrial plants on the 100 square meters was 1,630,
of which 1,565 were less than 1 meter high; 18 were between
1 and 2 meters high; 37 were between 2 and 12 meters high; and
10 were between 12 and 22 meters high. There were present 23
species of trees represented by 122 individuals, of which 94 were
less than 1 meter high, and 28 were more than 1 meter high.
This would indicate a high mortality among the small individ-
uals. Four of the 23 species are not found in Table XVII,
where all individuals more than 1 meter in height on the plot
of 2,500 square meters are enumerated. This would seem to
show that, if a plot larger than 2,500 square meters had been

96

MOUNT MAQUILING

used, the number of tree species found on it would have been
greatly increased. No shrubs were found on the area.

Table XXIII. — Composition of plot 10 meters square in midmountain forest
formation on Mount Maquiling ; altitude, 700 meters.
[Figures represent numbers of individuals.]

No.

1
2
3
4
5
6
7
8
9

10
11
12
13
14
15
16
17
18
19
20
21
22
23

Species.

TREES.

Aglaia sp _

Height in meters.

Total.

1
2
1
4

16
2
1
2
2

17
2
2
1
2

39
2

14
6
1
1
1
2
1

122

Otol.

lto2.

2 to 12.

12 to 22.

1
2

Arenga pinnuta _ _ . .

Astronia rolfei __

1
1

3
3

Cratoxylon celebicum _ _ _ _

Cyathea caudata

12
2

1

Elaeocarpus calomala _ .

Eugenia sp.. __ __ ._ _

1

Eugenia areuatinervia

Eugenia luzonensis

2
2

17

Eugenia mananquil __ _

Fieus ribes .__

2

Litsea sp _

2

Memecylon paniculatum __

1
1
4
2

1

Neonauclea calycina

Neolitsea villosa

34

1

Oreocnide trinervis _ _____

Pinanga barnesii __ _ _

14
3

1
1
1

Saurauia luzoniensis

3

Symploco8 ahernii

Terminalia sp

Urophyllum banahaense _

2

1

Weintnannia luzoniensis ___

Total

HERBS.

Alpinia brevilabris

94

2

16 J 10

24

10

1

46

5

699

463

2

99

1

_

11
1

46
8

699

463

2

115

25
26
27
28
29
30
31

32
33
34
35

CaXanthe triplicata. __> __

Chloranthus officinalis _

Donax cannaeformis _

3

Elatostema viridescens _ _

Elatostema carinoi _ ___

Strobilanthes pluriformis ... _ _ __

5

11

Total

1,325

5

15

1,345

VINES.

Calamus antl Daemonorops (rattans)

103
5

12
2
1

23

8

6

117
5
12

Freycinetia robinsonii _ . _

i

Freycinetia williamsii

1

2

36

Rourea volubUis

1

37

3

26

Total

Total of all species

146

11

6

163

1,565

18

37

10

1,630

MIDMOUNTAIN FOREST 97

Herbs were represented by 8 species and 1,345 individuals,
or 83 per cent of the total. Of these, 1,325 were less than 1
meter in height, and only 20 were more than 1 meter high. By
far the most numerous species were Elatostema viridescens, with
699 individuals, and E. carinoi, with 463 individuals. The next
most prominent species was Strobilanthes pluriformis, with 99
individuals. All three of these species have shallow root
systems and occur only in moist situations.

Of vines there were 6 species and 163 individuals. As in the
dipterocarp forest, the most prominent species were Calamus
and Daemonorops (rattans), these being represented by 117
individuals, 103 of which were less than 1 meter in height. The
next most prominent species was a climbing bamboo, Schizo-
stachyum diffusum, with 26 individuals.

On the plot of 100 square meters in the dipterocarp forest
there was a total of 492 individuals, whereas on the same-sized
plot in the midmountain forest there were 1,630 individuals,
or 3.3 times as many as in the dipterocarp forest. On the 100
square meter plot in the dipterocarp forest there were 427 indi-
viduals less than 1 meter in height, or an average of 4.3 plants
to the square meter. On the same-sized plot in the midmountain
forest there were 1,565 plants of similar height, or an average of
15.6 to the square meter. The difference in the density of the
ground covering in the two cases is very apparent upon a com-
parison of the two areas. The difference in the number of herbs
is particularly striking, as there were only 66 on the plot in the
dipterocarp forest and 1,345 on that in the midmountain forest.
They were not only more numerous in the midmountain forest,
but also more mesophytic in appearance. This difference is very
evidently connected with the moister condition prevailing in the
latter formation.

159549 7

MOSSY FOREST

The top of Mount Maquiling is in the cloud belt, and for a very
large portion of the time it is bathed in clouds. Consequently
the relative humidity is high and evaporation low. This condi-
tion is responsible for many features observed in the forest at
the summit of the mountain. This forest is, in many ways,
more interesting than any of those at lower elevations. It has
been designated the mossy forest because the branches and
trunks of the trees are largely covered with mosses and moss-
like plants. Plate XXVIII shows a typical view near the summit
of the mountain ; the epiphytic covering is very evident.

The mossy forest on Mount Maquiling may be called a Cyathea-
Astronia association, as Cyathea and Astronia are the two most
prominent genera. An exterior view of this forest is shown in
Plate XX, fig. 2. It is composed of a single story of low trees.
Slightly below the summit the average height of the canopy is
about 10 meters, while at the summit it is not more than 6 or
8 meters. The trees have a great tendency to send out
aerial roots, a feature which is apparently common to all tree
species growing in this situation. This tendency is probably
connected with the very moist condition of the atmosphere, and
causes the trees to assume very fantastic shapes. A rather ex-
treme case of aerial roots is shown in Plate XXII. These roots
frequently develop until they have the appearance of secondary
trunks, and in many cases it is impossible to identify the original
trunk. Much of the ground is very steep, and in such places
trees frequently incline downhill, or even fall to the ground. In
either case they usually send out additional roots from the trunks
and also from large branches. Such a condition naturally adds
to the peculiar appearance of the trees.

The covering of mosslike plants on the trees is usually several
centimeters in thickness and may be about 30 centimeters
thick. On the smaller branches mosses are the most con-
spicuous elements in this covering. Here the covering is usually
not complete, but occurs rather in isolated bunches which are,
however, frequently close to each other. Growing in with the
moss are a few species of small xerophytic-appearing orchids,
ferns, and some phanerogams. Plate XXIII shows a clump of
98

MOSSY FOREST 99

moss growing on a branch of a tree. The lower end of the cut
branch is seen in the lower left-hand corner of the picture. The
branch here is 3 centimeters in diameter. The greatest diameter
of the moss on this branch was 27 centimeters. To the right
in the picture the grasslike orchid Dendrochilum glumaceum is
seen growing from the moss. At the upper left is a specimen
of Rhododendron quadrasianum growing from the moss, while
in the center are two species of ferns. Rhododendron quadra-
sianum reaches a height of 2 meters or more and is probably the
largest epiphyte in the upper portion of the mossy forest. Plate
XXIV shows the connection of a large specimen of Rhododendron
with the plant on which it is growing. For convenience in
photographing, the branch on which the Rhododendron was
found was cut and placed upright on the earth, and the mosses
around the roots of the Rhododendron were removed. This
branch and the roots of the Rhododendron show clearly in the
center of the lower part of the picture, while all of the conspicu-
ous small leaves occupying the upper center belong to this plant
of Rhododendron. Note the mosses growing on the Rhododen~
dron. These were naturally somewhat disturbed in removing the
plant from its original position.

On. the trunks the epiphytes have a much more hygrophilous
appearance. Mosses are less conspicuous, their places being
taken largely by small filmy ferns and liverworts, while a small
species of Selaginella, S. maquiliensis, is very abundant. Grow-
ing in with these are larger filmy ferns, species of Polypodiaceae,
and phanerogamic epiphytes. In shallow ravines medium-sized
species of Hymenophyllaceae are very abundant on the trunks
and the lower branches of the trees.

Shreve * has shown that in the forest at high altitudes on the
Blue Mountains of Jamaica the epiphytes in the tops of the trees
are more xerophytic than those lower down. This same con-
dition in the Blue Mountains and on Mount Maquiling is due, in
both cases, to the fact that conditions are moister at lower eleva-
tions in the forest than in the tops of the trees. Plate XXV
shows a tree trunk covered largely with a growth of Selaginella
and the filmy fern Trichomanes proliferum. Plate XXVI shows
a covering of mosses and liverworts in which is growing the
conspicuous filmy fern Trichomanes apiifolium. Plate XXVII
shows a growth consisting largely of liverworts and mosses on
the small aerial roots of a tree. On the lower branches and on

* Shreve, F., A Montane Rain-forest, Pub. Carnegie Inst. Washington
<1914), No. 199, 1-110.

100 MOUNT MAQUILING

the aerial roots liverworts and mosses frequently form festoons.
In Plates XXVIII and XXIX is shown a typical covering of
liverworts and mosses on the lower portions of trees and on the
aerial roots. Bird's-nest ferns occur in the lower part of the
mossy forest, but they are smaller than at lower altitudes.

The epiphytic vine Nepenthes alata is more abundant than in
the upper part of the midmountain forest. It occurs in suffi-
cient numbers to be found easily, but does not form a conspicuous
part of the vegetation. This plant is shown in Plate XXX, fig. 1.
Strangling figs are found scattered in the lower part of the
mossy forest, but are not a prominent element.

Very frequently terrestrial plants are prominent as epiphytes.
A very conspicuous case is seen in Plate XXXI. This represents
a branch of a tree which is so completely covered by a growth
of mosslike plants as to conceal the branch. In the lower left-
hand corner of the picture the mossy covering is very evident.
Growing in this, and occupying most of the picture, is a growth
of Medinilla myrtiformis and M. venosa. These two species of
Medinilla are sometimes independent terrestrial shrubs, but are
more usually woody vines. Growing among the two species of
Medinilla shown in the picture, but hidden by them, are two
seedlings of different tree species, two species of Polypodiaceae,
several large filmy ferns, and Utricularia rosulata.

The tree fern Cyathea is very common and conspicuous, it
being the most numerous tree species in the mossy forest. It
grows luxuriantly among the other trees, but its crown is not
usually fully exposed to the action of sun and wind. Plate I
(frontispiece), shows a group of tree ferns {Cyathea) found
in a ravine a little below the top of the mountain.

Vines, both epiphytic and terrestrial, are fairly prominent,
although represented by comparatively few species. Perhaps
the most conspicuous are species of Freycinetia, particularly
Freycinetia williamsii. The habit of this plant is shown very
clearly in Plate XXX, fig. 2. A typical view in a region slightly
below the top of the mountain is given in Plate XXXII. It will
be seen that Freycinetia is conspicuous in giving character to
the appearance of the vegetation. Another very prominent vine
is the coarse climbing fern Oleandra colubrina. Species of Medi-
nilla are also numerous. Medinilla multiflora, with its large
clusters of pink flowers, is very conspicuous during its blooming
season. Among the other prominent vines are Trichosporinn
philippinense, Alyxia monilifera, Dichrotrichum chorisepaluni,
and Hoya odorata. Climbing palms (rattans) grow in the mossy
forest, but are not nearly so prominent as at lower elevations.

MOSSY FOREST 101

The ground covering varies in different situations ; but, except
in very dark places, it usually consists of a fairly dense herba-
ceous growth. When a tree sends out a considerable number of
large aerial roots and has its crown overgrown with vines and
epiphytes, the ground below is very densely shaded and is usually
absolutely bare. As in the midmountain forest, the most con-
spicuous large herb is Strohilanthes piriformis. The smaller
herbs which cover the ground consist largely of Polypodiaceae,
Hymenophyllaceae, species of Selaginella and of Elatostema, and
Argostemma wallichii. In shallow ravines medium-sized species
of Hymenophyllaceae frequently form a dense carpet over the
ground. The most prominent species of filmy ferns are Tricho-
manes apiifolium, T. pluma, Hymenophyllum javanicurn, and
the mosslike Trichomanes proliferum. A rather typical ground
covering of herbs is shown in Plate XXXIII. Here the most
prominent element is Selaginella.

The vegetation in the ravines and on the slopes shows some
striking differences. In general the trees are taller and the for-
est much more open in ravines than on ridges, so that in descend-
ing through a mossy forest, where there are no trails, it is
usually convenient to follow the ravines. Near the top of the
mountain the ravines are shallow, but the condition in them is
even more hygrophytic than on the ridges. This is accompanied
by a greater development of medium-sized filmy ferns on the
ground and on the lower part of the trees.

The above description applies particularly to the vegetation
around the top of the mountain. At lower elevations the vegeta-
tion grades into that of the midmountain forest. In the lower
portion of the mossy forest ravines are more developed, and
there is an accompanying greater difference in the density of
the vegetation in them and on ridges. Plate XXXV shows the
density of vegetation in a fairly level area near the lower limits
of the mossy forest. The vegetation in a shallow ravine at a
slightly higher elevation is shown in Plate XXXIV. The vegeta-
tion on the slope at the side of this ravine is shown in Plate
XXXVI. The more open character of the vegetation in the
ravine is very evident.

Showy flowers are conspicuous in the mossy forest. This is
in part due to the fact that the forest is low, and the flowers
are not so completely hidden by the foliage as at lower elevations.
Owing to the uniformity of conditions the blooming season of
most species is moreover very long, lasting in many cases for
several months. Among the most striking flowers are those of
Melastoma polyanthum, Medinilla fnultiflora, and Dichrotrichum

102 MOUNT MAQUILING

chorisepalum. Melastoma is a very common tree, and has large
pale purple flowers, which are produced in great abundance (see
Plate XXXVII, fig. 1). The flowers of Medinilla are bright
pink, produced in large clusters, and so are very striking. The
red clusters of Dichrotrichum, an epiphytic vine, are very hand-
some. All of these species have a long blooming season.
Clethra lancifolia, one of the commonest species in the forest,
has a shorter blooming season. During this season the trees
are covered with white flowers that remind one of the species
of this genus that are found in the United States. Climbing
begonias are fairly abundant and produce very striking displays.
Plate XXXVII, fig. 2, shows a branch covered with Begonia
aequata. Mixed with the Begonia are leaves of the epiphytic
fern Elaphoglossum. Dendrochilum venustulum, a common
epiphytic orchid, produces racemes of small, delicate, yellow flow-
ers. The blooming season of these is short and, as all of the
individuals flower at the same time, they make a very showy
display. The ground is frequently spotted with the pretty star-
shaped white flowers of Argostemma wallichii. Besides the
above there are many other plants which produce flowers suffi-
cient in beauty and numbers to add greatly to the attractiveness
of the forest.

Owing to the peculiar shapes of the trees, the abundance of
tree ferns and epiphytes, and the showy flowers, the mossy forest
is very picturesque.

The mossy forest on Mount Maquiling may be regarded as
typical of mossy forests in the Philippines, although the char-
acter of these forests varies greatly in different places. In
some the mosslike covering is composed very largely of true
mosses ; in others, of liverworts ; and in still others, of mosslike
filmy ferns. The height and specific composition of the trees
also varies greatly. • In many places the irregular growth of the
trees is not so conspicuous as on Mount Maquiling.

Mossy forests are usually found at or near the top of a moun-
tain. In some cases they occur at high altitudes, but toward
the summit give way to a forest that is much less mossy. On
the north slopes of Mount Banahao, on the trail leading from
Mahayhay to the summit, there is a conspicuous mossy forest
at an elevation of about 1,800 meters; while near the summit,
at an elevation of about 2,100 meters, there is a forest in which
mosses and mosslike plants are not particularly prominent.
Near the summit the forest is a two-story one, the first story
being composed of Podocarpus imbricatus, and the second, of
dicotyledonous trees. Two views in this forest are shown in

MOSSY FOREST 103

Plate XXXIX. Mossy forests appear to be confined to the
cloud belt, where the atmosphere is saturated with moisture,
or nearly so, during all parts of the year.

From the above discussion it will be seen that mossy forests
do not constitute a single homogeneous type. With our present
knowledge, however, anything approaching an exact classifica-
tion of them is impossible.

In the Philippines it is only in mountain regions that we find
a luxuriant development of epiphytes, and particularly of the
mossy forms characteristic of a mossy forest. How far this
condition is true of tropical regions in general is very hard to
determine from the available literature. In the first place, it is
extremely difficult to estimate the amount of epiphytic vegeta-
tion from descriptions, as the terms used are more or less
general, and the manner of their use depends to some extent
on the past experience^ the writer describing the forest. Thus,
one coming from a temperate country where there are no epi-
phytes, and visiting a forest of the midmountain type on Mount
Maquiling, would be apt to use some such expression as "the
trees were covered with epiphytes" or "were heavily laden with
epiphytes/' and some writers might even use such expressions
in describing a dipterocarp forest, on account of its aerial gar-
dens. Moreover, many writers on tropical vegetation have failed
to distinguish between lowland and mountain forests. Thus
Warming,* in discussing tropical rain forests, says: "The trees
forming the highest story have tall thick trunks which are un-
branched up to a height of 40 to 50 meters or more.'' In the
same paragraph and without indicating a difference in the size
of the trees he adds : "Trees of the forest situate in the cloud-
belt in Java and the Moluccas are enveloped in a soaking mossy
felt, which may be thicker than the trunks themselves and
imparts to them a peculiar, dark appearance."

In the Philippines the vegetation in the cloud belt is dwarfed,
and this is certainly true of the Gedeh in Java. In May, 1917,
the writer examined the vegetation of the twin peaks Pan-
gaerango and Gedeh. These form the summits of a large moun-
tain mass on the lower slopes of which is situated the mountain
station of Tjibodas. As this region is easily accessible from
Buitenzorg, the forests of the mountain are frequently referred
to in descriptions of Javan forests. The general character of
the vegetation is very similar to that found in the Philippines.

* Warming, Eug., Oecology of Plants. Translated into English by Percy
(;room and Isaac Bayley Balfour, Clarendon Press, Oxford (1909).

104 MOUNT MAQUILING

The forest decreases in height rapidly as higher elevations are
reached, until near the summits of the peaks the vegetation is,
if anything, more dwarfed than that of Mount Maquiling; and
it is only to the dwarfed mossy forest at higher altitudes that
the second sentence of the quotation from Warming could apply.

The forest at elevations of from 1,300 to 1,500 meters is com-
paratively high. Doctor Koorders has examined this forest for
tall trees. He measured a specimen of Altingia excelsa, which
was 49 meters high. This tree was, however, much taller than
the average height of the tallest story. In this region the forest
contains a greater development of epiphytes than is usual in
forests of similar heights in the Philippines, the epiphytic vegeta-
tion being similar in amount to that found in the midmountain
forest on Mount Maquiling, and therefore much less than that
of the mossy forest.

Shreve * gives a very interesting discussion of the forests
occurring above 1,370 meters on the Blue Mountains of Jamaica.
The general character of the forest would appear to be inter-
mediate between the midmountain and mossy types on Mount
Maquiling. On the windward slopes the character of the epiphy-
tic vegetation approaches that of the mossy type, and on the
leeward, that of the midmountain forest. This idea, derived
from Shreve's data, is in harmony with the recollections of the
writer, who visited the Blue Mountains of Jamaica in 1910.

Miss Gibbs f has described types of mossy forest from Mount
Kinabalu, in British North Borneo, and the high mountains of
Dutch New Guinea.

As mossy forests occur at high altitudes in widely separated
regions, it seems not unlikely that they are characteristic of the
cloud belt of tropical mountains in general. As will be shown
later, a heavy and evenly distributed rainfall does not neces-
sarily result in a thick mossy covering, unless the region is one
of frequent fogs or in which the atmosphere is nearly satur-
ated with moisture throughout the year.

DESCRIPTION OF PLOTS

As the trees in the mossy forest are low and the composition
of the stand much less complex than in the forests at lower

* Shreve, F., A Montane Rain-forest, Pub. Carnegie Inst. Washington
(1914), No. 199.

f Gibbs, L. S., A contribution to the flora and plant formations of Mount
Kinabalu and the highlands of Brit. N. Borneo, Jom^n. Linn. Soc. Bof
(1914), 42, 8. Idem, A Contribution to the Phytogeography and Flora of
the Arfak Mountains, etc. Dutch N. W. New Guinea. Taylor and Francis.
Red Lion Court, Fleet Street, London, July, 1917.

MOSSY FOREST

105

elevations, a different method of determining the composition
was adopted in the mossy forest. Instead of cutting the trees
the heights were measured by a tape fastened to a pole. Owing
to the small size of the trees and the less complex composition,
smaller plots were considered sufficient. For convenience meas-
urements were taken on ten separate plots, each 5 meters wide
by 10 meters long, so that the total of all plots was 0.05 hectare,
or one-fifth of the size of the plots used in the midmountain
and dipterocarp forests. The plots were situated just below
the summit of the east peak of Mount Maquiling. The heights
of all individuals more than 1 meter in height on the 0.05 hectare
in the mossy forest are given by species in Table XXIV. It

Table XXIV. — Height of all erect, woody plants more than 1 meter in
height on 0.05 hectare in mossy forest at the top of Mount Maquiling ;
altitude, 1,020 meters.

[Figures represent numbers of individuals.]

Total.

25

24

44

5

1

4

3

1

1

1

11

2

16

5

6

1

7

No.

.. . .

Species.

1 to 2.

11
1
12

2 to 4.

4
8
16

Heig
4 to 6.

3

13
13
3

ht in meters.

i

6 to 8. | 8 to 10.
4 3

10 to 12.12 to 14.

1

Astronia lagunensis

Clethra land folia

2

2
3

3

Cyathea caudata

4

Elaeocarpus argenteus

i
1

1

5

Eugenia sp ._

6

Evodia semecarpifolia

1

2

. i 1

7

Ficus banahaensis

Ficus warburgii .

1

'"""^■-■-~

1

8

1
1
1
5

9

Homalanthus alpinus. _ .

10

Ilexfoxworthyi

,

11

Itea maesaefolia .

2

3

1 ,

1 1

12

Machilus philippinensis __

13

Melastoma polyanthum,

Neolitsea villosa

4
2

7
2

5
1

14

I

15

Rapanea philippinensis

3 , 2

!

1

16

Symplocos floridissima . _ _
Symplocos merrilliana

Total

1
1

35

i

17

~~ IT

6

57

14

7

2 1 ll

157

will be seen that in all there were 17 species. In order to com-
pare the number of species occurring on an equal area in the
mossy, midmountain, and dipterocarp forests, it was necessary
to examine a larger area in the mossy forest than that from
which the data in Table XXIV were gathered. Such an exam-
ination of a much more extensive area than that covered by
the plots in the lower formations showed only 4 species not
mentioned in Table XXIV. These were Eurya acuminata, Glo-
(hidion ivilliamsii, Ficus validicaudata, and Eugenia robertii. It

106 MOUNT MAQUILING

may, therefore, be assumed that a plot of 0.25 hectare in the
mossy forest would not show more than 21 different species of
trees, while in the midmountain forest on a plot of similar size
there were 71 species represented by individuals more than 1
meter in height, and in the dipterocarp forest there were 92 spe-
cies of erect woody plants represented by individuals more than 2
meters in height. Any one or more of several possible causes may
have been instrumental in producing a forest of but few species
on the top of Mount Maquiling. A reduction in the number of
stories from three in the dipterocarp to two in the midmountain
and one in the mossy forest might be expected to be accompanied
by a decrease in the number of species. However, the number
of species in the mossy forest is much less than in either the
first or the second story in the midmountain forest; as on the
plot of 0.25 hectare in the latter forest there were 35 first-story
and 36 second-story species represented by individuals more than
1 meter in height. The unfavorable conditions in the mossy
forest, which have resulted in a dwarf vegetation might, how-
ever, be expected to be accompanied by a smaller number of
species than would be found in more favorable habitats.

Another point to be noted is that the dipterocarp forest on
the lower slopes of Mount Maquiling was probably continuous
with a wide area of similar forest stretching over the plain.
This condition would seem to be very favorable for the dispersal
of species, whereas the mossy forest covers only a very limited
area and is widely separated from similar types of forest. Of
the twenty-one tree species in the mossy forest eight appear as
understory trees in the dipterocarp forest, but some of them are
found only in the upper portion of the forest. These eight
species are Cyathea caudata, Elaeocarpits argenteus, Eugenia
robertii, Machilus philippinensis, Glochidion williamsii, Neolitsea
villosa, Symplocos floridissima, and S. merrilliana. With the
exception of Cyathea caudata, which is found only in the upper
limits of the dipterocarp forest, none of the species found in
both forests is among the more prominent ones in the mossy
forest. When we consider the number of species found in the
dipterocarp forest and that only eight of them were seen in a
large area in the mossy forest, it will be apparent that condi-
tions in the mossy forest are very unfavorable for species grow-
ing in the dipterocarp forest. This, together with the fact that
the mossy forest on Mount Maquiling is widely separated from
other similar forests, may account in part for the scarcity of
species in the mossy forest. The mossy forest on Mount Maqui-
ling is like other mossy forests in the Islands in being composed

MOSSY FOREST 107

of a small number of species. Similar reasons are probably
responsible for this condition in all cases. If the plots studied
in the mossy forest had been near the lower limits of this for-
mation, the number of species present would have been greater,
and more species common to both the dipterocarp and the mossy
forests would have been noted.

Although the number of species in the mossy forest is small,
the number of individuals is greater per unit of area than in
either the midmountain or the dipterocarp forest. On the 0.05
hectare in the mossy forest there were 157 individuals more
than 1 meter in height. Assuming that the number would be
proportional on a larger area, there would have been 785 on 0.25
hectare as against 577 in the midmountain forest ; and of erect
woody plants more than 2 meters in height, 610 as against 539
in the midmountain forest and 353 in the dipterocarp forest.
The increase in the number of individuals over that found in
the midmountain forest, as is the increase in the number in the
midmountain over that in the dipterocarp forest, is probably
connected with the absence of a high story which shuts out a
considerable amount of light from the smaller trees.

In Table XXIV the heights of individuals are classified ac-
cording to height classes of 2 meters. Those more than 4 meters
in height may be regarded as being in the main canopy. There
were 81 of these. On a plot of 0.25 hectare we would, there-
fore, expect to find about 405 individuals, whereas in the mid-
mountain forest there were 52 individuals in the first story, and
in the dipterocarp, 16. The increase in the number of dominant
trees as higher elevations are reached is evidently connected
with their smaller size. Table XXIV shows that of the 157 trees
on the area there were only 3 more than 12 meters in height.
The most numerous species were Cyathea caudata, with 44 in-
dividuals; Astronia lagunensis, with 25; and Clethra, with 24.
Although in this table Clethra appears to be about as abundant
as Astronia, at a slightly lower elevation in the mossy forest
there are other species of Astronia, and here Astronia is much
more prominent than Clethra. For this reason the forest has
been designated as the Cyathea-Astronia association. No meas-
urements of diameters of trees were taken as, owing to the
very irregular branching and the formation of aerial roots, this
was impracticable with the largest specimens.

In Table XXV the individual species are arranged according
to the plots on which they occurred. It will be seen that Cyathea
and Astronia are the only ones occurring in all of them. How-
ever, all of the individuals of the different species are fairly

108

MOUNT MAQUILING

well distributed in different plots, which would indicate that
the species distribution is rather uniform.

Table XXV. — Distribution in plots of 50 square meters of all erect woody
plants on 0.05 hectare in mossy forest at the top of Mount Maquiling<;
altitude, 1,020 meters.

[Figures represent numbers of individuals.]

No.

Species.

Plot No.

1

1

2
2
3

2

3

4

5

5

ft

1
1

7

I
7 ; S

«.)

10

Total.

1
2
3
4

5
6
7
8
9
10
11
12

13

14
15

16

17

Astronia lagunensis

dethra lancifolia

Cyathea caudata

Elaeocarpus argen-
teus

1
6
4

2

5
3

4

5
6
4

2

2

8

1

2
2

1

3
4

4

4
3

25
24
44

Eugenia sp._

1

i

4
■3

1

1

Evodia semeearpifolia.
Ficus banahaensis

1

1

1

1

1

1

1

-----

Ficus warburgii

1

Homalanthus alpinus .
Ilex foxworthyi

1

*

1
1

1
1

1

Itea mae8aefolia

Machilus philippinen-

sis

4

2

3

11

1
3

2

Melastoma polyan-
thum

8
1

3

9

ifi

Neolitsea villosa

Rapanea philippinen-

sis

3
3

1

1

1 i 5

1

a

Symplocos Jloridissi-

ffla _.

1
2

1

7

Symplocos merrilliana^
Total

4

1

i

22

27

14

24

8

13

15 r 6

18

10 ' 157

TABLE XXVI. — Height of all erect woody plants in 10 plots of 50 square
meters in mossy forest at the top of Mount Maquiling; altitude, about
lj020 meters.

[Figures represent numbers of individuals.]

Plot No.

lto2.

4

4
5

10
1
3
6

2 to 4.

7
9
3
6
4
4
1

Heig

_

4 to 6.

ht in meters.
6 to 8. 8 to 10.

10 to 12.

I
— | Total
12 to 14.

1

10
14
3
6
1
5
5
4
7
2

1

22

27
14

2

3 _

2
1

1
3
1
4
1

1
1

_._.*_..

1

4-

24

5

1

g

6

13

7 __ .

15

8

2
3

1

6

9

5
2

18

10 _

2
35

1

10

Total

41

57

14

7

.2

157

MOSSY FOREST 109

In Table XXVI the individuals in the different plots are dis-
tributed according to height. The number on a plot varied from
6 to 27. It will be seen that in general the plots with a small
number of individuals contained more large specimens than
those with a large number of individuals. This is due to the
fact that the large trees cast such a heavy shade that those under
them are at a great disadvantage.

OPENINGS IN THE MOSSY FOREST

Openings in the mossy forest caused by the falling of trees
are quickly invaded by a rapidly growing tree (Homalanthm
alpinus), a raspberry {Rubus fraxinifolins), and a coarse fern
(Histopteris incisa). These soon fill the area completely, but
apparently are gradually driven out by the trees of the mature
mossy forest.

COMPARISON OF VEGETATION AT DIFFERENT
ALTITUDES

In order to compare the vegetation in the dipterocarp, mid-
mountain, and mossy forests the figures for erect woody plants,
more than 2 meters in height, given in the tables describing
the plots in these different formations are summarized in Table
XXVII; and those for plants less than 1 meter in height, in
Table XXVIII. From Table XXVII it will be seen that the
tallest tree on the plot in the dipterocarp forest was 35.95 meters
in height; the tallest on the midmountain plot, 21.8 meters; and
the tallest on the mossy forest plot, 12.9 meters. The average
height of the first story in the dipterocarp forest was 27.2

Table XXVII. — Comparison of erect woody plants more than 2 meters in
height on 0.25 hectare in dipterocarp, midmountain, and mossy forests
on Mount Maquiling.

Number of stories of trees T

Height of tallest tree , meters. .

Average height of first-story trees ._ ~ do

Average height of second-story trees do

Average height of third-story trees do

Greatest diameter of trees in first story centimeters..

Average diameter of trees in first story do

Average diameter of trees more than 10 cm. in diameter in

second story centimeters..

Average diameter of trees more than 10 cm. in diameter in

third story centimeters..

Total volume-. cubic meters. .

Volume of first story ..... do

Volume of second story do

Volume of third story _ :._ do

Total species of erect woody plants more than 2 meters in height .

Species of first-story trees

Species of second-story trees

Species of third-story trees _

Total individuals of woody plants more than 2 meters in height.-..

Trees in first story

Trees in second story _

Erect woody plants in third story

Diptero-
carp for-
est; alti-
tude, 450
meters.

3
35.95
27.2
16.4

9.8
96.0
52.9

28.4

15.6

76.35

48.95

25.11
2.29

92

22

43

27
353

16

54
283

Mid-
mountain

forest;
altitude,

700
meters.

2

21.8

17.0
4.2
0.0

85.0

34.3

17.7

0.0
41. 13
33.28
7.85
0.0
70
35
35
0
539
52
487

Mossy |

forest;

altitude,

1,020
meters.

1

12.9

5.9

0.0

0.0

0.0

0.0

0. 0

o.o

21
21
0
0
610
405

110

COMPARISON OF VEGETATION AT DIFFERENT ALTITUDES HI

Table XXVIII. — Comparison of plants less than 1 meter in height on
plots of 100 sqware meters in dipterocarp and midmountain forests
on Mount Maquiling.

[Figures represent numbers of individuals.]

Species

Individuals

Tree seedlings:

Species

Individuals _
Shrubs:

Species

Individuals .
Herbs:

Species

Individuals _
Vines:

Species

Individuals -

Diptero-
carp for-
est.

42

427

24

151

66 I

9i
209

Mid-
moun-
tain
forest.

28
1.565

14
94

1,325

6
146

meters; in the midmountain, 17 meters; and in the mossy, 5.9
meters. The second story in the dipterocarp forest had an
average height of 16.4 meters, and in the midmountain forest,
4.2 meters. The greatest diameter of any tree on the plot in
the dipterocarp forest was 96 centimeters, and in the midmoun-
tain forest, 85 centimeters. The average diameter of all first-
story trees in the dipterocarp forest was 52.9 centimeters, and
the average of all first-story trees in the midmountain forest
was 34.3 centimeters. The total volume of all trees on the plot
in the dipterocarp forest was 76.35 cubic meters, and in the
midmountain forest/ 41.13 cubic meters. The volume of first-
story trees in the dipterocarp forest was 48.95 cubic meters, and
in the midmountain forest, 33.28; of the second-story trees in
the dipterocarp forest, 25.11 cubic meters, and in the mid-
mountain forest, 7.85 meters. The above figures show clearly
that there is a very great reduction in the size of the trees and
in the volume of timber as higher elevations are reached. This
condition is characteristic of mountains in the Philippines, but
the degree of dwarfing varies very greatly at the same altitude
on different mountains. Thus the mossy forest at the top of
Mount Pauai, at an elevation of 2,450 meters, would appear on
casual observation to be composed of larger trees than the mid-
mountain forest of Mount Maquiling. In the Philippines the
moist lowlands are usually covered with a tall dipterocarp forest

112 MOUNT MAQUILING

which gives way at higher elevations to another type, and this
in turn gives way to an elfin type, which is usually a mossy forest.
The dwarfing of trees as high elevations are reached is, of course,
characteristic of all high mountains, and the only striking thing
about the dwarfing on Mount Maquiling is the comparatively
low elevation at which it occurs.

An examination of Table XXVIII shows that the ground
covering on the plot in the dipterocarp forest was composed
very largely of seedlings of trees and vines, and in the mid-
mountain forest, of herbs. The ground covering in the mossy
forest is also composed largely of herbs. This increase in the
number of herbs in the ground covering at higher elevations
is also characteristic of mountains in the Philippines. However,
in lowland forests, where the environment is moister than in
the dipterocarp forest on Mount Maquiling, herbs are more
prominent.

In the dipterocarp forest the epiphytic species are mostly
phanerogams and large ferns, and these are confined chiefly to
the largest branches of the tallest trees, where they form aerial
gardens. In the midmountain forest the epiphytes consist of
phanerogams and large ferns and also small ferns, liverworts,
and mosses. Epiphytes are most prominent on the upper
branches of the tall trees ; they also occur to a considerable extent
on the trunks, but do not form a thick covering on the latter.
On the branches of the trees the phanerogams and the larger
ferns are the most prominent elements, while mosses and liver-
worts are more prominent on the trunks.

In the mossy forest liverworts, small ferns, mosses, and a
small species of Selaginella are the most conspicuous elements
among the epiphytes. Phanerogams and medium-sized ferns
are, however, also prominent. In this forest the trunks are
thickly covered with epiphytes, and epiphytes are also very
prominent on the branches of the trees. This increase in epi-
phytes at higher elevations is also characteristic of mountains
in the Philippines; but, like the size of the trees, the develop-
ment of epiphytes varies greatly at the same altitude on different
mountains. Where there is no pronounced dry season, epiphytes
are more prominent in the lowland forests than in the diptero-
carp forest of Mount Maquiling. On the north side of Mount
Banahao, which has an elevation of about 2,100 meters, epiphytes
are not nearly so prominent as in the mossy forest of Mount
Maquiling except in a limited area at an elevation of about 1,800
meters.

As a basis for a comparison of the formations on Mount Ma-

COMPARISON OF VEGETATION AT DIFFERENT ALTITUDES H3

quiling with those on moist tropical mountains in general, we
may quote the following discussion by Schimper:*

The basal region of tropical mountains generally has a greater
rainfall than have the neighbouring lowlands, and is accordingly covered
by formations that, in the latter, occupy moist stations, especially places
irrigated by the rivers. Rain-forest is here very widespread and
frequently of exceeding luxuriance.

The montane region in its lowe'r belts has, at the equator, a still
tropical although not equatorial character, but near the two tropics it has
from the first a temperate character. The difference between the equatorial
rain-forest of the basal region on the one hand, and the tropical forest
of the lower montane region on the other, is confined to the systematic
composition. In temperate montane formations, on the contrary, the
lower temperature is reflected in purely oecological characteristics in the
plant-life and impresses upon the formations the stamp of those of higher
latitudes. Hence in the montane region of moist tropical mountains,
sometimes at a less, sometimes at a greater altitude above sea-level, the
tropical rain-forest is replaced by temperate rain-forest, like that with
which we have become acquainted in the rainy lowlands of South Japan,
New Zealand, and South Chili.

The trees in it are evergreen; they never have plank-buttresses, and they
possess a more massive growth, a richer ramification, smaller and thicker
leaves than trees in the tropical rain-forest. Lianes are fewer in num-
ber and thinner in the stem; epiphytes are much smaller, usually her-
baceous, and are represented far more by cryptogams (mosses and ferns)
than by phanerogams. The extraordinarily luxuriant development of
epiphytic mosses exceeds that of the temperate lowland rain-forest, and
is to be attributed to the mists prevailing in the montane region. The
presence of many closely allied types of plants in the rain-forest of the
montane region of tropical mountains, and of the lowlands of higher
latitudes, adds a likeness in their flora to the likeness in their oecology.

The transition from the montane to the alpine region is characterized
by a reduction in the size of the trees and in the amount of their
foliage, which gradually acquires a pronounced xerophilous structure.
The stems become shorter and relatively thicker, the branches longer,
the entire growth becomes irregular, the characteristic form of elfin-tree
is revealed.

To the diminutive elfin-wood there succeeds a xerophilous belt of shrub,
then alpine grassland prevails, except on rocks and gravels where low
woody plants establish themselves. The grassland usually assumes the
form of alpine steppe. It consists of tufts of narrow-leaved grasses,
the spaces between which are sometimes bare, sometimes occupied by dwarf-
shrubs and perennial herbs, and the occurrence of dwarf-trees invests
it sometimes with the stamp of a brushwood-savannah. Higher up, on
the highest summits, grassland is gradually replaced by alpine desert.
Here grass appears hardly anywhere except in moist oases; dwarf-shrubs
and cushion-plants separated by wide gaps make up the scanty vegetation.

The character of the vegetation on different mountains varies

* Schimper, A. F., Plant-Geography upon a Physiological Basis.
Oxford (1903), 721.

159549 8

114 MOUNT MAQUILING

so greatly that it is only in a general, broad way that it is
possible to compare the formations on different mountains.
The dipterocarp forest on Mount Maquiling is a type of Schim-
per's rain forest.

The midmountain forest is a montane forest and would appear
to be somewhat intermediate between Schimper's description of
a tropical forest of the lower montane region and a temperate
montane forest, although it has more of a tropical than a
temperate aspect. The most prominent large tree in the mid-
mountain forest is Quercus soleriana, but this does not grow in
sufficient numbers to give the forest a temperate-zone character.
Vines are prominent elements in giving character to the ap-
pearance of the vegetation. By far the most prominent ones
are species of Freycinetia and climbing palms (rattans) . Erect
palms also occur in this formation. Plank buttresses and cauli-
flory, while less prominent than in the dipterocarp forest, are
found in the midmountain forest, as are also strangling figs.
Phanerogamic epiphytes grow in considerable abundance.

A comparison of the heights and diameters of the first-story
trees in the dipterocarp and midmountain forests on Mount
Maquiling shows that the relation of height to diameter is
approximately the same in both cases. Thus the average height
of the first-story trees in the dipterocarp forest is fifty-one times
as great as the average diameter, and in the midmountain forest
the average height of the first-story trees is fifty times as great
as the average diameter.

The ramification of the trees in the midmountain forest does
not appear to be greater than in the dipterocarp forest. On
the other hand, the midmountain forest has certain characteris-
tics that Schimper ascribes to a temperate montane forest. The
leaves of the trees in the midmountain forest are, as will be shown
later, smaller than in the dipterocarp forest. Lianes are also
probably fewer in number and certainly have thinner stems than
in the dipterocarp forest. Epiphytes are likewise smaller, in
general, and are represented more by cryptogams than by phan-
erogams. Thus, on account of its more open condition, the
greater development of epiphytic mosses and liverworts, and the
lesser development of palms, plank buttresses, and strangling
figs, the midmountain forest, though distinctly tropical in char-
acter, resembles a temperate forest more closely than does the
dipterocarp.

Apparently the mossy forest resembles most closely Schimper's
alpine region. The stems of the trees are shorter and relatively
thicker than at lower elevations, while their growth is very

COMPARISON OF VEGETATION AT DIFFERENT ALTITUDES H5

irregular and their form characteristically that of elfin trees.
This forest also has a tropical rather than a temperate aspect.
Clethra lancifolia may be regarded as representative of a tem-
perate-zone flora; but, while this tree is abundant, it does not
grow in sufficient numbers to give distinctive character to the
forest. Vines are also very prominent in the mossy forest; and
the most conspicuous ones, such as Freycinetia, climbing ferns,
species of Medinilla, climbing begonias, and members of the
Gesneriaceae, are certainly tropical and not temperate forms.
Phanerogamous epiphytes are prominent. Small individuals of
climbing palms, although not a conspicuous element in the vege-
tation, are nevertheless numerous, while a small erect palm,
Pinanga bamesii, occurs at the top of the mountain. Owing
to the peculiar shapes of the trees and the great development
of epiphytes and vines, the mossy forest is much less like an
ordinary temperate forest in appearance than is the dipterocarp
forest.

While there is at no elevation on Mount Maquiling a forest
with a temperate-zone appearance, such forests do occur in the
Philippines. On the high mountain mass of Central Luzon there
is a very considerable development of forest, composed of pure
stands of Pinus insidaris* This forest is very open, and the
ground is covered with grass, while epiphytes and vines are
conspicuously absent. It, therefore, has a temperate-zone aspect.
Plate XXXVIII shows a view in this forest. The pine forest
appears to have developed as a result of the removal of the
original forest; and its continued existence apparently depends
upon the action of fire, which sweeps through the grass and
destroys the seedlings of broad-leaved trees. The forest on the
top of Mount Banahao f has two stories, the first being composed
of Podocarpus imbricatus. Here again vines are conspicuously
absent and epiphytes not prominent enough to give character
to the appearance of the vegetation. This forest also has a
temperate-zone aspect (see Plate XXXIX).

* Whitford, H. N., The Forests of the Philippines, Bull. P. I. Bur. For.
(1911), No. 10.

t Brown, W. H., The rate of growth of Podocarpus imbricatus at the
top of Mount Banahao, Luzon, Philippine Islands, Phil. Joum. Set, Sec.
f (1917), 12, 317-329.

GPwOWTH

GENERAL DISCUSSION AND METHODS OF MEASUREMENT

A study of the vegetation at different elevations on Mount
Maquiling shows that one of the most conspicuous differences
in the types of vegetation is the dwarfing of trees as high
elevations are reached. It is quite evident that this dwarfing
of trees may be caused by any one of several very different
factors. The most obvious are periodical or continuous de-
struction of certain parts of the trees, a slow rate of growth,
or quick maturing and early death.

In considering the effect of environment on the size of vege-
tation it is important to know which of these three causes is
responsible for small size. Examination of the vegetation at
different elevations on Mount Maquiling shows that dwarfing is
a gradual process and is not connected with a destruction of
portions of the trees, except perhaps where they are in very
exposed situations. In some very steep places erosion has a
tendency to keep the trees small ; but, as we have seen, dwarfing
is in general independent of this factor. It remains, therefore,
to determine whether the dwarfing is connected with slow growth
or with a rapid maturing of the trees.

In order to answer this question a number of measurements
were made of the diameter growth of trees in the parang,
and in the dipterocarp, midmountain, and mossy forests.
Measurements of growth were not undertaken on a large scale
for the reason that, while the collection of the data here pre-
sented was in progress, Dr. E. B. Copeland was preparing ma-
terial for an extensive discussion of rates of growth of plants
in the Philippines and particularly those at Los Banos and on
Mount Maquiling. Doctor Copeland's data covered growth in
the length of plants ; and the data here presented, on growth in
diameter, were intended to be merely supplementary. Unfore-
seen circumstances have prevented the publication of Doctor
Copeland's data, but it may be said here that the results obtained
by him are in keeping with those here presented.

The object of the measurements made on Mount Maquiling
was to determine not only the rates of diameter growth but
also the ages of different-sized trees at various elevations. Since

116

GROWTH WJ

annual rings of growth are not known to occur in the Philippines,
the only method of calculating rates of diameter growth or the
ages of trees of various diameters is to make successive measure-
ments of the girth of the same trees. These measurements must
be made at exactly the same point, for a slight deviation in the
height at which they are made may show a considerable dif-
ference in the circumference. The method employed was to
drive a shingle nail a short distance into the tree, just below
the tape, at the time of the first measurement. In most of the
trees experimented with, the nail caused no swelling; where
swelling did occur, the measurements were discarded. A steel
tape, about a centimeter wide, was used in measuring all the
trees except a few very small ones, which were measured with a
narrower and more flexible steel tape. In using this method
it has been found practical to measure accurately the girths of
even large trees to the nearest 0.5 millimeter.

While the original measurements were of girth, they have
been converted into the more usual form of diameters and are
expressed in centimeters. In order that these figures might
be presented in a usable form, the trees have been grouped
according to species and the individual species placed in dia-
meter classes of either 5 or 10 centimeters. The average rates
of growth of the different diameter classes have then been cal-
culated and the results divided into the number of centimeters
in the diameter class. In this way we obtain figures represent-
ing approximately the number of years it takes the average
tree to pass through the different diameter classes. These fig-
ures, added together, give numbers that may be taken to repre-
sent the ages of trees of different sizes. That is, the average
rate of growth of trees in the diameter class of from 0 to 10
centimeters divided into 10 centimeters gives us the age of a
10-centimeter tree. If this figure is added to the quotient ob-
tained by dividing the average rate of growth of trees of the
10- to 20-centimeter diameter class into 10 centimeters, we obtain
the age of a tree 20 centimeters in diameter. If now the ages
of trees of the different diameter classes be plotted on coordi-
nate paper, we can obtain an approximation of the age of a tree
of any diameter.

In this method of measurement there are several sources of
error which should be taken into consideration. In the first
place trees are apt to show different rates of growth in different
years, and in order to secure average records the measurements
should extend over a series of years. While this is necessary
to enable us to make accurate calculations of the ages of trees,

118 MOUNT MAQUILING

it is not nearly so important in obtaining a comparison between
the rates of growth of trees at different elevations.

Some species have a great tendency to shed their bark in large
patches. Measurements of the growth of individuals of such
species are liable to be very inaccurate, but this error can be
overcome by the use of* large numbers of trees. Only one species
that shed its bark in noticeable patches was measured on Mount
Maquiling. In this case the patches were comparatively small,
and sufficient individual measurements were taken to make error
from this source negligible. A tree with a rough bark has an-
other disadvantage which is, if anything, more serious than
the one just mentioned; that is, the irregularities tend to keep
the tape from running straight around the tree and thus make
measurements less exact.

Successive measurements from which annual rates of growth
are calculated must, of course, be made at the same time of year,
as rates of growth may vary in different seasons.

The most serious error in estimating the rate of growth of a
tree from successive measurements of girth is due to the fact
that the girth of a tree may change due to moisture conditions
and independently of growth. Thus, there is a tendency for
tree trunks to shrink when evaporation is high, the reason for
which appears to be that under such conditions tissues may lose
more water than they absorb. This results in tree trunks being
smaller during the day than at night. Similar phenomena have
been observed in other plant parts. Thus, Darwin * has shown
that the growing fruit of Cucurbita may gain or lose weight
according to the moisture condition of the atmosphere. When
diminution in weight or size was proceeding rapidly, the fruit
showed a loss of 0.1 gram per minute, while shrinkage occurred
at the rate of 0.01 millimeter per minute. Livingston and
Brown f have shown that during the course of a day the leaves
of a plant may lose a very considerable proportion of their water
and regain it at night. Thodayt has found that the area of
leaves decreases during the day, while Lloyd § and Brown and

* Darwin, Francis, On the growth of the fruit of Cucurbita, Ann. Bot.
(1893), 7, 459-487.

f Livingston, B. E., and Brown, W. H., Relation of the daily march of
transpiration to variations in the water content of foliage leaves, Bot.
Gaz. (1912), 53, 309-330.

% Thoday, D., Experimental researches on vegetable assimilation and
respiration. V. A critical examination of Sachs* method for using increase
of dry weight as a measure of carbon dioxide assimilation in leaves,
Proc. Roy. Soc. London (1909), B, 82, 1-55.

§ Carnegie Inst. Wash. Year Book (1916), 15, 58.

GROWTH

119

Trelease * have shown that this may be true also of the length
of stems.

Kraus f has measured the diameter of a number of different
trees at various times of the day for a few days at Bombay,
Singapore, and at three places in Java— Buitenzorg, Garut, and
Tjibodas. In his paper dealing with this subject he does not
describe his method of measurement nor state whether his meas-
urements were made in millimeters or centimeters, but says
that his method is given in an earlier paper (not available in
Manila) dealing with variations in the diameters of trees in tem-
perate countries. From the descriptions of the trees measured
his measurements would appear to be in millimeters. The great-
est and smallest diameters found by Kraus for individual trees
are given in Table XXIX. All of the measurements of Kraus

Table XXIX. — Greatest and smallest diameters recorded by Kraus for
the same trees within a few days.

Locality.

Bombay

Do

Do

Do

Singapore ...
Do

Buitenzorg-.

Do

Do

Garut

Do

Do

Tjibodag

Do

Do

Do

Average -

Species.

Oreodoxa regia

Oreodoxa regia

Carica papaya

Plwmeria acutifolia

Eriodendron anfractuosum (kapok)

Carica papaya

Areca wendlandiana

Papaya branch a

Papaya branch b

Mangifera indica

Eriobotrya japonica

Ficus elastica

Castanospermum

Nauclea sp

Cinchona succirubra

Calyptrocalyx spicatua

Great-
est dia-
meter.

Least
diame-
ter.

mm.

Differ-
ence.

mm.

109.26

108.36

0.90

122.85

121. 83

1.02

97.37

97.00

0.37

48.29

47.75

0.54

72.60

71.05

1.55

86.53

85.92

0.61

92.29

91.81

0.48

72.30

71.70

0.60

107. 77

106. 98

0.79

70.75

69.30

1.45

60.20

59.70

0.50

131. 35

131. 17

0.18

64.20

63.83

0.37

150.35

149. 80

0.55

66.70

65.70

1.00

119.35

119. 10

0.25

92. 010

91. 313

0.697

_ . .

give concordant results except in the case of an individual of
Annona muricata, in the records for which there is very evi-
dently a serious typographical error. The figures for this indi-
vidual have therefore been omitted from Table XXIX.

* Brown, W. H., and Trelease, S. F., Alternate shrinkage and elongation
°f growing stems of Cestrum nocturnum, Phil. Journ. Sci.f Sec. C (1918),
1 3, 353-360.

t Kraus, G. von, Physiologisches aus den Tropen, Ann. Jard. Bot.
buitenzorg (1895), 12, 196-216.

120 MOUNT MAQUILING

Referring to Table XXIX it will be seen that the average of
the greatest changes in diameter of the trees measured by Kraus,
with the exception of this Annona rnuricata, was 0.697 millimeter.
The difference appears in many cases to have been entirely in-
dependent of growth, as frequently the smallest measurements
were made later than the largest. In some cases where the
largest diameters occur near the end of the period, a portion of
the differences between the greatest and smallest diameters may
have been due to growth, as the period of measurement fre-
quently covered several days; and, as will be shown later, trees
may make an appreciable growth in this length of time.

Derry,* in discussing the tapping of Hevea brasiliensis, says:

From a series of tests and measurements I conclude there can be no
doubt that the flow of latex depends entirely on the pressure of water, and
the contraction and expansion of a tree during the course of the day is
considerable. A tree of 3 feet girth at 3 feet from the ground measuring
exactly 3 feet at 6 A. M. would by afternoon, according to the brightness
of the day, contract to a maximum of 1/2 inch, and by 6 P. M. or soon
afterwards expand to early morning measurement. Or, if a ligature be
fixed tightly on a tree it can be observed that in the early morning the
ligature is fully stretched, and by afternoon, if a bright warm day, is
quite slack, or partly so, according to the day, and as the evening advances
gradually braces up.

Petch f arrived at very different conclusions concerning girth
changes in Hevea. He made measurements of the girth of this
plant in the early morning, at midday, and in the evening but
found no appreciable differences. As he measured his trees only
to the nearest millimeter, his measurements might have failed
to show changes corresponding to some of the smaller of those
observed in other trees by Kraus.

In discussing the results of Derry, Petch makes the following
statements :

The? kind of ligature employed has not been recorded, but it may be
pointed out that if a piece of string were tied round the stem in the early
morning when everything is damp it would naturally become slack, through
drying, by midday on a dry day.

* * * In ordinary estate measurements, in which the trees are not
measured at a fixed line, but only approximately at a height of 3 feet, it has
been found that the possible error is fully half an inch.

Petch made weekly measurements of the girth of Hevea brasi-
liensis, at 9.30 in the morning on the same day of the week,

* Derry, R., Experimental tapping of para rubber trees at the Botanic
Gardens, Singapore, Agr. Bull Straits & Fed. Malay States (1904), 3, 340.

% Petch, T., The girth increment of Hevea brasiliensis, Ann. Roy. Bot.
Gard.} Peradeniya (1916), 6, 77.

GROWTH 121

from 1912 to 1914. In the course of these measurements he
found a shrinkage during jthe dry season; but the greatest de-
crease recorded in nine wjbeks amounted to only 3 millimeters
in girth, and it was never greater than 1 millimeter per week.

In order to determine something of the variations in the girth
of tree trunks in the Philippines measurements were made on
a number of trees growing at Los Bafios, on a sunny day in
December. With one exception these were of rapidly growing
second-growth species and were scattered in the lawn around
the forest station, which was situated at the top of an exposed
ridge. They were, therefore, fully exposed to changes in light
and wind. These trees would be expected to show greater girth
variations than would trees growing in a forest, and partic-
ularly in a dense one such as the dipterocarp forest. The
exception mentioned was a large individual of Parashorea
malaanonan (plicata), growing at the edge of a ravine; its
crown was very fully exposed to the sun and wind.

The measurements were made with a steel tape, and in order
that the place of measurement might be located exactly this
was indicated by one or more shingle nails driven into the tree.
The tape used was a centimeter wide. This width gives the
tape considerable stiffness and keeps it from sagging; therefore,
measurements made with it, except in the case of very small
trees, are much more accurate than those made with a narrower
tape. Actual experience has proven that it is possible to meas-
ure girth accurately to the nearest 0.5 millimeter. The trees
under consideration were measured at two-hour intervals from
8 p. m. on December 12 to 6 p. m. on December 13, except that
no measurement was made at 4 a. m. The results are recorded
in Table XXX. From this table it will be seen that the greatest
average girth for all trees was at 6 a. m., and the least at 12
noon and 2 p. m., and that the average difference in girth be-
tween 6 a. m. and 2 p. m. was 1 millimeter. This would indi-
cate clearly that there might be an error of 1 millimeter between
measurements of girth made at 6 a. m. and those made at 12
noon. A further examination of Table XXX shows, however,
that the greatest average difference in girth between 8 a. m.
and 6 p. m, was 0.7 millimeter, aaid between 10 a. m. and 4 p. m.,
only 0.2 millimeter ; the latter is less than the smallest difference
that could be accurately measured by the method employed. It
would seem, therefore, that measurements taken during the
middle portion of the day, or between 10 a. m. and 4 p. m.,
should not be subject to any considerable error because of
changes in girth that occur during the day.

122

MOUNT MAQUILING

SO

& Is

•w

<© §

o

~ o

r-.

~ 00

ff

6

s> *©

-© e

%

S .

V

«> «>

C

8-5

*•§

Xi

t

^ e

fee

4)

>

ft. o»

6/)

00 J

B
E

so

<© -w

s> S

5- £

"** o

•&*

^

-w>

**

•«f»

fc>

T3 +>

c bo

©©©kOOOlOiOOU3©QQlO©l«©tfa©

§3 S3

W » .N «J ^

OQOOOOOQOIOOQUSIOOIOOIOO

Q0^Mrl'ldN^tjiO)iOlO,Hl>ril>«)«)ei5N

OQQOOiOOOOiflOOO

Mffl^N16C0l6OHMt-roT)t

00 * M ■* 16 oi ^i
ifl -* rf if |> W N

O U5 O U5 O

rf M M N tji

■* « rC lO N
tl" ^ n< t- ifl

O Q O
lO © r-t

c5 3 4

as ■*# o

o o o id o

§ $

S 8

©©©©.©©oua

\a -* ■** -<* c-

i-iN^t-oaoaie^ooio

0016M<*lONT»3(»lOlONt-Nt-»MMN

§ 3

9ttHN^»Ol6Ol0l6^MB

OQOOOU5QO»00»OOOOOQOU30
Tj«0«C>CO«OeO«OrHC^'i}<t-OU30lOl0^t-U3

U5^r|i^t-iONM''*'*M00NiOT|i'*'«li

OQOiOU5QQiOOOU3QOQQOU3lOQ

MOu5N»rFi50N^t«Oi60l5^MC-iO

ww^!jpc<ir)i^;a>W)U5c<it-<Nt--«Doocooa

OOOiOWOOOOOUaOOQQOOlOO
eOOUSCvllO'T^lOr-lpaTj't-OiOOua^^t-lO

OOOOOOOOOOkOOOQOOOUiQ

3

io555t-WN^^T)<M00NiO'«li'*T|iNN

?C

I

>

5

i

QQ^PQQ

i

GROWTH

123

Since trees decrease in girth during the day, it seems reason-
able to suppose that during the dry season there would also be
a tendency for them to decrease in girth, although this decrease
might be more than counterbalanced by the growth occurring
at this time. As we have seen, Petch found such a decrease in
Hevea. At Los Banos periodical measurements of the girth
of a number of rapidly growing second-growth trees were taken
at intervals of about a month during the dry season of 1913.
These measurements with few exceptions showed an increase
in girth throughout the dry season.

In order to make the results of the measurements taken at
Los Banos and given in Table XXX comparable with those of
Kraus, the maximum and minimum girths have been brought
together in Table XXXI together with the differences between

Table XXXI. — Greatest and least girth measurements in centimeters made
on trees from 8 p. m., December 12, to 6 p. m., December IS, 1918, at
the base of Mount Maquiling ; altitude, about 80 meters.

Species.

Parashorea malaanonan

Ficus hauili

Carica papaya

Do

Bauhinia malabarica

Trema orientalis. . .

Ficus ulmifolia

Litsea perrottetii

Psidium guajava

Trema orientalis

Do

Do

Cordia myxa

Do._._

Do

Do

Do

Melochia umbellata

Do

Averagre

Girth.

Maxi-

Mini-

Differ-

mum.

mum.

ence.
cm.

cm.

cm.

358. 40

358.25

0.15

44.30

44.20

0.10

45.00

44.90

0.10

43.65

43.40

0.25

75.60

75.50

0.10

52.40

52.30

0.10

24.60

24.50

0.10

44.15

44.00

0.15

49.25

49.10

0.15

45.40

45.35

0.05

35.80

35.65

0.15

82.00

81.90

a 10

27.50

27.40

0.10

52.00

51.90

0.10

47.50

47.40

0.10

46.50

46.40

0.10

48.40

48.30

0.10

23.80

23.75

0.05

22.50

22.40

0.10

61.51

61.40

0.11

these maximum and minimum girths. In this table it will be
seen that the greatest difference, 0.25 centimeter, is shown by
a specimen of Carica papaya, which is a semiherbaceous small
tree. The next greatest difference shown in Table XXXI is
0.15 centimeter. The differences shown in Table XXXI are less

124 MOUNT MAQUILING

than those given by Kraus, although the individual trees in
general are considerably larger. The only species considered
in both sets of measurements is Carica papaya, of which Kraus
measured three individuals while two were measured at Los
Baiios. The average of the greatest differences in diameter
found in Carica papaya by Kraus is 0.59 millimeter, while the
average for those measured at Los Baiios is 0.56 millimeter, the
two figures being thus very similar. Since the smaller trees
measured by Kraus showed greater differences in girth than
the larger ones measured at Los Baiios, it would seem that
changes in girth might by no means be proportional to the size
of the trees concerned, but that the smaller trees containing a
larger proportion of soft tissues would show a correspondingly
higher percentage of change in diameter. This conclusion is
rendered probable by an examination of Table XXXI. In this
table are given measurements of five individuals of Trema
orientalis. It will be noted that the smallest individual shows
the greatest change in girth, although it had less than half the
girth of the largest. Measurements are also given of five in-
dividuals of Cordia myxa, the largest of which had nearly twice
the girth of the smallest, while the changes in girth were equal
in the two cases. Again, by comparing the changes in girth
of the large Parashorea with the changes of the other trees,
it will be seen that the Parashorea, with a girth of 358 centi-
meters, showed no greater change in girth than Carica papaya,
with a girth of 44 centimeters; Litsea perrottetii, with 44;
Psidium guajava, with 49; or Trema orientalis, with 36.

We may now consider the effect that the above discussed
shrinkage and expansion of tree trunks may have had on the
accuracy of the calculations made from the measurements taken
at Los Banos. We have seen that the error due to measuring
parang trees at the base of Mount Maquiling at different times
of the day amounts to only a small fraction of a millimeter in
girth. An examination of the tables giving measurements of
yearly growth of second-growth trees will show that such an
error is small enough to be considered negligible.

The daily variations in girth in the dipterocarp forest should
be much less than in the parang, as moisture conditions in the
former are much more uniform than in the open. It does not
seem probable, therefore, that in determining the rates of growth
of these trees any considerable error can be introduced by
diurnal variations in the diameters. In the midmountain and
mossy forests evaporation is continually low and humidity higb

GROWTH 125

and uniform, so no considerable swelling and shrinking of tree
trunks is to be expected. We may, therefore, conclude that
diurnal changes in the dimensions of tree trunks are not the
cause of any considerable error in the calculation of the rates
of growth of trees on Mount Maquiling. In a later section
measurements of seasonal growth will be given, and in these
measurements this error may be considerable. This point will
be discussed later.

An important error in estimating age from consecutive meas-
urements of trees of different sizes is that, in obtaining averages
for the smaller classes, we may use measurements of rates of
growth of some trees that will not reach a larger diameter class
and that are growing more slowly than the larger trees grew
when they were of a smaller size. In general, the smaller the
trees measured and the taller and denser the forest, the more
important will this error become. At the top of Mount Banahao
there is a forest the top story of which is composed almost
entirely of Podocarpus imbricatus. On the ground under the
forest there are very numerous seedlings of Podocarpus, but
small trees are conspicuously absent. This would indicate that
the seedlings start, but that conditions are unfavorable for them
and that very few reach maturity. Evidently a measurement of
the average rates of growth of these seedlings might bear very
little, if any, relation to the rates of growth, as seedlings, of the
trees now forming the main canopy. The determination, in a
dense forest, of the seedlings or very small trees that will reach
maturity is practically impossible. Therefore, in estimating
the ages of trees from successive measurements of girth there
must necessarily be considerable error due to the fact that there
is so much uncertainty about the rates of growth of very small
individuals. In the measurements on Mount Maquiling this
error, as will be shown later, is not important except in the
case of the smallest diameter classes.

GROWTH OF PARANG TREES

Nearly all tree species growing in the parang are small.
A second-growth forest 10 meters in height would be considered
exceptionally tall. The trees usually flower when small, many
of the species producing seeds before reaching a meter in height.
The second-growth trees are in many ways comparable with
weeds in temperate countries. Their success is apparently due
to the fact that they can quickly invade open ground or areas
covered with low vegetation. As most of the species are in-

126 MOUNT MAQUILING

tolerant of shade, they of course disappear with the advent
of species belonging to a more stable forest. Measurements
are not necessary to prove that the small size of these trees
is not connected with a slow rate of growth, as casual observa-
tion shows that they may cover an area in a few years, and
that in the same length of time individuals may reach con-
siderable dimensions. As a second-growth forest grows older
it naturally becomes denser, owing to the large size of individual
trees and also to invasion by vines and other plants. As density
increases the rates of growth of course become slow ; and under
a second-growth forest the rate may be extremely slow. How-
ever, even second-growth trees growing in an open situation
do not attain large dimensions, but mature and disappear at
an early age.

Measurements of rates of growth of the parang species were
begun January 21, 1913, and ended January 21, 1915. The
trees were all in the neighborhood of the forest station, which
was situated at the top of a broad ridge at the base of Mount
Maquiling at an altitude of about 80 meters. The trees were
in three different localities. A few were in the large lawn
surrounding the station, and these are classified in the following
tables as growing in the open. Many were in a young second-
growth forest on the gently sloping side of the ridge. As the
trees in this forest became larger, the canopy naturally increased
in density, and this was accompanied by a decrease in the rates
of growth. The remainder of the trees were in a plot used as
a nursery for tree seedlings. As the trees in this plot grew
larger, some were removed, so that they might not cast too
dense a shade on the seedlings. Throughout the experiment,
therefore, these trees were under conditions similar to those
of trees growing in a very open forest. A few of the trees
in the nursery were in a portion that was irrigated during
the dry season. While this might be considered a decidedly
artificial environment, it is similar to that of trees growing near
a stream.

Owing to the diversity of conditions to which the trees meas-
ured were subjected, the measurements may be considered as
giving a fair idea of the average rates of growth of trees under
various conditions in this locality. Most of the trees less than
5 centimeters in diameter were in the forest. They were, there-
fore, subjected to shading by larger individuals and were prob-
ably growing at a slower rate than were those now composing
the major portion of the canopy when the latter were in the
0- to 5-centimeter class. On the other hand, the rates of growth

GROWTH 127

calculated for the 0- to 5 -centimeter class were all for trees
approaching the upper limit of this class, and in some cases at
least this may have had a tendency to make the rates of growth
calculated for this class appear too high. In the measurement,
of the 0- to 5-centimeter class, there were, therefore, two sources
of error which probably counterbalanced each other to some
extent. From observation of the rates of growth of young
trees and from an examination of the rates shown in the tables,
it seems hardly probable that these two sources have produced
any very serious error in the general results obtained.

In the tables dealing with rates of growth of the parang
species the individuals have been classified according to location ;
that is, as to whether they were in the open, in the forest,
or in the nursery. They have, moreover, been grouped according
to their diameter classes. The diameters of the trees at the
time of the first measurement are also recorded, while the
measurements for the two years are given separately. In a
number of cases a tree in one diameter class grew sufficiently
during the first year to place it in a larger diameter class the
second year. In such cases the measurement for the second
year appears in both classes. In the smaller class the meas-
urement is given in italics and is not included in the calculation
of the average rates of growth for that class. In the larger
class the diameter recorded is that measured at the beginning
of the second year. Thus, a tree measuring at the beginning
of the period 4.58 centimeters in diameter and growing 1.90
centimeters during the first year has passed into the 5- to 10-
centimeter class, and in this class its diameter is given as 6.48
centimeters. In a considerable number of cases measurements
are given for the first and not for the second year. This is
particularly true of trees growing in the nursery and is due to
the fact that, as shading in the nursery became more intense,
some trees were removed. In the other two situations there
are also trees for which measurements were not obtained the
second year. This was due to the removal of some trees during
the construction of a road.

The tables also contain calculations of the number of years
required by a tree to pass through the different diameter classes.
At the end of each table is given a summary of the average rate
of growth of all trees of a given diameter class and the number
of years required by the average to pass through the different
classes. For convenience the species forming the second-growth
forest have been divided into two classes; namely, those that

128

MOUNT MAQUILING

reach a diameter of 20 centimeters or more, and those that do
not attain a diameter of 20 centimeters.

DIAMETER GROWTH OF PARANG SPECIES THAT REACH A DIAMETER OF 20 CENTI-
METERS OR MORE

Mallotus ricinoides. — This is a small tree that is frequently
very prominent in the earlier stages of a second-growth forest.
It is common and widely distributed in the Indo-Malayan region.
Measurements of growth for this species are given in Table
XXXII. Most of the individuals were in the young forest, while

Table XXXII. — Annual diameter growth of MalloUis ricinoides (alim) at
the base of Mount Maquiling ; altitude, about 80 meters.

[Diameters and growth are given in centimeters.]

Position of tree.

In the forest.

Do

Do

Do

Do

Do

Do

Do

Do_.

Do

Diameter class in centimeters.

0to5.

Di-
ame-
ter.

4.83
4.58
4.58

Growth.

I

1913. J 1914.

1.55 | 0.67
1. 96 1. 91
1. 58 1. 78

Average.-
Years in class _

In the nursery _

Do

Do

Average. _
Years in class.

1.70 ;
2.9 !

Di-
ame-
ter.

9.28
9.42
9.08
6.11
5.79
8.66
9.55
6.38
6.54
6.16

6.73
7.63
7.10

Growth.

0.84
1.59
1.53
2.02
2.55
1.44
2.09

1.72
2.9

0.8k
1.11
1.21
0.97
1.31
0.9k
1.16
0.67
1.91
1.78

1.33
3.8

3.08
3.16
3.35

3.20
1.6

8.8k

Di-
ame
ter.

10 to 20.
Growth.

16.92
17.66
10.80
10.22
10.12
11.01
10.61
10.10
11.64

1913. 1914,

4.35
2.02
1.75
2.00

10.22
11.99
10.79

2.53
4.0

1.02
3.13

2.07

4.8

3.59
1.62
1.26
1.16
0.84
1.11
1.21
0.94
1.16

Di-
ame-
ter.

21.27

1.16

8.6

3.34

20 to 30.
Growth.
1913. 1914.
3.59

AVERAGE ANNUAL RATE OF GROWTH OF ALL TREES FOR 1913 AND 1914.

Diameter class.

0 to 5 centimeters _.
6 to 10 centimeters .
10 to 20 centimeters
20 to 30 centimeters

Average
rate of
growth.

1.70
1.89
1.79
3.59

Years in
class. I

2.9
2.6
5.6

2.8

GROWTH 129

the remainder were in the nursery. It will be noticed that in
only one ease did a tree in the forest grow more rapidly during
the second year than in the first, and that with two exceptions
the trees showed a considerably slower rate of growth during
the second year. This was very evidently due to greater
crowding as the individuals became larger. In only one case
were measurements obtained on a tree in the nursery for the
two years and this one grew more in the second year than in
the first. The average annual rates of growth of the Q- to
5-centimeter class was 1.7 centimeters ; of the 5- to 10-class, 1.89 ;
of the 10- to 20-class, 1.79; and of the 20- to 30-class, 3.59
centimeters. The last figure is based on the measurement of
only one individual for the year 1914. This same individual
was in the 10- to 20-centimeter class the previous year and
showed the fastest growth of any tree in this class. This faster
rate was probably due, at least in part, to its large size, which
prevented it from receiving as much shade as did the smaller
individuals.

With the exception of this largest class all of the diameter
classes showed approximately the same rate of diameter growth.
According to the estimated number of years it takes a tree to
pass through the different diameter classes, a tree 30 centimeters
in diameter would be 13.9 years of age.

In order to compare the rates of growth of the second-growth
species at the base of Mount Maquiling with those of trees grow-
ing in the United States, the approximate time required to
produce different wood crops has been taken from the Woods-
man's Handbook* and is presented in Table XLII. In the orig-
inal publication, these figures are found in Table LXIII, which
gives the number of years required by different species to reach
diameters of 6, 8, 11, 14, and 18 inches. In our Table XLII the
data for 18 inches are omitted. For convenience we may com-
pare the length of time required, by these species to reach a
diameter of 11 inches, or 27.9 centimeters, with the time re-
quired for Mallotus to attain a diameter of 30 centimeters. The
fastest growing of the species for which data are given for a
diameter of 11 inches is red gum in South Carolina, which
attained this diameter in thirty years, whereas Mallotus
ricinoides reaches a diameter of 30 centimeters in approximately
fourteen years. In other words, Mallotus ricinoides apparently
grows about twice as fast as the most rapidly growing species

* Graves, H. S., and Ziegler, E. A., The Woodsman's Handbook, Bull.
U. S. Dept. Agr.y Forest Service (1910), No. 36.

159549 9

130

MOUNT MAQUILING

mentioned in Table XLII. The number of years required by
the average of all the species in Table XLII to reach a diameter
of 11 inches is sixty-seven years.

Columbia serratifolia. — This species is a small tree, reaching a
height of 10 to 14 meters, and has a fairly dense crown for a
second-growth tree. It is widely distributed in the Philippines
and is prominent in the second-growth forest at the base of
Mount Maquiling. All trees measured were in the young forest,
and the results are recorded in Table XXXIII. The average

Table XXXIII. — Annual diameter growth of Columbia serratifolm
(anilao) in young forest at the base of Mount Maquiling ; altitude ,
about 80 meters.

[Diameters and growth

are given in centimeters.]

Position of tree.

Diameter class in centimeters.

0 to 5.

5 to 10. 10 to 20

i

wrth.

20 to 35.

Di-
ame-
ter.

Growth.

Di-

Growth.

Di-
ame-
ter.

Gro

Di-
ame-
ter.

Growth.

1913.

1914.

ter.

1913.

1914.

1913.

2.73
1.81

1914.

1913.

4.31

2.18

!
1914. I

In young forest

Do _

4.60

2.09

S.A1

6.67
7.82
6.69
6.83

2.34
2.58

0.77

3.18
2.32
2.41
0.19

11.14
11.57
10.40

1.91
1.46
2.32

20.26
32.41

1.91

Do

Do

Average _

Years in class

2.09
2.4

1.89
2.6

1.93
2.6

2.27
4.4

1.90
5.3

3.24
4.6

1.91
7.9

AVERAGE ANNUAL GROWTH FOR 1913 AND 1914.

Diameter class.

Average
rate of
growth.

~v~

2.09
1.91
2.05
2.80

Years in
class.

2.4

2.6

4.9
fi.4

10 to 20 centimeters ' _

annual rate of growth of all trees in the 0- to 5-centimeter class
is 2.09 centimeters; in the 5- to 10-elass, 1.91 centimeters; in
the 10- to 20-class, 2.05 centimeters; and in the 20- to 35-class,
2.80 centimeters. As in the case of Mallotus ricinoides there
is comparatively little difference in the rates of growth of the
diameter classes 0 to 5, 5 to 10, and 10 to 20 centimeters.
The 20- to 35-centimeter class showed a somewhat more rapid
rate, which is probably due, as in the case of Mallotus ricinoides,
to the fact that the large trees are not subject to as much shading

GROWTH

131

as are the smaller ones. The rate of growth of Columbia serra-
tifolia is approximately the same as that of Mallotus ricinoides,
as according to the calculations it takes a tree 15.3 years to reach
a diameter of 35 centimeters.

Bauhinia malabarica. — This is a small tree with a dense crown,
and is frequently prominent in the first stage of invasion of
grassland by a second-growth forest. Its ability to endure in
such situations is due to its being more fire-resisting than are
most second-growth species.

The results of the measurements of Bauhinia are recorded in
Table XXXIV. All of the trees except one were growing in

Table XXXIV.— Annual diameter growth of Bauhinia malabarica (ali-
bangbang) at the base of Mount Maquiling; altitude, about 80 meters.

[Diameters and growth are given in centimeters.]

Position of tree.

Diameter class in centimeters.

5 to 10.

10 to 20.

20 to 30.

Diam-
eter.

Growth.

Diam-
eter.

Growth.

Diam-

Growth.

1913.

1914.

1913.

1914.

ett

jr.

1913.

2.73
2.72

1914.

3.08
3.27
2.23

In the open

5.72

3.15

4.14

18.40

2.40

2.23

23

Do

23.87
20.80

Do

In the forest

8.53

0.98

0.72

Average

2.06
2.4

2.43
2.1

2.40
4.2

2.72
3.7

2.86
3.5

Years in class

AVERAGE ANNUAL GROWTH FOR 1913 AND 1914.

Diameter class.

.

Average
rate of
growth.

Years in

class.

5 to 10 centimeters

2.25

2.40

9. 81

2.2
4.2
a r

10 to 20 centimeters „

20 to 30 centimeters ._ _ ___

the open, and with one exception those in the open showed a
faster diameter growth during the second than the first year,
whereas the tree in the forest showed a slower rate. This again
points to the conclusion that, where the growth of trees in the
forest was slower during the second year, the lower rate was
due to crowding.

The 5- to 10-centimeter class has an average annual rate of
growth of 2.25 centimeters ; the 10- to 20-class, 2.40 centimeters ;
and the 20- to 30-class, 2.81 centimeters. The time required for

132

MOUNT MAQUILING

Bauhinia to grow from 5 to 30 centimeters is, according to the
calculations, ten years; which would seem to show that this
tree grows about as rapidly as the two species previously con-
sidered. Observations of the growth of seedlings, however,
indicate that very young plants of Bauhinia malabarica grow
more slowly than do those of most second-growth species.

Trema orientalis. — This species is intolerant of shade; it has
small leaves and a very open canopy. It is widely distributed in
the Indo-Malayan region and in the Philippines is a very common
second-growth tree. It is particularly prominent in invasions of
bare ground, where it frequently forms pure stands of consider-
able extent.* The rapid invasion of areas by this species has
been discussed in connection with the general description of
the parang and the dipterocarp forest. Trema is a small tree,
reaching a height of from 5 to 8 meters, and during its earlier
stages is an extremely rapid grower. The measurements of
this species are given in Table XXXV. It will be seen that the

Table XXXV. — Annual diameter grovjth of Trema orientalis (anabion)
at the base of Mount Maquiling ; altitude, about 80 meters.

[Diameters and growth are given in centimeters.]

Position of tree.

In the open

Do

In the forest _ -

Average _
Years in class ~

Diameter class in centimeters.

Diam-
eter.

10 to 20.

Growth.
1913.

20 to 30.

! Growth.

11.90
10.78
10.72

I

3.67
6.17
3.73

4.52
2.2

Diam-
eter.

3.85 ! 25.91

5.81 |

0.94 J 25.31

1913. I 1914.

1.36 I 0.94

i

3.11 | 1.45

3.53 |

2.8 i

2.23 | 1.19
4. 5 8. 4

AVERAGE ANNUAL RATE OF GROWTH OF ALL TREES FOR 1913 AND 1914.

!

Diameter class.

10 to 20 centimeters .
20 to 30 centimeters -

Average
rate of
growth.

4.03
1.71

Years in
class.

2.5

5.8

average rate of growth of trees in the 10- to 20-centimeter class
was 4.03 centimeters per year, and that the greatest growth made

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil Journ. Scl, Sec. A (1914), 9, 413-561.

GROWTH

133

by an individual during a year was 6.17 centimeters. The oldest
individuals measured were approaching the age of maturity
and showed a slower rate of growth than did the larger indi-
viduals of the three species previously considered.

Table XXXVI. — Annual diameter growth of Litsea glutinosa (puso puso)
at the base of Mount Maquiling ; altitude, about 80 meters.

[Diameters and growth are given in centimeters.]

Diameter class in centimeters.

Position of tree.

In the forest .

Do

Do

Do

Do

Average .
Years in class _

In nursery .

Do

Do
Do
Do
Do
Do
Do
Do
Do
Do
Do
Do
Do
Do
Do

0 to 5. I

Growth. i
Diam- I Diam-

eter, eter.

1913. 1914.

3.24 0.24 0.22 j

3.11 0.51 I 0.S5 |

3.59 i 0.79 j 0.78 j

4.76 | 1.09 0.76 \

0.66
7.6 j

0.45
11.1

7.67
6.08
5.52
5.22

5.85

2.12

Growth.

1913. 1914.

2.05
1.43
0.65

1.82

1.49
3.4

0.65
0.92
0.67
1.65
0.76

0.93
5.4

5.30

2.45

5.14

1.77

7.35

2.67

6.32

2.84

9.27

3.40

7.20

1.87

7.79

2.71

6.28

2.23

7.69

1.86

8.61

2.35

7.15

2.24

6.04

2.13

5.31

1.29

6.83

1.70

7.00

2.51

7.00

2.03
1.65

Average ,
Years in class _

2.12 |

2.4 !

2.27
2.2

2.06

2.4

AVERAGE ANNUAL RATE OF GROWTH OF ALL TREES FOR 1913 AND 1914.

Diameter class.

0 to 5 centimeters .
5 to 10 centimeters .

Average
rate of
growth.

0.76
1.88

Years ir
class.

6.6
2.7

134 MOUNT MAQU1LING

Litsea glutinosa. — This species reaches a height of 10 meters
or less and has a moderately dense crown. It is widely dis-
tributed in the Philippines at low altitudes and in the Indo-
Malayan region in general. In the Philippines it is rather
common in second-growth forests.

The trees measured were in the forest and in the nursery.
The results are presented in Table XXXVI. There were four
individuals of the 0- to 5-centimeter class in the forest and one
in the nursery. All of those in the forest had a comparatively
slow rate of growth, the fastest being 1.09 centimeters and the
average 0.55, while the individual in the nursery grew 2.12
centimeters. The slow rate of growth made by those in the
forest is probably connected with the fact that they were small
individuals and were shaded. The trees in the 5- to 10-centi-
meter class showed an annual rate of growth of 1.88 centimeters,
which is approximately equal to that of the species previously
considered.

Most of the individuals in the forest, as in the case of the
other species, showed a slower rate of growth in the second
than in the first year.

Macaranga spp. — These trees belong to two species, M. bicolor
and M. tanarius. The two species are so very similar in general
appearance that it is often impossible to distinguish them from
sterile specimens. They have large leaves and spreading crowns
which cast a fairly dense shade. Both species may be prom-
inent in the invasions of cleared land by second-growth forest,
and they also occur in considerable numbers in the early stages
of the invasion of grassland by second-growth forests. The
trees reach a height of 4 to 8 meters. Macaranga tanarius
is widespread in the Malayan Peninsula and Archipelago
and is common and widely distributed in the Philippines. Ma-
caranga bicolor is endemic in the Philippines and is widely
distributed in the northern part of the Islands.

The record of growth of these species is given in Table
XXXVII. Macaranga, in the 5- to 10-centimeter class, showed a
faster annual rate of growth, 2.83 centimeters, than any tree
previously considered. Between 10 and 20 centimeters it showed
about an average rate, 2.45 centimeters. The measurements
of the 20- to 35-centimeter class were based on only two indi-
viduals, but these showed a lower average, 2.04 centimeters,
than any of the other species except Trema orientalis. This is
due, as in the case of Trema, to the fact that the older trees had
passed their age of most rapid growth.

GROWTH

135

Table XXXVII. — Annual diameter growth of Macaranga spp. (binunga)
at the base of Mount Maquiling; altitude, about 80 meters.

[Diameters and growth are given in centimeters.]

i

Diameter class in centimeters.

Position of tree.

5 to 10.

10 to 20.

20 to 35.

I

j Diam-
eter.

Growth.

Diam-
eter.

Gnr
1913.

*vth.
1914.

Diam-
eter.

Growth.

1913.

1914.

1913.

-

1914.

In young forest

14.77
16.67
15.82
11.67
10.98
13.15
11.47
10.67
11.77
10.92
10.61
10.56

3.04
2.45
3.86
3.35
2.55

Do

8.90
9.46
9.27
5.52
8.33
5.40
8.25
7.62
9.29
8.06
5.33
6.11
5.69

4.25
4.96
2.20
2.48
2.34
1.87
3.52
3.30
1.32
2.50
2.41
2.30
2.35

2.75

1.8

2.5U

1.08
2.73
1.78
1.72
S.02
1.81
1.62
2. 46
2.58
1.97
2.16

32.63
20.74

2.66
1.55

2.27
1.68

Do

Do

Do

2.31
2.54
1.08
1.78
3.02
1.81
1.62
2.46

Do

Do

Do

Do

Do

Do

Do

Do ....

Do

Average

2.23
2.2

3.05
3.3

2.08
4.8

2.10
7.1

1.97
7.6

Years in class

In nursery

5.08
5.92
5.19
9.86
9.05
7.10
7.94

3.01
2.62
3.52
4.43
3.55
3.08
3.56

Do

Do

Do

Do

Do

Do

Average

3.40
1.5

Years in class

AVERAGE ANNIL

A.L RAT

nE OF GROWT1

1 OF A

LL TRE

ES FOR 1913 AND 1914.

- *

Di

ameter class.

Av
ra
gn

erage
te of
>wth.

9 83

Years in
class.

5 to 10 centimeters ...

1.8
4.1

7 A

10 to 20 centimeters

2.45

20 to 35 centimeters -_-

The time required for Macaranga to grow from 5 to 35 centi-
meters in diameter is approximately the same as that required
by the other species to make a growth of 30 centimeters. The
more rapid growth of the trees in the forest during the first
than the second year is again apparent.

136

MOUNT MAQUILING

Artocarpus cumingiana, — This is a medium-sized species and
attains larger dimensions than any tree previously considered.
It has large leaves, which are from 18 to 35 centimeters in length.
It is found scattered along the edges of dipterocarp forests
and on the moister slopes of drier types, and is not so charac-
teristically a second-growth species as are the trees previously
considered. Artocarpus cumingiana is endemic in the Philip-
pines and is common and widely distributed at low and medium
altitudes.

The rates of growth of Artocarpus are given in Table
XXXVIII. The 0- to 5-centimeter class showed an annual rate
of growth of 1 centimeter; the 5- to 10- class, an average rate
of 1.53 centimeters; and the 10- to 20- class, 1.77 centimeters.
Artocarpus thus appears to have a slower rate of growth than any
of the species previously discussed. According to the calcula-
tions it requires 13.9 years to reach a diameter of 20 centimeters,
which is exactly the length of time required by Mallotus rici-
noides to reach a diameter of 30 centimeters.

Table XXXVIII. — Annual diameter growth of Artocarpus cumingiana
(anubing) at the base of Mount Maquiling; altitude, about 80 meters.

[Diameters and growth are given in centimeters.]

Position of tree.

Diameter class in centimeters.

0to5.

5 to 10.

10 to 20.

Diam-
eter.

Growth.

Diam-
eter.

Growth.

Diam-
eter.

10.70

Growth.

1913.

1914.

1913.

1914.

1913.

1914.
1.60

In the forest

6.73
6.12
9.00
6.41
5.73

1.53
1.73
1.70
1.33
1.37

1.59
1.60
1.60
1.24
1.64

Do

Do

._

i

Do ._._

Do . .

Average _.

1.53
3.1

1.52
3.3

1.60
6.3

Years in class

In nursery

4.32

1.00

5.34

2.67 1

11.48

1.95 1 -

AVERAGE ANNUAL RATE OF GROWTH OF ALL TREES FOR 1913 AND 1914.

Diameter class.

Average
rate of
growth.

Years in
class.

5.0

1.00
1.53

1.77

3.3

5.6

GROWTH

137

Miscellaneous species. — -Besides the above-mentioned trees, a
few individuals of a number of other species were also measured.
The results are given in Table XXXIX. The average rates of
growth of these miscellaneous species are very similar to those
of the species already considered.

Table XXXIX. — Annual diameter growth of miscellaneous trees that
reach a diameter of 20 centimeters or more at the base of Mount
Maquiling ; altitude, about 80 meters.

[Diameters and growth are given in centimeters.]

Species.

Position of tree.
In theforest

D

5

Diam-
eter.

ameter class
to 10.
Growth.

in cen
1

Diam-
eter.

i
timeters.

0 to 20.

Growth. |

1913.

1914.

1913.

1914. |

Cordia myxa (anonang)

Do ._

16.64
15.32
15.65
14.18
13.44

1.85
2.23
2.15
2.48
3.89

1.24

do

0.64

Do

do

0.62

Do

__ do

0.79

Do

In the open

Alstonia seholaris (dita)

Sapindus saponaria

In nursery _

7.52
7.69
7.74
5.39

3.30
1.28
2.85
1.80

3.47
0.79

In the forest.. .

Do

Do

do

i

Antidesma ghaesembiUa

Mcdlotus philippensia (banato)..
Canarium villosum

19.40
11.20

1.97
1.74

do

1
1.12 :

do

6.03
5.62
6.22

7.40
8.00

1.80
2.23
1.61
2.31
1.87

Do

do

2.07
1.95
1.62
1.54

Do

do._

Glochidion pkilippicum

do

1

Polyscias nodosa

do

i

Litsea perrottetii (marang)

Premna odorata

In the open

15.19
7.03
6.96
9.01
7.00
7.14

2.15
2.12
1.58
1.55
4.46
4.82

In nursery .

Ficus nota (tibig)

Do

In the forest..

0.92

do

0.92

Do

do...

Do__.

do -

Average

2.12
2.4

1.91
2.6

2.20
4.5

0.89

Years in class

11.2

DISCUSSION OF GROWTH OF SECOND-GROWTH SPECIES THAT REACH A DIAMETER
OF 20 CENTIMETERS OR MORE

In Table XL are given the average rates of growth of indi-
viduals belonging to species that reach a diameter of 20 centi-
meters or more. The average annual rate of growth for the
0- to 5-centimeter class was 1.39 centimeters; for the 5- to 10-
class, 2.08 centimeters; for the 10- to 20- class, 2.19 centimeters;
and for the 20- to 30- or the 35- class, 2.59 centimeters. Ac-

138

MOUNT MAQUILING

cording to the calculations of the number of years required for
the average second-growth tree to pass through the different dia-
meter classes, such a tree would reach a diameter of 30 centi-
meters in 14.5 years. An average second-growth tree of 30
or 35 centimeters in diameter has about attained a maximum
size, and it is either in a stage where it is losing its vitality
or is nearing that stage.

Table XL. — Average annual diameter growth of species that reach a
diameter of more than 20 centimeters at the base of Mount Maquiling;
altitudey about 80 meters,

[Growth is given in centimeters.]

Species.

Trema orientalis (anabion )

Columbia serratifolia (anilao)

Bauhinia malabarica (alibangbang)_

Litsea glutinosa (puso puso)

Macaranga spp. (binuriga). ___

Artocarpus cumingiana (anubing)

Mallotus ricinoides (alim )

Cordia myxa (anonang) :___

Alstonia scholaris (dita)

Sapindus saponaria

Antidesma ghaesembilla

Mallotus philippensis ( banato)

Canarium villosum

Glochidion philippicum

Polyscias nodosa

Litsea perrottetii (marang)

Premna odorata

Ficusnota (tibig).,

Average

Years in class

Diameter class in centimeters.

0to5.

2.09

0.76

1.00
1.70

1.39

5 to 10.

1.91
2.25
1.86
2.83
1.53
1.89

3.38
1.68

1.93
1.96
1.70

2.08
2.4

10 to 20.

4.03
2.05
2.40

2.45
1.77
1.79
1.76

1.97
1.43

2.15
2.12
2.37

2.19
4.6

20 to 30
or 35.

1.71
2.80
2.81

2.04
3.59

2.59
* 3. 9

a Calculated for 10 centimeters.

The fastest rates of diameter growth shown by the various
species in the different diameter classes are given in Table
XLI. In this table the rates of all the species are recorded
except those of the miscellaneous ones that were represented
by only one individual. The average of these fastest rates of
growth for the 0- to 5-centimeter class is 1.79 centimeters; for
the 5- to 10- class, 3.25 centimeters; for the 10- to 20- class, 3.73
centimeters; and for the 20- to 30- or the 35- class, 3.09 centi-
meters. According to these figures the average of these fastest-
growing individuals should reach a diameter of 30 centimeters
in ten years; a similar rate is shown by Columbia serratifolia,

GROWTH

139

while Mallotus ricinoides shows a rate of 30 centimeters in nine
years. From these calculations it seems probable that an aver-
age second-growth tree under favorable conditions may reach
full size in nine or ten years.

Table XLI. — Fastest rates of diameter growth shown by species that
reach a diameter of 20 centimeters or more at the base of Mount
Maquiling ; altitude, about 80 meter s.a

[Rates of growth are given in centimeters.]

Diameter class in centimeters.

Species.

1 0 to 5.

Trema orientalis (anabion)

Columbia serratifolia (aniiao)

Bauhinia malabarica (alibangbang) .

Litsea glutinosa (puso puso)

Macaranga spp. (binuiiga)

Mallotus ricinoides (alim)

Artocarpus cumingiana (anubing)_.

Cordia myxa (anonang)

Alstonia scholaris (dita)

Sapindus saponaria

Canarium villosum

Ficus nota (tibig)

Average^,

Years in class T

2.09

2.12

1.96
1.00

1.79

2.8

5 to 10. J 10 to 20.

6.17
2.73
2.40

3.18 |
4.14 J
3.40 |
4.96 !
3.35
1.70 !

4.35
1.60
3.89

3.47
2.85 |
2.23 !

20 to 30
or 35.

3.11
4.31
3.27

2.66
3.59
1.60

"I

3.25 I
1.5 !

3.73

2.7

i»3.2

* Species represented by one individual are omitted, except in the case of Alstonia scholaris.
h Calculated for 10 centimeters.

Table XLII. — Approximate time required to produce different wood crops
in the United States. Data taken from The Woodsman's Handbook,
table 63.

Locality.

Diameter.

Species.

6
inches,
15.2 cm.

Years.
30

8
inches,
20.3 cm.

Years.
40
80
50
85
100
90
45*
40
40
85

11
inches,
27.9 cm.

Years.
60
100

14
inches,
35.6 cm.

Years.

NORTHERN FOREST.

Aspen _ __

Beech* ... _

Birch, paper .*__

Maine

Birch, yellow

New York _ .

Hemlock* .. _

Michigan

130

Maple, sugar*. .

do

Pine, jack

Minnesota _ _ _ -

Wisconsin

30
32
32

Pine, red

Pine, white _.

55
55

75

Spruce, red

do

Tamarack

Minnesota

65

150

a Species tolerant of shade which should show better results in second growth.

140

MOUNT MAQUILING

Table XLII. — Approximate time required to produce different wood crops
in the United States. Data taken from The Woodsman's Handbook,
table 63 — Continued.

Species.

Locality.

Diameter.

6
inches,
15.2 cm.

8
inches,
20. 3 cm.

11
inches,
27.9 cm.

14
inches,
35.6 cm.

CENTRAL HARDWOOD FOREST.

Chestnut »>

Maryland ._

Years.
20
50
25
25
35

Years.
25
65
35
30
45
45
25

Years.
40

50
45
80

Years.
55

Hickory (mockernut) *>

Mississippi

Oak, black

Kentucky

Oak, red _ _ .

.-. do „

Oak, white

do ___. -

Poplar, yellow _..

Tennessee c__

Poplar, yellow b

Virginia d ,___

Illinois

20

20
23

FARM-TIMBER PLANTATIONS.

Catalpab

Larch, European b _ __

_ do - -

Maple, silver^.

do

25
35

18

30

45

P 15

Walnut, black b

do

25

Cottonwood *> _

Nebraska

SOUTHERN FOREST.

Ash, white

45
65

Cedar, eastern red

35

Cottonwood __

Cypress .

40

65
30
40
75
70
75

76
100
75

45

75

Gum, red

Pine, loblolly ...

South Carolina

do

20

25

56

Pine, longleaf __ ....

-. do —

100

Pine, scrub

30

40
55

60
50

35
75
50
50
35
25

Pine, shortleaf _ . _-

ROCKY MOUNTAIN FOREST.

Fir, Douglas .

Arkansas

I
100

50
45
10

25

50

Pine, lodgepole ._

Pine, western yellow ._.

PACIFIC COAST FOREST.

Fir, Douglas

Montana

Arizona

Washington __.

California

Fir, white

Hemlock, western

70
65
45
35

Pine, sugar ._ _.

Pine, western yellow

California

40
25
20

1

do .-_ _.

55 !

Redwood

do

50

Average

32

47

67

68

b Species growing under favorable conditions when measured.

* Virgin forest.

• Second growth.

GROWTH 141

TABLE XLIII. — Comparison between the number of years required by
second-growth and United States species to reach certain diameters.

Species.

Locality.

Diameter.

6

inches,

15.2

cm.

Years.

32

8
7
8
11
6

8

inches,

20.3

cm.

11

inches,

27.9

cm.

14

inches,

35.6

cm.

Years.

68
17
15

Average of species in Table XLII___

Average of species in Table XL

Columbia serratifolia . _

United States

Years.

47
11
10
11

14
8

Years.

67
14

13

Base of Mount Maquiling.
do

Mallotus ricinoides ._

do

Artocarpus cuminqiana

do.._ _____

Macaranga spp .__

do

30
35

40

15

50
55

Gum, red __

South Carolina

Redwood

California _

20
20

25
25
18
15

Pine, loblolly

South Carolina

Cottonwood

Nebraska

Do

Mississippi

It will be seen that a second-growth forest reaches its maximum
size in a comparatively few years. In Table XLIII are brought
together the average rates of growth of all the American species
in Table XLII; the average rates of growth of such second-
growth species at the base of Mount Maquiling as attain a
diameter of 20 centimeters or more; the rates of Columbia
serratifoUa, Macaranga spp., Mallotus ricinoides, and Artocarpus
cumingiana at the base of Mount Maquiling; and of the fastest-
growing American species listed in Table XLII, namely red gum
and loblolly pine in South Carolina, redwood in California, and
cottonwood in Nebraska and Mississippi. For convenience in
making comparisons, the number of years required for the species
at the base of Mount Maquiling to reach the diameters mentioned
in Table XLII have been calculated. A comparison of the rates
of growth of these various species is shown graphically in fig. 1.
An examination of Table XLIII shows that the average rate of
growth of the second-growth species at the base of Mount Ma-
quiling was approximately four times the average rate of the
American species given in Table XLII. The only American
species that approaches the average second-growth species in
rapidity of growth is cottonwood in Mississippi, which attains
a diameter of 8 inches in 15 years, while the average of the
second-growth species reaches the same diameter in 11 years. It
will be noted, however, that Macaranga showed a rate of growth
about twice as rapid as that of cottonwood in Mississippi. The
second-growth specks, with the exception of Artocarpus cumin-

142

MOUNT MAQUILING

a

Q _».«,

01

; \

i \

— — —

I

u

■i

i \

!

i
i

2

60

\
\
\
\
\
\

*

o

en

u

\
\

o \

\
\
\

\

I

'I

\

\

V

\

b
__ L _

"3
V

U
as
ft

s

o

\
\

\

•4\ 1

_ J . *>A.

.5

'3
c

\

\

\

V

\\l 1 ■ S-

o a,

J .s

&■ -

•* \ ■-■
\
\

\
\

\
\
\
\
\

(TV _

%

oL • v%

\

\
\

\

\

O

o

^•-

1^

********

\
\ \

\
\

o

CO

o

">^o

[:-::^
^

'"OOv

\

o
be

o

i

v \ -

CO

PS

•gj^auipuao ui aa^auiBiQ

grta-na, grow more than twice as rapidly as red gum and loblolly
pine in Carolina, or redwood in California. The average calcu-
lated age of a second-growth tree 6 inches, or 15 centimeters, in
diameter is 8 years, while redwood and loblolly pine of the same
size are 20 years old. In order to attain a diameter of 14 inches,
or 35.6 centimeters, redwood would required years and loblolly

GROWTH

143

pine 55 years; while the average second-growth tree requires
only 17 years; Columbia serratifolia, 15 years; and Macaranga
spp., 15 years.

The rapid growth made by the second-growth species at the
base of Mount Maquiling is not characteristic of all tropical trees.
Brown and Matthews* have shown that trees growing in the
virgin forest may have a very slow rate of growth. In the early
stages this may be much slower than that of temperate-zone

Table XLIV. — Annual diameter growth of Pterocarpus indicus and En-
terolobium saman in the open at the base of Mount Maquiling ; altitude,
about 80 meters.

[Diameters and growth are given

in

centimeters.]

Diameter class in centimeters.

Species.

5 to 10.

10 to 20.

20 to 30.

Diam-
eter.

Growth.

Diam-

Growth.

Diam-
eter.

Growth.

1913.

1914.

eter

6

1913.

1914.

1913.

1914.

Enterolobium saman (rain

6.18

5.85

7.11

10.1

10.78

10.50
7.41
4.89

20.94

10.50

Do

12.03
12.02

Pterocarpus indicus (narra)

6.77

5.25

4.89

ANNUAL RATE OF GROWTH FOR 1913 AND 1914.

Diameter class.

G

Enterolobium
saman.

Pterocarpus in-
dicus.

rowth.

Years in

class.

Gro

wth.

Years in
class.

5 to 10 centimeters

5.85
9.09
10.50

0.9
1.1
1-0

5.25

10

10 to 20 centimeters

4.89

2.0

20 to 30 centimeters

trees. The more rapid growth of the second-growth trees is
due in part, of course, to the fact that they are not shaded as
are the smaller trees in the virgin forest. The very rapid growth
is moreover connected with the individual peculiarities of the
species, for many trees of the tropics — perhaps most of them — do
not show such extremely rapid rates of growth. Most fruit trees
and many of the better shade trees grow comparatively slowly,
and it will be shown later that forest trees in the open may make

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil Journ. Sci., Sec. A (1914), 9, 413-561.

144 MOUNT MAQUILING

a much slower growth than the second-growth trees. The
second-growth trees mentioned do not, however, show an extreme
rate for tropical trees. In Table XLIV are given the rates of
growth of two individuals of Enterolobium saman and one of
Pterocarpus indicus.

Enterolobium saman is a native of the West Indies and is
widely used in the tropics as a shade tree. It is a medium-sized
tree, reaching a height of 20 to 25 meters, and has wide-spreading
branches. The faster-growing of the two individuals of En-
terolobium grew 10.78 centimeters in diameter during the first
year and 10.50 during the second. This rate is much more rapid
than that of any individual of the second-growth trees measured.
The other Enterolobium grew 5.85 centimeters the first year and
7.41 the second. This also is a faster rate than that shown by
any second-growth individual. According to the calculations
made for these two individuals, it would take only three years
for Enterolobium to grow 25 centimeters in diameter. While
this rate appears rapid, a much higher rate would probably
be shown by measuring a greater number of individuals of
Enterolobium; but these two were the only ones available for
measurement at the forest station at the base of Mount
Maquiling.

Pterocarpus indicus (narra) is a medium-sized forest tree,
reaching a height of 20 to 30 meters and an average diameter of
70 to 80 centimeters. An exceptional tree may reach a diameter
of 150 to 200 centimeters. Narra does best in fairly open
situations and is nearly deciduous for a short time during the
dry season. The wood produced by this species is very valuable
for cabinet work, furniture, etc. A considerable number of in-
dividuals of narra were grown in the plantation of the Bureau
of Forestry at the forest station. One individual growing in the
open in a favorable situation made an exceptionally rapid growth,
and the measurements of this individual are the ones that are
given in Table XLIV. During the first year it made a growth
of 5.25 centimeters, and during the second, 4.89 centimeters.
This rate of growth would be very rapid for a second-growth
species, but it must be remembered that this was an exceptional
tree.

ANNUAL DIAMETER GROWTH OF SECOND-GROWTH SPECIES THAT DO NOT REACH
A DIAMETER OF 20 CENTIMETERS

Ficus hauili. — This species is a small tree, reaching a height
of 3 to 8 meters. It is endemic in the Philippines and is dis-
tributed throughout the Islands at low altitudes. Ficus hauW

GROWTH

145

is prominent in the second growth at the base of Mount
Maquiling.

Table XLV. — Annual diameter growth of Ficus hauili (hauili) at the
base of Mount Maquiling ; altitude, about 80 meters.

[Diameters and growth are given in centimeters.]

Diameter class in centimeters.

Position of tree.

0to5.

I ""

Growth.

5 to 10.

! Growth.

Diam- Diam- J Diam-

eter, eter. j ! j eter.

1913. 1914. j 1913. ! 1914. j 1913.

10 to 15.
Growth.
1914.

In the forest .
Do

4. 71 2. 05
4.77 ' 1.09

Do.

Do.

Do.

Do.

Do-

Do

Do.

3.32
3.90 I

0.58
3.32

i

7.72 ; 2.82

7.11 ! 2.01

5.74

9.49

5.00

6.38

5.23

6.76

5.86

1.68 ;
2.20
1.26
2.45 !
1.64 '

Average 1.76 j

Years in class j 2.8 j

2.00
2.5

In nursery _

Do

Do

Do

Do

Do

Do

Do

8.60 :
5.02 |
9.19 j
6.68 j
5.62
9.01
7.15
5.24 !

1.59
2.57

2.38
2.83
2.23
4.14
3.84
2.15

0. 94
1.S8
0.46

14.09
13.20
12.82
11.69

0.93
1.56
1.43

1.38

1.22

1

0.79

V

0. 98

0.64

1.31

3.8

0.84
6.0

"~~~"~\

1.38
3.6

2. 07
3.40

11.38
10.64 '

io. 19 •

2.24
3.85

4.75
2.82

2.07

2. 00

Average .
Years in class..

2.72
1.9

2.70
1.85 |

3.04

1.6 ■

3.05
1.6

AVERAGE ANNUAL RATE OF GROWTH OF ALL TREES FOR 1913 AND 1914.

Diameter class.

0 to 5 centimeters

5 to 10 centimeters

10 to 15 centimeters

Average
rate of
growth.

1.76

2.01 |
2.28 I

Years in
class.

2.8
2.6
2.2

The rates of growth of this species are recorded in Table XLV.
They are similar to those for species attaining a diameter of
20 or more centimeters. The average rate of growth of the
0- to 5-centimeter class is 1.76 centimeters; of the 5- to 10-class,
2.01 centimeters; and of the 10- to 15-class, 2.28 centimeters.
According to these figures it would take a tree 7.5 years to reach

159549-

146

MOUNT MAQUILING

a diameter of 15 centimeters. Ficus hauili made the second
most rapid growth of any species classified as not reaching a
diameter of 20 centimeters.

The individuals of Ficus hauili were in the forest and in the
nursery. It will be noted that no individual in the forest made
so rapid a growth during the second as in the first year, while
three of the five in the nursery, for which two years' measure-
ments were obtained, grew more rapidly the second year than
the first. The species in question, like those previously con-
sidered, had a slower rate of growth when the forest became
more crowded.

Table XLVI. — Annual diameter growth of Ficus ulmifolia (isis) at the
base of Mount Maquiling ; altitude, about 80 meters.

[Diameters and growth are given in centimeters.]

Position of tree.

Diameter class

in centimeters.

0to5.

5 to 10.

Diam-
eter.

Growth.

Diam-
eter.

Growth.

1913.

0.21
0.77

1914.

1913.

2.05
0.37

1914.
0.95

In the forest _ _ __•

3.77
3.43

0.23
0.22

5.81
5.70

Do

0.49
10.2

0.22
22.7

1.26

0.95

4.0 J 5.3

In the open

7.79

6.90
5.73
5.00
6.40
4.85
6.12
6.20
6.40
6.92
6.91
6.71
5.31

0.85

0.73

In nursery _ _ _ __

1.30
1.31
2.21
0.76
1.27
2.37
2.88
3.30
4.68
3.37
2.77
1.03

Do _ —

Do _- - -

Do

Do ._

Do

Do 1 . _—

Do

Do

Do —

Do — —

Do - _

Average

2.27
2.2

Years in class

AVERAGE ANNUAL RATE OF GROWTH OF ALL TREES F(

)R 1913 AND

1914.

Diameter class.

Average
rate of
growth.

0.36
1.89

Years in
class.

0 to 5 centimeters

13.9

2.6

5 to 10 centimeters

GROWTH

147

Ficus ulmifolia. — This species is usually a very small tree,
reaching a height of from 3 to 5 meters. It is endemic in the
Philippines and is rather common in the second-growth forests
throughout the Archipelago.

Table XLVII. — Annual diameter growth of Premna cumingiana (maguili)
at the base of Mount Maquiling; altitude, about SO meters.

[Diameters and growth are given in centimeters.]

Position of tree.

In the forest.
Do

Do

Do

Do

Average _
Years in class.

In nursery-
Do

Do

Do

Do

Average .
Years in class _

Diameter class in centimeters.

0to6.

Diam-
eter.

4.02
4.40
4.37
4.30
4.39

Growth.

1913. 1914.

0.27
0.25
1.12
0.17
0.32

0.43
11.6

Diam-
eter.

5 to 10.
Growth.
1913. 1914.

0.63
0.27
0.0S
0.08
0.13

0.28
17.8

4.98
4.23

1.23

1.00

1.11
4.5

7.50
7.06
6.20
5.49

6.36
8.26
6.89
5.09
7.50

1.55
0.82
0.29

0.89
5.6

0.99
0.52
0.48
0.03

0.50
10.0

0.22
1.59
1.47
1.50
1.55

1.27
3.9

AVERAGE ANNUAL RATE OF GROWTH OF ALL TREES FOR 1913 AND 1914.

Diameter class.

0 to 5 centimeters- ..
5 to 10 centimeters .

Average
rate of
growth.

0.50
.92

Years in
class.

10.0
5.4

The rates of growth of this species are recorded in Table
XLVI. All individuals measured were less than 10 centimeters
in diameter at the time of the first measurement. The small
individuals of Ficus ulmifolia showed a very slow rate of growth,
the 0- to 5-centimeter class averaging only 0.36 centimeter. The
larger individuals, however, made a more rapid growth, the 5-
to 10-class averaging 1.89 centimeters. As in the case of the

148 MOUNT MAQUILING

other species, the trees in the forest made a slower growth during
the second year than the first. The trees in the nursery, where
they were not crowded, showed a considerably faster rate than
did those in the forest. According to the calculations of rates
of growth the average individual of Ficus ulmifolia requires 16.5
years to reach a diameter of 15 centimeters.

Premna cumingiana. — This species is a very small tree. It
is endemic in the Philippines and is common and widely dis-
tributed in second-growth forests at low altitudes.

The results of the measurements of this species are given in
Table XLVII. They show a slower rate of growth than that of
any of the species so far considered, the average rate of the
0- to 5-centimeter class being 0.5 centimeter and of the 5- to
10-class, 0.92 centimeter. These figures would seem to show
that it would take an individual 15.4 years to reach a diameter
of 10 centimeters.

Miscellaneous species. — In addition to the species discussed
measurements were made of a few individuals of a number
of different species that do not reach a diameter of 20 centi-
meters. The results are given in Table XLVIII. One of these,
Melochia umbellata, is of particular interest. This is the most
numerous species in the second-growth forest at the base of
Mount Maquilirig and shows a rapid rate of growth. When
young it has a smooth bark; but, as it reaches full size, the
bark becomes very rough and irregular, so that it is not prac-
ticable to determine the rates of growth of old individuals by
the methods adopted. Measurements were started on a con-
siderable number of individuals, but in only five cases did the
bark remain smooth throughout the first year. The results of
the measurements of these five individuals are given in Table
XLVIII. The fastest growth made was 5.02 centimeters, while
the average rate was 3.27. This is the fastest average rate
recorded for any of the trees that do not reach a diameter of
20 centimeters and, with two exceptions, was faster than that
of any single diameter class of any species that attains a greater
diameter. When Melochia has grown to approximately full size,
the bark rapidly becomes rough, and the trees die in a com-
paratively short time. From the average rate of growth re-
corded in Table XLVIII it would seem that this species may reach
maturity and die in three or four years.

The other miscellaneous species showed a slower rate of growth
than Melochia umbellata.

GROWTH

149

Table XLVIII. — Annual diameter growth of miscellaneous trees which do
not reach a diameter of 20 centimeters at the base of Mount Maqui-
ling; altitude , about 80 meters.

[Diameters and growth are given in centimeters.]

I
Species. !

I

1

Position of tree.

Diameter class

in centimeters.

Oto 5.

i
|

wth.

5 to 10.

Diam- ,

Gro

Diam-
eter.

Growth.

eter.

1913.

1914.

1913.

i
1914. 1

Leucaena glauca (ipil ipil) 1

Dysoxylum decandrum 1

Pipturus arborescens (dalunot) ~ J
Do,

9.19
8.51
9.06
5.78
6.30
7.74
8.93
8.13
5.74
7.98
5.28
6.79
5.11

1.37
0.71
1.58
2.04
0.78
4.34
5.02
3.53
1.20
2.24
1.03
2.67
2.01

1 21

In the open

i

0 35 !

do

0.83 j

do

Do _

In nursery

:

Melochia umbellata (labayo)

Do...

In the open

I

In nursery

Do

do

1

Do

do

Do

do „-

Voacanga globosa (bayag-usa) _ .
Do -. —

In the forest

In nursery ._

3.91

0.94

0.38

0.68 |

Do .--

do

Mussaenda philippica (cahoy da-
laga) .

In the forest

do

4.51

3.49
4.64
4.86
4.32
3.56

0.87

0.35
1.09
0.21
0.63
0.16

0.67

0.22
O.St

0.38
0.29

;

i

_.._ do

6.48
5.78

0.38

0.63
0.32

Do

„...do

Do

.__. do

Psidium guajava ( guava)

Do

do

.__ do

8.00
6.86
5.56
7.89
5.30
7.69
8.19
5.45
8.69

1.70
0.29
0.53
1.39
0.43
0.25
1.64
0.37
2.55

1.05
0.22
0.24

Do .

_.. do

Do - ...

4.99
1

1.71

In the forest

!
0. 25 i

Do ._ ._

____do 1 i

0.67 1

Do

do ----- L— _.-

0.87

Do

.. do ! !.

0. 37

i

i Do

In nursery

!

0.75
6.7

0.39
12.8

1.65
3.0

0.59
8.5

SUMMARY OF RATES OF GROWTH OF SMALL SECOND-GROWTH SPECIES

In Table XLIX are recorded the average rates of growth of
the different diameter classes of all trees that do not reach a
diameter of 20 centimeters. The rate of growth of the 0- to
5-class was 0.64 centimeter; of the 5- to 10-class, 1.40 centi-
meters; and of the 10- to 15-class, 1.60 centimeters. Accord-
ing to these figures it would take an average tree 11.4 years
to reach a diameter of 10 centimeters and 14.5 years to attain
a diameter of 15 centimeters. The average rates of growth ate

150

MOUNT MAQUILING

much slower than those of the species that reach a diameter of
more than 20 centimeters. According to the figures given in
Table XL a diameter of 30 centimeters is attained in the same
length of time that would be required by the average of the
small trees to reach a diameter of 15 centimeters. It would thus
appear that the average smaller species and the average larger
species reach maturity in about the same length of time.

Table XLIX. — Average annual diameter growth of species which do not
reach a diameter of 20 centimeters at the base of Mount Maquiling;
altitude, about 80 meters.

[Growth is given in centimeters.]

Species.

Ficus ulmifolia (isis)

Ficus hauili (hauili)

Premna cumingiana (mag-uili)

Leucaena glauca (ipil ipil)

Dysoxylum decandrum

Pipturus arborescens (dalunot)

Melochia umbellata (labayo)

Voacanga globosa (bayag-usa)

Mussaenda philippica (cahoy dalaga) ..

Ficus sp

Leea manillensis

Psidium guajava (guava)

Mallotus moluccanus (alim)

Average

Years in class

Diameter class in centi-
meters.

0.36
1.76
0. 50

0.66
0.77
0.28
0.58
0.22

0.64

7.8

5 to 10.

1.89
2.01
0.92
1.29
0.53
1.81
3.27
1.60

0.44
0.77
0.82

1.40
3.6

10 to 15.

0.92

1.60
8.1

GENERAL DISCUSSION

A consideration of the rates of growth of second-growth species
shows very clearly that their small size is not connected with a
slow rate of growth; it also emphasizes the fact that they are
weed species that can quickly invade open ground, mature early,
and produce seeds before a more stable forest has had time to
develop. The rapid growth of the species does, however, show
that conditions at the base of Mount Maquiling are very favor-
able for plant growth. In the same locality agricultural crops
that can stand a short but not very severe dry season do well.
It may, therefore, be concluded that environmental 'Conditions
at the base of Mount Maquiling are favorable for plant growth.
As previously pointed out, the few scattered specimens of large
trees remaining from the original forest indicate that this area
was originally covered by a tall forest.

GROWTH 151

GROWTH IN DIPTEROCARP FOREST

Measurements of the rates of growth of trees in the dipterocarp
forest of Mount Maquiling were begun by Mr. D. M. Matthews
and the writer in January, 1913. The results of the first year's
measurements on Mount Maquiling, together with those of more
extensive measurements in other dipterocarp forests, have been
published in considerable detail.* The measurements here pre-
sented are in continuation of those started by Brown and Mat-
thews in 1913 and cover four years. The results are essentially
similar to those published; and, as these rates of growth have
previously been compared with those in other regions in the
Philippines, as well as in America, no extensive comparison of
the rates for trees in the dipterocarp forest on Mount Maquiling
with those in other localities will be attempted.

The measurements in the dipterocarp forest of Mount Ma-
quiling were taken at an elevation of approximately 300 meters,
in an area in which there has been very little logging. This
area was on the side of Molauin River opposite station 2 and
about the same distance from the river as was this station.
The environmental conditions may, therefore, be considered as
practically the same as those obtaining at station 2.

The three species concerned are Parashorea malaanonan (bag-
tican lauan) which, it will be remembered, is the dominant
tree in the dipterocarp forest; Diplodiscus paniculatus (balobo),
a second-story tree, which is the most numerous tree species
in the forest; and Dillenia philippinensis (catmon), which is
another common second-story tree.

The first measurements of Parashorea were taken on January
13, 1913; the second, January 13, 1914; the third, January,
1915; and the fourth, in January, 1917. The results are pre-
sented in Table L, in which are given the diameters at the
time of the first measurement, the diameter growth for 1913
and 1914, and the average annual diameter growth for 1915
and 1916; also the average rates of growth for the four-year
period and the average number of years that it would take,
according to these figures, for a tree to pass through a given
diameter class.

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil. Journ. Sci., Sec. A (1914), 9, 413-561.

152

MOUNT MAQUILING

Table L. — Annual diameter growth of Parashorea malaanonan (bagtican
lauan) in virgin forest on Mount Maquiling; altitude, about 800 meters.

[Diameters and growth are given in centimeters.]

No. of tree in class.

Diameter class in centimeters.

0 to 5.

5 to 10.

Diam-
eter.

Annual grdwth.

Diam-
eter.

5.19

7.40
7.29
9.11
6.28
5.56
7.18
8.80
5.39
5.80

Annual growth.

1913.

1914.

1915
and
1916.

1913.

1914.

1915
and
1916.

1 _

3.88
4.15
4.61
2.43

0.112
0.217
0.000
0.070

0.000
0.175
0.032
0.192

0.016
0.056

0.143
0.121
0.395
0.339
0.378
0.366
' 0.280
0.447
0.280
0. 028

0.28
18

0.000
0.194
0.194
0.159
0.016
0.317
0.079
0.445
0.588
0.192

0.000
0.119

2_._

3

0.923

4 .—

0.374
0.016

5 - _

6

7

8 ...

I
9__ l

10 .... L

0.10'
50

0.10
50

0.04
125

0.22
23

0.29

17

Average annual growth for
four years

0.07
71

0.27
19

Average years in class

No. of tree in class.

Diameter class

in centimeters.

lot

3 20.

20 to 30.

Diam-
eter.

Annual growth.

Diam-
eter.

25.70
27.50
29.20
29.95
27.00
22.65
26.50
25.55
20.80
26.95
26.15
29.00
28.90
26.85
26.00
27.90
26.50
27.95
22.20

Annual growth.

1913.

1914.

1915
and
1916.

0.032
0.803
0.016
0.446
1.511
0.127
0.390
0.016
0.016
0.239
0.700
0.350
0.239
0.335
0.430
0.653
0.104
0.303
0.533

1913.

0.445
1.045
0.617
0.445
1.006
0.620
0.429
1.132
0.500
0.344
0.364
0.902
0.568
0.785'
0.141
1.083
1.001
0.140
0.255

1914.

1915
and
1916.

1__

14.92
19.35
15.00
19.55
13.21
17.38
15.78
12.72
18.90
17.20
16.20
12.10
11.09
19.42
12.61
10.15
14.00
14.30
14.19
13.39
11.44

0.127

0. 236
0.497
0.318
0.141
0.345

0.188
0.408
0.379

0. 494
0.461
0.916
0.681
0.239
0.277
0.377
0.168
0.364

0.032
1.002
0.032
0.223
0.207
0.159
0.715
0.111
0.032
0.318
0.732
0.223
0.366
0.366
0.700
0.732
0.238
0.335
0.604
0.286

0.446
1.208
0.572
0.350
1.050
0.732
0.350
1.060
0.476
0.016
0.238
1.352
0.572
0.589
0.143
1.143
0.541
0.175
0.271

0.295

1.002

3

0.406

0.135

5 ___

0.708

6.... __ .

0.485

7. _

0.104

0.899

9

10 _

0.191
0.024

11

0.183

0.414

13

0.350

14

IB

0.477
0.199

16

0.692

17

0.374

18

0.024

19

0.080

20

21

Average

0.62
16

0.59
17

0.39
26

0.37
27

0.38
26

0.37

Years in class

27

Average annual growth for
four years

0.38
26

0.49
20

Average years in class

GROWTH

153

Table L.-— Annual diameter growth of Parashorea malaanonan (bagtican
latum) in virgin forest on Mount Maquiling; altitude, about 800.
meters — Continued.

No. of tree in class.

10..
11..
12-
13..
14..
15_.
16..
17..
18-
19..
20..
21..
22..
23_.
24..
25-
26..
27.
28..

Average .
Years in class .,

Average annual growth for

four years _.

Average years in class _.

Diameter class in centimeters.

30 to 40.

Diam-
eter.

39.60
36.20
30.40
38.65
33.00
39.00
36.55
34.60
31.65
35.40
33.50
39.75

Annual growth.

1913.

1.047
1.536
0.492
1.881
0.318
1.088
0.236
1.058
0.506
1.079
0.949
0.858

0.92
11

1914.

1.033
2.116
0.875
0.621
0.207
0.924
0.175
0.700
0.493
0.954
0.747
0.651

1915
and
1916.

0.716
1.479
0.255
0.430
0.143
0.978
0.024
0.708
0.327
1.344
0.493
0.708

0.79
13

0.1
16

0.74
13.5

Diam-
eter.

45.70
46.80
42.75
44.10
49.25
46.60
45.50
47.50
43.10
44.25
43.40
40.90
43.25
46.80
46.75
47.35
40.75
42.50
43.30
49.20
46.70
46.75
48.80
49.75
41.10
49.00
43.40
46.00

40 to 50.

Annual growth.

1913. i 1914.

0.859
0.664
0.804
1.110
0.903
0.698
1.071
1.186
0.830
0.455
0.567
0.600
0.513
1.050
1.217
0.661
1.315
1.827
0.774
0.521
0.268
0.477
1.116
0.784
0.999
1.006
0.286
0.661

0.83
12

0.891
1.018
0.646
1.354
1.210
0.748
1.081
1.720
0.907
0.382
0.922
0.684
0.541
1.142
0.794
1.241
1.064
2.039
0.779
0.604
0.620
0.589
0.668
0.604
1.098
0.573
0.700
1.044

0.S
11

0.82
12

1915
and
1916.

0.676
0.923
0.509
1.058
0.955
0.279
0.509
1.742
0.573
0.255
0.366*
0.477
0.374
0.835
0.875
0.891
0.621
1.559
0.819
0.414
0.803
1.114
0.875
0.525
1.082
0.907
0.796
0.629

0.77
13

154

MOUNT MAQUILING

Table L. — Annual diameter growth of Parashorea malaanonan (bagtican
lauan) in virgin forest on Mount Maquiling; altitude , a%out $00
meters — Continued.

No. of tree in class.

Diameter class in centimeters.

5,0 to 60.

Diam-
eter.

54.60
54.90
59.50
54.50
51.15
58.15
57.90

Annual growth.

1913. 1914.

Average |

Years in class j

I
Average annual growth for ■

four years i

Average years in class

0.366
0.901
0.924
0.593
1.222
1. 659f
0.532

0.254
1.160
0.700
0.923
1.580
1.353
0.793

0.97
10

1915
and
1916.

0.183
1.169
0.557
0.629
1.209
1.861

0.94
11

0.94
11

60 to 70.

Diam-
eter.

Annual growth.

67.10
62.80
64.50
62.70
60.25
60.50
63.20
67.30
64.90
62.70

1913.

0.236
0.524
2.140
Q.478
0.823
0.674
0.344
0.028
0.276
0.478

0.60
17

1914.

0.558
0.858
1.683
0.494
1.018
1.082
0.890
0.441
0.923
0.441

0.84
12

1915
and
1916.

0.581
0.915
0.470
0.327
0.803
1.901
0.501

0.782

0.78
13

0.75

*

Diameter class, 70 to 8
meters.

0 centi-
wth.

No. of tree in class.

Annual gro

Diam-
eter.

1913.

1914.

1915
and
1916.

1 _ . .

78.90

0.349

0.921

1.042

0.35

0.92

1.04

29

11

10

0.84

12

The measurements taken in January, 1917, were made on
the occasion of a hurried trip to Los Baiios ; a few of the trees
previously measured were not relocated, as the band of white
paint with which they had been marked four years previously
had largely disappeared. This accounts for the blanks in the
column for 1915 and 1916.

It will be seen that the same tree frequently shows very
different rates of growth in the different years. This may

GROWTH 155

very well be connected with differences in exposure due to
changes in the size of the crowns of the trees composing the
canopy. When, however, the average rates for all the trees
in a class are calculated, the averages for the different years
are much more similar than are the rates for the individuals.
Moreover, the total number of years required by a tree to grow
from a diameter of 5 centimeters to the largest diameter is
very similar for all of the different years. It seems probable,
therefore, that the rates of growth calculated in Table L are
approximately average rates for Parashorea at this altitude on
Mount Maquiling.

This does not mean, however, that from these figures we can
accurately calculate the ages of trees of small diameters; for,
as has already been pointed out, many of ^the small trees may
not reach mature size. This is particularly true of those in
the 0- to 5-centimeter class. In Brown and Matthews's Table
XVI * in which are presented the rates of growth of Para-
shorea on Mount Maquiling, tree 3 in the 0- to 5-centimeter
class showed no growth. At the end of 1914 this tree still ap-
peared healthy, but again showed no growth. In January, 1917,
it was found to be dead.

Tree 3, in the 0- to 5-centimeter class in Table L, showed
no growth during 1913, but in 1914 grew 0.032 centimeter in
diameter and in 1915 and 1916 made an average annual growth
of 0.056 centimeter. Tree 1, in the same class in Table L,
showed a growth of 0.112 centimeter in 1913, and no growth in
1914. This tree was not relocated in January, 1917, but was
observed later when it was apparently vigorous. It will be seen,
therefore, that it is not possible to tell by the appearance of
a tree or by its rate of growth for a year whether or not it
will continue to exist.

The rates shown for the 0- to 5-centimeter class are very
varied, as are also the averages for the different years. It is,
therefore, probable that there is a considerable error* in esti-
mating the age of trees in this class ; but this error is not likely
to be large enough to produce a very considerable error in es-
timating the ages of trees of large size.

The average rates of growth of trees in the 5- to 10-centi-
meter class agree much more closely than do those of trees
in the 0- to 5-class, and it seems probable that a calculation
from these figures, of the number of years required for a tree

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil. Journ. Set., Sec. A (1914), 9, 413-561.

156 MOUNT MAQUILING

to grow from 5 to 10 centimeters, is fairly close to the actual
time involved. The trees in this class are tall enough to be
high in the forest.

Trees which are more than 20 centimeters in diameter are
in the first story, and the calculations of the number of years
required for them to pass through the higher diameter classes
should be fairly accurate. In discussing the composition of the
dipterocarp forest it was shown that trees even less than 20
centimeters in diameter may be in the first story.

If the rates as calculated above are applicable to the trees
in the forest as a whole, then the number of individuals in a
diameter class divided by the number of years calculated for a
tree to pass through the same diameter class should be practically
constant for all classes. Such a calculation based on the number
of trees in different diameter classes on a square hectare indicates
that there is a very low rate of mortality in trees between 5 and
40 centimeters in diameter, and so the calculations of the rates
of growth for diameters above the 0- to 5-class may be regarded
as fairly accurate.

While the method of calculating the age of a tree is subject to
the error above mentioned, this error does not affect the validity
of a comparison of rates of growth of trees of various diam-
eters in different situations, for the measurements represent
the actual rates of growth of average trees of different diameters.

In fig. 2 there is presented a curve of the rates of growth
of Parashorea. In this curve the ordinates represent diameters
and the abscissae years. According to the curve, it takes an
average individual of Parashorea one hundred ninety-seven years
to reach a diameter of 80 centimeters. This slow rate of growth
is very evidently due to the fact that the trees are suppressed
while young ; as, according to the curve, it would require seventy-
one years for a tree to reach a diameter of 5 centimeters. After
the trees have come to be in the main canopy they show a
rapid rate of growth.

The following conclusions of Brown and Matthews give a
comparison of the rates of growth of Parashorea with those of
trees in America:

It will be seen from the curves that the rate of growth of white oak
is faster than that of Parashorea, until the trees are 37.5 centimeters in
diameter, while yellow poplar grows faster than Parashorea until it attains
a diameter of 65 centimeters. Yellow pine in New Mexico and oak on site
I in Europe show rates of growth intermediate between white oak and
yellow poplar. It is also to be noted that the curve for Parashorea crosses
those of all of the temperate zone species and in the larger diameter
classes lies considerably above them. This shows clearly that in the latter

GROWTH

157

part of the life of Parashorea it is distinctly the fastest growing of all
the species here considered. Yellow poplar, the fastest growing of the
temperate zone species, takes one hundred fifteen years to grow from 30
centimeters in diameter to 70 centimeters, while Parashorea makes the
same growth in fifty years. The results would seem to show clearly that
only the larger individuals of Parashorea are in a position to take advan-
tage of the more favorable conditions for growth which exist in the tropics
and that throughout the earlier period of their existence they maintain
themselves and grow under very adverse conditions; that is, Parashorea
in a virgin forest passes through an exceptionally long suppression period
as compared with trees in a deciduous forest of the temperate zone.

The figures for the rates of growth of Parashorea, as cal-
culated by Brown and Matthews, and as given in Table L, show
some slight differences, but not enough to affect the general
conclusions reached by them.

Measurements were also begun by Brown and Matthews of
fifty individuals of Parashorea growing in a pure stand near the
base of Mount Maquiling at an altitude of about 100 meters.
None of these trees were more than 14 centimeters in diameter.
This stand was located at the edge of the forest near a large
seed tree, and probably became established under a canopy
which has since disappeared. The straggling individuals near

10 20 30

Age in years.

SO $0 70 80 90 100 110 120 130 140 150 160 170 180 190

70

-----

—

--■■

1

:.-J -

1

— -

6~\ —

£0

j

1

- I

i

t

-----

_

_

{—•

1 ;
J

|

1 r-

-i *

-X-.L _

/! !
f " ! -

50

~-4—

)•--■ -

i

~4

i

A

i C'Ji

f

/-I

-■ i

40

H

'"A

— - \— }■ - r- - ' -

_. X - -

J

£-- : -

— I —

f

-

! ! ! f/

!

!

h $

r t
|

i ; ; $Y i i !

^

^ _ 1 ^

-—\'-/> ;P;-- j— - -

J./ . / 1 j
- 'A'-\-\ ;■;- '

zo

._._

—-•

' * 1 ~'~"

\ —

Jr

10

^0ti

--y

■~

..-^

— i

>

/'

-

;

i
.. 1

Fig. 2. Rates of growth of trees in dipterocarp forest on Mount Maquiling ; altitude,

300 meters.

158

MOUNT MAQUILING

the edge of the stand were in an exposed situation. They were
smaller than those in the main stand and showed a slower rate
of growth. While, thus, too great exposure appears to be in-
jurious to young plants of Parashorea, the trees growing in a
pure stand in the open show a much faster rate of growth than
those in the virgin forest. The results of the measurements
of these trees are given in Table LI.

TABLE LI. — Annual diameter growth of Parashorea malaanonan (bagtican
lauan) in open at base of Mount Maquiling ; altitude, about 100 meters.

[Diameters and growth are given in centimeters.]

No. of tree in class.

Diameter class in centimeters.

|

0to5.

5 to 10.

10 to 15. ,

Diam-
eter.

Annual growth.

Diam-
eter.

Annual growth.

Diam-
eter.

10.05
13.60
13.80
10.95
10.24
10.88
11.10

Annual growth.

1913
and
1914.

1915
and
1916.

1913
and
1914.

'o. 986
0.366
0.581
0.653
0.501
0:565
0.493
0.287
0.438
0.740
0.629
0.955
0.467
0.247
0.358
0.414
0.430
0.525
0.641
0.509
0.891
0.891
0.875
0.287
0.970
0.661
0.605

1915
and
1916.

1913
and
1914.

0.557
0.883
0.756
1.034
0.297
0.780
0.748

1915 j
and i
1916. ]

1 .

4.95
4.17
4.14
3.60
3.74
4.29
3.30
4.62
3.43
4.35
4.70
4.92
4.87

0.541
0.350
0.374
0.859
0. 581
0.994
0.183
0.398
0.175
0.454
0.509
0.327
0.462

0.335

0.191

0.127
0.048

0.827
0.605

7.10
7.60
6.15
5.15
6.04
5.39
6.95
6.10
5.15
5.06
7.35
7.37
6.16
5.42
6.00
6.40
5.04
6.69
5.75
5.51
5.02
6.63
5.90
9.00
9.20
7.97
9.30

i

2

0 827

3

4

5 ..-

0 637

6

7

0.716
0 796

8 _.

9

10- -

11 _

0.462

|

12

I

13

14

0.063
0.112
0.589
0.653
0.859
0.159

15 -

—

16 -

!

17- _ _.

18—

19

20-—

21- _

0.700

22

23 fc .

24 _

0.621
0.939
0.501
0.438

—

26

26 ..-

27.-

Average

0.477
10.5

0.356
14.0

0.688
8.5

0.508
9.8

- ; 0.722

1 6.9

0.744

Years in class

6.7

Average annual growth
for four years..

0-417

0.548

i
i
_.! 0.733

Average years in class -

15

>

]

hi

6.i

I

GROWTlf 159

The measurements were made at the same times as those of
Parashorea growing in the forest. Between January, 1915, and
January, 1917, many of these trees were cut down so that the
number measured in January, 1917, was considerably smaller
than on the other dates.

In fig. 2 is also shown a curve for Parashorea growing in the
open, the rates of growth of the smaller diameters being based
on the figures in Table LI, and those for the larger classes, on
the figures in Table L. The rate of growth of the 20- to 30-
centimeter class was obtained by calculation.

According to Table LI, a tree in the open would require 13.6
years to grow from 10 to 20 centimeters in diameter, and accord-
ing to Table L a tree would grow from 30 to 40 centimeters
in diameter in 13.5 years. A tree 30 to 40 centimeters in diam-
eter in the virgin forest is in the main canopy and so may
be regarded as growing in the open. Trees 20 to 30 centi-
meters in diameter are not so completely exposed and show a
slower rate of growth than either the 10- to 20-centimeter
class in the open or the 30- to 40-class in the forest. It would
seem, however, that, if they were growing fully exposed, they
should make as rapid growth as those of the 10- to 20-centi-
meter class in the open. In calculating the age of the trees
in the open the figure 13.5 has been used as the number of
years required by a tree to grow from 20 to 30 centimeters.
This figure is identical with that for trees 30 to 40 centi-
meters in diameter in the forest, and only one-tenth of a year
faster than that for trees 10 to 20 centimeters in diameter in
the open.

It will be seen that the growth as calculated for individuals
in the open is very much faster than that for those in the
forest as, according to the estimates, a tree 80 centimeters in
diameter in the open would be 111 years old, while one in the
forest of the same size would have an age of 197 years. The
great difference in the rates of growth of young individuals in
the open and in the forest is shown very clearly. A tree 20
centimeters in diameter in the open has an estimated age of
35 years, and one in the forest, 116 years.

This shows very clearly that the slow growth of the smaller
sizes of Parashorea malaanonan in the forest is due to adverse
conditions existing under the dense canopy of the first and
second story.

Measurements of the growth of Diplodisctts paniculatus (ba-
lobo) are given in Table LII. These measurements covered the

160

MOUNT? MAQUILING

Table LII. — Annual diameter growth of Diplodiscus paniculatus (balobo)
for 1918 and 1914 in dipterocarp forest on Mount Maquiling ; altitude,
about 800 meters.

[Diameters and growth are given in centimeters.]

Ot

Diameter class in centimeters.

No. of tree in class.

olO.

10 to 20.

20 to 30.

Diam-
eter.

Growth.

Diam-
eter.

10.32
10.82
11.72
11.78
12.00
12.10
12.58
12.69
13.19
13.20
13.21
14.55
14.60
14.68
16.20
17.38

Growth.

0.07
0.27
0.11
0.31
0.57
0.02
0.08
0.13
0.55
0.45
0.25
0.67
0.51
0.25
0.30
0.19
0.52
0.26
0.51
0.15

Diam-
eter.

21.20
21.40
21.80
23.70
24.15
24.70
25.40
26.35

Growth.
0.56

1 ■

5.00
5.72
6.22
6.30
6.43
6.43
7.10
7.41
7.62
7.71
7.91
8.97
9.10
9.80

0.08
0.03
0.11
0.11
0.05
0.09
0.37
0.04
.0.31
0.16
0.10
0.33
0.18
0.20

2... ._

0.33

3 _ _

0.58

4

5

6

7 ....

8 .

9__ _

0.27
0,38
0.57
0.45
0.40

10

11 ...

12. . _

13

14

15

16 .

17

17.63
17.70

18

19 . .

18.30
18.33

20

Average for 1913 and 1914

0.15
66.7

0.31
32.3

0.44
22.7

Years in class.. ... _ __ ...

period between January, 1913, and January, 1915. They were
made on approximately the same dates as those for Parashorea.
The trees were in the same area as the specimens of Parashorea
measured in the forest. From a comparison of the rates of
growth of Diplodiscus, as shown in Table LII, with those of
Parashorea in Table L it will be seen that the rates of growth
of Diplodiscus are slightly slower than those of Parashorea. The
rates for Diplodiscus as calculated in Table LII are plotted in
fig. 2 together with those for Parashorea. In this figure the
curve for Diplodiscus is above that for Parashorea. This is very
evidently due to the fact that no trees of Diplodiscus less than
5 centimeters in diameter were measured, and so the rate of
growth of the 0- to 10-centimeter class is based entirely on
trees more than 5 centimeters in fliameter. Had trees of Diplo-
discus in the 0- to 5-centimeter class been included in the measure-
ments, the curve for this species would probably lie below that

GROWTH

161

for Parashorea, as we have seen that the larger diameter classes
of Diplodiscus show a slower rate of growth than those of the
same classes of Parashorea. Brown and Matthews* found that,
in general, second-story species showed a slower rate of growth
than the dominant dipterocarps.

The rates of growth for Dillenia philippinensis in 1913 and
1914 are given in Table LIIL This species was growing in
the same situation as Parashorea and Diplodiscus, and the meas-
urements were made at the same time as those for Diplodiscus.
The rates of growth of this species will be discussed later
in connection with measurements of the same species growing
in the midmountain forest.

Table LIII. — Annual diameter growth of Dillenia philippinensis (catmon)
for 1913 and 19 1U in dipterocarp forest on Mount Maquiling; altitude,
about S00 meters.

[Diameters and growth are given in centimeters.]

No. of tree in class.

Ot

Diameter class

in centimeters.

olO.

10 to 20.

20 to 30.

20.0 0.35
22.3 0.43
22.5 ! 0.42

30 to 40.

Diam-
eter.

8.0

Growth.
0.46

Diam-
eter.

Growth.

Diam-
eter.

33.9

Growth.

1

15.1

0.55

0.24

2

3 .

4

27.9
28.1
29.5

0.17
0.44
0.53

5

6 . !...

!

Average annual
growth

0.46
22

0.55

18

0.39
26

!

! 8.24

49

Years in class L_

1

GROWTH IN THE MIDMOUNTAIN FOREST

Measurements of growth in the midmountain forest were
made at an elevation of 740 meters and included three species:
Astronia pulchra, which, as before mentioned, is the dominant
species in a limited area at this elevation ; Dillenia philippinensis
(catmon), a second-story tree; and Dillenia reifferscheidia (cat-
mon carabao), another second-story species. The trees were
located in the immediate neighborhood of the station at which

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil. Journ. Set., Sec. A (1914), 9, 413-561.

159549 11

162

MOUNT MAQUILING

measurements were made of the environmental factors. This
station is shown on the map, Plate XLI, as station 4.

The first measurement was taken January 23, 1913, and
subsequent measurements on about the same date in January,
1914, 1915, and 1917. The rates of growth of Astronia pulchra
for these different periods are given in Table LIV. As was the
ease with Parashorea, the same trees frequently showed very
different rates of growth for the different years. The average
rates of growth for the whole period are plotted in fig. 3.

Table LIV. — Annual diameter growth of Astronia pulchra in midmountain
forest on Mount Maquiling ; altitude, 740 meters.

[Diameters and growth are given in centimeters.]

Diameter class in centimeters.

0 to 10.

10 to 20.

No. of tree in class.

Diam-
eter.

7.8
9.8
7.3

Annual growth.

Diam-
eter.

17.9
17.6
15.6
17.7
18.0
14.8
14.1
17.8
19.5
18.9
18.3
13.6
12.5
13.5
18.4
15.1
15.7
12.8
14.2
12.5
13.2

Annual growth.

1

1913. 1914.

1915
and
1916.

0.18
0.11

1913.

0.22
0.36
0.39
0.27
0.18
0.00
0.00
0.01
0.04
0.43
0.54
0.21
0.04
0.00
0.21
0.15
0.27
0.22
0.00
0.00
0.12

0.17
58.8

1914.

1915
and
1916.

1

2

0.03
0.03
0.01

0.31
0.01
0.05

0.30
0.28
0.15
0.17
0.12
0.00
0.00
0.03
0.08
0.45
0.44
0.00
0.00
0.00
0.23
0.03
0.41
0.18
0.18
0.10
0.04

0.15
66.7

0.30
0.35

3

0.03

4

0.10

5 . .-

0.08

6. _ ...

0.06

7..

0.03

8

0.00

9 _.

0.02

10 . .

0.16

11

0.19

12

0.08

13

0.00

14

0.03

15

0.11

16 „

0.14

17...

i

0.29

18.

|

0. 03

19

0. 08

20 -.

0.02

21 _.

0. 05

0.15
66.7

Average

0.02
600.0

0.12
83.3

0.10

Years in class

100.0

Average annual growth for
four years

0.11
90.9

0.13
76.9

Average years in class.

GROWTH

163

Table LIV. — Annual diameter growth of Astronia pulchra in midmountain
forest on Mount Maquiling ; altitude, 7^0 meters — Continued.

Diameter class

in centimeters.

o40.

lual growth.

20 to 30.

vth.

Diam-
eter.

36.5
33.2
32.7
34.7
35.4
34.2
31.7

30 t

No. of tree in class.

Diam-
eter.

Annual gro^,

Am

1913.

1914.

1915
and

1916.

1913.

1914.

1915
and
1916.

l.„_

26.9
21.6
24.5
28.2
21.5
27.7
20.2
22.6
24.0
29.3
27.3
28.5
25.0
29.4
23.1
27.2
22.7
25.9
21.2

0.24
0.22
0.13
0.31
0.06
0.16
0.54
0.27
0.30
0.30
0.10
0.24
0.03
0.25
0.09
0.21
0.18
0.55
0.36

0.34
0.38
0.05
0.49
0.10
0.34
0.32
0.33
0.34
0.32
0.14
0.26
0.13
0.65
0.09
0.31
0.28
0.53
0.34

0.29
0.40
0.15
0.38
0.14
0.41
0.18
0.14
0.19
0.23
0.23
0.31
0.08
0.03
0.06
0.19
0.18
0.41
0.21

0.25
0.30
0.43
0.12
0.63
0.57
0.22

0.13
0.36
0.47
0.36
0.63
0.45
0.18

0.28
0.25
0.27
0.25
0.63
0.62
0.21

2

3

4 _

5

6

7

8

9..__ _

10

11

12

1... . ..

13

14

15

16

17

18

!

19

0.36
27.8

0.37
27.0

Average

0.24
41.7

0.30
33.3

0.22
45.5

0.35

Years in class ..J

28.6

Average annual growth for
four years

0.25
40.0

0.36
27-8

Average years in class

Diameter class, 40 to 50 centi-
meters.

No. of tree in class.

Diam-
eter.

48.9

Annual growth.

1913.

1914.

1915
and
1916.

1

0.36

0.56

0.40

Average

0.36
27.8

0.56
17.9

0.40

Years in class

25.0

Average annual growth for four years

0 43

Average years in class

23 a

164

MOUNT MAQUILING

^

7

4-0

£G

so

Age in years.

.. 100 120

14-0

160

ISO

200

/

•^

.. >

- —

u

f

o

V

-

^

«f

.2

0)

A

t/

y

-u^"'*

^

vp

Ml'

Oni~

*~~*

^-^

1

rfP

Jstr

,njf£

jcfm^-

^--

.--

~*-~~

1

Fig. 3. Diameter growth of Parashorea at 300 meters',

meters' altitude.

and Astronia pulchra at 740

As no measurements were obtained of trees less than 5 centi-
meters in diameter, the curve in fig. 3 has been plotted to show
the number of years required for an average tree to grow from
5 centimeters to larger diameters up to 50 centimeters, and in the
same figure there is also plotted a similar curve for Parashorea
malaanonan at an altitude of 300 meters. A comparison of these
curves shows that, whereas Parashorea malaanonan requires
about ninety years to grow from 5 to 50 centimeters, Astronia
pulchra takes two hundred thirteen years to make the same
growth. Both of these species may be regarded as being in the
same story when they are more than 20 centimeters in diameter.
It may, therefore, be more accurate to compare the rates of
growth of these species for diameters of between 20 and 50
centimeters. Parashorea makes this growth in forty-five and
one-half years, while Astronia requires ninety-one years or twice
as long as Parashorea. This difference in rate of growth is
roughly proportionate to the greatest height attained by the two
species at the altitudes concerned, for at 300 meters' elevation
Parashorea attains a height of about 38 meters, while Astronia
pulchra at 740 meters grows to a height of about 20 meters.

GROWTH

165

Table LV. — Annual diameter growth of Dillenia philippinensis in mid-
mountain forest on Mount Maquiling; altitude, 7^0 meters.

[Diameters and growth are given in centimeters.]

Diameter class in centimeters.

i

•

Diam-
eter.

8.3
5.5

0 tt

Ann

) 10.

10 to 20.

wth.

No. of tree in class.

ual growth.

Diam-
eter.

Annual gro

1913.

1914.

1915
and
1916.

1913.

1914.

1915
and
1916.

1

0.19 0.09 0.21
0.07 0.17 0.18

14.9

0.10

j 2

i Average.

0.13 I 0.13 0.20

76.9 76.9 50.0

1 i

0.17
59

0.10
100.0

0.22
45.5

n ir;

0.14
71.4

Years in class

Average annual growth for
four years

Average years in class __

67

No. of tree in class

Diameter class, 20 t
centimeters.

o30
ivth.

.

Diam-
eter.

20.2

Annual gro^

_ .

1913.

1914.

1915
and
1916.

1— .

0.18 0.20

0.11

2

Average

0 18 ft on \ n 11

Years in class-. __

55.6

50 0 90 9

Arerage annual growth for four years __
Arerage years in class..

0 IK

67

- ._

166

MOUNT MAQUILING

TABLE L VI. — Annual diameter growth of Dillenia reifferscheidia in mid-

mountain forest on Mount Maquiling; altitude , 740 meters.

[Diameters and growth are given in centimeters.]

No. of tree jn class.

1 .

Diameter class

in centimeters.

10 to 20.

20 to 30.

Diam-
eter.

14.3

Annual growth.

1915

1913. 1914. and

1916,

Diam-
eter.

Ann
1913.

lual groA
1914.

vth.

1915
and
1916.

0.10

0.16

0.08

2

25.1

0.33

0.23

0.16

0.16
62.5

Average

0.10
100.0

0.16
62.5

0.08

0.33
30.3

0.23
43.5

Years in class

125 0

Average annual growth for
four years

0.11

0.22
4fi

Average years in class

91

In Table LV the rates of growth for Dillenia philippinensis
are given, and in Table LVI those for Dillenia reifferscheidia.
The results are plotted in fig. 4, together with those for Dillenia
philippinensis at an altitude of 300 meters. From these figures
it will be seen that at an altitude of 740 meters Dillenia philip-
pinensis and Dillenia reifferscheidia have about the same rate

20

40

so

Age

80

in years

100

IZ0

140

160

180

(frt- ^

u
.1

■fPrf

^

430~

i—

-~^

<^

c
.S M

S

^
Zf

^^-^

yrlL

^''

,ninfn

$£.

7*0J2

' ~~*\t

"0f

i.

Q

0*

en'\ar

0*

cheti

a, a,t

^

>>■

^

FIG. 4. Rates of growth of DiUenia at altitudes of 300 and 740 meters.

of growth, and that this rate is much slower than that for
Dillenia philippinensis at 300 meters. According to the curves
in this figure, Dillenia philippinensis at an altitude of 300 meters
attains a diameter of 30 centimeters in sixty-six years, while
at 740 meters it requires one hundred ninety-three years to
reach the same diameter. The figures on which these curves
are based are not numerous enough to permit any exact com-

GROWTH 167

parison, but they indicate very clearly that at high altitudes
Dillenia grows much more slowly than at low elevations.

GROWTH IN MOSSY FOREST

Owing to the irregular shapes of the tree trunks. and the
great development of the aerial roots, it is impracticable to
measure the diameter growth of most of the trees in the mossy
forest. For this reason the second-growth species, Homalanthus
alpinus, was selected for measurement. This tree, as previously
pointed out, invades open places that are caused by the death
or removal of trees forming the canopy of the mossy forest. At
an altitude of about 1,000 meters there was a small area in
which Homalanthus alpinus formed a very open, pure stand.
Measurements of individuals in this area were made on January
16, 1913, and about the same date in January, 1914 and 1915.
The results are presented in Table LVII.

Table LVII. — Annual diameter growth of Homalanthus alpinus in mossy
forest on Mount Maquiling ; altitude, about 1,000 meters.

[Diameter and growth are given in centimeters.]

Diameter class in centimeters.

No. of tree in class.

0 to 10.

Growth.

1913. I 1914.

i

0.21 j 0.23
0.06 0.04
0 06 0 00

Diam-
eter.

10.1
10.2
in o

10 to 20.

Diam-
eter.

5.1
5.3
5.7
6.0
6.2
6.3
6.4
6.6
7.0
7.3
7.4
7.5
7.8
8.1
8.2
8.2
8.5
8.6
9.5
9.7

Growth.

1

1913.

0.61
0.76
0.43
0.18
0.18

1914.

0.55
0.34
0.29
0.38
0.24

9

3

4 .

0.25 \ 0.43 | 11.6

5.__*_ .

6

0.52 0.92
0.00 ' 0.04
0.00 j 0.20
0.04 ! 0.04
0.34 0.14
0.09 j 0,09
0.28 0.70
0.77 0.69
0.27 0.13
0.03 0.11

7

I

8

9

10

i

11

i

12

!

13

_ -|

14

15

16_.

0.13
0.63
0.15
0.13
0.28

0.21
1.95
0.65
0.47
0.20

1?..

18

19

20..__

Average __.

0 22

n ?*7

Average for 1913 and 1914

0.29
34

0.39

Years in class

.... . .

168

MOUNT MAQUILING

There were no trees in this area less than 5 centimeters in
diameter, and so the figures for the 0- to 10-centimeter class
are based on trees measuring more than 5 centimeters in dia-
meter. The average annual rate of growth of trees in the 0-
to 10-centimeter class was 0.29 centimeter, and in the 10- to
20- class, 0.39 centimeter. From these figures it was calculated
that a tree would require thirty-four years to reach a diameter
of 10 centimeters, and twenty-six years to grow from 10 to 20
centimeters.

In fig. 5 the rates of growth of Homalanthus alpinus at an
elevation of about 1,000 meters are compared with the average
rates of growth of second-growth species at the base of Mount
Maquiling, at an altitude of about 80 meters. As no trees of
Homalanthus less than 5 centimeters in diameter were measured,
the curves in fig. 5 are drawn to show the rates of growth from
a diameter of 5 to one of 20 centimeters. In the figure are
shown separately the average rates of growth of second-growth
trees that reach a diameter of more than 20 centimeters and

Years.

I

S

I
S

01

s

d

/

S;

—

.x"***

•zxr-

■ <*$

§7

4

/

.^"

h

t'

iit '!

qoJ?

— i

$

4\

jj0

ojpj!!^

V

HojUi

—

■-

—

—

--^'

—

—

—

—

— -

—

*//

^,.

-•*■""'

__

i 1

--

-

—

-

--

— -

-

Fig. 5. Rates of growth of second-growth trees on Mount Maquiling at altitudes of

80 and 1,000 meters.

of those that do not reach a diameter of 20 centimeters. As
Homalanthus is a small tree, it may perhaps be best compared
with the average of the smaller second-growth species at an
altitude of 80 meters. According to the curve in fig. 5, the
average small second-growth tree at an altitude of 80 meters
requires about ten years to grow from 5 to 20 centimeters,
while Homalanthus requires forty-three years to make the same
growth. This difference in rate is probably greater than the
difference in the height of the canopy of the forest which formerly
existed at 80 meters, and that which is now found at 1,000
meters; as at the lower elevation trees may have reached a

GROWTH 169

height of about 45 meters, while at 1,000 meters the tallest
ones are about 14 meters in height.

CONCLUSIONS

A comparison of the rates of growth of trees in the dipterocarp
with those in the midmountain forest, and of those in the second-
growth at 80 meters with the second-growth tree Homalanthus
alpinus at 1,000 meters would seem to indicate that the rates of
growth are roughly proportionate to the heights of the virgin
forests at different altitudes. Such a conclusion as this can of
course only be accepted in the most general terms, as it is well
known that trees of different species, even though they reach
about the same size, may show different rates of growth. It
would seem, however, that the much slower rate at which trees
grow at high than at low altitudes on Mount Maquiling may
very well be connected with the dwarfing as higher altitudes
are reached; and, if we assume that the trees have approx-
imately equal lengths of life, this would certainly be sufficient
to account for the dwarfing at high altitudes.

Trees at all altitudes are subject to fungus attacks; and,
as they reach their largest size, the trunks become hollow; this
is apparently just as true of trees at high as at low altitudes.
The lower temperature at high altitudes would, in all proba-
bility, retard the rate of growth of fungi; but, as the trees are
smaller at high altitudes, there is no reason for supposing that
fungi would not grow in them just as fast in proportion to
their size as they would in larger trees at lower elevations.

We have previously seen that on the steeper slopes trees are
smaller than in more level places and that in the first case
the small size may be connected with erosion ; but even on level
areas dwarfing is pronounced, and the measurements given
in this paper for heights at different elevations were recorded
from trees growing in level situations or on gentle slopes.

We may, therefore, tentatively conclude that the smaller size
of the trees at high elevations is connected, to a large extent at
least, with the slow rate of growth. If the slow growth at
the higher altitudes is not directly responsible for the small
size of the trees, the same factors that limit the rates of grow7th
may also limit the size attained.

Dr. F. T. MacLean informs me that while working on aspen
he found that, if a tree were subnormal in height while attaining
its growth in height, it would be subnormal in height at matu-
rity and, moreover, the degree of dwarfing at a given age would
be proportional to the height of the tree when mature. This
affords some evidence that rates of growth in height may be
roughly proportional to the heights of trees when mature.

170 MOUNT MAQUILING

Further evidence on this point is afforded by a comparison of
the rates of growth of trees on Mount Maquiling with other
species growing on other mountains. Brown * has made a study
of the rates of growth of Podocarpus on Mount Banahao at an
altitude of 2,100 meters. Podocarpus at this altitude reaches
a height of about 14 meters, while the average height of the
main canopy, composed entirely of Podocarpus, is about 12 me-
ters. These trees are much shorter than Astronia pulchra on
Mount Maquiling, and the rate of growth is much slower. Ac-
cording to the figures in Table LIV an individual of Astronia
pulchra 50 centimeters in diameter would be 259 years old
while, according to the curve given by Brown, Podocarpus at
the top of Mount Banahao would require 444 years to reach
the same size. The measurements in these two cases are com-
parable, as in both cases the smallest trees measured were in
the 5- to 10-centimeter class. Here again the rates of growth
are approximately proportional to the size of the trees.

Koorders,f in studying the forest at an altitude of about 1,500
meters on the Gedeh in Java, measured a tree of Altingia excelsa
49 meters in height. Brown and Yates t found that the
trees in this forest grow about as rapidly as those in the
tall dipterocarp forests at low altitudes in the Philippines.
Brown and Matthews § have further shown that trees in tall
dipterocarp forests at low altitudes made a faster growth than
those in lower forests at higher altitudes.

* Brown, W. H., The rate of growth of Podocarpus imbricatus at the
top of Mount Banahao, Luzon, Philippine Islands, Phil. Journ. Sci., Sec
C (1917), 12, 317-329.

f Koorders, S. H., Floristischer Ueberblick iiber die Blutenpflanzen lies
Urwaldes von Tjibodas auf dem Vulkan Gede in West- Java nebst einer
Numerliste und einer system atischen Uebersicht der dort fur botanische
Untersuchungen von mir numerierten Waldbaume, Engl. Bot. Jahrb. (1914),
50, Suppl., 278-303.

% Brown, W. H., and Yates, H. S., The rate of growth of some trees on
the Gedeh, Java, Phil. Journ. Sci., Sec. C (1917), 12, 305.

§ Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
Phil Journ. Sci.y Sec. A (1914), 9, 413-561.

CHEMICAL AND PHYSICAL COMPOSITION OF THE SOIL
AT DIFFERENT ELEVATIONS

The composition of the soil at different elevations on Mount
Maquiling has been studied by Brown and Arguelles.* The
soil of Mount Maquiling is of volcanic origin. An account of
the geology has been given by Abella.f

On the lower slopes there are layers of soft volcanic tuff. At
elevations of from 50 to 100 meters these layers of tuff, which
are mixed with layers of soil, may be many meters thick and are
frequently near the surface. The layers near the surface, how-
ever, are usually thin, soft, and very much broken. Such a
layer, about 30 centimeters thick, is frequently found about 30
centimeters below the surface, and traces occur at elevations
above 300 meters. West and Cox t give analyses of a number
of samples of similar tuff. These analyses indicate that the
tuff should disintegrate into a fertile soil. Where the surface
layers of the tuff are shallow and much broken, they appear
to have little if any effect in determining the character of the
vegetation. No thick layers of tuff have been observed ex-
cept around the base of the mountain, where the original vege-
tation has been almost entirely removed.

Except around the base the soil is deep on all parts of the
mountain, and rock outcrops are very scarce except in the beds
of streams. It was thought at first that the soil near the top
might be shallow, and in order to test the depth at the summit
of the east peak a soil auger was sunk into the soil to the
depth of a meter in a large number of places without anywhere
encountering rock.

* Brown, W. H., and Arguelles, A. S., The composition and moisture
content of the soils in the types of vegetation at different elevations on
Mount Maquiling, Phil Joum. Sci., Sec. A (1917), 12, 221-233.

t Abella y Casariego, D. E., El Monte Maquilin. Madrid (1885).

JWest, A. P., and Cox, A. J., Burning tests of Philippine Portland
cement raw materials, Phil. Joum. Sci., Sec. A (1914), 9, 79.

171

172

MOUNT MAQUILING

The chemical composition of the soil at different elevations,
as given by Brown and Argiielles,* is presented in Table LVIII.

Table LVIII. — Chemical analyses of soils from Mount Maquiling.

[Water-free basis ; numbers give percentages.]

Loss on ignition

Nitrogen (N2)

Phosphoric anhydride (P2O5) -.

Lime (CaO) .

Magnesia (MgO)

Potash (K2O)

Soda (Na20)

Humus

Soil acidity (CaC03 equivalent)

Source of soil.

Grass-
land.

Diptero-

carp
forest.

10.08

Mid-
moun-
tain
forest. '

13.56

10.32

0.150

0.137

0.199

0.278

.0. 106

0.104

0.86

1.01

0.31

0.62

0.61

0.49

0.294

0.241

0.189

0.37

0.44

0.53

1.36

1.06

1.71

0.0069

0.0100

0.0094

Mossy
forest.

29.97
0.644
0.112
0.52
0.79
0. 170
0.34
8.06
0.0082

The sample from the grassland was taken on the ridge at sta-
tion 1, at an elevation of about 100 meters ; that from the dipter-
ocarp forest, at station 2, at an elevation of 300 meters; that
from the midmountain forest, at station 4, at an elevation of
about 740 meters; and that from the mossy forest, at station
5, at an elevation of 1,050 meters. From the table it will be
seen that none of the soils is strikingly deficient in any impor-
tant element, and none can be considered as acid. The amount
of nitrogen and humus is greatest in the mossy forest, where
the vegetation is most dwarfed. It is to be noted that the
smallest amount of nitrogen and humus is shown by the sample
from the tall dipterocarp forest. The chemical analyses of the
soil, as shown in Table LVIII, do not indicate that there is any
connection between its chemical composition and the dwarfing
of the vegetation as higher elevations are reached.

The physical analyses of the soils, as given by Brown and
Arguelles,f are presented in Table LIX. There is nothing in
these analyses to indicate that the soils should not all produce
a luxuriant type of vegetation. If any distinction can be made
it seems that the soil of the mossy forest should be the best,
as it is a fine, sandy loam, while that of the dipterocarp forest
and grassland is a loamy clay.

* Loc. cit.

t Loc. cit.

CHEMICAL AND PHYSICAL COMPOSITION OF SOIL

173

Table LIX. — Mechanical analyses of soils from Mount Maquiling.

[Water-free basis ; numbers give percentages.]

Classification of soil.

Coarse sand-__
Medium sand -

Fine sand

Very fine sand

Silt

Very fine silt..
Clay

Diameter of particles.

mm.

Over 2

2tol

1.0to0.5

0.5 to 0.25

0.25 to 0.10

0.10 to 0.05

0.05 to 0.01

0.01 to 0.002

Less than 0.002..

Source

of soil.

Grass-
land.

Dipter-
ocarp
forest.

Mid-
moun-
tain
forest.

Mossy
forest.

nil nil

nil

nil

0.9 0.5

0.7

nil

2.2 j 1.3

0.9

5.9

5.4

4.5

4.1

23.3

12.5

9.8

8.8

31.4

10.8

7.8

12.3

13.2

13.6

13.5

4.9

11.2

36.5

41.7

! 39.4

9.4

19.0

21.4

1 29.6

5.6

The chemical analyses do not indicate the amount of material
available for plants, as soils from which soluble constituents
have been largely leached out might still show a high percentage
of necessary elements, these elements being in a form not readily
available for plants. There is, however, no reason for think-
ing that the soil in the low type of vegetation, at the top of
the mountain, is leached out to a greater extent than at other
elevations, as the rainfall at the top is no heavier than in the
dipterocarp forest at 300 meters' elevation, and not so heavy
as in the dipterocarp forest at 450 meters' elevation or in the
midmountain forest at an altitude of 740 meters. It also seems
improbable that any considerable amount of dissolved matter is
carried from the top of the mountain to the high ridges on
which the vegetation was measured. These are never flooded
but, on the contrary, the streams are confined to deep and
narrow valleys. The soil in all of the virgin types of vegetation
is always comparatively moist, while the streams increase in
size as they flow down the mountain. This would indicate that
little, if any, dissolved matter which comes from near the top
of the mountain is conveyed from the drainage to the ridges
at lower elevations by water carried by capillary attraction.

There is, moreover, no reason for considering one type as
being better drained or aerated than another, as the mountain
is cut up into ridges and valleys, thus assuring good drainage.
The only obvious difference in the various types of vegetation
that we might expect would be connected with the character of

174 MOUNT MAQUILING

the soil is the difference in the height of the trees at different
elevations. But there appears to be nothing in the character
of the soil that would indicate that it is responsible for this
difference.

The shallow nature of the soil at the base of the mountain
might lead us to believe that this soil would be the poorest
for plant growth; but we find that plants in this soil make an
exceedingly rapid growth, and the remnants of the original
vegetation which are now to be found there indicate that it
was originally covered by a tall forest.

GENERAL REMARKS ON RECORDS OF MEASUREMENTS

LOCATION OF STATIONS

The measurements of environmental factors were taken at
five different stations at different altitudes, as shown on the
map (Plate XLI).

Station 1 was on a ridge in the parang. The majority of
the instruments at this station were placed at a short distance
from the buildings of the division of investigation of the Bureau
of Forestry as located in 1912. These were at the front of a
long, broad ridge on the right of Molauin River. The instru-
ments were scattered for a considerable distance along this
ridge, so that they might be in different types of vegetation.
The altitudes varied from 75 to about 100 meters.

Station 2 was in the dipterocarp forest at an altitude of
about 300 meters and was on the top of a ridge, on the left of
Molauin River. One evaporimeter was placed in a ravine a
few meters from the bank of Molauin River, at about the
point where the trail up the mountain comes nearest to the river.
From the map it will be seen that this was some little distance
from the main station. This evaporimeter was also at an ele-
vation of 300 meters.

Station 3 was also in the dipterocarp forest and at an ele-
vation of 450 meters. This station, like the others, was on a
ridge. The clearing on plot 2, which was at the same eleva-
tion, was used to measure conditions in the open at this altitude.

Station 4 was on a ridge in the midmountain forest at an alti-
tude of 740 meters. A ravine is located on the left of the ridge,
and one evaporimeter was placed in this ravine about 30 or 40
meters below the elevation of the main station.

Station 5 was in the mossy forest on the summit of the east
peak of Mount Maquiling.

DATES OF MEASUREMENTS

The installation of the instruments at the various stations
was begun in October, 1911, and as soon as any instrument
was installed weekly readings of that instrument were begun.
As considerable time was required to make these installations

175

176 MOUNT MAQUILING

the readings were not all begun at the same time. At first
readings were always taken on Saturday, but of course at
different hours of the day, as it was impossible to read the in-
struments at different stations at anything approximating the
same hour. As more instruments were installed, it became im-
possible to read them all on the same day. Most of the readings
for stations 1 and 2 were then taken on Friday afternoon, and
those for the other stations on Saturday. At station 3 the
instruments were not installed until July, 1913. After this two
whole days were occupied in taking readings. Beginning July,
1913, daily readings were also taken with a large number of
instruments at station 1 in the immediate neighborhood of the
forestry buildings. After this the instruments at station 1,
which were read once a week, were read on Friday morning;
those at station 2, later on the same day; and those at station
3, on Friday afternoon. The readings for stations 4 and 5 were
recorded on Saturday; those for station 4 being taken in the
morning, and those for station 5, about midday or early in the
afternoon. However, in order that the readings at the different
stations might be readily compared without the inconvenience
of using different dates, a common date for all was adopted;
and, no matter at what time the readings were taken, the week
has been regarded as ending on Friday at midnight.

FORM OF RECORDS

As most of the readings were taken weekly, the tables have
been calculated for weeks ending Friday at midnight, and the
data then assembled in the form of averages, totals, and maxima
and minima for four-week periods. These four-week periods
for the different years of course ended on different days of the
month. Thus, the period ending December 6, 1912, would cor-
respond with the periods ending December 5, 1913, and Decem-
ber 4, 1914, respectively. The averages, totals, and maxima
and minima for corresponding four-week periods were then cal-
culated for the entire period from October, 1912, to January 1,
1915, the dates used being those for 1913. The figures in the
tables to follow represent the weekly readings from October,
1912, to January 1, 1915, and the data for corresponding four-
week periods for the three years. The data for the four-week
periods of the single years have been omitted, as the readings
for the two years proved to be very similar. All of the data in
the different tables have been calculated at least twice, and the
results compared. It is believed, therefore, that the results
are about as accurate as could be expected.

GENERAL REMARKS ON RECORDS OF MEASUREMENTS 177

It is usually customary to give records of temperature and
relative humidity according to calendar months. As the data
from Mount Maquiling are presented for periods of four weeks
rather than for calendar months it has seemed desirable, for
purposes of comparison, to prepare summary tables of the data
obtained from the recording instruments in the more usual
form of calendar months. Such tables are presented in the
appendix.

PRESENTATION OF RESULTS

The results of the measurements taken on Mount Maquiling
have been recorded in considerable detail. This has been deemed
advisable, as the records are much more extensive than any that
have been previously given for conditions obtaining in tropical
vegetation. It is believed they will be of value in presenting
an actual picture of environmental conditions, and they may be
of service in the future in interpreting the relation of environ-
ment to different types of tropical vegetation in a more exact
manner than is now possible.

The method used by some writers, of presenting their results
only in the form of curves or of curves with the addition of
very short general statements or concise summaries, usually
brings out very clearly the points emphasized in the paper ; but
it does not make the results readily usable for comparison by
other workers. In preparing the present paper the writer has
seen a number of articles the results of which it would have
been very interesting to compare in some detail with those here
presented, but to do so was impracticable owing to the methods
of presentation just mentioned.

159549 12

TEMPERATURE

Two kinds of instruments were used to record temperature;
namely, recording thermometers, and maximum and minimum
thermometers. The recording thermometers were placed in
wooden cases with open bottoms and louvre sides and were about
75 centimeters above the ground. The cases were placed under
the forest in all instances, except at 450 meters' elevation,
where there were two cases — one under the forest and the
other in the open. The records from the recording thermometers
are presented in the form of maxima, minima, means, averages
of daily maxima, and averages of daily minima.

The means were taken from the original records by a plani-
meter. This method is very accurate when used in conjunction
with the oblong sheets of a Richard Freres recording ther-
mometer, the type of thermometer used at the base* of the
mountain where variations in temperature are greatest. At
elevations of 300 meters and more the records were obtained
from Draper recording thermometers. As the records from
these instruments are circular, this method produces an error
due to the fact that the area per degree varies with different
temperatures. This error would be considerable if the difference
between the daily maximum and minimum temperatures were
great, and if the maximum and minimum temperatures were
maintained for a considerable portion of the day. However,
as the average daily variation in temperature on Mount Ma-
quiling was in no situation where circular records were used
more than 3.4° C, and as the maxima and minima were main-
tained for only very short periods, this error becomes negligible.
The records used read in Fahrenheit, and the results were con-
verted to centigrade. If a temperature of 80° F. were maintained
for one-half of each day in the week, and a temperature of
70° F. for the other half, then the error in calculating the mean
with a planimeter would amount to considerably less than 0.2° C.
Such a case would be extreme, as a daily variation of 10° F.
is much greater than the average daily variation recorded for
any situation on Mount Maquiling, where circular records were
used. Moreover, the maximum and minimum temperatures are
only maintained for very short periods of time, so that the
error for a range of 10° F. would be much less than that just
178

TEMPERATURE 179

calculated. The error due to the use of a planimeter with the
records on Mount Maquiling should be a fraction of a tenth
of a degree and therefore a negligible quantity.

The maximum and minimum thermometers were placed in
the tops of trees at the different elevations and also in the
crowns of second-story trees in the dipterocarp forest at 300
and at 450 meters' elevation. In most cases they were in large
boxes with perforated bottoms and with holes in the tops and
so fixed as to permit free movement of air without exposure
to direct sunlight. The thermometer in the top of the second-
story tree at the base was suspended under a A-shaped top,
without bottom or sides. These instruments probably recorded
the minimum temperature accurately, but the maximum may
very well have been affected to some extent by radiation. How-
ever, a comparison of the temperatures at the tops of the trees
at 450 meters' elevation and in the case in the open at the
same elevation would indicate that radiation did not raise the
temperature recorded by these thermometers to any very con-
siderable extent.

In the following discussion all temperatures are given in
degrees centigrade.

TEMPERATURE IN THE PARANG

The taking of temperature records at the base of Mount Ma-
quiling was begun by Dr. F. W. Foxworthy in October, 1911.
These records were made with a Richard Freres recording
thermometer, which at first was placed in a very open room
in a bamboo house. Later, when the writer began recording
climatic data on Mount Maquiling, Doctor Foxworthy transferred
this instrument to a case which was placed under a canopy of
second-growth trees, where Doctor Foxworthy continued to take
records until June, 1913, when the instrument was turned over
to the writer. A comparison of simultaneous records taken in
an open bamboo house and under the second-growth trees has
shown that the temperatures in the two places are very similar,
and so the earlier records taken by Doctor Foxworthy have
been included in the tables for temperatures under the second-
growth trees at the base of Mount Maquiling at an elevation of
80 meters. The recording of temperatures in this situation was
continued until January 1, 1915. The results are presented in
Table LX in the form of weekly maxima, weekly minima, means,
and averages of daily maxima and minima. The figures in Table
LX are summarized for corresponding four-week periods for
the different years in Table LXI.

180

MOUNT MAQUILING

Table LX. — Temperature for weekly periods under second-growth
near the base of Mount Maquiling; altitude, 80 meters.
[Numbers give degrees centigrade.]

trees

Week ending-

1911.
October 6

October 13

October 20

October 27

November 3

November 10

November 17

November 24 _

December 1

December 8 -

December 15

December 22

December 29

1912.

January 5

January 12

January 19

January 26 ...

February 2 ^

February 9

February 16

February 23

March 1 ___

March 8._

March 15

March 22-__

March 29

April 5--.

April 12

April 19 _

April 26

May 3

May 10 .

May 17

May 24 _.

May 31

June 7

June 14 __

June21._ ._

June 28

July 5

July 12

July 19

Maxi-
mum.

Mini-
mum.

Mean.

Average of daily

Maxima.

Minim

32.3

23.1

26.7

31.8

0 23. £

31.1

22.9

26.7

30.3

23. E

31.3

23.0

25.3

29.1

23.5

31.6

21.6

« 25.0

29.0

22. t

30.1

21.1

26.7

29.6

23. C

30.3

19.9

26.0

29,1

21. i

29.1

21.1

26.0

28.7

22.4

29.6

21.6

25.0

28.1

22. £

29.6

20.0

25.0

28.5

21. r

29.9

21.9

26.2

28.9

22. J

31.9

20.3

25.0

29.4

22.5

29.1

21.8

24.1

28.2

22. E

28.8

20.3

24.1

28.2

21. i

29.0

20.5

25.0

27.5

21. E

28.0

20.0

24.6

27.0

21.4

28.1

20.2

24.6

27.8

20. £

29.0

19.4

24.3

27.7

20. C

28.6

19.9

24.0

27.0

20.5

28.2

19.9

23.6

26.0

20. r

29.0

19.8

25.5

28.4

21. £

31.5

21.0

25.5

28.7

22. r

30.7

20.7

26.4

29.8

21. J

31.0

20.7

26.2

30.0

21. «

33.7

21.0

26.7

32.3

22. £

31.7

21.1

26.0

30.0

22. (

32.0

21.5

27.0

30.8

22. £

31.5

21.9

26.2

30.6

22. c

33.7

22.0

27.0

32.3

23.2

32.0

22.5

27.4

31.1

23.2

32.6

23.1

28.1

32.2

23/

33.6

22.4

28.0

32.6

24. £

33.9

22.3

27.1

32.2

23. £

34.2

22.5

28.3

33.0

23. £

34.4

22.7

27.6

32.5

24. C

33.1

23.0

27.1

32.3

23/

33.0

22.7

28.0

32.1

24.2

31.4

22.4

25.2

29.7

22/

33.6

22.1

26.4

31.9

22/

32.7

21.9

26.7

31.7

22/

32.1

21.9

26.0

31.3

23 J

32.0

22.5

26.0

30.3

23/

31.0

22.4

25.0

28.4

23/

TEMPERATURE

181

TABLE LX.— Temperature for tveekly periods under second-growth trees
near the base of Mount Maquiling; altitude, 80 meters — Continued.

Week ending -

1912.

July 26

August 2

August 9

August 16

August 23

August 30

September 6

September 13

September 20

September 27

October 4

October 11

October 18

October 25

November 1

November 8

November 15

November 22

November 29

December 6

December 18

December 20

December 27

1913.
January 3 ,

January 10

January 17

January 24

January 31

February 7

February 14

February 21

February 28

March 7

March 14

March 21

March 28

April 4

April 11

April 18

April 25

May 2

May 9

May 16

Maxi-
mum.

30.0
28.1
28.1
27.1
30.0
28.1
30.2
30.7
30.2
30.8
30.4
29.1
29.9
29.0
30.6
29.2
29.0
29.5
29.0
29.0
28.0
28.9
28.5

28.0
28.1
29.0
29.0
26.8
28.9
29.4
29.3
30.1
30.0
31.7
31.5
31.1
30.7
30.4
29.7
31.5
31.4
28.5
32.2

Mini-
mum,.

21.9
20.9
20.6
20.2
22.7
21.4
20.3
21.3
22.8
22.9
22.6
22.5
22.1
22.0
22.0
22.9
22.9
22.7
22.6
22.1
20.1
19.9
21.1

22.1
21.9
21.4
21.0
20.6
20.9
21.2
20.0
21.7
22.1
21.3
22.7
20.8
20.1
19.6
21.0
22.0
22.3
22.4
22. 5

Mean.

26.4
23.6
23.2
26.0
28.0
25.3
25.1
25.3
26.0
27.0
25.5
26.0
25.0
25.5
26.2
26.0
26.0
25.5
25.0
25.3
24.1
24.6
24.3

24.1
24.6
24.6
24.3
23.2
23.4
24.6
24.1
24.6
25.7
26.1
26.3
26.1
25.6
25.0
26.1
26.2
26.4
26.7
26.5

Average of daily-

Maxima.

Minima.

28.6

22.9

25.9

22.2

27.5

21.1

26.1

20.7

28.8

23.3

27.1

22.8

27.3

21.7

28.6

23.1

29.4

24.6

29.7

23.6

28.5

23.6

27.7

23.1

27.6

23.3

27.6

23.4

29.1

23.4

27.9

23.5

28.1

23.5

28.3

23.2

27.1

23.4

28.0

22.8

26.5

22.3

27.8

21.7

26.8

22.3

26.6

23.0

27.2

23.0

27.4

22.2

28.1

22.1

25.8

21.7

27. 0

22.1

28.3

22.0

28.6

22.0

28.4

22.5

28.0

22.5

30.9

22.9

30.9

23.4

30.3

21.9

29.0

22.1

28.9

21.0

28.7

21.9

30.7 !

27.0

31.1

182

MOUNT MAQUILING

Table LX. — Temperature for weekly periods under second-growth trees
near the base of Mount Maquiling ; altitude, 80 meters — Continued.

Week ending-

1913.

May 23

May 30

June 6

June 13

June 20

June 27

July4

July 11

July 18 _.__ _

July 25

August 1

Augusts

August 15

August 22

August 29

September 5 ._

September 12

September 19

September 26

October 3

October 10

October 17

October 24

October 31 -__. _

November 7

November 14

November 21

November 28

December 5 .__

December 12

December 19. _

December 26

1914.

January 2

January 9 .

January 16

January 23

January 30 w

February 6

February 13

February 20 _

February 27

March 6 _

March 13

March 20

March 27

April 3

Maxi-

Mini-

mum.

mum.

33.0

23.0

31.1

24.0

33.0

24.0

32.2

22.9

33.9

22.0

31.1

22.5

32.0

24.0

31.9

23.5

30.9

23.5

*29.0

23.5

30.0

24.0

30.2

22.0

31.0

22.1

30.1

22.8

29.5

22.8

29.5

22.3

31.0

22.0

30.0

22.9

30.0

22.7

32.0

23.0

29.9

22.5

29.1

22.5

27.5

22.8

29.0

21.0

29.0

23.1

28.0

22.0

27.5

22.4

27.5

22.5

27.5

22.1

27.6

22.7

27.0

22.6

28.5

22.4

26.9

22.0

28.0

21.0

27.3

20.0

27.0

20.3

27.5

20.3

28.3

20.3

26.7

20.4

30.0

20.8

31.5

20.6

32.6

23.0

33.5

22.5

32.9

23.0

33.0

23.5

33.3

24.0

Average of daily-

Maxima.

26.4
27.3
28.0
27.0
27.1
26.0
26.7
26.4
26.0
26.2
26.0
25.0
26.4
25.0
25.5
26.0
26.0
26.2
23.2
27.0
26.0
24.6
25.2
26.4
25.0
25.3
25.0
24.6
24.6
24.6
24.6
25.0

23.6
23.6
24.0
24.0
23.4
24.3
23.7
25.0
25.5
27.0
28.0
27.4
28.6
28.3

31.0
31.1
31.6
31.6
31.7
30.8
30.2
30.3
28.1
27.8
28.4
28.4
29.7
28.8
28.6
28.7
29.2
29.5
29.3
30.3
28.7
26.6
27.0
27.1
26.9
26.2
26.1
25.8
26.8
26.5
25.8
26.4

25.2
25.6
26.0
26.4
26.7
27.1
25.6
28.4
30.1
30.0
32.2
31.6
31.9
32.6

Minima.

TEMPERATURE

183

Table LX. — Temperature for weekly periods under second-growth trees
near the base of Mount Maquiling; altitude, 80 meters — Continued.

Week ending—

1914.

April 10 .......

April 17

April 24

May 1

May 8

May 15

May 22

May 29

June 5

June 12

June 19

June 26

July 3

July 10

July 17

July 24

July 31..

August 7

August 14

August 21

August 28

September 4 . .
September 11 .
September 18 .
September 25 .

October 2

October 9

October 16

October 23

October 30

November 6...
November 13..
November 20..
November 27..
December 4...
December 11 ..
December 18..
December 25..

January 1

1915.

Maxi-
mum.

33.4
33.0
33.8
34.1
34.6
34.0
34.0
34.0
33.6
32.5
32.7
29.5
30.4
31.9
32.0
30.1
31.4
31.0
29.7
31.0
30.9
30.8
30.0
30.9
31.0
31.0
31.0
30.0
29.9
30.0
80.0
31.0
30.3
31.1
29.9
29.3
29.7
29.3

Mini-
mum.

25.0
23.5
25.4
25.5
25.5
25.0
23.4
25.3
25.4
24.0
24.5
23.7
23.5
24.3
24.0
24.0
23.1
23.9
22.8
23.4
24.4
24.0
23.5
22.8
22.3
21.8
24.0
24.0
23.4
24.0
24.0
24.0
24.0
23.0
23.6
22.9
23.3
23.0

22.3

Mean.

28.6
28.3
29.0
29.5
28.3
28.6
29.0
29.5
26.2
28.3
27.4
26.0
27.2
28.0
28.3
26.0
26.7
26.3
26.5
28.9
28.1
26.4
26.7
26.2
26.0
26.0
26.7
26.0
25.3
26.4
27.1
27.0
26.4
26.8
25.2
25.0
25.3
25.8

25.0

Average of daily-

Maxima. Minima.

31.5
32.5
32.1
33.4
33.6
32.3
32.5
33.7
31.2
32.1
80.5
28.7
29.8
29.2
31.1
29.0
29.3
30.1
28.5
30.1
29.8
28.2
28.2
29.3
29.3
28.8
29.7
29.2
28.2
29.4
29.4
29.6
29.4
29.8
27.8
28.1
28.2
28.0

28.3 !

25.6
24.9
25.9
25.9
26.0
25.4
25.0
25.8
25.7
25.5
25.6
24.1
24.7
25.6
26.8
24.7
24.0
24. 3
24.4
24.9
26.7
25.5
25.0
23.7
23.3
23.6
24.9
24.5
24.0
24.5
24.6
24.8
24.6
24.6
24.1
24.1
24.1
24.1

22.7

184

MOUNT MAQUILING

Table LXI. — Temperature for periods of four weeks from October, 1911 %
to January, 1915, under second-growth trees near the base of Mount
Maquiling ; altitude, 80 meters.

[Numbers give degrees centigrade.]

Four weeks ending-

January 31

29.0

February 28 _. _

31.5

March 28

33.7

April 25

33.8

May 23

34.6

June 20

34.0

July 18

32.7

August 15 _

31.4

September 12

31.0

October 10

32.3

November 7

31.6

December 5

31.1

January 2

31.9

Average .

Maxi-
mum.

Mini-
mum.

19.4
19.8
20.7
19.6
22.3
22.0
22.5
20.2
20.3
21.8
19.9
20.0
19.9

Average of daily

Mean,

The temperatures as recorded in these tables are very similar
to those for most places in the lowlands in the Philippines.
Table LXI shows a mean annual temperature for the period
from October, 1911, to January, 1915, of 26.1°. The mean tem-
perature for Manila * from 1885 to 1907 was 26.8°. The abso-
lute maximum recorded for Manila during the same years was
37.7°, and the minimum, 15°. As might be expected from the
longer time covered by the Manila records, the extremes are
greater than those recorded for Los Baiios; the maximum in
the latter place being 34.6°, and the minimum, 19.4°.

From Table LXI it will be seen that the average variation
in the mean temperature is comparatively slight. Thus, the
lowest mean temperature for a corresponding four-week period
is 24.1°, and the highest, 27.7°, a difference of 3.6°. The highest
mean temperature for any week was 29.5°, for the weeks ending
May 1 and May 29, 1914; and the lowest was 23.2°, for the
weeks ending January 31 and September 26, 1913, respectively.

The average daily variation in temperature is also compara-
tively slight, the average daily maximum for the entire period
from October, 1911, to January, 1915, being 29.2°, and the
average daily minimum, 23.3°, or an average daily range of 5.9°.

Temperatures were also recorded, in the manner previously
described, in the top of a comparatively tall second-growth tree
The position of this instrument was changed several times

* Annual Rept. P. I. Weath. Bur. (1907), 151.

TEMPERATURE 185

owing to attacks of termites. Similar trees were selected in
each case, and these changes in position seem to have had little
or no effect on the results. The trees selected were in each
case situated at the top of a ridge. In preparing a place for
the instrument one of the tallest trees was always chosen. The
top of the main stem was then cut off, so that the stem might
form a support for the instrument case. The remainder of the
tree was then trimmed, so that the instrument was placed in
the very top of the canopy.

The thermometer placed in the top of the tree was read weekly
until July, 1913, after which daily readings were taken. Sum-
maries of the weekly readings will be presented later in com-
parison tables. The results of the daily readings are recorded in
Table LXII in the form of weekly maxima, weekly minima, and

Table LXII. — Temperature for weekly periods in the top of a second-growth
tree near the base of Mount Maquiling; altitude, 80 meters.

[Numbers give degrees centigrade.]

Week ending—

1913.

July 4

July 11

July 18

July 25

August 1 _.

August 8

August 15

August 22

August 29

September 5

September 12

September 19

September 26

October 3

October 10— '.__

October 17

October 24

October 31

November7

November 14

November 21

November 28

December 5

December 12

December 19

December 26

1914.

January 2

January 9

January 16

Maxi-

Mini-
mum.

Average

of daily-

mum.

Maxima.

Minima.

41.0

26.0

39.5

28.3

38.5

26.0

37.3

26.6

39.5

21.0

33.1

25.4

34.5

28.5

31.8

25.6

36.5

26.0

31.6

26.3

34.5

24.5

32.8

26.4

37.5

24.5

35.5

26.6

39.5

25.5

35.3

26.1

37.0

25.0

34.4

25.7

37.5

24.5

33.9

26.0

38.5

24.5

33.8

26.2

38.5

25.5

35.4

26.7

40.5

25.5

37.2

26.1

41.5

25.5

39. 0

26.3

39.0

25.5

36.9

26.2

37.5

24.5

32.8

25.7

40.0

25.5

36.6

25.8

38.5

24.5

36.1

26.1

35.5

26.0

33.6

26.4

35.5

24.0

32.6

25.6

35.0

24. 5

33.4

25.2

35.0

24.0

31.8

25.1

37.0

25.0

35.1

25.4

33.0

24.5

30.7

25.3

35.5

24.5

31.1

25.6

34. 5

24.5

32.4

25.4

35.0

24.2

31.1

25.1

37.5

22.5

31.8

23.9

33.5

21.5

32.1

23.9

186

MOUNT MAQUILING

Table LXII. — Temperature for weekly periods in the top of a second-growth
tree near the base of Mount Maquiling ; altitude, 80 meters — Continued.

Week ending-

1914.

January 23 _

January 30

February 6

February 13

February 20

February 27

March 6

March 13

March 20

March 27

Aprils

April 10

Aprill7

April 24

May 1 __

May 8 ....

May 15

May 22-_„

May 29

June 5 _ ,

June 12

June 19

June 26

July 3

July 10

July 17

July 24

July 31

August 7

August 14 _.

August 21

August 28

September 4

September 11

September 18

September 25 _

October 2

October 9

October 16

October 23 „

October 30 _

November 6

November 13

November 20

November 27 _.

December 4.._ _

December 11

December 18

December 25._ _.

1915.
January 1 ..

Maxi-
mum.

36.9

Mini-
mum.

37.0

23.0

33.8

35.0

23.0

32.4

35.5

23.5

33.5

34.5

23.1

31.9

34.5

22.5

31.9

36. 0

22.5

34.3

33.1

24.5

32.5

37.0

24.0

35.3

36.0

24.5

24.5

35.5

25.0

34.9

35.5

24.5

34.4

37.0

26.0

34.5

38.0

24.5

35.1

38.9

26.0

35.9

39.1

26.5

37.4

38.2

26.9

36.8

39.0

26.5

37.2

40.0

26.2

37.5

40.9

25.5

38.9

41.0

25.1

33.3

40.9

26.2

39.0

39.5

26.6

37.4

38.0

25.2

35.4

38.9

26.0

36.6

36.5

25.9

33.6

39.5

25.0

36.3

46.5

25.0

41.4

48.0

24.9

37.6

47.6

25.1

44.5

44.0

25.0

38.1

43.0

23.9

40.1

38.5

24.6

35.5

39.5

25.0

32.5

34.1

24.1

30.8

40.0

23.5

36.9

44.0

24.8

40.5

41.2

24.9

36.3

43.5

25.0

38.9

41.6

25.0

39.8

37.9

25.0

35.8

37.2

24.9

35.8

39.0

25.0

36.8

38.9

25.0

35.8

37.8

25.0

36.6

39.5

26.0

87.1

34.8

25.0

32.4

34.0

24.6

33.1

35.8

24.8

33.7

38.1

23.5

35.3

24.0

Average of daily-

Maxima. Manima.

35.2

TEMPERATURE

187

averages of daily maxima and minima. The figures in this table
are summarized for corresponding four- week periods for the two
years, in the form of maxima, minima, and averages of daily
maxima and minima in Table LXIII.

Table LXIII. — Temperature for periods of four weeks from July, 1913, to
January, 1915, in the top of a second-growth tree near the base of
Mount Maquilmg; altitude, 80 meters.

[Numbers give degrees centigrade.]

Four weeks ending —

Maxi-
mum.

37.5
36.0
37.0
38.9
40.0
41.0
41.0
48.0
43.0
44.0
41.6
39.5
38.1

Mini-
mum.

Average of daily-

Maxima.

32.5
32.9
34.3
35.0
37.2
37.2
36.1
36.7
34.6
37.7
36.0
34.4
32.8

Minima.

23.8
24.2
25.3
26.1
27.1
26.8
26.9
25.9
26.0
25.9
26.0
25.6
25.4

January 30

21.5
22.5
24.0
24.5
26.2
25.1
21.0
23.5
23.9
23.5
24.5
24.0
23.5

February 27

March27

April 24 .

May 22

June 19 .-_ .

July 17 ..

August 14 ._.

September 11-

October 9-_- _

November6 - _

December 4

January 1 ._.

Average

40.4

23.7

35.2

25.8

The maximum temperature for the whole period was 48°, and
the minimum was 21.0°. The average daily maximum for the
entire period was 35.2°; and the average daily minimum, 25.8°.
The average daily maximum was 6° higher than under the
second-growth trees. The average daily minimum was also
higher in the top of the tree than under the second-growth
trees. The patch of second-growth trees under which the re-
cording instrument was placed was very open, especially on the
side toward the mountain, so that the thermometer was exposed
to the cold winds which come down the mountain at night. As
cold wind settles at the bottom this may account for the minimum
temperatures under the trees being lower than in the top of
the tree.

TEMPERATURE IN THE DIPTEROCARP FOREST

The records of temperature in the dipterocarp forest were
obtained at two stations; namely, station 2, at an elevation of
300 meters, and station 3, at an elevation of 450 meters. For
convenience the temperatures at these two stations will be dis-
cussed separately.

188

MOUNT MAQUILING

At 300 meters' elevation the records of temperature were
obtained by means of a Draper recording thermometer in the
undergrowth and by maximum and minimum thermometers in
the crown of a second-story tree and in the top of a first-story
tree. The first-story tree was a dominant Parashorea makt-
anonan, which projected above the main canopy. The extreme
top of this tree was removed and a place for the instrument
prepared in the manner described for the second-growth tree.

The temperatures in the undergrowth are recorded in Table
LXIV, in the form of weekly maxima, weekly minima, ipeans,
and average of daily maxima and minima. These figures are
summarized in Table LXV.

Table LXIV. — Temperature for weekly periods in undergrowth in the dip-
terocarp forest on Mount Maquiling ; altitude, 800 meters.

[Numbers give degrees centigrade.]

Week ending-

1912.
October 11

October 18

October 25

November 1

November 8

November 15

November 22

November 29

December 6

December 13

December 20

December 27

1913.
January 3 _

January 10

January 17

January 24 __.

January 31

February 7

February 14

February 21

February 28

March 7

March 14

March 21

March 28

April 4

April 11

April 18

April 25

May 2.

Maxi-
mum.

26.6
25.6
24.8
26.6
26.1
25.6
25.9
25.6
25.6
24.5
24.5
23.9

24.2
23.9
24.8
24.5
22.2
23.9

Mini-
mum.

21.7
21.7
21.1
21.1
22.2
21.1
20.8
21.1
20.8
19.4
19.2
20.0

20. 0
20.8
20.3
20.3
18.6
18.9

Mean.

23.2

22.8
22.7
24.0
22.9
22.8
22.8
22.7
22.3
21.7
21.8
21.6

21.7
22.2
22.0
21.9
20.5
21.6

Average of daily-

Maxima.

Minima

25.2

22.2

24.3

22.4

24.2

22.2

25.9

22.8

24.6

22.4

24.6

22.1

24.4

21.8

24.0

22.0

24.4

21.6

22.6

• 20.6

23.4

20.4

22.7

20.7

22.7

21.0

23.2
23.4

21.4
20.8

23.2
21.6
22.6

25.0

19.4

21.8

23.9

25.0

19.4

22.1

23.9

25.6

19.7

22.2

24.2

25.0

19.4

21.9

23.2

27.2

20.3

23.5

26.0

27.7

21.1

23.4

26.6

27.5

19.4

23.3

26.9

27.5

20. 3

23.3

26.4

27.7

19.4

23.7

26.8

26.6

21.4

23.8

25.9

28.0

21.4

24.4

26.7

28.0

21.7

24.5

27.4

20.8
19.9
20.3
20.4
20.5
21.n
21.1
21.6
21.2
20.7
21.2
20.8
22.4
22.2
23.2

TEMPERATURE

189

Table LXIV. — Temperature for weekly periods in undergrowth in the dip-
terocarp forest on Mount Maquiling; altitude, 300 meters — Continued.

Week ending-

May 9

May 16

May 23

May 30

June 6

June 13

June 20

June 27

July 4

July 11

July 18

July 25

August 1 ,.

August 8

August 15

August 22

August 29

September 5 ..
September 12 -
September 19 .
September 26 .

October 3

October 10 .._.
October 17 ....
October 24 .__.

October 31

November 7._.
November 14..
November 21..
November 28. .
December 5 ...
December 12 ..
December 19 ._
December 26 ..

January 2

January 9

January 16

January 23

January 30

February 6

February 13___
February 20.. _
February 27 ...

March 6

March 13

March 20

March 27

1913.

Maxi-

Mini-
mum.

Mean.

Average of daily-

mum.

Maxima.

Minima.

25.9

21.1

23.2

24.7

22.1

28.3

20.5

24.3

27.4

21.8

28.3

21.7

24.4

26.7

22.5

27.7

21.7

24.5

27.0

22.6

29.7

22.7

25.3

28.1

23.5

29.4

21.7

25.6

28.5

22.7

29.7

21.7

25.1

27.8

22.7

27.7

20.5

23.9

26.7

21.6

27.2

21.7

24.0

26.0

22.4

27.2

22.0

23.9

26.1

22.5

27.2

21.4

23.3

24.6

22.1

25.6

21.7

23.1

24.9

22.0

26.1

21.7

23.2

24.8

22.5 |

27.2

21.4

22.7

25.0

22.0 |

27.4

21.1

24.4

26.0

22.8 1

27.4

21.7

23.7

25.6

22.1 j

25.6

20.5

22.7

24.7

21.9 !

26.4

21.1

23.3

25.3

22.0

27.4

21.1

23.8

25.8

21.9

26.9

20.8

24.0

' 26.0

22.5

26.6

21.1

23.3

25.8

22.1

27.7

21.4

23.8

26.4

22.2

26.4

21.1

23.3

25.6

21.9

25.8

21.1

22.9

24.8

21.8

25.6

20.8

22.7

24.9

21.4

25.6

19.4

22.5

24.6

21.1

25.6

21.7

22.7

24.1

22.3

25.0

19.4

22.6

23.8

21.2

24.5

20.0

21.7

23.3

20.9

24.5

19.4

21.5

22.7

20.6

23.9

20.5

22.2

23.2

20.7

24.2

20.0

21.5

22.7

20.9

23.8

20.3

22.0

22.7

21.0

25.0

20.0

22.0

23.2

21.1

23.3

19.7

21.3

22.3

20.4

23.3

18.0

20.3

21.6

19.2

23.3

16.6

20.5

22.0

18.9

23.0

18.9

21.0

22.5

19.7

23.9

18.6

20.5

22.6

19.2

24.2

19.2

21.1

23.3

19.8

23.6

18.6

21.0

22.3

19.4

24.2

18.0

21.1

22.8

18.6

21.4

17.4

21.3

22.4

18.5

27.7

19.7

22.2

24.8

20.9

27.5

18.9

23.4

25.8

20.8

27.1

20.3

22.9

26.0

21.1 i

27.7

20.5

22.8

26.4

26.4 i

190

MOUNT MAQUILING

Table LXIV. — Temperature for weekly periods in undergrowth in the dip-
terocarp forest on Mount Maquiling ; altitude, SOO meters — Continued.

Week ending —

April 3

April 10

April 17

April 24

May 1

May 8

May 15

May 22

May 29

June 5

June 12

June 19

June 26

July 3

July 10

July 17

July 24

July 31

August 7

August 14

August 21

August 28

September 4 . _
September 11 _
September 18..
September 25 _.

October 2

October 16

October 23

October 30

November 6 __.
November 13 -
November 20 .
November 27 _
December 4___
December 11. _
December 18. _
December 25__

Maxi-
mum.

1915.

January 1 .

27.5
27.5
28.3
28.3
29.4
28.3
28.9
29.4
27.5
26.6
28.6
28.4
26.6
27.7
27.7
28.0
26.1
26.6
28.6
25.6
27.2
27.5
26.1
26.6
25.9
26.3
25.9
25.6
25.3
25.0
25.3
25.0
25.6
25.6
25.0
24.8
24.5
23.9

23.9

Mini-
mum.

20.0
22.2
20.5
22.5
22.2
22.2
22.2
22.2
21.4
18.9
22.0
22.0
20.8
21.7
21.7
21.7
20.5
19.4
21.1
21.1
21.1
20.8
21.4
20.8
19.7
20.5
20.5
20.8
20.5
21.1
20.5
21.4
21.1
21.1
21.1
20.5
20.8
20.0

19.4

Mean.

23.4
24.1
23.9
24.6
24.8
25.2
25.4
25.2
25.2
24.1
25.1
24.7
23.5
24.1
23.5
25.6
23.5
23.9
24.2
22.9
24.1
24.7
23.5
22.7
22.4
23.3
22.9
22.7
22.7
22.8
22.9
22.8
23.3
23.5
22.4
22.7
22.4
21.8

21.2

Average of daily-

Maxima, i Minima.

26.7

21.0

26.0

22.3

27.1

22.0

26.8

22.6

27.7

22.5

28.0

22.8

28.2

23.1

28.4

22.7

26.7

22.2

23.8

21.1

27.6

22.8

26.3

22.6

25.8

22.3

26.0

22.6

25.5

22.8

26.7

24.3

25.9

21.8

25.7

21.7

26.8

21.9

24.7

22.4

26.3

22.3

26.0

23.1

24.4

22.4

24.7

22.2

24.8

20.6

25.9

21.9

24.7

21.3

24.6

21.3

23.9

21.5

24.4

21.4

24.2

21.5

24.7

22. 1

24.9

22. 0

25.1

22.1

23.4

21.8

23.7

21.6

23.6

21.3

23.3

20.7

23.1

TEMPERATURE

191

Table LXV. — Temperature for periods of four weeks from October, 1912,
to January, 1915, in undergrowth in the dipterocarp forest on Mount
Maquiling ; altitude, 800 meters.

[Numbers give degrees centigrade.]

Four weeks ending —

January 31

February 28. _.

March 28

April 25

May 23

June 20 .

July 18

August 15

September 12

October 10

November 7 ...
December 5 . . .
January 2

Maxi-
mum.

24.8
25.6
27.7
28.3
29.4
29.7
28.0

Mini-
mum.

16.6
17.4
18.9
19.4
20.5
18.9
20.5

Average .

28.0

19.4

27.5

20.5

27.7

19.7

26.6

19.4

25.9

19.4

25.0

19.2

27.2

19.2

Mean.

21.2
21.5
22.9
23.9
24.7
25.0
24.0
23.5
23.6
23.3
22.9
22.6
21.8

i Average of daily-

Maxima. ! Minima.

23.1

22.5
23.2
25.8
26.6
27.4
27.0
25.9
25.5
25.4
25.5
24.6
24.1
23.0

25.1

20.0
19.8
21.8
21.9
22.6
22.6
22.6
22.2
22.2
21.8
21.9
21.6
20.8

21.7

As might be expected, the temperature was lower in the
dipterocarp forest at an elevation of 300 meters than in the
second-growth forest at the base of the mountain. The mean for
the entire period from November, 1912, to January, 1915, was
23.1°, the maximum was 29.7°, and the minimum was 16.6°.
The extreme range was not very different from that recorded
under the second-growth trees. In the dipterocarp forest the
extreme range was 13.3°, and under the second-growth trees it
was 15.2°. The average daily maximum in the dipterocarp
forest was 25.1°, and the average daily minimum was 21.7°; so
that the average daily variation was 3.4°, against 5.9° under
the second-growth trees. This difference in range in the two
situations would very evidently appear to be connected with the
evener conditions found in the dipterocarp forest, which result
from the development of a dense canopy that almost excludes
the direct sun and very greatly reduces the velocity of the wind.
The effect of the canopy in reducing the velocity of the wind
under the forest is evident on the most casual observation, for a
fairly strong wind may be blowing over the tops of the trees when
there is practically no motion in the undergrowth. Were it not
for this lessened wind movement, it would be almost or quite
impossible to take photographs in the forest ; as, in order to get
detail in the subdued light, an exposure of several minutes is
frequently necessary.

192

MOUNT MAQUILING

The highest mean temperature recorded for any week was
25.6°, for the week ending June 13, 1913; and the lowest was
20.3°, for the week ending January 9, 1914.

The above discussion of temperature in the dipterocarp forest
at an elevation of 300 meters shows that plants in the under-
growth developed under very even temperature conditions.

The maximum and minimum thermometers in the trees were
read weekly. In Table LXVI are shown the weekly maxima

Table LXVL-

-Temperature for weekly periods in the dipterocarp forest on
Mount Maquiling ; altitude, 300 meters.

[Numbers give degrees centigrade.]

Week ending —

1912.

October 26

November 1

November 8

November 15

November 22

November 29

December 6

December 13

December 20

December 27

1913.

January 3

January 10

January 17

January 24

January 31

February 7

February 14

February 21

February 28

March 7 __

March 14

March 21

March 28

April 4

April 11 _

April 18

April 25

May 2 ..._ _

May 9

May 16

May 23

May 30

June6-_.

June 13

In top of tall tree.

In secor
tre

Maxi-

id-story
e.

Mini-

Maxi-

Mini-

mum.

mum.

mum.

mum.

29.5

20.0

31.5

20.5
20.5

31.5

28.0

19.5

26.5

21.5

32.0

19.0

25.0

20.5 !

29.7

19.5

25.0

20.5 !

26.0

19.0

24.0

21.0

27.0

17.5

23.5

19.0 i

32.0

19.0

24.5

19.0

30. 5

21.5

28.0

17.0

29.5

19.0

24.0

21.0

28.0

20.0

24.0

20.5

29.5

18.0

24.5

20.5

37.0

21.5

25.0

20.0

29.0

17.0

27.0

18.0

32.5

19.5

29.0

19.0

35.0

19.5

24.0

20.0

28.0

19.0

24.0

20.0

37.0

18.5

30.5

17.5

35.0

22.0

27.0

20.5

39.0

18.0

31.5

20.0

39.0

22.5

26.5

21.6

35.5

18.5

26.5

20.5

32.5

19.0

27.0

20.6

33.0

19.0

27.0

20.5

33.0

20.5

27.0

22.0

32.0

21.0

27.0

22.0

33.0

20.5

27.0

22.5

28.0

20.0

25.6

21.5

34.0

20.5

28.0

21.0

35.5

21.0

28.0

22.0

33.0

20.5

27.5

22.5

36.0

22.0

29.0

24.0

34.5

21.5

29.0

23.0

In undergrowth.

Maxi-

Mini-

mum.

mum.

24.8

21.1

26.6

21.1

26.1

22.2

25.6

21.1

25.9

20.8

25.6

21.1

25.6

20.8

24.5

19.4

24.5

19.2

23.9

20. 0

24.2

20.0

23.9

20.8

24.8

20.3

24.5

20.3

22.2

18.6

23.9

18.9

25.0

19.4

25.0

19.4

25.6

19.7

25.0

19.4

27.2

20.3

27.7

21.1

27.5

19.4

27.5

20-3

27.7

19.4

26.6

21.4

28.0

21.4

28.0

21.7

25.9

21.1

28.3

20.5

28.3

21.7

27.7

21.7

29.7

22.7

29.4

21.7

TEMPERATURE

193

Table LXVI. — Temperature for weekly periods in the dipterocarp forest on
Mount Maquiling; altitude, 300 meters — Continued.

Week ending -

1913.

June 20

June 27

July 4

July 11

July 18

July 25

August 1

August 8

August 15

August 22

August 29

September 5

September 12

September 19 __

September 26

October 3

October 10

October 17

October 24

October 31

November 7 .

November 14

November 21

November 28

December 5

December 12

December 19

December 26

1914.

January 2

January 9

January 16

January 23

January 30

February 6. __„

February 13

February 20 ..__

February 27

March 6

March 13

March 20

March 27

169549 13

In top of tall tree.

Maxi-
mum.

36.7
34.0
32.5
33.5
33.5
32.1
30.5
29.5
28.5
32.5
30.5
30.0
30.5
32.5
35.0
36.5
34.5
34.5
32.5
31.5
27.5
28.5
29.0
29.0
31.0
26.5
26.5
29.5

81.0
29.5
27.0
29.0
31.5
28.5
30.0
28.5
33.5
28.0
30.5
37.0
34.5

Mini-
mum.

In second- story
tree.

21.3

21.0

20.0

21.0

22.0

21.0

20.5

20.5

19.5

21.0

23.5

20.5

19.5

20.5 |

20.5 J

21.0 |

20.5 |

19.5 |

21.5 I

18.5 1

20.5 I

19.5

19.0

19.0

19.0

19.5

19.0

19.5

Maxi-
mum.

29.5
27.5
27.5
27.0
26.0
24.0
25.5
25.0
28.0
27.5
25.5
26.5
27.5
27.5
27.5
28.5
26.5
26.5
27.0
26.5
26.0
25.5
25.0
24.5
24.5
24.5
24.5
24.5

18.5

25.1

16.5

24.1

15.9

23.5

17.5

23.5

17.0

24.1

18.0

30.0

17.5

26.0

17.2

25.5

17.0

26.0

19.5

26.0

19.2

28.0

20.0

28.0

19.5

28.0

In undergrowth.

Mini-
mum.

21.5

22.0

21.9

22.0

22.0

22.5

21.5

21.0

22.0

21.5

21.5 j

20.5 |

21.0 j

22.0

21.5

22.0

22.0

21.5

20.5

19.5

22.0

19.5

20.0

19.5

20.0

21.0

21.0

21.0

20.0
18.0
17.0
19.5
19.5
19.5
19.0
18.5
18.9
2.1.0
20.5
20.5
21.0

Maxi-
mum.

29.7
27.7
27.2
27.2
27.2
25.6
26.1
27.2
27.4
27.4
25.6
26.4
27.4
26.9
26.6
27.7
26.4
25.8
25.6
25.6
25.6
25.0
24.5
24.5
23.9
24.2
23.8
25.0

23.3
23.3
23.3
23.0
23.9
24.2
23.6
24.2
21.4
27.7
27.5
27.1
27.7

194

MOUNT MAQUILING

Table LXVI. — Temperature for weekly periods in the dipterocarp forest on
Mount Maquiling ; altitude, 300 meters — Continued.

Week ending —

1914.

April 3

April 10

April 17

April 24

May 1

May 8

May 15

May 22.-_

May 29

June 5 --

June 12.

June 19

June 26

July 3

July 10

July 17

July 24

July 31

August 7

August 14

August 21

August 28

September 4 ___x

September 11

September 18

September 25

October 2

October 9

October 16

October 23

October 30

November 6

November 13

November 20

November 27

December 4

December 11

December 18

December 25

1915.
January 1

In top of tall tree.

Maxi-
mum.

30.0
32.0
33.0
29.2
83.0
35.5
38.0
32.5
33.2
33.0
38.0
37.5
30.1
35.0
32.5
34.1
33.9
32.0
30.8
36.5
32.5
32.2
30.0
30.5
36.5
40.0
36.0
38.0
33.2
32.0
31.4
31.0
31.0
30.5
30.5
31.1
31.8
30.8
33.0

Mini-
mum.

18.5
20.5
19.0
21.5
22.1
21.9
23.0
21.5
21.5
19.5
22.0
20.0
21.0
21.0
21.5
19.0
19.9
21.0
20.6
21.9
21.0
21.0
20.0
20.5
19.5
20.0
19.5
20*0
21.0
20.8
20.0
20.0
20.0
20.9
21.5
21.0
19.5
20.5
20.0

18.5

In second- story
tree.

Maxi-
mum.

28.0
28.0
28.0
28.5
29.3
29.5
29.5
29.9
30.9
30.2
30.5
29.9
28.0
29.5
28.9
29.5
28.5
28.2
29.5
26.8
28.5
28.0
27.0
25.5
26.5
28.0
27.5
28.0
26.9
26.9
27.0
27.2
26.1
26.5
26.8
25.0
25.0
25.0
26.0

24.2

Mini-
mum.

20.0
22.0
20.5
22.5
22.9
23.1
23.1
23. G
21.9
21.5
22.5
21.6
22.0
21.8
21.9
21.2
21.0
20.5
21.5
21.5
21.0
21.0
21.9
21.5
19.9
21.0
21.0
21.0
21.0
20.8
21.0
21.0
21.5
21.9
22.0
21.3
21.0
20.3
20.2

19.8

In undergrowth.

Maxi-
mum.

27.5
27.5
28.3
28.3
29.4
28.3
28.9
29.4
27.5
26.6
28.6
28.4
26.6
27.7
27.7
28.0
26.1
26.6
28.0
25.6
27.2
27.5
26.1
26.6
25.9
26.3
25.9

25.6
25.3
25.0
25.3
25.0
25.6
25.6
25.0
24.8
24.5
23.9

23.9

and minima in the top of the first-story tree, in the crown of the
second-story tree, and in the undergrowth. These results are
summarized in Table LXVII and plotted in fig. 6. From Table
LXVII it will be seen that the average weekly maximum in

TEMPERATURE

195

Periods of four weeks ending —

Jon 31 Feb28Mort8ApK25Moy23June20Julyl8Aug.l5$epUZ OcUO Nov.7 Dec 5 Jan £

Fig. 6. Average of weekly maximum and minimum temperatures in dipterocarp
forest on Mount Maquiling ; altitude, 300 meters.

196

MOUNT MAQUIUNG

Table LXVII. — Average of weekly maximum and minimum temperatures
for periods of four weeks from October, 1912, to January, 1915, in the
dipterocarp forest on Mount Maqwiling ; altitude, 300 meters.

[Numbers give degrees centigrade.]

Four weeks ending —

January 31

February 28.__

March 28

April 25

May 23

June 20

July 18

August 15

September 12 _
October 10 .__.
November 7___

Deeember 5

January 2

Average-

Undergrowth.

Second

story.
Mini-

Domina
Maxi-

nt tree.

Maxi-

Mini-

Maxi-

Mini-

mum.
23.7

mum.
19.0

mum.
24.5

mum.
19.2

mum.
30.1

mum.

17.9

24.2

18.9

26.9

19.1

31.6

18.3

27.2

20.0

27.7

20,7

34.8

20.0

27.7

21.0

27.6

21.3

31.9

19.9

28.3

21.8

28.4

22.4

33.7

21.3

28.5

21.6

29.6

22.4

35.3

21.1

27.4

21.5

28.0

21.9

33.2

20.8

26.6

21.0

27.0

21.5

31.8

20.7

26.8

21.1

27.1

21.3

31.1

20.9

26.5

20.7

27.5

21.3

36.1

20.2

25.6

21.0

26.8

21.0

31.4

20.3

25.2

20.7

25.4

20.8

29.7

19.8

24.2

20.0

24.9

20.0

29.9

19.3

26.3

20.6

27.0

21.0

32.4

20.0

the dominant tree is considerably higher than in the second-
story tree. In the dominant tree the average weekly maximum
temperature was 32.4° ; in the second-story tree, 27° ; and in
the undergrowth, 26.3°. The average weekly minima in the
three cases are very similar, being in the dominant tree, 20° ;
in the second-story tree, 21°; and in the undergrowth, 20.6°.
The lowest average minimum is shown in the dominant tree,
and the highest is shown in the second-story tree. Although
the differences are comparatively slight, this relation seems
to be fairly regular for the different periods, and a similar
condition has been found to obtain at an elevation of 450 meters.
It would thus appear that this relation is not accidental.

That the lowest minimum should occur in the top of the
dominant tree is very readily explained by the fact that this
situation is more exposed to radiation and to the cold winds
which come down the mountain at night. That the average
minimum in the undergrowth should be lower than in the
second story is probably due to the fact that cold air sinks
while warm air rises.

The reason for the differences in the maximum temperatures
is very plain : the dominant trees are fully exposed to the action
of the sun and also to the warm winds forced up the mountain
from lower elevations during the day ; while the second story is

TEMPERATURE

197

much less exposed to these conditions, and the undergrowth still
less.

The absolute maximum for the entire period in the dominant
tree was 40°, and the minimum was 15.9°. In the second-story
tree the maximum was 31.5°, and the minimum was 17°. In
the undergrowth the maximum was 29.7°, and the minimum,
16.6°. This again shows the difference in the range of tem-
perature in the dominant tree, in the second story, and in the
undergrowth.

The records of temperature at an elevation of 450 meters
were begun July, 1913, and continued to January 1, 1915. Tem-
perature in the undergrowth was taken by means of a Draper
recording thermometer in the type of case previously described.
Another similar instrument was placed in a case of the same
type in the 0.25-heetare clearing shown on the map as plot 2
(Plate XLI). This plot was on the top of a ridge. Standing
near the instrument it was possible to look over a wide stretch
of the surrounding country, so that this instrument was very
freely exposed to the wind. Maximum and minimum thermo-
meters, which were read weekly, were also placed in the crown
of a second-story tree and in the top of a dominant tree, as was
done at an elevation of 300 meters.

The records for the temperature in the undergrowth are* given
in Table LXVIII in the form of weekly maxima, weekly minima,

Table LXVIII. — Temperature for weekly periods in undergrowth in the dip-
terocarp forest on Mount Maquiling ; altitude, 4-50 meters.

[Numbers give degrees centigrade.]

_ __ _..

- —

. .

Average of daily — j

Week ending —

Maxi-
mum.

Mini-
mum.

Mean.

Maxima.

Minima. |

1

1913.

August 1 .__ _

28. 0
25.6

20.8
20.8

23.2
22.4

24.1
23.8

22.9
21.9

August 8

August 15

26.4
26.1

21.7
21.4

23.9
22.9

25.2
24.8

22.6
22.3

August 22

August29 . ._ . .

25.0
25.9

21.1
21.1

22.7
22.8

24.0
24.4

22.0
22.0

September 5

September 12

26.6

21.4

23.3

24.8

22.2

September 19

26.6

22.7

23.9

25.6

23.1

September 26

26.4

22.2

23.4

25.3

22.5

October3 _. ..

27.5
25.6

22.0
21.4

23.9
23.0

26.0
25.0

22.8
22.4

October 10

October 17

25.0
25.3
25.3
25.6

20.0
21.4
20.5
21.4

22.4
22.5
22.5
22.4

23.9
24.3
24.0
23.8

21.5
21.8
21.6
22.2

October24_

October 31 _„.

November 7

November 14 _

24.8

20.3

22.0

23.2

21.3

198

MOUNT MAQUILING

Table LXVIIL— Temperature for weekly periods in undergrowth in the dip-
terocarp forest on Mount Maquiling; altitude , 450 meters — Cont.

Week ending-

1913.

November 21 .

November 28.. -._ -

December 5

December 12

December 19 __

December 26 __ _.-_.

1914.
January 2

January 9

January 16 .__ __

January 23

January 30

February 6

February 13

February 20 __„.

February 27

March 6. ._

March 13. __ __

March 20

March 27

April 3"_.__ _ ._ _

April 10 ....

April 17

April 24 __ ....

May 1 _ -..

May 8 '.

May 15

May22_...

May 29 „

June 5 _

June 12 —

June 19 .— _ _

June 26 _ ._.

July 3

July 10

July 17 _

July 24

July 31 _

August 7

August 14-_

August 21

August 28

September 4 _.

September 11 _

September 18 _

September 25 _ A.

October 2 . _

October 9 ..__

October 16

Maxi-
mum.

23.6
24.5
23.6
23.9
23.0

22.0
22.2
22.2
23.0
23.0
23.3
22.7
23.9
24.5
25.9
26.6
25.9
26.4
27.2
26.4
27.5
27.5
28.0
27.1
27.5
28.3
28.6
27.2
27.2
27.2
25.9
26.1
25.9
25.9
25.0
26.4
26.7
25.0
26.1
25.9
24.5
25.0
26.4
26.1
26.1
25.6
25.0

Mini-
mum.

20.5
19.7
20.5
20.0
20.0
19.7

18.9
17.4
17.2
19.2
18.9
19.4
18.9
18.6
18.6
19.7
19.7
21.0
20.5
20.3
21.4
21.4
22.5
22.5
22.7
22.5
23.0
22.5
20.5
23.0
21.4
20.5
22.2
21.4
21.6
21.4
21.6
22.2
21.4
21.1
20.7
20.5
20.0
20.8
21.1
20.5
21.4
21.1

Average of daily-

Mean.

Maxima.

Minima.

21.4

22.9

20.9

21.3

22.4

20.5

22.7

22.9

21.1

21.3

22.3

20.7

21.7

22.2

20.7

21.1

22.4

20.6

20.5

21.4

19.5

20.0

20.7

18.7

19.4

21.2

19.1

20.7

22.1

19.6

20.2

22.1

19.3

20.7

22.6

19.9

20.5

21.5

19.2

20.2

22.2

19.2

21.3

23.4

19.7

22.2

23.5

20.6

23.3

25.5

21.5

22.7

24.8

21.2

22.9

25.1

21.2

23.4

25.9

21.3

23.3

24.9

22.2

23.6

26.3

22.1

24.4

26.0

23.0

24.7

26.8

22.8

24.8

26.7

23.2

25.5

27.0

23.4

25.2

26.7

23.7

25.2

27.7

23.6

23.4

24.8

22.2

25.2

26.6

23.5

24.1

25.5

22.8

23.3

25.1

22.3

24.1

25.4

22.8

22.7

24.0

22.5

24.5

25.8

23.2

22.9

24.2

22.1

23.5

24.9

22.6

24.5

26.0

22.6

22.7

23.8

22.1

23.9

25.5

22.5

23.5

24.7

22.7

22.7

23.2

21.8

22.2

23.2

21.5

22.4

24.4

21.3

23.9

26.5

22.0

22.9

24.8

21.4

22.7

24.4

22.0

22.4

24.1

21.6

TEMPERATURE

199

Table LXVIII. — Temperature for weekly periods in undergrowth in the dip-
terocarp forest on Mount Maquiling; altitude, 450 meters — Cont.

Week ending —

1914.

October 23

October 30

November 6

November 13_

November 20

November 27

December 4

December 11

December 18_._

December 25

1915.
January 1

Maxi-
mum.

Mini-
mum.

I

24.5
25.0
25.0
24.8
24.8
24.9
23.9
•23.6
23.6
23.6

23.6

20.8
20.6
21.1
21.4
21.1
21.4
20.5
20.5
20.5
20.5

Mean.

22.4
21.9
22.4
22.4
22.7
22.4
21.7
22.2
21.7
21.8

Average of daily-

Maxima.

Minima.

23.4

21.3

23.9

21.8

24.3

21.6

24.0

21.8

24.4

22.0

24.3

22.0

22.7

21.1

22.8

21.0

22.7

21.1

22.9

21.1

22.9

20.9

means, and averages of daily maxima and minima. These figures
are summarized in Table LXIX. The temperatures are very-
similar to those at an elevation of 300 meters. The mean was,
however, 0.3° lower, while the average daily range was 2.6°,
as compared with 3.4° at 300 meters' elevation.

Table LXIX. — Temperature for periods of four weeks from August, 1918,
to January, 1915, in undergrowth in the dipterocarp forest on Mount
Maquiling ; altitude, 450 meters.

[Numbers give degrees centigrade.]

Maxi-
mum.

23.0
24.5
26.6
27.5
28.3
28.6
26.1
28.0
26.6
27.5
25.6
24.9
23.9

Mini-
mum.

17.2
18.6
19.7
20.3
22.5
20.5
20.5
20.8
20.0
20.5
20.0
19.7
18.9

I
Mean.

20.1
20.7
22.8
23.7
25.1
24.5
23.7
23.3
23.0
23.3
22.4
22.1
21.5

Average of daily— ;

Four weeks ending-

Maxima.

21.5
22.4
24.7
25.8
26.8
26.2
25.0
24.6
24.4
25.2
24.0
23.4
22.5

Minima.

19.2
19.6
21.1
22.2
23.3
23.0
22.7
22.5
22.1
22.2
21.7
21.4
20.7

January 30

February 27 _

March 27

April24

May22 _. _

June 19 _

July 17 .

August 14

September 11

October9 _

November 6 _.

December 4 _ _

January 1

Average _

26.2

19.9

22.8

24.3

21.7

The temperature in the clearing is given in Table LXX in
the form of weekly maxima, weekly minima, means, and average

200

MOUNT MAQUILING

Table LXX. — Shade temperature in the open on Mount Maquiling; altitude,

Jf50 meter 8,

[Numbers give degrees centigrade.]

Week ending-

1914.

April 24 —•_-—

May 1-..

May 8

May 15

May 22

May 29 -

June 5

June 12

June 19

June 26

July3

July 10

July 17. ._

July 24

July 31 ._ _._

August 7

August 14 .

August 21 __

August 28

September 4

September 11 ___

September 18 ._ __

September 25

October2

October 9

October 16

October 23

October 30

November 6

November 13

November 20

November 27..--

December 4 _

December 11

December 18

December 25

1915.
January 1

Maxi-
mum.

31.

32.

33.

31.

32.

31.

30.

30.

30.

31.

29.

32.

32.

28.

30.

28.

26.

26.

32.

32.

30.

30.

29.

30.

81.

29.

30.

29.

30.

27,

27.2

29.0

30.8

27.2

Mini-
mum.

22.8
21.2
22.8
22.0
22.8
22.3
21.0
22.8
21.1
22.0
21.7
21.7
21.1
21.1
21.2
21.7
21.7
20.6
20.1
21.2
20.5
20.5
20.8
20.5
21.7
21.1
20.5
20.5
20.0
20.6
21.1
20.6
20.8
20.0
20.2
20.5

19.5

Mean.

25.5
26.2
25.5
25.6
26.1
23.8
24.2
26.3
24.7
24.8
25.3
23.7
25.4
24.3
24.6
25.8
23.3
24.7
24.2
23.1
22.4
23.2
24.7
23.9
24.2
23.6
23.1
23.1
23.8
23.7
24.0
24.1
22.3
22.4
22.4
24.8

22.0

Average of daily— j

Maxima.

28.7
31.4
29.5
30.1
30.6
27.0
27.4
30.6
28.5
28.8
29.2
27.3
29.0
28.0
29.0
30.8
25.2
28.3
26.4
24.3
24.0
26.8
29.4
28.2
28.0
27.6
26.9
27.5
28.2
28.2
28.1
27.6
24.5
25.2
25.9
28.5

25.7

Minima. i

23.0
22.9
23.1
23.1
28.4
22.6
22.3
23.4
22.7
22.7
22.7
22.3
22.8
22.1
22.3
22.3
22.2
22.3
22.6
22.2
21.7
21.1
21.7
21.4
22.1
21.5
21.3
20.9
21.1
21.5
21.5
21.6
21.5
21.1
21.0
21.7

20.0

daily maxima and minima, and the results are summarized in
Table LXXI. The temperatures in the open are slightly higher
than those in the forest.

The figures in Table LXXI cover only the period from April
24, 1914, to January 1, 1915. The mean temperature for this

TEMPERATURE

201

*

TABLE LXXI. — Shade temperature in the open on Mount Maquiling; altitude,

U50 meters.

[Numbers give degrees centigrade.]

Four weeks ending-

flay 22

June 19

July 17

August 14

September 11

October 9

November 6 _
December 4 . . .

January 1

Average-

Maxi-
mum.

33.3
33.4
31.7
32.8
30.5
32.3
31.1
30.0

30.8

Mini-
mum.

21.2
21.0
21.1
21.1
20.1
20.5
20.0
20.5 |

19.5 |

Mean.

25.9
24.8
24.8
24.5
23.6
24.0
23.4
23.5

22.9

; Average of daily —

Maxima, j Minima.

24.2

30.4

23.1

28.4

22.8

28.6

22.6

28.3

22.2

25.8

22.2

28.1

21.6

27.6

•21.2

27.1

21.5

26.3 ! 21.0

27.8 j

22.0

period was 24.2°; whereas for the same period it was 23.2° in
the undergrowth, or 1° less than in the open. The average daily
maximum was 27.8° in the open and 24.7° in the forest, or
3.1° less in the forest than in the open. The average daily
minimum for the same period was 22° in the open and 22.2°
in the forest. The higher average maximum in the open, like
the higher average maximum in the tops of the trees, is connected
with the more open exposure, while the lower average minimum
in the open is apparently due to the same cause.

These figures would seem to show very clearly that the
forest canopy has an equalizing influence on the temperature
under it, as here the average maximum is lower than in the
open while the average minimum is higher. The greatest effect
of the forest canopy, however, would seem to be due to its in-
fluence in reducing the maximum.

The difference between the average maximum under the
forest and that in the open, as shown by the above figures for
shade temperatures, is of course much less than the actual
difference to which plants under the forest and in the open are
exposed, as in the latter case the effect of sunlight is important.

In Table LXXII are shown the weekly maximum and minimum
temperatures in the top of a dominant Parashorea, in the crown
of a second-story tree, in the undergrowth, and in the clearing.
These results are averaged for corresponding four-week periods
in Table LXXIII and plotted in fig. 7. From Table LXXIII it
will be seen that the average weekly temperatures in the top

202

MOUNT MAQUILING

Table LXXII. — Temperature for weekly periods in the dipterocarp forest on
Mount Maquiling ; altitude, A50 meters.

[Numbers give degrees centigrade.]

Week ending —

1913.
August 15 -_ .. . _ ... _

In clearing,

about 75 cm.

above the

ground.

In dipterocarp forest. j

In top of tall
tree.

Maxi- Mini-
mum, mum.

In secon
tr<

d-story
ie.

Mini-
mum.

22.0
22.5
22.5
20.3
20.9
23.1
22.5
22.0
22.5
20.3
20.3
20.3
22.0
19.1
20.3
19.1
20.9
20.3
20.3
20.3

19.1
17.5
17.0
19.1
19.1
19.7
19.1
18.6
18.6
20.3
19.7
20.3
20.3
20.3
20.9
20.9
22.5
22.5
23.1
23.1
23.1
23.1
20.9

~ !
In under-
growth.

Maxi-
mum.

Mini-
mum.

Maxi-
mum.

Maxi-
mum.

26.4
26.1
25.0
25.9
26.6
26.6
26.4
27.5
25.6
25.0
25.3
25.3
25.6
24.8
23.6
24.5
23.6
23.9
23.0
23.9

22.0
22.2
22.2
23.0
23.0
23.3
22.7
23.9
24.5
25.9
26.6
25.9
26.4
27.2
26.4
,27.5
27.5
28.0
27.1
27.5
28.3
28.6
27.2

Mini-
mum.

21.7
21.4
21.1
21.1
21.4 i

29.4
30.6
30.0
29.4
31.1
30.6
32.2
35.6
33.3
33.9
34.5
32.7
29.4
28.9
30.0
, 27.7
30.6
26.6
28.3
29.4

31.2
28.3
26.1
28.3
27.7
30.0
29.4
29.4
32.7
28.9
33.9
30.6
30.6
32.2
31.2
31.7
31.7
33.9
30.6
31.7
32.2
32.7
32.7

18.9
19.4
18.3
18.3
18.9
20.5
20.5
20.5
20.5
18.3
18.9
18.3
20.0
17.7
18.9
17.7
18.9
18.9
18.3
18.3

17.7
16.0
16.0
18.3
18.3
18.9
18.3
17.7
17.7
18.9
19.4
18.9
20.0
18.3
20.0
20.5
21.7
20.5
21.7
22.2
22.2
22.2
20.0

31.7
27.7
27.7
26.6
26.6
27.2
27.2
27.7
26.6
26.6
26.6
26.1
25.6
25.0
24.5
24.5
25.0
24.5
24.5
25.6

28.3
25.0
23.3
23.9
23.3
25.0
24.5
24.5
26.6
26.6
28.9
28.3
27.2
27.7
27.7
27.7
27.7
28.3
28.3
28.3
29.4
29.4
28.9

August22

August 29 .

September 5.

September 12 \

September 19 I !

22.7

1

September 26 1 _J

22.2 !

October 3

22.0
21.4
20.0
21.4

October 10 I

October 17...

October 24. _.

October 31

20.5 I

November 7

21.4 |

November 14 __

20.3 j

November 21 .. __ __

20.5 !

November 28 ._

1

19.7 I

December 5--_ .* i

20.5

December 12 __.

I

20.0 j

December J 9 _

1

20.0 ;

December 26... ....

19.7 !

1914.
January2... _

18.9

January 16 i

17.4
17.2
19.2
18.9
19.4
18.9
18.6
18.6
19.7
19.7
21.0

January 23

January 30

February 6

February 13 i

February 20

February 27 .....' !

March 13

March 20

March 27

20.5

April3 _

20.3

April 10

21.4
21.4

April 17

April 24 1

33.8
33.3
30.3
31.4
32.8
33.4
31.4

22.8
21.2
22.8
22.0
22.8
22.3
21.0

22.5

May 1 _

22.5

May8

22.7

May 15...

22.5

May 22

23.0

May29

22.5

June 5 _

20.5

TEMPERATURE

203

Table LXXII. — Temperature for weekly periods in the dipterocarp forest on
Mount Maquiling ; altitude, U50 meters — Continued.

Week ending—

1914.

June 12

June 19

June 26

July 3

July 10

July 17

July 24

July 31

August 7

August 14

August 21

August 28

September 4. .
September 11.
September 18.
September 25.

October 2

October 9

October 16

October 23

October 30. _._
November 6 ...
November 13 _.
November 20 ..
November 27 ..

December 4

December 11...
December 18 . ..
December 25...

1915.

January 1

In clearing,

about 75 cm.

above the

ground.

Maxi- j Mini-
mum, j mum.

27.2

22.8
21.1
22.0
21.7
21.7
21.1
21.1
21.2
21.7
21.7
20.6
20.1
21.2
20.5
20.5
20.8
20.5
21.7
21.1
20.5
20.5
20.0
20.6
21.1
20.5
20.8
20.0
20.2
20.5

19.5

In dipterocarp forest.

In top
tr

of tall
ee.

Mini-
mum.

In second-story
tree.

In u
gnr

nder-
cvth.

Mini-
mum.

Maxi-
mum.

Maxi-
mum.

Mini-
mum.

Maxi-
mum.

37.8

22.7

28.3

23.7

27.2

23.0

31.2

20.0

28.3

21.4

27.2

21.4

29.4

20.5

27.2

22.0

25.9

20.5

31.2

21.7

27.2

23.1

26.1

22.2

31.2

18.9

27.2

22.0

25.9

21.4

32.7

20.5

27.2

21.4

25.9

21.6

32.2

20.0

31.2

21.4

25.0

21.4 \

30.6

20.0

27.2

21.4

26.4

21.6 i

32.7

21.1

28.3

22.5

26.7

22.2 !

35.6

20.5

26.1

22.0

25.0

21.4

32.2

20.0

27.7

20.9

26.1

21.1

28.9

18.9

26.6

19.7

25.9

20.7

31.7

18.3

25.6

20.9

24.5

20.5

26.1

18.5

25.6

21.4

25.0

20.0

35.0

20.0

27.2

21.4

26.4

20.8

31.7

19.4

27.7

20.9

26.1

21.1

31.7

20.5

27.2

20.9

26.1

20.5

33.3

20.5

28.3

21.4

25.6

21.4

31.7

21.1

28.9

20.9

25.0

21.1

30.6

19.4

25.6

20.9

24.5

20.8

31.7

19.4

26.6

20.9

25.0

20.6

33.9

20.0

26.6

20.9

25.0

21.1

33.9

18.9

26.1

20.3

24.8

21.4

32.2

20.5

26.1

21.4

24.8

21.1

30.0

20.5

27.7

22.0

24.9

21.4

32.5

19.4

25.6

20.9

23.9

20.5

32.5

19.4

25.0

20.3

23.6

20.5

31.7

18.3

25.0

20.9

23.6

20.5

32.2

^ 20.0

27.2

20.9

23.6

20.5

30.0

19.4

24.5

19.7

23.6

20.0

of the dominant tree are slightly higher than those in the clear-
ing. As previously mentioned, it is possible that the tempera-
tures as recorded in the top of the dominant tree may be slightly
too high, on account of radiation. It is, however, not improb-
able that the temperatures in the tops of the tall trees are higher
than in the clearing, as the former situation is perhaps more
freely exposed to the influence of the hot winds which come up
from lower elevations.

As was the case at an elevation of 300 meters, the average
maximum temperatures in the second-story tree and under-

204

MOUNT MAQUILING

growth are considerably lower than in the top of the dominant
tree. In the undergrowth the average maximum temperatures
are again lower than in the second story. The minimum tem-
peratures in the three situations are very similar, just as was
the case at an elevation of 300 meters. Here again the lowest
average minimum is in the top of the dominant tree, and the
highest is in the second-story tree.

Periods of four weeks ending —

Jan. J0 Feb. 27 Mar £7 Apr. Z* Moy2ZJunel9 July 17 fag.!* Sept. 1 1 Oct. 9 Nov. 6 Dec. 4 Jan. I

Fio. 7. Average weekly maximum and minimum temperatures in dipterocarp
forest on Mount Msquiling; altitude, 450 meters.

TEMPEKATURE

205

Table LXXIII. — Average weekly maximum and minimum temperatures, for
periods of four weeks from August, 1913, to January, 1915, in the dip-
terocarp forest on Mount Maquiling ; altitude, 450 meters.

[Numbers give degrees centigrade.]

Four weeks ending-

January 30

February 27

March 27

April 24

May 22

June 19 €.

July 17

August 14

September 11

October 9 ..

November 6

December 4

January 1

Average _

In clearing,

about 75 cm.

above the

ground.

In dipterocarp forest.

In top of tall
tree.

Maxi-
mum.

32.2
32.2
30.9
30.6
28.0
31.4
30.1
29.1
28.6

Mini- 1 Maxi-
mum. ' mum.

22.2
21.8
21.6
21.4
20.6
20.9
20.5
20.8
20.1 j

27.6
30.4
31.0
31.7
32.1
33.6
31.1
32.8
30.0
32.9
32.3
30.8
30.3

30.3 21.1

31.3

Mini-
mum.

17.2
18.2
19.3
20.1
21.7
21.2
20.4
20.4
18.8
20.3
19.5
19.0
18.8

In second-
story tree.

Maxi-
mum.

19.6

25.
27.
27.
28.
28.
27.
28.
26.
27.
26.
25.
25.

Mini-
mum.

26.9

18.2
19.0
20.2
21.2
23.0
22.3
22.1
21.8
21.2
21.9
20.8
20.6
20.3

21.0

In under-
growth.

Maxi-
mum.

22.6
23.6
26.2
27.2
27.7
27.6
25.7
25.8
25.7
26.3
25.1
24.4
23.4

25.5

Mini-
mum.

18.2
18.9
20.2
21.4
22.7
21.9
21.4
21.7
21.0
21.6
20.9
20.7
20.1

20.8

TEMPERATURES IN THE MIDMOUNTAIN FOREST

The temperature in the undergrowth in the midmountain
forest was recorded by means of a Draper recording thermo-
meter.

This was placed in the type of case previously described. The
case was located at the side of a broad ridge at an elevation of
740 meters. This station is designated on the map (Plate XLI)
as station 4. Maximum and minimum thermometers were also
placed in the top of a dominant tree in the immediate neigh-
borhood and read weekly.

In Table LXXIV are recorded the weekly maxima, weekly
minima, means, and averages of daily maxima and minima in
the undergrowth, and these results are summarized for cor-
responding four-week periods in Table LXXV. The mean
temperature for the entire period was 21.4°, which is 1.7° lower
than the mean in the dipterocarp forest at an elevation of
800 meters and 4.7° lower than that under the second-growth
trees at an elevation of 80 meters. The maximum temperature
for the whole period was 27.5°, as compared with a maximum

206

MOUNT MAQUIUNG

TABLE LXXIV. — Temperature for weekly periods in undergrowth in the mid-
mountain forest on Mount Maquiling ; altitude, 7JfO meters,

[Numbers give degrees centigrade.]

Week ending -

1912.

November 8

November 15

November 22...

November 29 ...

December 6

December 13

December 20

December 27

1913.

January 3

January 10

January 17

January 24

January 31

February 7

February 14

February 21

February 28

*March7

March 14

March 21

March 28

April 4

April 11

April 18

April 25

May 2

May 9

May 16

May 23

May 30

June 6

June 13_

June 20

June 27

July 4

July 11 ._.

July 18

July 25

August 1

August 8

August 15

August 22..

August 29.

September 5 , ...

September 12

September 19

September 26 .__

Maxi-
mum.

22.7
21.7
23.9
22.7
23.3
21.1
23.3
22.2

21.7
22.5
22.7
x22.2
20.0
22.7
22.2
21.7
22.5
22.5
24.5
25.0
24.5
24.2
25.0
23.9
24.5
24.5
23.3
27.2
26.4
25.0
26.6
26.6
26.9
26.4
25.3
25.6
24.5
22.5
23.3
22.7
24.5
24.5
25.0
24.5
25.0
25.9
25.3

Mini-
mum.

19.4
18.9
15.5
18.9
18.9
17.1
18.0
16.3

18.9
18.3
18.9
18.0
16.3
16.6
16.9
17.7
17.1
18.3
18.0
19.4
18.3
18.3
18.3
20.0
19.4
20.0
20.0
21.4
20.5
20.8
21.1
21.1
21.4
21.1
21.1
20.8
19.4
19.4
20.0
20.0
20.0
20.0
19.4
19.7
20.0
20.5
21.1

Mean.

20.4
20.1
20.6
20.4
21.0
19.4
19.9
19.9

20.3
20.1
20.5
20.2
17.9
18.3
19.3
19.2
19.8
19.8
21.5
20.9
21.6
21.0
21.6
21.8
21.8
21.9
20.9
23.2
22.4
22.5
22.8
23.2
23.1
22.6
22.5
22.1
21.7
20.6
21.1
21.2
21.7
21.8
21.1
21.2
22.1
22.6
22.6

Average of daily—

Maxima.

21.7
21.4
22.2
21.9
22.2
20.3
21.6
21.0

21.1
21.3
21.5
21.8
19.3
20.0
20.5
20.9
21.5
21.1
23.3
23.3
24.0
23.4
23.8
23.2
23.6
23.5
22.2
25.4
24.8
24.6
25.1
25.8
25.3
25.2
24.4
24.4
22.7
21.7
22.1
22.1
23.6
23.1
23.0
22.7
23.2
24.1
24.2

TEMPERATURE

207

Table LXXIV. — Temperature for weekly periods in undergrowth in the mid-
mountain forest on Mount Maquiling; altitude, 7UO meters — Continued.

Week ending: —

October 3

October 10-..

October 17

October 24 ...
October 31 ...
November 7...
November 14.
November 21.
November 28. .
December 5 ...
December 12 _.
December 19 _.
December 26 ..

January 2

January 9.__
January 16 ._
January 23 ._
January 30. _
February 6__
February 13.
February 20.
February 27.

March 6

March 13

March 20

March 27

April 3

April 10

April 17

April 24

May 1

May 8

May 15

May 22

May 29

June 5

June 12

June 19

June 26

July 3

July 10

July 17

July 24

July 31

August 7

August 14

August 21

1913.

1914.

Maxi-

Mini-
mum.

Mean.

Average of daily—

mum.

Maxima.

Minima.

25.6

20.3

22.3

24.8

21.2

24.5

19.4

21.7

23.8

21.0

23.3

19.2

21.2

22.5

20.5

24.2

19.7

21.1

23.1

20.3

23.6

18.9

20.2

22.3

20.1

23.9

20.0

21.5

22.5

20.5

22.5

18.0

20.5

21.8

20.1

22.7

19.4

20.4

21.7

20.0

22.5

17.7

19.5

20.8

19.1

22.2

18.6

20.1

21.7

19.6

22.5

18.9

20.2

20.9

19.5

22.0

19.2

21.0

21.2

19.9

22.7

18.6

20.4

21.6

19.5

22.5

17.7

19.3

20.5

18.7

22.2

15.5

18.3

19.9

17.6

20.8

15.5

18.7

20.1

17.6

21.4

18.0

19.2

20.9

18.4

21.4

17.1

18.8

20.3

17.6

22.2

17.7

19.4

21.2

18.5

21.7

16.9

19.1

20.2

17.7

22.2

17.1

19.1

20.9

17.6

22.5

17.4

20.0

22.2

18.5

23.9

18.3

21.2

22.1

19.3

25.9

18.6

22.2

24.4

20.2

24.8

19.7

21.2

23.3

20.0

24.8

19.4

21.2

23.4

20.1

25.3

18.6

21.9

24.5

19.9

25.3

20.5

21.7

23.4

21.0

25.6

19.2

22.7

24.7

20.7

25.6

21.1

22.6

24.6

21.6

26.4

20.8

23.3

25.8

21.8

25.9

21.4

23.4

25.4

21.9

26.6

21.4

23.8

26.0

22.3

26.6

22.2

25.0

26.0

22.5

27.5

21.4

24.1

26.-7

22.1

26.6

18.9

22.3

23.8

21.1

26.6

22.2

23.9

26.0

22.5

26.9

20.3

22.7

24.9

21.8

25.6

18.3

22.4

24.6

21.2

26.6

21.1

22.7

25.0

21.9

25.3

21.1

22.2

23.1

21.8

24.2

21.1

22.3

23.8

21.8

25.0

20.5

22.4

24.1

21.3

25.6

20.5

22.8

24.1

21.7

27.2

21.1

23.3

26.0

21.6

24.6

20.5

21.8

23.0

21.3

25.9

20.8

22.8

24.6

21.6

\ 208

MOUNT MAQUILING

Table LXXIV. — Temperature for weekly periods in undergrowth in the mid-
mountain forest on Mount Maquiling; altitude, 7k0 meters — Continued.

August 28

September 4__
September 11 _
September 18.
September 25.

October2

October 9

October 16

October 23

October 30

November 6__
November 13.
November 20- .
November 27 _
December 4 . . .
December 11 _.
December 18 _
December 25 .

Week ending-

1914.

Maxi-
mum.

23.9

23.
26.
25.
26.
25.
24.
23.
23.
23.
23.
23.
23.
23.
22.
22.
23.

Mini-
mum.

19.7
20.0
19.7
20.0
20.5
20.5
20.5
18.9
19.4
19.7
18.3
19.4
20.0
20.5
18.9
18.9
19.4
19.4

Average of daily-

Maxima.

Minima.

21.9

23.0

21.2

21.7

22.4

21.1

21.8

22.3*

21.2

22.2

23.8

20.8

22.7

24.7

21.6

22.4

24.2

21.4

22.2

23.8

21.2

21.1

22.8

20.2

21.0

22.1

20.2

21.3

22.3

20.1

21.7

22.5

19.9

21.4

22.5

20.5

21.8

22.8

20.9

22.2

23.2

21.2

19.6

22.0

20.6

19.6

21.7

20.1

19.4

21.8

20.©

19.5

22.2

20.2

Table LXXV. — Temperature for periods of four weeks from November,
1912 > to January, 1&15, in undergrowth in the midmountain forest on
Mount Maquiling ; altitude, 7U0 meters,

[Numbers give degrees centigrade.]

Four weeks ending-

January 31

February 28 ■_.

March 28

April 25

May 23... .1...

June 20 ...

July 18-. 1

August 15

September 12 .
October 10 ....
November 7__.
December 5 . _ .
January 2

Average

Max-

Min-
imum.

Mean.

Average

of daily -
Minima

imum.

Maxima.

22.7

15.5

19.3

20.7 ! 18.4

22.7

16.6

19.3

20.9 \ 18.2

25.9

18.0

21.3

23.1 j 19.7

25.6

18.3

21.9

23.9 i 20.4

27.2

20.0

23.0

24.9 21.5

27.5

18.9

23.1

25.3

21.8

26.6

18.3

22.3

24.2

21.6

27.2

19.4

21.9

23.4

21.0

25.9

19.4

21.9

23.1

21.0

26.6

19.4

22.4

24.2

21.3

24.2

18.3

21.2

22.5

20.3

23.9

15.5

20.6

22.0

20.1

23.6

16.3

19.9

21.8

19.5

25.4

18.0

21.4

23.0 J 20.4

— —

TEMPERATURE 209

of 29.7° in the dipterocarp forest at an elevation of 300 meters
and 34.6° under the second-growth trees at the base of the
mountain. The minimum temperature was 15.5°, as compared
with 16.6° at an elevation of 300 meters and 19.4° at an al-
titude of 80 meters. The total range for the entire period
was 12°, as compared with 13.1° at an elevation of 300 meters
and 15.2° at the base of the mountain. The average daily
maximum for the entire period was 23°, and the average daily
minimum, 20.4°, the average daily range being 2.6°. This is
even less than the small range at an altitude of 300 meters,
which was 3.4°.

Table LXXVI. — Temperature for weekly periods in the top of a dominant
tree in the midmountain forest on Mount Maquiling; altitude, 740 meters.

[Numbers give degrees centigrade.]

Week ending —

1912.
November 1

November 8

November 15

November 22

November 29

December 6

December 13

December 20

December 27

1913.

January 3

January 10

January 17 .__•

January 24

January 31

February 7

February 14

February 21

February 28

March 7

March 14

March 21

March 28

April 4

April 11

April 18

April 25

May 2

May 9

May 16

May 23

159549 14

Maxi-
mum.

23.5
25.5
25.0
29.0
30.0
30.5
26.0
32.0
32.0

27.0
27.0
27.0
30.5
29.0
32.5
34.0
27.5
36.0
32.0
36.5
35.0
35.5
38.0
34.5
82.0
29.0
25.5
26.0
33.5
34.5

Mini-
mum.

20.0
19.0
21.0
18.0
1.8.0
17.5
15.5
16.5
18.0

18.5
18.0
17.0
17.0
14.0
16.0
17.5
16.5
17.5
17.0
11.5
19.0
17.6
18.0
17.0
19.5
19.0
19.0
19.0
19.0
19.5

Week ending-

May 30_..'_

June6

June 13

June 20

June 27

July 4

July 11

July 18

July 25

August 1

August 8

August 15

August 22

August 29

September 5. _
September 12 _
September 19 _
September 26 _

Octobers

October 10. ___

October 17

October 24 ....

October 31

November 7 . _
November 14 _
November 21 .
November 28 .
December 5...
December 12 ..
December 19 __
December 26..

Maxi-
mum.

31.5
34.0
34.0
34.6
35.0
32.0
30.5
30.0
28.0
25.0
27.0
27.0
31.5
31.5
27.5
28.0
31.0
33.5
35.0
31.5
29.0
29.5
31.5
26.0
27.0
27.5
26.0
29.5
24.5
27.5
27.1

Mini-
mum,

19.5
21.0
20.0
19.0
19.6
19.5
21.5
19.6
19.0
18.5
18.0
18.5
19.0
18.5
18.5
18.5
20.0
18.5
19.0
19.0
18.0
17.5
16.5
19.0
16.0
17.5
16.5
18.0
18.5
18.5
17.9

210

MOUNT MAQUILING

TABLE LXXVL — Temperature for weekly periods in the top of a dominant
tree in the midmountain forest on Mount Maquiling; altitude, 740
meters — Continued.

Week ending —

1914.

January 2 . _ _
January 9 .._
January 16 ._
January 23 ._
January 30 . -
February 6 ._
February 13 _
February 20 .
February 27 .

March 6

March 13

March 20 _...

March 27

April 3

April 10

April 17

April 24

May 1

May 8

May 15

May 22

May 29

June 5

June 12

June 19

June 26 _

July 3 _.

Maxi-
mum.

25.5

29.9
33.5
29.0
31.0
32.0
32.5
35.2
34.0
33.5
34.5
32.5
34.5
36.0
36.3
35.0
37.1
34.2
36.1
35.5
33.8
37.0
32.5
32.0

Mini-
mum.

17.0
14.0
14.0
16.0
16.0
16.0
15.5
15.0
15.1
17.0
16.0
17.9
17.0
17.1
18.0
18.0
18.5
18.9
20.0
18.5
19.1
20.1
19.0
20.0
19.0
19.5
19.0

Week ending-

July 10

July 17

July 24

July 31

August 7

August 14

August 21

August 28

September 4 - -
September 11 .
September 18 -
September 25 -

October 2

October 9

October 16

October 23. -_

October 30

November 6 _ -
November 13 .
November 20 .
November 27 -
December 4___
December 1L -
December 18. -
December 25. _

1915.

January 1.

Maxi-

Mini-

mum.

mum.

26.5

18.0

30.2

18.5

32.5

19.0

32.4

18.9

34.5

19.0

30.5

18.5

32.0

18.8

24.9

19.2

23.5

19.0

24.5

19.0

32.5

17.1

32.0

18.5

31.0

21.0

3.1.5

18.5

32.8

18.2

28.0

17.9

27.5

18.0

29.5

18.9

28.0

19.0

30.0

19.0

29.5

19.0

25.0

18.0

25.5

18.3

29.0

17.0

29.0

18.0

23.5

17.0

--

The weekly maximum and minimum temperatures in the top
of the dominant tree are given in Table LXXVI. In Table
LXXVII these results are averaged for corresponding four-week
periods for the entire period, and in the same table are also given
similar figures for temperatures in the undergrowth. In this
table, as in similar comparison tables for lower elevations, the
average maximum temperature was considerably higher in the
dominant tree than in the undergrowth, being in the former case
30.4°, and in the latter, 24.3°. The minimum temperatures are
again much more alike. The average weekly minimum tempera-
ture for the dominant tree (18.1°) is slightly lower than that
in the undergrowth (19.4°). The absolute maximum tempera-
ture in the dominant tree occurred during the week ending June
19, 1914, and was 37.0°, and in the undergrowth it was 27.5°
on May 25, 1914. The absolute minimum temperature in the top
of the tree was 11.5° and was recorded during the week ending

TEMPERATURE

211

Table LXXVII. — Average of weekly maximum and minimum temperatures
for periods of four weeks from October, 1912, to January, 1915, in the
midmountain forest on Mount Maquiling; altitude, 740 meters.

[Numbers give degrees centigrade.]

In under-
growth.

Four weeks ending—

In dominant
tree.

January 31

February 28

March 28

April 25

May 23

June 20

July 18

August 15

September 12 ._

October 10

November 7

December 5

January 2

Average

Maxi-
mum.

21.7
22.3
24.5
25.0

Mini-
mum.

17.2 ;
17.2

18.8 ,
19.5 ]

Maxi-
mum.

28.4 I

32.5 I
34.8 J
32.1

Mini-
mum.

15.8
16.2
16.7
18.2

25.9

21.0

29.9

19.1

26.6

20.9 !

33.5

19.7

25.5

20.5 !

31.9

19.4

24.5

20.3

26.8

18.7

24.4

20.0 i

29.6

18.8

25.6

20.4 ;

32.8

19.0

23. 7

19.3 !

26.8

18.5

! 23.1

18.7 !

28.1

18.1

! 22.5

18.5 |

27.8

17.6

24.3

19.4

30.4

18.1

March 14, 1913, and in the undergrowth it was 15.5°, on January
9 and 10, 1914.

TEMPERATURE IN THE MOSSY FOREST

The temperature in the mossy forest was recorded on the top
of the east peak at an elevation of 1,050 meters. As in the
midmountain forest, the temperature under the trees was taken
by means of a Draper recording thermometer, and in the top of
the dominant tree, by means of maximum and minimum thermo-
meters. The temperatures under the trees are given in Table
LXXVIII in the form of weekly maxima, weekly minima, means,
and averages of daily maxima and minima. These results are
summarized, for corresponding four-week periods for the entire
period, in Table LXXIX. The mean temperature for the whole
period was 17.8° ; the absolute maximum, 26.1° ; the absolute
minimum, 12.2° ; the average daily maximum, 19.3° ; and the
average daily minimum, 16.9°. These temperatures are consider-
ably lower than those in the midmountain forest, but the ranges
are very similar. The average daily range in the mossy forest
was 2.4°, and in the midmountain forest, 2.6°. The extreme
range in the mossy forest was 13.9°, and in the midmountain
forest, 12°. The mean temperature for the entire period was
3.6° higher in the midmountain than in the mossy forest.

212

MOUNT MAQUILING

Table LXXVIII. — Temperature for weekly periods under the mossy forest
at the top of Mount Maquiling ; altitude, 1,050 meters.

[Numbers give degrees centigrade.]

Week ending-

1912.

October 25

November 1

November 8 T Z_

November 15

November 22

November 29

December 6

December 13

December 20

1913.

January 3

January 10 _

January 17

January 24

January 31

February 7

February 14

February 21

February 28

March 7

March 14

March 21

March 28

April 4

April 11

April 18

April 25

May 2

May 9

May 16

May 23

May 30*

June 6

June 13

June 20 __.

June 27

July 4

July 11

July 18

July 25...

August 1 ._'

August 8...

August 15

August 22

August 29 _

September 5 _..

September 12

Average of daily-

Mini-
mum.

Mean.

mum.

Maxima.

Minima.

19.4

16.6

17.8

18.7

17.4

22.0

16.9

19.2

20.4

18.0

21.4

17.1

18.8

19.8

17.9

20.5

17.1

18.3

19.4

17.8

21.1

16.6

17.8

19.4

17.4

20.3

16.0

18.1

19.1

17.0

20.5

15.5

17.5

19.4

16.5

18.3

13.9

16.5

17.5

15.6

19.7

14.8

17.1

18.7

16.3

19.2

14.2

16.5

17.6

15.5

19.4

16.0

17.1

18.3

16.9

20.3

16.0

17.2

19.0

16.7

20.3

15.0

17.1

19.0

16.1

17.1

13.9

15.3

16.5

15.1

19.7

14.5

17.2

18.4

16.0

20.3

14.2

16.0

17.9

15.4

18.9

14.8

16.5

17. 5

15.9

19.2

12.8

16.0

18.1

15.5

19.7

15.5

16.9

18.2

16.1

21.1

13.9

18.2

20.3

17.1

22.2

15.5

17.3

19.4

16.2

21.7

14.8

17.2

19.6

16.1

20.0

13.3

17.0

18.8

15.7

21.1

15.3

17.7

20.1

16.0

21.7

16.9

18.4.

20.3

17.6

20.0

16.0

18.2

19.6

17.2

20.0

16.9

18.3

19.3

17.5

20.8

17.1

18.7

19.3

17.9

23.0

16.9

19.5

22.2

17.6

23.3

17.4

19.3

21.3

18.1

21.7

17.7

19.3

21.0

18.5

23.9

18.0

19.8

21.4

18.8

23.9

16.9

19.9

22. 9

18.2

23.9

17.1

19.4

22.1

18.5

23.3

16.9

19.3

21.8

18. 0

22.5

17.1

19.4

21.1

18.2

22.0

17.1

19.1

21.0

17.9

21.4

17.1

18.7

19.8

18.4

20.0

17.4

18.4

19.1

17.8

20.3

17.1

17.9

19.5

17.6

20.0

16.0

17.7

19.1

17.3

20.8

16.3

18.4

19.8

17.5

21.7

16.0

18.7

19.3

17.5

21.4

16.6

18.1

19.9

17.2

20.8

15.8

18.2

19.6

17.1

22.2

16.6

18.4

20.2

18.1

TEMPERATURE

213

Table LXXVIII. — Temperature for weekly periods under the mossy forest
at the top of Mount Maquiling ; altitude , 1,050 meters — Continued.

Week ending-

September 19 .
September 26 .

October 3

October 10 __■_.

October 17

October 24

October 31

November 7

November 14. _
November 21__
November 28 ._

December 5

December 12 . _
December 19 _ .
December 26 __

January 2

January 9...
January 16 . _ .
January 23 ._.
January 30..
February 6__
February 13.
February 20..
February 27.

March 6

March 13

March 20

March 27

April 3

April 10

April 17

April 24

May 1

May 8

May 15

May 22

May 29

June 5

June 12

June 19

June 26

July 3

July 10

July 17 .......

July 24

July 31

August 7

1914.

Maxi-
mum.

23.0
22.0
21.4
20.0
19.7
19.7
19.2
20.5
19.7
19.4
19.2
18.9
19.4
19.2
19.7

18.9
17.4
16.9
17.4
16.9
18.6
16.9
17.1
19.4
20.5
21.1
20.8
19.4
19.2
20.5
21.2
22.3
21.7
21.1
22.2
22.6
23.3
23.9
23.9
23.3
22.7
23.3
26.1
20.0
22.0
19.4
22.3

Mini-
mum.

17.7
16.9
16.0
16.0
15.5
16.0
14.5
16.0
13.9
15.0
15.5
15.0
15.5
15.8
16.0

13.9
12.8
12.2
13.9
13.3
14.8
12.8
13.3
13.1
13.9
14.5
15.8
15.0
14.5
16.0
15.5
17.1
16.0
17.1
17.1
17.4
17.1
16.9
17.1
16.6
17.1
17.1
18.3
16.6
14.8
14.2
15.6

Average of daily-

Mean.

Maxima.

Minima.

18.8

20.7

18.5

19.2

20.6

18.0

18.7

20.6

17.3

18.2

19.4

17.6

17.9

19.2

17.1

17.0

18.9

16.6

17.0

17.7

16.3

18.4

19.2

18.0

17.6

18.2

16.9

16.6

17.6

16.1

16.1

16.9

17.2

16.6

17.9

16.0

16.9

17.6

16.5

17.1

18.0

16.5

17.7

18.2

16.7

15.6

16.9

15.3

14.9

15.7

14.3

14.9

15.9

14.3

15.4

16.5

14.8

15.1

16.0

14.3

15.8

17.2

15.7

15.1

16.2

14.6

15.0

16.0

14.9

15.7

18.0

14.4

16.2

17.8

15.6

17.2

19.3

16.1

16.6

17.9

16.2

16.8

18.1

15.8

17.2

19.9

15.7

17.8

19.1

17.1

18.5

19.9

16.9

18.9

20.5

17.5

18.7

20.3

17.1

18.9

20.1

17.7

19.5

21.0

18.4

19.6

21.8

18.0

20.2

22.1

18.2

19.1

20.7

17.8

20.5

22.4

18.5

19.1

20.6

18.1

19.4

21.2

18.9

18.9

21.5

18.4

20.7

22.6

20.6

19.0

19.5

17.6

18.2

19.8

17.0

16.7

18.1

15.9

17.6

20.6

16.9

214

MOUNT MAQUILING

Table LXXVIII. — Temperature for weekly periods wider the mossy forest
at the top of Mount Maquiling; altitude, 1,050 meters — Continued.

Week ending —

1914.

August 14

August 21

August 28

September 4

September 11

September 18

September 25

October 2

October 9 .

October 16

October 23

October 30

November 6

November 13

November 20

November 27

December 4

December 11 ..-

December 18

December 25

1915.
January 1

Maxi-
mum.

Mini-
mum.

18.0

15.3
14.8
15.3
15.9
15.9
13.7
16.5
15.3
16.2
15.3
15.9
15.9
14.8
13.6
14.8
15.3
16.5
16.4
15.1
15.9

14.8 |

17.5
18.0
17.2
17.6
17.5
17.0
18.2
17.7
17.6
17.0
17.1
16.6
15.2
17.5
17.5
17.6
17.6
17.4
17.2
17.3

16.2

Average of daily

Maxima. Minima.

18.4
19.8
18.0
18.3
18.1
18.5
21.1
20.1
19.6
17.7
17.8
17.8
18.1
18.1
18.1
18.1
18.1
18.0
17.7
18.4

17.0 i

16.4
16.7
17.0
17.1
17.1
15.5
17.1
16.2
16.9
16.3
16.6
14.4
17.1
16.8
16.4
17.0
17.2
16.9
16.4
16.5

Table LXXIX. — Temperature for periods of four weeks from November f
1912, to January, 1915, under the mossy forest at the top of Mount Ma-
quiling; altitude, 1,050 meters.

[Numbers give degrees centigrade.]

Four weeks ending-

January 31__.
February 28.

March 28

April 25

May 23

June 20

July 18

August IB

September 12
October 10...
November 7_
December 5. .
January 2._.

Average.

Maxi-
mum.

20.3
20.3
22.2
22.3
23.3
23.9
26.1
22.3
22.2
23.7
22.0
21.1
20.3

Mini-
mum.

12.2
12.8
13.9
13.3
16.0
16.6
16.6
14.2
14.8
13.7
14.5
13.6
13.9

22.3

14.3

Mean.

15.9
15.9
17.1
18.0
19.1
19.7
19.3
17.8
18.0
18.2
17.6
17.4
16.8

17.8

Average of daily-

Maxima.

Minima.

17.1

15.3

17.4

15.3

18.9

16.2

19.8

16.7

20.7

17.8

21.9

18.3

21.1

18.5

19.3

17.1

19.2

17.3

20.1

17.1

18.7

17.0

18.3

16.9

17.8

16.1

19.3

16.9

TEMPERATURE

215

Table LXXX records the weekly maximum and minimum
temperatures in the top of the dominant tree. The absolute
maximum was 39.5°, and the minimum, 9.5°.

The results of Table LXXX are summarized for corresponding
four-week periods for the different years in Table LXXXI, in
which table are also given similar figures for temperatures un-
der the trees. As in previous cases the maximum temperature
in the dominant tree was higher than that under the trees, the
average weekly maximum being 28.1° in the top of the tree and
20.6° in the undergrowth. The minimum temperatures show
a different condition from that found at any lower elevation
in the virgin forest, the average minimum under the trees being
lower than in the top of the dominant tree. The average mini-
mum in the first case was 15.7°, and in the latter, 17.3°.

Table LXXX. — Temperature for weekly periods in the top of a dominant
tree in the mossy forest on Mount Maquiling ; altitude, 1,050 meters.

[Numbers gife degrees centigrade.]

Week ending-

1912.

October 18

October 25

November 1 ___

November 8

November 15

November 22

November 29

December 6

December 13-..

December 20

December 27

1913.

January 3

January 10

January 17

January 24

January 31

February 7

February 14

February 21

February 28

&farch7

March 14

March 21

March 28

April 4

April 11

April 18

.April 25

May 2

Maxi-

Mini-

mum.

mum.

21.5

17.5

21.5

18.0

22.5

18.5

26.5

18.5

26.0

18.5

29.5

17.5

25.0

17.0

25.0

16.5

26.0

14.6

30.0

15.0

28.0

16.0

27.5

18.0

28.0

18.0

30.0

16.5

37.5

17.0

22.0

14.0

26.5

15.5

35.5

16.5

29.0

16.0

37.0

16.5

33.0

10.5

39.5

9.5

35.0

16.5

32.5

16.5

28.0

16.0

28.0

17.0

27.0

19.0

26.0

18.0

24.5

18.0

Week ending-

1913.

May 9

May 16

May 23

May 30

June 6

June 13

June 20

June27--._--_

July 4

July 11

July 18

July 25

August 1

August 8

August 15

August 22

August 29

September 5

September 12

September 19

September 26

October 3

October 10...

October 17

October 24

October 31

November 7 ___

November 14

November 21

November 28

.-/

Maxi-

Mini-

mum.

mum.

22.0

19.0

32.0

18.0

33.5

18.5

28.0

19.0

30.5

20.0

31.0

18.5

33.5

18.5

30.5

18.0

30.0

18.5

31.0

19.0

22.6

20.5

21.5

18.5

21.5

18.0

27.5

21.6

23.0

18.0

^23.5

18.0

26.5

18.5

26.5

17.0

27.5

18.5

31.5

18.5

28.5

18.0

30.0

17.5

29.0

18.5

26.0

17.5

29.5

16.5

23.6

15.6

21.5

17.5

21.5

15.0

20.5

17.6

25.5

15.5

216

MOUNT MAQUILING

Table LXXX. — Temperature for weekly periods in the top of a dominant
tree in the mossy forest on Mount Maquiling ; altitude, 1,050 me-
ters— Continued.

Week ending—

1913.

December 5 . _ .
December 12 _
December 19.
December 26.

1914.

January 2 ...
January 9 - _ .
January 16 _.
January 23 . -
January 30 ._
February 6 _.
February 13 .
February 20 .
February 27 -

March 6

March 13

March 20 ....

March 27

April 3

April 10

April 17

April 24

May 1

May 8

May 15

May 22

May 29

June 5

June 12

June 19

Maxi-
mum.

27.5
21.5
23.5
27.5 I

I

26.0 |

Mini-
mum.

17.5
18.0
18.0
16.5

16.5
13.5
13.9
14.5
15.0
15.2
14.1
14.0
15.0
16.0
15.5
17.0
16.0
15.9
17.5
17.5
18.0
27.5
17.5
18.5
18.0
18.0
18.5
18.0
18.9

Week ending—

1914.

June 26

July 3

July 10

July 17

July 24

July 31

August 7

August 14

August 21 ____

August 28

September 4 _ _
September 11 .
September 18 -
September 25 .

October 2

October 9

October 16. —
October 23.-. .
October 30. ...
November 6 ._
November 13 .
November 20 _
November 27 .
December 4 ...
December 11 _
December 18 -
December 25 -

1
January 1

Maxi-
mum.

Mini-
mum.

17.6
17.0
17.9
17.5
27.5
17.1
16.5
17.5
18.2
19.0
18.0
18.0
14.0
17.5
17.9
17.9
17.5
17.0
17.0
17.0
18.0
18.0
18.0
18.0
17.0
16.2
17.0

The most obvious explanation of the fact that the temperature
in the undergrowth is lower than in the dominant tree at this
elevation and higher at lower elevations is that this station,
being on the top of an isolated peak, was not so exposed to the
downward sweep of cold winds as were the stations at lower
elevations.

COMPARISON OF TEMPERATURES AT DIFFERENT ELEVATIONS

In order that the temperatures at different elevations might be
conveniently compared, the maxima, minima, means, average
daily maxima and minima, and in the cases of the maximum and
minimum thermometers, the average weekly maxima and minima
for corresponding four-week periods, have been brought to-
gether in a series of tables and curves.

TEMPERATURE

217

Table LXXXI. — Average of weekly maximum and minimum temperatures
for periods of four weeks from October, 1912, to January, 1915, in the
mossy forest at the summit of Mount Maquiling ; altitude, 1,050 meters.

[Numbers give degrees centigrade.]

In undergrowth.

Four weeks ending-

January 31 ___
February 28 „

March 28

April 25

May 23

June 20

July 18

August 15

September 12 .

October 10

November 7 _ _
December 5__-
January 2

Average

Maxi-
mum.

18.3

18.8

20.9

20.8

21.9

23.5

22.7

20.6 |

20.4 I

21.7

19.8

19.7

19.1

Mini-
mum.

20.6

14.2
13.8
14.9
15.6
17.0
17.2
17.2
15.9
15.9
16.1
15.7
15.4
15.1

15.7

In dominant tree.

Maxi- Mini-
mum, mum.

29.4
32.0
35.0
27.3
28.0
30.8
28.5
23.4
26.0
29.8
24.1
25.1
26.8

28.1

15.3
15.4
14.7
17.4
18.2
18.7
18.3
19.4
18.2
17.5
17.3
17.3
16.7

17.3

Table LXXXII. — Mean temperature for periods of four weeks from Octo-
ber, 1912, to January, 1915, under trees at different elevations on
Mount Maquiling.

[Numbers give degrees centigrade.]

Four weeks ending-

January 31

February 28__

March 28

April 25

May 23

June 20

July 18

August 15

September 12 .

October 10

November 7__
December 5-_
January 2

Average

Elevation in meters.

80.

300.

450.

740.

1, 050.

24.0

21.2

20.1

19.3

16.9

24.4

21.5

20.7

19.3

15.9

27.0

22.9

22.8

21.3

17.1

27.2

23.9

23.7

21.9

18.0

27.7

24.7

25.1

23.0

19.1

27.7

25.0

24.5

23.1

19.7

26.9

24.0

23.7

22.3

19.3

26.2

23.5

23.3

21.9

17.8

26.6

23.6

23.0

21.9

18.0

25.9

23.3

23.3

22.4

18.2

25.7

22.9

22.4

21.2

17.6

25.6

22.6

22.1

20.6

17.4

24.7

21.8 | 21.5

19.9

16.8

26.1

23.1

22.8

21.4

17.8

The mean temperatures under the trees at different elevations
are presented in Table LXXXII and plotted in fig. 8. The
temperatures for the dipterocarp forest at an elevation of 450

218 MOUNT MAQUILING

meters do not cover as long a period as do those at other ele-
vations, and perhaps owing to this fact they show some minor
variations. The curve for this elevation is omitted in the follow-
ing discussion.

Fig. 8 shows that in all cases the lowest mean was in January
or February, after which the temperature rose, reaching a maxi-
mum during the period ending June 20. The mean then became
lower until the period ending August 15, after which there was
another rise, a second but lower maximum occurring during the
period ending September 12 or October 10, after which the tem-
perature again fell. The low point in the curve for the period
ending August 15 is apparently connected with the occurrence of
the rainy season, as there is much more rain during this season
than at any other time, and the sky is frequently overcast by
clouds. A comparison of these curves for temperature with
those which will be given later for light would seem to indicate
that the variations in temperature are caused largely by varia-
tions in light intensity at different periods.

One of the most striking things brought out by these curves
is the similarity in the range of temperature at different eleva-
tions. In the parang at an elevation of 80 meters the greatest
difference between the mean temperatures for any corresponding
four- week period was 3.7° ; in the dipterocarp forest at an
elevation of 300 meters, 3.8° ; in the midmountain forest at an
elevation of 740 meters, 3.8° ; and in the mossy forest, 3.8°.
The range for four-week periods is, therefore, exactly the same
in the mossy forest, the midmountain forest, and the dipterocarp
forest at an elevation of 300 meters; while in the parang it is
0.1° less than at the higher altitudes. The mean temperature
for the entire period at an elevation of 80 meters is 26.1° ; at
300 meters, 23.1° ; at 450 meters, 22.8° ; at 740 meters, 21.4° ;
and at 1,050 meters, 17.8°.

The average daily minimum temperatures under the forest
for corresponding four-week periods at different elevations are
given in Table LXXXIII, and the average daily maxima are
given in Table LXXXIV. In fig. 9 the yearly means, yearly
average daily maxima, and yearly average daily minima for the
different stations are plotted in separate curves. These curves
show at once that the greatest average daily range is at an eleva-
tion of 80 meters, and that the daily range decreases as higher
altitudes are reached. The average daily range for the parang
is 5.5° ; in the dipterocarp forest at an elevation of 300 meters,
3.4° ; in the dipterocarp forest at an elevation of 450 meters,

TEMPERATURE

219

26

25

24

•B 23

•3 22

S 21

20

!9

17

f$

Periods of four weeks ending —
.31 Feb.28 Marfd Apr. 85 Maf23June20Ju/yl8 Auff. 15. Sept/2 Oct/0 Nov. 7 Dec. 5 Jan. Z

fay23June20Ju/yl

- -\i-

1

I !

... f_.

1

.#.

-6

«?■

F==dr

fc

■>

-v

. A

\.

X

Fig. 8. Mean temperature under trees at different altitudes on Mount
Maquiling.

220

MOUNT MAQUILING

100

zoo

300

Altitude in meters.

400 500 600

700

800

900

1000

—

28

i

e

0)

— .

<\

—

—

X

^ -

—

__._

--

09

u 24

bC

V

V

N

)>dz?

?f

'^OA

tizg.

<K

>

N

K-

5*^3

—

12

**s

!^

(

2^

u

3

^t

S

— <

^

**%

'?»?

■»„,

--G

s

14

2t^

a

>

*>

H

'v

V

X

N

IS

*s.

V

"1

Fig. 9. Average daily maxima and minima and mean temperatures under trees at
different altitudes on Mount Maquiling.

Table LXXXIII. — Averages of daily minimum temperature for periods of
four weeks from October, 1912, to January, 1915, under trees at dif-
ferent elevations on Mount Maquiling.

[Numbers give degrees centigrade.]

Four weeks ending-

January 31

February 28 ...

March 28

April 25

May 23

June 20

July 18

August 15

September 12 .
October 10 ._„.
November 7...
December 5 ...
January 2

Average

Elevation in meters.

80.

22.0
21.9
23.4
23.6
24.4
24.5
24.9 '
24.2
24.5 |
23.9 |
23.7 |
23.7 |
23.0 j

300.

450.

20.0 i

19.8

21.8

21.9

22.6

22.6

22.6

22.2

22.2

21.8

21.9

21.6

20.8

19.2
19.5
21.1
22.2
23.3
23.0
22.7
22.5
22.1
22.2
21.7
21.4
20.7

740.

23.7 j

21.'

21.7

18.4

18.2

19.7

20.4

21.5

21.8

21.6

21.0

21.0

21.3

20.3

20.1 j

19.5

20.4

., 050.

15.3
15.3
16.2
16.7
17.8
18.3
18.5
17.1
17.3
17.1
17. 0
16.9
16.1

16.9

2.6° ; in the midmountain forest, 2.6° ; and in the mossy
forest, 2.4°.

The curves for the average daily maximum, mean, and aver-
age daily minimum for different elevations have the same general

TEMPERATURE

221

Table LXXXIV. — Averages of daily maximum temperature for periods of
four weeks from October, 1912, to January, 1915, under trees at dif-
ferent elevations on Mount Maquiling.

[Numbers give degrees centigrade.]

Four weeks ending —

Elevation in meters.

80.

300.

450.

740.

1,050.

January 31

26.7
28.0
30.7
30.7
31.5
31.7
29.8
28.9
29.0
29.4
28.0
27.8
27.0

22.5
23.2
25.8

21.5
22.4
9d 7

20.7
20.9
23.1
23.9
24.9
25.3
24.2
23.4
23.1
24.2
22.5
22.0
21.3

17.1
17.4
18.9
19.8
20.7
21.9
21.1
19.3
19.2
20.1
18.7
18.3
17.8

February 28

March 28 . .

April 25

26.6 | 25.8
27.4 | 26.8
27.0 | 26.2
25. 9 2K 0

May 23

June20

July 18

August 15

25.5
25.4
25.5
24.6
24.1
23.0

24.6
24.4
25.2
24.0
23.4
22.5

September 12_ _ __

October 10

November 7

December 5- _

January 2 ._.

Average

29.2

25.1

24.3

23.0

19.3

form. They show that the fall in temperature in proportion
to the rise in elevation was much greater between the parang
and the dipterocarp forest at 300 meters than it was between
the latter station and the midmountain forest, while the fall was
more rapid in proportion to the rise in elevation between the
midmountain forest and the mossy forest on the top of the moun-
tain than it was between the dipterocarp forest at 300 meters'
elevation and the midmountain forest at 740 meters' altitude.

The great difference in temperature in the parang and the
dipterocarp forest is very probably connected with the fact that
this latter forest keeps almost all of the direct sunlight from
reaching the ground, and also prevents a free movement of the
warm winds coming from lower elevations, while the large leaf
surface exposed to evaporation has a considerable tendency to
cool the atmosphere. It will be noted that the curve for the
maximum temperatures has the steepest slope between elevations
of 80 and 300 meters, while the curve for the average daily
minima is less steep than either of the other two. This is very
natural and is due to the fact that under the forest the heating
effect of the sun, which causes high maximum temperatures, is
greatly minimized. This would of course account for the low
average daily maxima in the dipterocarp forest and also for the
lower average mean.

Between the two stations in the dipterocarp forest there is less

222

MOUNT MAQUJLING

difference, as compared with the difference in altitude, in the
mean and average daily maximum than there is between stations
at higher elevations; while the differences in average daily
maxima, means, and average daily minima, as compared with
elevation, are greater between the midmountain forest and mossy
forest than between the stations in the dipterocarp forest and
the midmountain forest. This would seem to indicate that a
dense dipterocarp forest has an equalizing effect on the tem-
perature, whereas as high elevations are reached the under-
growth is less protected from atmospheric changes outside of the
forest. This is due to the fact that, as higher elevations are
reached, the forest becomes progressively lower and more open.
Maximum and minimum temperatures for corresponding four-
week periods in the undergrowth are given in Tables LXXXV
and LXXXVI.

Table LXXXV. — Maximum temperature for periods of four weeks from
October, 1912, to January, 1915, under trees at different elevations on
Mount Maquiling.

[Numbers give degrees centigrade.]

Four weeks ending-

Elevation in meters.

January 31 .__
February 28 -

March 28

April 25

May 23

June 20

July 18

August 15

September 12-

October 10

November 7 .-
December 5-__
January 2

Average .

29.0
31.5
33.5
33.8
34.6
34.0
32.0
31.4
31.0
32.0
30.6
31.1
29.7

31.9

300.

450.

24.8

23.0

25.6

24.5

27.7

26.6

28.3

27.5

29.4

28.3

29.7

28.6

28.0

26.1

28.0

28.0

27.5

26.6

27.7

27.5

26.6

25.6

25.9

24.9

25.0

23.9

27.2

26.2

740.

22.7
22.7
25.9
25.6
27.2
27.5
26.6
27.2 j
25.9 I
26.6
24.2 I
23.9 j
23.6 !

1,050.

20.3
20.3
22.2
22.3
23.3
23.9
26.1
22. 3
22.2
23.7
22.0
21.1
20.3

22.3

CALCULATION OF MEAN TEMPERATURES FROM MAXIMUM AND
MINIMUM TEMPERATURES

Where it is inconvenient to use recording instruments, mean
temperatures are very frequently calculated from the averages
of maximum and minimum temperatures, and so it may be of
interest here to see how closely a mean calculated from averages
of maxima and minima corresponds with the mean as observed.
In Table LXXXVII such a calculation is made for temperatures

TEMPERATURE

223

Table LXXXVI. — Minimum temperature for periods of four weeks from
October, 1912, to January, 1915, under trees at different elevations on
Mount Maquiling.

[Numbers give degrees centigrade.]

Four weeks ending-

January 31

February 28 ___

March 28

April 25

May 23

June 20

July 18

August 15

September 12 _ _

October 10

November 7 .__

December 5

January 2

Average .

Elevation in meters-.

0.

300.

450.

740.

20.0 |

16.6

17.2

15.5

20.0 ;

17.4

18.6

16.6

20.8 !

18.9

19.7

18.0

19.6 !

19.4

20.3

18.3

22.3 i

20.5

22.5

20.0

22.0

18.9

20.5

18.9

22.5

20.5

20.5

18.3

22.0

19.4

20.8

19.4

22.0

20. 5

20. 0

19.4

21.8

19.7

20.5

19.4

21. 0

19.4

20.0

18.3

22.0

19.4

19.7

15.5

19.9 |

19.2

18.9

16.3

21.2

19.9 j

18.0 i

0.

1, 050.

15.0

12.2

15.0

12.8

15.5

13.9

16.0

13.3

18.0

16.0

18.9

16.6

17.5

.16.6

18.0

14.2

17.5

14.8

17.0

13.7

17.0

14.5

16.5

13.6

16.0

13.9

16.8

14.3

at the base of the mountain. In this table are given the average
daily maxima and minima for the years 1912, 1913, and 1914 ;
;he mean calculated from the averages of maxima and minima ;
the observed mean; and the differences between the calculated
mean and the observed mean. The table shows that the average
difference between the calculated mean and the observed mean
for the entire period was 0.2°, whereas the average daily range
was 5.8°. The error in calculating the mean from the daily
maxima and minima would in this case be small. It is, how
ever, 3.4 per cent of the average daily range.

Table LXXXVII. — Calculation of mean temperature at the base of Mount
Maquiling, from average of daily maxima and minima as compared
with observed mean.

[Numbers give degrees centigrade.]

Differ-

Year.

Average
daily

Average
daily

Average
maxima

and
minima.

Mean.

ence be- :
tween j
calcula-

maxima.

minima.

ted and j
observed

mean.

— ,

1912 ..

29.2
28.6

22.7
23.2

25.95
25.9

25.9
25.6

0 05

1913

0.3

1914 .

29.7

24.2

26.95

26.7

0 25 i

Average _

29.2

23.4

26.3

26.1

0.2 1

1

224

MOUNT MAQUILING

Table LXXXVIII. — Calculation of mean temperature under trees from
average of daily maxima and minima as compared with observed mean
at different elevations on Mount Maquiling.

[Numbers give degrees centigrade.]

Year.

1913

1914.

Average

Average of maximum and

minimum

Mean

Difference. __.

Elevation in meters.

Maxi-
mum.

28.6
29.7
29.15

Mini-
mum.

23.2
24.3
23.75

26. 45

26.15

0.3

300.

Maxi-
mum.

25.1
25.1
25.1

Mini-
mum.

21.6
21.6
21.6

23.35

23.1

0.25

450.

Under trees.

Maxi-
mum.

23.9
24.4
24.15

Mini-
mum.

21.8
21.6
21.7

In open.

Maxi-
mum.

27.8

Mini-
mum.

22.0

-|-

22.9

22.7

0.2

24.9

24.2

0.7

Year.

1913.
1914.

Average .

Average of maximum and minimum

Mean __ _ _

Difference __.

Elevation

in meters.

740.

1,050. |

Maxi-

Mini-

Maxi-

Mini-

mum.

mum.

mum.

mum.

22.8

20.2

19.4

17.1

23.3

20.6

18.9

16.6

23.05

20.4

19.15

16.85 ;

21.7

18.0

21.4

17. 65 ;

0

3

0

35 ;

In Table LXXXVIII are given similar calculations for the
different elevations for the years 1913 and 1914. For these
years the error in the parang was 0.3° ; in the dipterocarp forest
at 300 meters' elevation, 0.25°; in the dipterocarp forest at
450 meters, 0.2° ; in the open at 450 meters, 0.7° ; in the mid-
mountain forest at 740 meters, 0.3° ; and in the mossy forest
at 1,050 meters, 0.35°. All these differences, except that in the
open, appear small. The error in the case of the mossy forest
is, however, 15 per cent of the average daily range ; in the mid-
mountain forest, 11 per cent; in the dipterocarp forest at 450
meters' elevation, 8 per cent ; and in the dipterocarp forest at 300
meters' elevation, 7 per cent. The actual differences between

TEMPERATURE

225

the mean temperatures as calculated from the average daily max-
ima and minima and the mean as observed were, therefore,
small in degree, but considerable in proportion to the total range.
The error in the case of the clearing at 450 meters' altitude
is no greater in proportion to the range than in some of the
other cases, being 12 per cent. As in ecological work it is fre-
quently possible to use only maximum and minimum thermom-
eters and to read these not oftener than once a week, it may
be of interest to see how close the averages of weekly maxima
and minima come to the true mean. The results of such a
calculation are given in Table LXXXIX. The actual differ-
ences in most cases are not very much greater than when the
mean is calculated from average daily maxima and minima.

Table LXXXIX. — Calculation of mean temperature under trees from aver-
age of weekly maxima and minima as compared with observed mean
at different elevations on Mount Maquiling.

[Numbers give degrees centigrade.]

80.

Elevation

in meters.

Year.

300.

I
450. j 740.

1,050.

Maxi-
mum.

29.9
31.0
30.45

26.
26.

0

Mini-
mum.

22.2
23.3
22.75

60
15
45

Maxi-
mum.

26.3
26.2
26.25

23.
23.

0.

Mini-
mum.

20.7
20.5
20.6

Maxi-
mum.

25.0
25.5
25.25

Mini- ; Maxi-
mum. 1 mum.

Mini-
mum.

Maxi-
mum.

20.7
20.3
20.5

Mini-
mum.

1913 --

20.9 | 24.0

19.3

15.9

1914 .

20.8 | 24.5 19.6
20.85 24.25 j 19.45

05 21. 85
70 21. 40
3 0.4

15.4

15.65

Average of maximum
and minimum

Mean

Difference

40 23.
10 1 22.
3 0.

18.20
17.65
0.55

It is to be noted that all of these errors are in the same di-
rection, and so it would seem that when working with maximum
and minimum thermometers in forests in which conditions are
similar to those on Mount Maquiling fairly accurate means
could be obtained from averages of weekly maxima and minima.
The similarity between the mean calculated from the average
maxima and minima and the mean observed is, however, very
probably due in part to the fact that the ranges in temperature
are slight.

The average weekly maximum and minimum temperatures
for corresponding four-week periods in the tops of the domi-
nant trees at different elevations are given in Table XC. The
results are plotted in fig. 10.

I59549 15

226

MOUNT MAQUILING

Elevation in meters

ZOO

400

600

800

iOOO

38

~ —

36

34-

32

^

1
;

T

r >^<

!?7^. •

w r

30

1

<gj2^

i
i

\

\

\^

28

\

\!

\

\
\

\

26

***

^

^

%,

|

1

Z4

o

*

ZZ

\ i

\ \

A

Y

^ i

ZO

3£v*

;

| D

V,

■^<*

*«|

k~r-" — T-—

^-- ! -

18

"*3

*•#

*^o

16

-....

—~~ K

\

b

Fig. 10. Average of weekly maximum and minimum temperatures
at different altitudes on Mount Maquiling.

TEMPERATURE 227

Table XC— Average of weekly maximum and minimum temperatures for
periods of four weeks from October, 1912, to January, 1915, in the
tops of tall trees at different elevations on Mount Maquiling.

[Numbers give degrees centigrade.]
MAXIMA.

Four weeks ending-

Elevation in meters.

January 31

February 28..
March 28

April 25.

May 23

June 20

July 18

August 15

September 12.

October 10

November 7...
December 5 ...
January 2

Average..

36.5
36.5
37.7
37.3
38.0
39.4
38.8
41.2
38.5
41.1
38.4
37.1
36.2

300.

30.1
31.6
34.8
31.9
33.7
35.3
33.2
31.8
31.1
36.1
31.4
29.7
29.9

32.4

I

27.6
30.4
31.0
31.7
32.1
33.6
31.1
32.8
30.0
32.9
32.3
30.8
30.3

31.3

740.

28.4
32.5
34.8
32.1
29.9
33.5
31.9
26.8
29.6
32.8
26.8
28.1
27.8

0.4

1, 050.

29.4
32.0
35.0
27.3
28.0
30.8
28.5
23.4
26.0
29.8
24.1
25.1
26.3

28.1

MINIMA.

January 31

February 28...

March 28

April 25

May 23

June 20

July 18

August 15

September 12 .

October 10

November 7...
December 5__.
January 2

Average.-

22.2

17.9

17.2

15.8

21.8

18.3

18.2

16.2

23.5

20.0

19.3

16.7

24.1

19.9

20.1

18.2

25.5

21.3

21.7

19.1

24.2

21.1

21.2

19.7

25.0

20.8

20.4

19.4

24.7

20.7

19.7

18.7

24.7

20.9

18.8

18.8

25.1

20.2

20.3

19.0

24.2

20.3

19.5

18.5

24.2

19.8

19.0

18.1

23.3

19.3

18.8

17.6

24.0

20.0

19.6

18.1

15.3
15.4
14.7
17.4
18.2
18.7
18.3
19.4
18.2
17.5
17.3
17.3
16.7

17.3

RELATION OF TEMPERATURE TO VEGETATION

Lehenbauer * has made an extensive study of the relation
of the rate of growth of maize seedlings to temperature. He
found that the optimum temperature varied with the length of
the exposure. For three-hour exposures it was 29° ; for nine or
twelve hours it was 32° ; while for periods of eighteen or twenty-
one hours, and probably for twenty-four or twenty-seven hours,

* Lehenbauer, P. A., Growth of maize seedlings in relation to temper-
ature, Physiol Res. (1914), 1, 247-288. *

228 MOUNT MAQUILING

it was also 32° ; for longer periods it appeared to shift to 31°.
An examination of Table LXXXII shows that the mean tem-
perature, even at the base of Mount Maquiling, was lower than
any of the optima obtained by Lehenbauer, the highest mean
temperature in the parang for any corresponding four-week
period being 27.7°. From Table LXXXIV it would appear that
the average daily maximum at all elevations above 80 meters
was also lower than any of the optima obtained by Lehenbauer.
At an elevation of 80 meters the highest average daily maximum
for any corresponding four-week period was 31.7°, and the
lowest, 26.7°. It would seem, therefore, that the average daily
maximum temperature at an elevation of 80 meters would be
about optimum for the growth of maize seedlings.

A careful study of the influence of temperature on the rates
of growth of roots of Pisum sativum has been made by Leitch.*
According to her results, the optimum temperature appeared to
be between 28° and 30°. These figures are not very different
from those obtained by Lehenbauer.

The mean temperature at the base of Mount Maquiling was
26.1°, and at the top, 17.8°; According to Lehenbauer's curve
for twelve-hour periods, maize seedlings would grow just about
three times as fast at the former as at the latter temperature.
If this difference is applicable to the rates of growth on Mount
Maquiling, it would account for a considerable part, although
not for all, of the differences between the rates of growth at
the top of the mountain and those at lower elevations. However,
when we compare the size of the trees at an elevation of 450
meters (where the exact measurements in the dipterocarp forest
were made) with the size of those in the mossy forest, the
difference in temperature would account for only about half of
the difference in corresponding rates of growth, as the tallest
trees in the dipterocarp forest at 450 meters' elevation are about
four and one-half times as high as at the top of the mountain.
The difference in temperature in these two situations would,
according to Lehenbauer's curve, account for an increase in the
rate of growth in the dipterocarp forest over that in the mossy
forest of about 130 per cent.

Individuals of Parashorea malaanonan between 20 and 50 cen-
timeters in diameter at an altitude of 300 meters grow twice as
fast as similar-sized individuals of Astroniq, pulchra at an altitude
of 740 meters; whereas the temperature, according to Lehen-

* Leitch, I., Some experiments on the influence of temperature on the
rate of growth in Pisum sativum, Ann. Bot. (1916), 30, 25-46.

TEMPERATURE 229

bauer's curve, would account for an increase of only 12 per cent
in the rate of growth of Parashorea at 300 meters' elevation
over that for Astronia. Leitch's curve for the relation of tem-
perature to growth shows even smaller differences in the rates of
growth for different temperatures than does Lehenbauer's.

In considering the rates of growth as related to temperature
it must be remembered, however, that Lehenbauer's and Leitch's
seedlings were growing from a reserve food supply, whereas
trees under natural conditions obtain their food as they grow;
and so, in the latter case, light must be taken into consideration.
This will be done under the heading of Light.

The effect of temperature on the rate of photosynthesis is
interesting in this connection. Brown and Heise have shown *
that variations in temperature, such as occur at different
elevations on Mount Maquiling, would apparently have com-
paratively little effect on the rate of photosynthesis. Kreusler
has made an extensive study of the relation of temperature to
the rate of photosynthesis. The writer has been unable to see
copies of Kreusler's original publications and so has had to
depend on the reviews for his results. According to Paladdin,f
Kreusler found that at 15.8° the amount of carbon dioxide
decomposed was 2.8, at 20.6° it was 2.6, and at 25° it was 2.9.
In the present discussion, Matthaei's criticism of Kreusler's re-
sults to the effect that he measured the temperature of the
air and not that of the leaves is of little or no importance.
The results, as just quoted, would seem to show that, with such
temperatures as occur on Mount Maquiling, the effect of varia-
tions in temperature would be negligible. According to Brown
and Heise's interpretation of Matthaei's $ results, there would
be little if any difference in the rate of photosynthesis of cherry
laurel with the variations that occur on Maquiling. As the
work of Kreusler and Matthaei is apparently the most careful
and exact on the subject of the relation of temperature to rates
of photosynthesis in land plants, we would appear to be justified
in leaving out of consideration, in the following discussion, any
possible effect of changes in temperature on the rate of photosyn-

* Brown, W. H., and Heise, G. W., The application of photochemical
coefficients to' the velocity of carbon dioxide assimilation, Phil. Journ. Sci.,
Sec. C (1917), 12, 1-25.

t Livingston, B. E.-Paladdin, V. I., Plant Physiology. Philadelphia
^918), 35.

t Matthaei, G. L. C., Experimental researches on vegetable assimilation,
HI. On the effect of temperature on carbon dioxide assimilation, Phil.
Trans. Roy. Soc. London (1905), B197, 47-105.

230 MOUNT MAQUILING

thesis, as any changes that might occur would probably be too
small to have an appreciable effect on the vegetation.

A comparison of temperatures with rates of growth and sizes
of trees on different mountains would indicate that, in the trop-
ics under natural conditions, rates of growth or sizes of trees
are not controlled entirely by the temperature.

At an elevation of about 1,500 meters on the Gedeh in Java
there is a high forest in which Koorders * has measured a tree
that was 49 meters in height. According to von Faber f the
mean temperature in this forest for 1912 was 18°, and for 1913,
17.3°. These temperatures are very similar to the tempera-
ture obtaining at the top of Mount Maquiling. Brown and
Yates J have shown that the trees in the forest on the Gedeh
at elevations of about 1,500 meters grow about as rapidly as
those in the dipterocarp forest at low elevations in the Philip-
pines. It would seem certain from this that the sizes of trees
and rates of growth on tropical mountains may not correspond
to the temperatures to which the plants are subjected.

On top of Mount Banahao, Luzon, Philippine Islands, at an
altitude of 2,100 meters there is a forest composed of Podocarpus
irnbricatus, which reaches a height of about 14 meters, the
average height of the canopy being about 12 meters. This forest
is, therefore, taller than that occurring near the top of Mount
Maquiling. The mean temperature, however, is 14.6° at the top
of Mount Banahao and 17.8° at the top of Mount Maquiling.

The difference between the light intensity at an elevation of
450 meters and that at 1,050 meters on Mount Maquiling would
apparently account for as great a difference in the rates of
growth as would the temperature according to Lehenbauer's
curve.

We may, therefore, conclude that, while variations in tem-
perature at different elevations on Mount Maquiling probably
have considerable influence in producing changes in rates of
growth and in size of trees, such variations in temperature
are not sufficient to account for the observed differences in the
vegetation.

* Koorders, S. H., Floristischer Ueberblick uber die Bliitenpflanzen des
Urwaldes auf dem Vulkan Gede in West Java nebst einer systematischen
Uebersicht der dort fur botanische Untersuchungen von mir numerierten
Waldbaume, Engl Bot. Jahrb. (1914), 50, Suppl. 278-303.

fVon Faber, D. C, Physiologisehe Fragmente aus einem tropischen
Urwald, Jahrb. Wiss. Bot. (1915), 56, 197-220.

% Brown, W. H., and Yates, H. S., The rate of growth of some trees on
the Gedeh, Java, Phil Journ. Sci., Sec. C (1917), 12, 305-316.

TEMPERATURE 231

In Table XC are given the averages of the weekly max-
imum temperatures in the tops of the trees at different ele-
vations on Mount Maquiling. An examination of this table
would indicate that, while the maximum temperatures in trees
at elevations of 300 meters or more are comparatively close to
the optima as calculated by Lehenbauer, those at the base are
higher, the average of the weekly maxima being 38.2°. As,
however, these maximum temperatures are maintained for only
short periods, it is not to be expected that they would have much
effect in retarding growth.

LIGHT

METHODS OF MEASUREMENT

No very satisfactory method of obtaining summations of light
intensity for weekly periods has as yet been devised. The most
practical instrument for the purpose is probably the Livingston
radio-atmometer . *

The radio-atmometer is similar to the ordinary atmometer,
except that the surface when wet is nearly black, whereas that of
the ordinary form is white. After the readings have been re-
duced to Livingston's standard, the difference between the evap-
oration from the black cup and that from the white cup gives
a fair measure of the effect of the heat rays of light in producing
evaporation. This difference can, therefore, be used as a rough
measure of light intensity.

In the operation of the radio-atmometer, when only a single
black and a single white cup are used, there is a serious error
due to the fact that both cups may show deviations from their
coefficients of correction as obtained by standardization. In the
use of an ordinary atmometer this error is not serious, for an
error of 2 or 3 per cent in the readings of evaporation is cer-
tainly within the limits within which we can ordinarily apply the
results. However, the error is greatly magnified when we use
the difference between the rates of evaporation from the two cups,
for then the total error of both (unless the errors are in the
same direction) will either be added to or be subtracted from a
very much smaller amount than the total evaporation from either
cup. This error can be obviated to a great extent by the use
of duplicate instruments and by averaging the rates for a con-
siderable period. In the work on Mount Maquiling two or more
instruments of both types were always used at each station.
Owing to the possible seriousness of the above-mentioned error,
the detailed results are not presented, although they do not
indicate that the error is as great in practice as it might be in
theory.

LIGHT INTENSITY AT DIFFERENT ELEVATIONS

Light intensity as measured by the difference in evaporation
from a radio-atmometer and from an ordinary atmometer, from

* For a discussion of this instrument see Livingston, B. E., Atmometry
and the porous cup atmometer, Plant World (1915), 18, 21.
232

LIGHT 233

October, 1912, to January, 1915, is presented in Table XCI in the
form of average daily differences in cubic centimeters for cor-
responding four- week periods. The presentation of data in this
form should certainly give sufficient averages to obviate any
considerable error from the source just discussed. There is,
howeyer, another possible source of error in the readings on
Mount Maquiling, which is not obviated by such averages. At
the base of the mountain the cups always appeared dry and
felt only slightly moist, whereas at the top of the mountain
they had a very wet appearance, as though the outer surface of
the cups were constantly covered with a film of moisture. Now,
it seems possible that the effect of sunlight might be more
pronounced on a very wet surface than on a drier one. This
error is probably not serious, but its magnitude is uncertain.

Table XCI. — Average daily light intensity for periods of four weeks from
October, 1912, to January, 1915, in tops of dominant trees at different
elevations on Mount Maquiling, as measured by the difference betiveen
the evaporation from a white and from a black Livingston atmometer.

[Numbers give the difference in evaporation in cubic centimeters from a white and from a
black Livingston atmometer.]

Elevation in meters.

Four weeks ending-

January 31

February 28 :

March 28

April 25 r

May 23

June 20

July 18

August 15

September 12

October 10

November 7

December 5

January 2

Average ._• 6.4

-- ■

r

_

80.

300.

450.

740. j

1,050.

5.5

4.8

4.1

2.9 ;

2.6

5.5

5.0

4.1

3.6 [

3.1

7.9

7.0

5.2

6.1 1

3.7

9.0

7.9

5.4

4.6 [

3.0

7.1

6.9

6.9

4.1 |

2.6

7.7

6.3

6.5

5.0 j

3.0

7.2

5.9

4.6

4.3

2.4

5.3

5.1

4.9

3.8 !

3. 0

4.9

5.0

4.5

3.2 |

2.1

6.6

7.2

6.2

5.3 :

3.6

5.9

6.2

5.2

4.3 :

3.0

5.5

5.3

4.5

3.4 i

2.5

5.3

4.7

4.3

2.8

2.0

4.0 j

2.8

The results in Table XCI show that the yearly average of
light intensity, as recorded by a radio-atmometer, decreases
considerably as higher elevations .are reached. Measured in
terms of evaporation in cubic centimeters, the average light
intensity at the base was 6.4 ; at 300 meters, 5.9 ; at 450 meters,
>.l; at 740 meters, 4; and at 1,050 meters, 2.8. It will be seen
that the light intensity at the top of the mountain, as measured

234

MOUNT MAQUILING

in this manner, is only 44 per cent of that at the base or, in
other words, that the light intensity at the base is 2.3 times as
great as at the top.

Periods of four weeks ending —

Jan 31 Feb.m VacZ8 Apr Z5MayZ3 JuneZO July 18 AuglS Sept fZ Oct 'JO Nov. 7 Dec 5 Jan. Z

Fig. 11. Average daily light intensity in the top of dominant trees at different
altitudes on Mount Maquiling.

The light intensity at different elevations is shown for four-
week periods in fig. 11. At an elevation of 80 meters it will
be noted that there are two maximum and minimum periods.
The light intensity is low in February, rises and reaches a
maximum during the period ending April 25, after which it

LIGHT 235

falls, reaching the lowest minimum during the period ending
September 12. Following this there is another, though lower,
maximum for the period ending October 10, and thereafter a
steady fall until the period ending January 2.

In the region under discussion the sun is overhead during
the last week in April, and it will be noticed that this is about
the period of maximum insolation. The sun is again overhead
in August, which is during the rainy or typhoon season, when
the sky is overcast with clouds for a considerable portion of the
time. In consequence, this period, instead of being one of high
insolation, is one during which the average intensity of the light
approaches the minimum.

The curves for the dipterocarp forest are similar in form to
the curve for the parang ; but at 740 meters, in the midmountain
forest, there is not so marked a difference with the change of
seasons. At the top of the mountain, in the mossy forest, the
light intensity during the rainy season and at the end of the
year is not much less than at other times. This change in the
form of the curves, as higher elevations are reached, is prob-
ably due to the increased cloudiness at the top of the mountain.
These curves indicate that the highest maximum for a four- week
period in the mossy forest was 3.7, and in the parang, 9. It
will thus be seen that for any considerable period, the light in-
tensity at the top of the mountain is very much less than at
the base.

RELATION OF LIGHT INTENSITY TO VEGETATION

In attempting to interpret the effect of light on vegetation
we are met by the same difficulties that so often occur in eco-
logical work in attempting to relate environment to vegetation ;
that is, a lack of knowledge of the relation of environmental
factors to physiological processes. Many writers have supposed
that the rate of photosynthesis is proportional to the light
intensity until a certain maximum is reached, and that further
increases in light have no effect. This maximum has been
variously estimated at between one-quarter and full sunlight.
However, Brown and Heise * have shown that the published
literature affords no evidence of such a relation; but that, on
the contrary, at least up to about full sunlight, there is a rise in
the rate of photosynthesis for every increase in the intensity of
the light, but that the augmentation in the rate of photosynthesis

* Brown, W. H., and Heise, G. W., The relation between light intensity
and carbon dioxide assimilation, Phil. Journ. ScL, Sec. C (1917), 12, 85-95.

236 MOUNT MAQUILING

becomes progressively less and less with progressive increases
in light intensity. Unfortunately, most of the work on the
relationship of photosynthesis to light intensity has been done
by the bubble-counting method on submerged plants. Kniep *
has shown that the oxygen content of bubbles varies from 22 to
45 per cent, depending upon the intensity of the light. His paper
makes it very clear that the number of bubbles given off by a
plant is not necessarily proportional to the assimilation. It is,
however, certain that for variations in light intensity up to
one-quarter or one-half of full sunlight the effect of increased
light on photosynthesis is very marked.

Despite the lack of information concerning the relation be-
tween light intensity and photosynthesis, it seems advisable to
try to determine something of the effect of varying light inten-
sities at different elevations upon the vegetation. An examina-
tion of Table XCI shows that for the four-week period ending
April 25 there was an average light intensity of 9 for the two
years at an elevation of 80 meters, and the individual tables make
it fairly certain that the light intensity for a day may be about
13. It would appear, therefore, that the average daily light
intensity for the entire year at 80 meters, 6.4, is probably not
much more than half the maximum intensity for an entire day.
It must also be remembered that during the morning and after-
noon hours there are considerable periods when the sun is
shining, but when the intensity of the light (even with a prac-
tically clear sky) is much less than full midday sunlight; more-
over, that at any time only a part of a tree will receive full
sunlight, while during considerable portions of a day a large part
of the crown is in the shade. It would seem, therefore, that
any considerable decrease in the average light intensity from
that found at the base would result in a decreased rate of photo-
synthesis and consequently slower growth, and perhaps a smaller
size of the vegetation. The highest average light intensity at
the top of the mountain for any four-week period was 3.7,
which is only 28 per cent of the probable highest value for a
clear day at the base. As mentioned above, the average light
intensity at the top of the mountain is only 44 per cent of that
at the base. From these figures it would seem highly probable
that the decreased light at the top of the mountain would ac-
count for a considerable diminution in the rate of photosynthesis
and growth and, perhaps, for a smaller size in the trees.

* Kniep, H., Ueber den Gasaustausch der Wasserpflanzen, Jahrb. Wi**-
Bot. (1915), 56, 460-510.

LIGHT 237

It will be noted that the difference in intensity of light as
measured by the radio-atmometer was much less between ele-
vations of 80 and 450 meters than between 450 and 1,050 meters.
It has also been shown that the variation in the sizes of the trees
in the dipterocarp forest is comparatively slight, and it is not
probable that the forest which formerly existed at an eleva-
tion of 80 meters was much taller than that now growing at
slightly higher altitudes. The difference in light intensity be-
tween the two elevations in the dipterocarp forest is about as
great as the difference in the size of the trees. However, the
difference in light intensity between elevations of 450 and 1,050
meters is not nearly so great as the difference in the size of the
vegetation. The light intensity as measured by a radio-atmo-
meter is 1.8 times as great at 450 meters as at 1,050 meters,
while the vegetation is at least three times as tall at the former
altitude as at the latter. Moreover, the light intensity at 300
meters is 1.5 times as great as at 750 meters, while the difference
in the rates of growth of the trees at these two elevations is
very much greater. It would thus seem that the decrease in
light intensity at higher elevations probably has a very impor-
tant influence in retarding the rates of photosynthesis and prob-
ably of growth, but that the differences in light do not appear
to be sufficient to account entirely for the slow rates of growth
at 740 meters and at the top of the mountain or for the smaller
sizes of the trees in these two situations.

The discussion of the effect of temperature and light seems
to show that neither of these factors alone is sufficient to account
for the differences in the rates of growth and the heights of
vegetation at different altitudes. It will be interesting, there-
fore, to see whether the two together can account for such dif-
ferences. Livingston and Livingston * have suggested a means
of estimating the effect of temperature on growth in different
localities. They assume that the rate of growth is unity at
40° F., and that it doubles for every rise of 10° C. ; in other words,
that the effect of temperature on growth follows the well-known
Van Hoff principle: If t is taken as the normal daily mean
temperature on the Fahrenheit scale, and if U is the correspond-
ing temperature coefficient for growth, then, according to the
above assumption,

18

* Livingston, B. E., and Livingston, G. J., Temperature coefficients in
plant geography and climatology, Bot. Gaz. (1913), 56, 349-375.

238

MOUNT MAQUILING

The indices obtained in this manner are called exponential indices.
The time element is taken into account by adding together
the efficiency indices for all the days of the frostless season.
Livingston * has devised another series of indices based on
Lehenbauer's work on the relation of temperature to the growth
of maize seedlings; these are designated physiological indices.
In Table XCII are shown the average daily temperature indi-
ces, according to the exponential system, for four-week periods

Table XCII.— Exponential temperature indices for different elevations on

Mount Maquiling.

[Numbers give average daily temperature indices.]

Four weeks ending —

January 31

February 28

March 28

April 25

May 23

June 20

July 18

August 15

September 12 . -

October 10

November 7

December 5

January 2

Average .

80.

Elevation in meters.

300.

450.
2. 9391

740.
2.8284

3. 8480

3. 1748

4.0000

3.2986

3.0545

2.8284

4. 8490

3. 5629

3.5629

3. 1748

4.8490

3.8480

3.8480

3. 2986

5.0396

4. 1572

4. 1572

3. 5629

5. 0396

4. 1572

4.0000

3. 7024

4.6662

3. 8480

3.8480

3.4283

4.4902

3. 7024

3.7024

3.2986

4. 6662

3. 8480

3. 5629

3. 4283

4. 4902

3. 7024

3.7024

3.4283

4.3206

3. 5629

3.4283

3. 1748

4.3206

3. 5629

3. 4283

3. 0545

4. 1572

3. 2986

3. 2986

2. 9391

4. 5182

3. 6711

3. 5794

3.2421

2. 2451
2.2451
2. 4245
2. 5198
2. 7212
2. 8284
2. 8284
2. 5198
2. 5198
2. 6192
2. 5198
2. 4245
2.3331

2. 5191

at different elevations on Mount Maquiling ; and in Table XCIII,
the average daily physiological indices. In order to take light
into account the light intensity, as measured in cubic centime-
ters by the difference between the rate of evaporation from the
white and from the radio-atmometers, has been multiplied by the
average temperature indices for different elevations on Mount
Maquiling. In the following discussion these products are, for
convenience, called temperature-light indices. The results are
given in Table XCIV, together with the heights of the vegetation
at different altitudes.

At the top of the mountain the tallest trees are not more
than 8 meters high, while at about 30 meters below the summit,
in the plots where exact measurements were taken, the tallest

* Livingston, B. E., Physiological temperature indices for the study of
plant growth in relation to climatic conditions. Physiological Research''*
(1916), 1, 399-420.

LIGHT

239

Table XCIII. — Physiological temperature indices for different elevations

on Mount Maquiling.

[Numbers give average daily temperature indices.]

Four weeks ending-

January 31 79.111

February 28 79.111

March 28 101.222

April 25 101.222

May 23 _.__ 108.444

June 20 _.. 108.444

July 18 . 101.222

August 15 1 94.000

Elevation in meters.
80. 300. 450.

September 12 ..

October 10

November 7

December 5

January 2

Average .

101.222
94.000
94.000
94.000
86.556

95. 581

54.778
63.444
71. Ill
79. Ill
86. 556
86.556
79. Ill
79. Ill
79. Ill
71. Ill
71. Ill
71.111
63.444

73. 513

46.000
54.778
71. Ill
79. Ill
86. 556
86. 556
79. Ill
71.111
71.111
71.111
63.444
63.444
63.444

69.761

740.

1,050.

38.000

21. 556

38.000

21. 556

54. 778

26.000

63. 444

31.333

71.111

38.000

71.111

46.000

63. 444

38. 000

63.444

31.333

63.444

31.333

63. 444

31.333

54. 778

31.333

54. 778

26.000

46.000

26.000

57. 367

30.752

Table XCIV. — Temperature-light indices as compared with the heights of
trees at different elevations on Mount Maquiling.

Altitude.

Exponen-
tial tem-
perature-
light index.

Meters.

80

300

450

740

1,050

Physio-
logical tem-
perature-
light index.

28. 9165
21. 6595
18. 2549
12. 9684
7.0535

611.7184
433. 7267
355. 7811
229. 4680
86. 1056

Exponen-
tial tem-
perature-
light index

X2.

57. 8330
43.3190
36.5098
25. 9368
14. 1070

Physio-
logical tem-
perature-
light index

■:• 10.

61. 1718
43.3727
35. 5781
22. 9468
8. 6106

Height of
trees.

Meters.

38
36
22

8-14

trees are about 14 meters in height. It is not improbable that
at the very summit the small size of the trees is due in part to
rapid erosion, as the ground near the summit is very steep;
however, many of the trees are fairly erect. As there is some
doubt as to whether 8 or 14 meters should be taken as the height
of the trees at the summit, both figures have been included in
the table. The temperature-light indices are, of course, simply
ratios. In order to have these of the same general magnitude
as the heights of the vegetation, the exponential temperature-
Hght indices have been multiplied by 2 and the results given in
column 4, Table XCIV. Likewise, the physiological temperature-
%ht indices have been divided by 10 and the results given in
column 5, Table XCIV. If now we compare the results with

240 MOUNT MAQUILING

the heights of the trees, we find that the agreement is strik-
ingly close, particularly at higher elevations. At the top of the
mountain the figure obtained by the use of the exponential
temperature-light indices is 14.1, and that by the physiological
indices is 8.6; whereas the height of the trees, as before men-
tioned, can be taken as either 8 or 14 meters. At 740 meters, in
the midmountain forest, the exponential indices gave the figure
25.9, and the physiological indices gave 22.9, whereas tfie height
of the trees was 22 meters. At 450 meters the use of the expo-
nential indices gave 36.5, and the physiological indices gave 35.6,
while the trees were about 36 meters in height. At 300 meters
the exponential indices gave 43.3, and the physiological indices
gave 43.4, whereas the height of the trees was about 38 meters.
At an elevation of 80 meters the forest has been removed, but we
have no reason for believing that the trees were more than 40
or 45 meters in height. The use of the exponential temperature
indices at this altitude gave 57.8, and the physiological indices
gave 61.2. Both of these figures are, therefore, probably much
higher than would be required by the height of the vegetation
that formerly existed in this area. However, it should be remem-
bered that at lower elevations the rate of evaporation is much
greater than at higher altitudes, while, as will be shown later,
the water content of the soil is lower. These two factors might
very well account for a lower height of vegetation than could
be produced by the temperature and light if other conditions
were favorable. The figures derived from the temperature-light
indices do, however, agree almost exactly with the height of
trees at this elevation in regions where there is a mor§ even
distribution of rainfall and no distinct dry season. In such
favorable situations trees reach a height of 60 meters. The
figures obtained from the temperature-light indices at an eleva-
tion of 300 meters are also somewhat too high, but this discrep-
ancy may again be due to moisture conditions, as the effect
of the dry season on the . vegetation at this altitude is marked.
Parashorea shows its slowest rate of growth during the dry
season, and the canopy of the forest is much less dense during
this season than at other times.

It should be remembered, moreover, that photosynthesis is
not proportional to light intensity and that, as greater light
intensities are reached, the rate of photosynthesis increases less
and less with the augmentation of light intensity. This may
explain in part the lack of agreement between the temperature-
light indices and the heights of the trees at lower elevations.

LIGHT

241

Leitch * has made a very careful study of the influence of
temperature on the rates of growth of roots of Pisum sativum.
For the purpose of showing how the figures for growth at dif-
ferent temperatures as obtained by Leitch, and multiplied by
the light intensity as measured at different elevations on Mount
Maquiling, correspond to the heights of the vegetation and the
rates of growth, her figures have been treated in a manner
similar to Livingston's treatment of Lehenbauer's results. Al-
though Livingston's temperature indices were calculated for
four-week periods on Mount Maquiling, the results obtained are
very much like those produced by simply using the mean tem-
peratures for the entire year. For this reason, in dealing with
Leitch's results, the growth figures corresponding to the different
annual mean temperatures on Mount Maquiling have been calcu-
lated from her curve showing the relation of temperature to
growth in millimeters for twenty-two and one-half hours. These
figures are shown in Table XCV. In the same table are also
given the light intensities at different elevations on Mount
Maquiling and the products of the figures for light intensity
by the figures for growth. In the following discussion these
products will be called Pisum temperature-light indices. As
these indices can only be regarded as ratios they have been
divided by 3.2, in order to have them of the same general mag-
nitude as the heights of the vegetation. The results and the
heights of the vegetation at different elevations on Mount Ma-
quiling are also recorded in Table XCV. An examination of
Table XCV shows that the ratios obtained by the use of Leitch's
measurements are, like those obtained from Livingston's tem-
perature indices, very similar to the heights of the trees.

Table XCV.— Pisum temperature-light indices as compared with the heights
of trees at different elevations on Mount Maquiling.

Growth

figures

Tem-

Altitude.

corre-
sponding

Light in-
tensity.

perature-
light

to tem-

index.

1

perature.

Meters.

80

24.5

6.4

156.8

j 300

22.5

6.9

132.8

J 450

22.0

5.1

112.2

| 740

20.5

4.0

82.0

j * 1,050

16.5

2.8

46.2

Tem-
perature-
light
index
:3.2

49.0
41.5
35.1
26.6
14.4

Height

of
vegeta-
tion.

Meters.

38

22

8-14

* Leitch, I., Some experiments on the influence of temperature on the
rate of growth in Pisum sativum, Ann. Bot. (1916). 30, 25-46.

159549 ir,

242

MOUNT MAQUILING

It would probably be better to compare the volume, rather
than the heights of the vegetation, with the temperature-light
indices, but this would be much more difficult. However, a com-
parison of the volume of the dipterocarp and the midmountain
forests, as previously given, indicates that the volume and the
heights of the forests are roughly proportionate.

Table XCVI. — Ratios of temperature-light indices and rates of growth of
Parashorea and Astronia.

Meters.
300
740

Exponen-
tial tem-
perature-
light
index.

1.7
1.0

Physio-
logical
tempera-
ture-
light
index.

1.9
1.0

Pisum
tempera-
ture-
light

index.

1.6
1.0

Rate

of

growth.

It is interesting to compare the ratios of temperature-light
indices not only with the heights of the vegetation, but also with
the rates of growth of trees at different elevations. Such com-
parison is made in Table XCVI. In this table the average rates
of growth of Parashorea malaanonan, for diameter classes be-
tween 20 and 50 centimeters, at an elevation of 300 meters, have
been divided by the average rates of growth of Astronia pulchra,
of similar sizes, at an elevation of 740 meters. These classes
were selected as the trees in them wfcre in the dominant story
in both cases. The ratio as thus calculated is 2 to 1, using the
rate of Astronia as unity. In order to have the ratios of
the temperature-light indices comparable with the ratios for
growth, the temperature-light indices for an elevation of 740
meters have been divided into those for 300 meters. The tem-
perature-light index obtained by the use of the Livingston phy-
siological temperature indices at 740 meters is to that at 300
meters as 1 to 1.9. This result is as close to the ratio for rates
of growth at these two elevations as could be expected from the
use of two different species. The ratio obtained with Leitch's
figures is 1 to 1.6. This ratio is not so similar to that for growth
as is the ratio of the physiological indices, but when we consider
that Leitch was working with the roots of a small herbaceous
plant, the difference is not surprising. In Table XCVII similar
comparisons are made between the rates of growth of second-
growth trees at the base of the mountain and a second-growth
tree, Homalanthus alpinus, at an altitude of 1,050 meters. In

LIGHT

243

the discussion of the growth of parang species these trees are
divided into two classes; namely, those which do not reach a
diameter of 20 centimeters and those which attain a diameter
greater than 20 centimeters. In Table XCVII the ratios between
the rates of growth of Homalanthus alpinus and both of these
classes are given, for the average of the diameter classes of
5 to 10 centimeters and of 10 to 15 centimeters. In this table
are also shown the ratios obtained by dividing the temperature-
light indices for an elevation of 80 meters by those at an eleva-
tion of 1,050 meters. The smaller trees at the base of the
mountain showed an average rate of growth 4.4 times that of
Homalanthus alpinus, and the larger trees a rate which was
6.3 times as great as that of Homalanthus. The physiological
temperature-light indices gave a ratio of 7.1 to 1, and the Pisum
indices gave 3.4 to 1. The ratios for the trees of both sizes
are intermediate between these two ratios. The physiological
temperature-light indices gave a ratio which was greater than
that for the large trees and Homalanthus alpinus, and the Pisum
indices showed a lower ratio than that for the smaller trees and
Homalanthus alpinus. The ratio for exponential temperature-
light indices is fairly close to that for Homalanthus alpinus and
the smaller trees. These results are probably about as close
as could be expected under the circumstances. The ratios of
growth to temperature-light indices are not so close as those
for these indices and the heights of the vegetation, but they do
show the same general sort of agreement.

Table XCVII. — Ratios of temperature -light indices and rates of growth of

second-growth trees.

Altitude,

Meters.
80

1,000

Exponen-j Physiolo- pisum
tialtem- jgicaltem- ternpera_ Rate of
perature- perature- ture.light growth.

light light j . d

I index. index

4.1
1.0

7.1 I

i
1.0 t

3.4 .

: *6.3
1,4.4
1.0 i 1.0

■ Trees which attain diameters greater than 20 centimeters.
b Trees which do not reach a diameter of 20 centimeters.

The agreement between ratios for the heights of the vegeta-
tion and the ratios obtained by multiplying the figures for light
intensity and temperature indices together would appear to
he too close to be accidental; and, if this treatment is justified,
the combination of temperature and light intensity would seem

244 MOUNT MAQUILING

to be sufficient to account for the differences in the rates of
growth and the heights of the trees at different elevations in the
virgin forest. Such a relation, while it may seem probable,
needs the further corroboration of other similar cases or of
exact laboratory experimentation to show that a combination of
light and temperature can produce similar results. Of course,
even supposing that light and temperature are responsible for
the rates of growth and sizes of the trees at different elevations,
such results could not be expected to be duplicated in all cases,
as other factors must be taken into account. A further discus-
sion of these points will be given in connection with evaporation.

RAINFALL

The recording of the rainfall at the base of Mount Maquiling
was begun by Dr. F. W. Foxworthy on August 16, 1911. His
records between this date and October, 1912, when the writer
began to take them, are included in the records for the base of
the mountain. Most of the records were, however, begun in
October, 1912, and were taken by means of a rain gauge of the
same type as that used by the United States Weather Service.
At an elevation of 80 meters the gauges were read daily at about
6 o'clock in the morning, and at higher elevations they were
read weekly.

At an elevation of 300 meters one rain gauge was placed in
the top of a dominant Parashorea, and another in a small
clearing. The records from these two gauges varied somewhat
during different weeks. Frequently when the wind velocity
was high, the reading from the gauge in the top of the tree
was higher than from the one in the clearing; on the other
hand, when the rain was not accompanied by high wind velocity,
the gauge in the clearing sometimes gave a slightly higher
reading than the one in the top of the tree. This was probably
due to the fact that the rate of evaporation was greater in the
top of the tree than in the clearing. In the following tables
the highest of the two readings is used, as it is believed that
this method gives the most accurate measurement of the actual
rainfall.

The figures recorded in this publication, for rainfall at 300
meters' elevation, are slightly different from those previously
given by Brown and Matthews. The difference is due to the
fact that the results here presented were obtained from two
gauges, as just described; whereas in the former paper readings
from only one gauge were given.

At 450 meters' elevation a gauge was placed in the center
of a 0.25-heetare clearing ; and at 740 meters in the top of a
dominant tree. At the summit of the east peak the gauge was
in a clearing that was sufficiently large to prevent the trees
from interfering with the entrance of water into the gauge.

When a gauge is read weekly the readings are, of course, sub-
let to an error due to evaporation; but at the higher eleva-
tions, where rates of evaporation are low, this error is probably
111 considerable. However, in order to find out what this error
rnight be under extreme conditions, one gauge was read weekly

245

246

MOUNT MAQUILING

for a considerable period at an elevation of 80 meters, and it
was found that the results shown by the gauge read weekly
varied only very slightly from those recorded by the one
read daily; so that we may conclude that errors in the total
amount of rainfall, due to evaporation, are almost negligible at
all elevations at which the readings were taken weekly.

RAINFALL AT THE BASE OF THE MOUNTAIN

The daily readings of rainfall at an elevation of 80 meters
are given in Table XCVIII. The results are plotted by months
for the different years in fig. 12. An examination of this figure
shows not only that there is a very marked difference between
the dry and the rainy seasons, but also that there is considerable
irregularity in the seasons during different years.

Table XCVIII. — Rainfall in centimeters at the base of Mount Maquiling.

AUGUST 16 TO DECEMBER 31, 1911.

Day.

August.

Sep-
tember.

October.

No-
vember.

De-
cember.

1 _

2 -

0.051

3 .

0.127

0.076

0.025

4 j

0.051

5 . .

0.024

6

7 __

0.787

8

0.229

9

10 ,

0.203

0.061

0.178

11 ._ ___

12 .

0.127

18

0.813

14 - -

15 __

16 ._

0.508

0.203

0.178

17 .

4.013

18 _ .

2.464
2.845
1.651
0.533

1.016
0.254
2.413
0.508
3.127

0.025
0.381
0.025
0.254

0.559
0.635
0.051
0.178
0.127

19

20

21 -.-

0.432

22 - —

0.025

28 . --

0.025

0.025
0.051
0.203

0.025

24 -

0.152

0.076

26 _

2.743
0.102

0.381

26 - ---

27

28 . -.

1.295
2.691
0.838

0.076

29

0.051

30

31

0.152

Total

10. 615

12. 804

3.250

1.829

5. 535

RAINFALL

247

Table XCVIIL— Rainfall in centimeters at the base of Mount Maquiling-

Continued.

li.

12..
13..
14..
15..
16..
17..
18..
19..
20..
21..
22..
23..
24 .
25..
26 ..
27..
28..
29..
30..
31..

Day.

Total .

Day.

YEAR 1912.

0.10

0.33
1.80
0.28
0.03
0.03

0.41
0.08
0.13

0.10

0.89
0.71
1.04
0.79
0.30
0.08

0.25

0.30
0.08
0.08

3.90

0.05
0.07
0.10

0.25
0.08

4.46

1.30

0.33

1.75

0.25
2.29

2.64

0.15

5.08

0.33 15.44 8.12

2.06

2.17
0.32

0.62
1.19

0.33

| 0.86
| 0.45

0.21
1.68 I

0.21

OT

11.68
0.66
1.03

1.11
2.75
2.18

-I.

|

0.69
0.23

0.03

0.18

0.28

0.36
0.15
0.15

1.78

3.28
0.45
0.41
1.02
4.59
3.28

5.04
2.05
0.90

0.08
0.41
2.85

2.62

2.87
0.25

2.01

1.27
2.66

0.18
0.55

3.44

1.8

6.97
2.99
0.29
0.58
2.25

2.21
2.41

0.82 |

1.52 12.30

0.41
0.08
0.49
2.01

29.50 46.00 131.84

1. 03 0. 01

0.21
4.80

4.22
1.61
0.70
0.08
2.09
2.47
0.06
0.29
1.80
2.93
9.31
3.07
0.25
0.39

0.01
0.41
3.95
0.06
1.44
0.49

0.04

0.49
0.20
0.70
0.06

1.61
0.21
0.21
0.05

2.17

0.01
2.69

40.09

7.52
0.62

YEAR 1913.

8.42

0.04
0.04
0.19

0.12

0.16

1.12 I

1.44
0.37
0.41
1.72

0.21

0.33

0.16

0.34
0.36

2.08
1.06

■M

oa

S

<

Xi

§
a
w

t
O

0.42

0.43

0.15

0.19

1.12

2.31

0.48

0.85

3.46

0.74

0.11

0.18

1.46

0.83

0.24

0.48

0.14
0.03

0.69
0.94
0.20
0.27
0.26

• Daily record lost. Doctor Foxworthy's record book shows five days with showers.

248

MOUNT MAQUILING

Table XCVIII. — Rainfall in centimeters at the base of Mount Maquiling

Continued.

YEAR 1913— Continued.

10.
11.
12.
13.
14.
15-
16.
17..
18.
19-.
20,
21.
22..
23.
24..
25!.
26..
27..
28-.
29.
30..
31-

Day.

Total .

1.56
0.25
0.45
0.07

0.04
0.08
0.25

12.57

0.11

0.16

0.66

0.78

1.73

0.45
1.29
0.45
2.46

0.12
0.37
0.12

0.07

0.29
0.12

0.21

0.39

2.58

2.34

0.62
0.06
0.29

10.84

0.41
0.06
0.05
0.01
1.68

0.04
1.03

1.58
0.04
1.85

7.29

0.03
0.85
0.12
3.63
0.15
0.31
3.95
2.78
0.51
1.06
1.31
1.04
0.36
2.85
0.58
0.10
0.59
0.26

2.55
8.70
4.35
0.72

42.77

0.19

0.07
1.91
0.13
0.23
0.28
1.51
8.10
0.84
0.06
0.08
0.15
0.36
0.05
0.55
0.07
0.85
1.46
0.10
0.30
0.14

0.10
3.22
16.90
1.19

23.31

m

0.87

1.41
0.28

0.03
0.67
0.85
0.49

0.11

0.10
2.05
6.80
1.27

1.44

0.12

29.45

0.10

16.12

1.57
0.81
0.29
0.09
0.09

0.15
0.05

0.19
1.86
0.18
0.12
0.56

0.13

1.25
0.02
0.24

10.13

YEAR 1914.

Day.

CJ

3
fl
CO

fa

o

S3

~4

•c

ft

<

g

s

6

>-3

>>

»"9

00

S3

bo
<

§

ft
a)

Li

S

O

O

u

V

XI

1

>
o

u

V
J2
g

V
V

Q

1

0.31
2.17
7.90
3.46
0.14

0.01
0.35
0.13
0.29
2.97
0.17
1.70
2.33
0.12

0.42
0.19
0.18
0.91
0.80
1.36
0.44
0.73
2.50
0.03

4.52
14.00
5.80
9.50
9.70
2.12
0.42
3.33
8.80
2.48
0.02
0.10
1.37
0.44
0.79
0.01

0.04
0.15

0.19

2 '

0.31

3

0.15
0.39

0.39

4

0.01
0.58

0.69

5

0.32

0.16

6— _

0.26

7

0.91
0.73
trace.
0.26

0.23
0.03

0.33
0.11

0.14

8 _ _

0.19
0.24

0.02

0.08

9

0.58
0.71

0.28

0.55

10 .„_

0.71

11 ._

0.04

0.83
0.77

0.41
0.57
0.29

0.01

0.08

12 ._ ...

0.19

13

0.16
0.14
0.05

1.06

14

0.04
0.03

0.24

4.93
0.54

trac^

15

0.01

16

0.59

0.51

0.07

0.03

RAINFALL

Table XCVIII. — Rainfall in centimeters at the

Continued.

YEAR 1914-Continued.

249

of Mount Maquiling —

Day.

>»
u

g

»-9

u ■
08

g

fa

o

2

ft

c

»-9

»-3

CO

3

bo

U

a

ft
<u

u

JS

0

i

£

0
Z

0.02

0)

s

0

17...

0.06
0.01

0.87
1.06
0.29
1.02
0.56

0.03
0.55

2.56
0.15
3.27

0.83
0.05

0.04
0.97
0.46

18

i

0.03
5.54
7.60
0.56

0.03

19

1

0.03
0.31
3.44
1.31

i

20

21

0.43

0.09

0.05

i

0 06

22

0.72
0.02

0.02
0.15
trace

23

0.41
0.21
0.03

0.67

trace.

1. Ub 0. cb Z. U4

24

0.11 0.61

trace

0.75
5.21

25

26

0:23
0.24

0.02

0.03

U. DO

0.67
0.05

0.11

' 1 A A

0.64

27

0.49

0.07

j 1.44

0.86

0.01

28

0.31
0.93
0.40
0.54

2.48

trace,
trace.

29

0.06
0.68
0.30

0.70
0.52

0.54
0.39

0.78

30 .

0.11

31

0.32

0.03
0.19

5.84

Total

1.69

1.20

0.40

8.33

7.75

33.10

14.73

18.34

69.87

5.97

7.37

250

MOUNT MAQUILING

RAINFALL AT DIFFERENT ELEVATIONS

Rainfall was measured at the five stations at which tem-
perature-recording instruments were placed; that is, at eleva-
tions of 80, 300, 450, 740, and 1,050 meters, respectively. A
rain gauge was also placed in an open plot on the opposite slope
of the east peak at an elevation of about 1,000 meters.

The weekly readings of rainfall at the different elevations
are given in Table XCIX, and these are summarized for cor-
responding four-week periods for the individual years in Table
C, and for the entire period in Table CI. The rainfall for the
different four-week periods for 1914 are plotted in fig. 13.

Ian. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Fig. 12. Monthly rainfall at the base of Mount Maquiling ; altitude, 80 meters.

RAINFALL

251

Period.

JanJO Feb.27 Mar.27 Apr 24 May22 June 13 Juif/7 Aug/4 .SeZtJl Oct! No, 6 Dec 4 Jan J

Fig. 13. Rainfall at different altitudes on Mount Maquiling.

252

MOUNT MAQUILING

TABLE XCIX. — Rainfall for weekly periods in the open at different elevation*

on Mount Maquiling.

[Numbers give rainfall in centimeters.]

Week ending —

Altitude in meters.

1,050.

21.30
30.40
4.69
2.40
8.30
2.22
6.04
14.50
0.58
5.08
1.27
6.30

8.20
3.95
1.20
5.10
5.00
1.39
0.92
1.00
3.42
2.75
0.05
0.15
0.18
0.22
0.00
0.70
1.55
1.77
6.00
2.25
4.34
2.82
0.12
0.80
2.94
1.09
3.81
3.57

14.00
7.40

16.10
6.40

11.30
3.88

80.

13.50
19.93
2.72
2.71
4.76
2.46
3.83
9.69
0.62
1.92
0.31
3.88

10.48
0.35
0.00
1.56
1.14
0.08
0.11
0.82
0.78
0.61
1.12
0.00
0.00
0.00
0.00
4.65
0.61
0.07
4.23
0.33
5.31
0.97
0.21
0.33
0.53
4.33
4.36
4.50

12.39
6.83

17.00
5.46
2.81

11.10

300.

4.20
17.80
3.29
2.48
6.30
1.57
4.01
12.02
0.69
2.32
0.51
4.20

9.70
1.84
0.28
1.80
1.75
0.59
0.25
1.41
1.68
1.85
0.02
0.00
0.00
0.00
0.08
0.37
0.60
0.05
6.10
1.54
3.42
8.90
0.46
0.74
4.31
2.75
6.90
2.72

14.50
7.70

21. 50
4.92
1.41

13.10

450.

740.

1,000.

1912.
October 11. _

October 18

October 25

November 1

November 8 . 1 .

9.20
1.71
6.33
18.80
0.00
4.06
0.84
6.55

8.90
3.70
1.10
3.90
4.05
1.13
0.50
0.69
2.74
2.47
0.05
0.00
0.05
0.06
0.19
0.51
1.00
0.55
9.20
2.20
4.62
1.94
0.11
0.07
5.10
1.88
7.20
4.67
19.50
13.50
30.55
7.10
12.10
4.75

November 15 .. _ .

November 22

November 29

Decern ber 6

December 13.._ _.

December 20 .

December 27 . ._

1913.

January 3 ___

January 10

January 17

January 24

January 31

February 7 : ....

February 14

February 21

February 28 .

March 7

March 14 _ ■_

March 21

March 28 -_ _

.

April 4 ...

April 11

April 18

April 25

May 2 _

May 9 r__

May 16 _ .

1$ay23

May30 ..

June6.__ ...

June 13

June 20

3.11

June27 . _. .. _

7.01
4.81
14.00
11.50
29.04
7.40
1.31
13.70

1.13

July4-__. _.

6.42

July 11 .

4.05

July 18

13. 10

July 25

5.30

August 1

12. 5fi

August 8-_ . .

5.50

August 15

9.40

August 22

3.9R

RAINFALL

253

Table XCIX. — Rainfall for weekly periods in the open at different elevations
on Mount Maquiling — Continued.

Week ending—

1913.

August 29

September 5

September 12

September 19

September 26

October 3 ■_.

October 10

October 17

October 24

October 31

November 7

November 14 _.

November 21

November 28

December 5

December 12

December 19

December 26

1914.

January 2

January 9

January 16

January 23

January 30

February 6

February 13

February 20

February 27 _

March 6

March 13

March 20

March 27

April 3

April 10

April 17

April 24

Mayl

May 8

May 15 j

May 22 j

May 29 j

June 5 I

June 12 __ I

June 19 I

June 26

Altitude in meters.
300. 450. 740.

3.38

6.50

3.28

4.35

21.69

23.60

2.28

11.60

2.32

2.47

2.43

3.12

2.05

1.42

11.66

15.60

0.00

0.39

0.10

0.24

2.27

1.31

3.11

3.21

2.43

2.57

2.06

2.25

0.69

0.85

2.25

2.73

4.28

4.69

3.86

3.74

0.66

0.99

0.97

1.32

0.07

0.24

0.41

0.75

0.24

0.16

0.32

0.32

0.20

0.36

0.19

0.21

0.49

0.61

0.00

0.13

0.02

0.00

0.31

0.43

0.07

0.11

0.00

0.00

1.29

1.25

5.47

6.60

1.10

1.66

0.47

0.17

0.00

0.00

1.60

1.93

5.09

5.90

0.08

0.27

14.96

20.60

0.69

0.46

7.02

22.90

10.19

3.25

1.19,
7.50 ;

29.00 ;

14.00 |
2.71 |
2.60 j
1.65 |

20.90 j
0.38
0.27
1.62
3.61
3.31
2.48
1.21
3.22
6.10
4.24

1.44

1.82

0.46

1.12

0.19

0.42

0.68

0.25

0.77

0.26 j

0.00 |

0.60 j

0.16 ;

0.00 I

0.96 j

7.60 j

1.94

0.00

0.00

2.54

6.10

0.26

22.80
0.35

23.10
3.21

11.70
7.60

35.40
2.02
2.57
2.41
1.87

21.50
0.89
0.32
3.65
2.32
4.67
1.59
1.46
3.43

12.10
1.17

2.99
1.97
1.07
1.53
0.18
0.52
1.71
0.19
0.93
0.62
0.19
1.13
0.19
0.09
2.52
8.60
2.26
0.06
0.00
1.21
4.96
1.41

26.10
0.26

20.30
3.26

1,050,

1,000.

6.70

4.00

5.70

4.74

23.90

13.10

1.54

1.65

3.03

3.76

0.26

2.31

2.14

2.24

12.90

7.50

1.02

0.86

0.36

0.32

4.21

4.51

2.83

3.34

4.87

6.70

1.24

2.36

1.33

1.99

3.57

4.44

8.50

12.60

1.05

1.45

3.84

4.77

2.24

2.86

1.26

1.56

1.48

1.86

0.15

0.19

0.64

0.81

2.13

2.86

0.08

0.16

0.96

1.13

0.84

0.96

0.14

0.11

. 1.08

1.33

0.23

0.26

0.14

0.11

2.37

2.86

10.80

10.60

2.67

3.18

0.02

0.05

0.00

0.11

2.18

1.98

4.06

4.12

1.85

1.47

16.60

9.10

0.21

0.27

19.90

17.80

2.63

3.89

254

MOUNT MAQUILING

Tabi^: XCIX.— Rainfall for weekly periods in the open at different elevations
on Mount Maquiling — Continued.

Week ending-

1914.

July3 ._

July 10_„__

July 17

July 24

July 31

August 7

August 14

August 21

August 28-

September 4

September 11

September 18

September 25

October 2

October 9

October 16

October 23

October 30

November 6

November 13 ...

November 20

November 27 .

December 4

December 11

December 18

December 25

1915.
January 1

Altitude in meters.
740.

80.

300.

450.

1.71

2.75

3.73

7.58

13.60

16.80

1.39

1.63

3.35

3.89

8.30

7.50

1.38

1.41

1.61

0.61

1.53

1.89

6.92

8.20

10.80

3.32

1.03

1.36

5.62

10.00

11.40

35.69

47.50

55.60

26.87

30.80

39.90

3.59

3.74

3.53

0.74

0.72

1.21

4.85

4.17

5.40

2.24

2.46

2.68

0.26

0.26

0.04

1.73

2.38

2.61

1.76

1.17

2.76

0.19

0.63

0.49

0.70

1.79

2.33

0.09

0.33

0.21

0.76

0.92

0.97

7.22

10.20

10.20

1.96

2.11

3.19

1.33

1.99

2.94

0.76

0.81

1.02

0.25

0.51

0.63

5.08
18.50
4.30
5.70
2.22
2.20
11.10
11.60
2.46
60.10
28.20
1.73
3.25
4.42
1.79
0.87
2.23
3.23
0.38
2.77
0.35
10.40
3.91
3.89
3.01
1.08

0.81

1,050.

6.20
9.70
4.60
8.90
2.10
2.38
8.60

10.60
1.77

52.60

24.50
1.11
2.66
2.31
1.99
1.68
1.81

• 3.82
0.95
2.53
0.43
8.60
3.21
4.35
2.56
0.94

1,000.

5.09

6.70

4.05

7.30

1.75

2.36

3.97
12.10

1.50
44.10
17.20

0.85

2.99

4.00

2.24

1.67

2.26

4.79

1.19

3.19

0.54

9.80

3.97

4.89 j

3.17 |

1.46 !

!

1.14 I

RAINFALL

255

Table G. — Total rainfall for periods of four weeks in the open at different
elevations on Mount Maquiling.

[Rainfall is given in centimeters.]

Four weeks ending —

Elevation

in meters

80.

300.

450.

740.

1,050.

1,000.

1912.

30.12
16.60

16.59

29.87
18.29

16.73

45.79
23.34

20.85

December 6

26.84
20.35

1913.

Total

63.31

64.89

47.19

89.98

1913.

3.05

1.79

1.73

5.26

9.94

2.04

25.58

32.10

39.35

9.08

14.03

8.29

10.45

5.67

3.93

1.87

1.05

11.11

9.41

26.87

35.53

47.55

18.61

17.54

8.88

12.15

12.75

5.06

2.57

1.76

16.57

7.22

33.25

63.25

59.45

8.87

26.36

10.04

19.69

15.25
6.73
3.13
2.47
14.36
6.68
22.47
41.20
40.18
6.96
18.49
10.27

16.96

February 28

March 28 _.

April 25

May 23 . - -

June 20 ._

July 18 _—

49.25
51.39
20.86
23.17
10.61

15.00

24.70
32.75
25.77
9.96
13.19
14.39

23.16
143. 92

August 15

September 12

October 10 _ __-

November 7

December 5

1914.
January 2

Total — _

162. 69

200.17

170.28

266.84

205. 15

1914.
January 30

1.69

1.20

0.40

7.86

7.16

22.75

20.87

12.80

71.50

11.42

8.94

8.77

4.30

2.47

1.50

0.67

9.51

8.00

44.23

21.23

19.44

89.33

11.09

4.44

13.24

5.42

3.59

2.12

1.02

10.50

8.64

46.51

27.09

21.80

108.26

12.82

5.90

13.71

7.78

4.75

3.35

2.13

13.37

6.23

48.07

31.14

21.22

102.66

11.19

6.71

17.43

8.79

5.13

3.81

2.29

15.88

6.26

37.56

23.13

21.98

89.47

8.07

8.26

14.77

8.84.

6.46
4.96
2.66
16.75
6.26
28.64
19.73
15.38
74.90
10.08
9.91
17.50

10.66

February 27 _

March 27 _ _

April 24 _

May 22

June 19 _ _

July 17 _

August 14 _ _ _

September 11

October 9

November 6

December 4

1915.
January 1 „

Total

174.66

230.57

269.74

277.04

245.45

223.89

256

MOUNT MAQUILING

Table CI. — Average rainfall for periods of four weeks from October, 1912
to January, 1915, in the open at different elevations on Mount Maquiling.

[Rainfall is given in centimeters.]

Elevation in meters.

Four weeks ending-

January 31 _i 2.37

February 28 I 1.60

March28 1.07 j

April 25 \ 6.56 \

May23 _.:.. t 8.55

June 20 j 12.40

July 18 | 23.23

August 15 | 22.45

September 12 ! 55.43

October 10 .___! 10.25

November7 .._ I 16.03

December 5 \ 11.22

January 2 j 10.45

Total j 181.61

300.

4.

2.

1.

5.

9.
26.
24.
27.
68.
14.
17,
13.
11.

226. 73

450.

740.

1,050.

1,000.

3.59

8.75 'j

10.19

6.46

2.12

4.21 j

5.27

4.96

1.02

2.35 !

2.71

2.66

10.50

7.57 !

9.18

16.75

8.64

11.40 '

10.31

6.26

46.51

27.65 !

22.12

28.64

27.09

32.20 |

22.80

22.22

35.53

42.24 |

31.59

24.07

79.83

81.06 j

64.83

50.34

16.84

10.03

7.52

10.02

14.54

16.54 >

24.18

11.55

12.16

18. 10 i

16.13

15.95

11.39

16.28 |

15.55

16.91

269.76

278.38 !

242.38

216.79

The average rainfall at the base was 182 centimeters. This
approaches the lower limit given by Schimper * for a rain forest.
The amount of rainfall increases as higher elevations are reached,
up to 740 meters. At 300 meters the average annual rainfall
was 227 centimeters; at 450 meters, 270 centimeters; and at
740 meters, 278 centimeters. As might have been expected, the
rainfall was less at the top of the mountain than at an elevation
of 740 meters. At the top of the mountain, or 1,050 meters'
elevation, the average annual rainfall was 242 centimeters, which
amount is intermediate between that for elevations of 300 and of
450 meters. It will thus be seen that the rainfall in the mossy
forest is about the same in amount as in the dipterocarp forest
and is less than in the upper part of the dipterocarp forest;
and that the midmountain forest apparently received more rain
than either the dipterocarp or the mossy forest. The seasonal
distribution of rain is approximately the same at all elevations,
as may be seen by referring to fig. 13, in which are plotted the
four-weekly rates for the year 1914 at the different elevations.
This figure shows very clearly that the seasonal variations in
rainfall are very similar at all elevations, and that in every case
the distinction between the rainy season and the dry season is
very marked.

* Schimper, A. F. W., Plant Geography upon a Physiological Basis
English translation by W. R. Fisher, Oxford (1903).

RAINFALL 257

RELATION OF RAINFALL TO VEGETATION

A consideration of Table CI and fig. 13 would indicate that
the rainfall, as a direct factor, is not responsible for the pro-
gressive changes which we find in the vegetation between lower
and higher altitudes. Rainfall, of course, affects vegetation by
its influence on evaporation and soil moisture; but in the case
of Mount Maquiling these factors seem to be influenced more by
changes in humidity, due to the ascent of air, than by rainfall.
Humidity increases with rising elevations clear to the top oi
the mountain, whereas rainfall is greatest at elevations below the
top. The amount of soil moisture also increases with rising
elevations, clear to the top of the mountain, while evaporation
decreases. The rainfall on Mount Maquiling cannot be con-
sidered exceptionally heavy at any elevation; but at all alti-
tudes above 80 meters it would appear, according to the data
given by Schimper, to be more than sufficient for the development
of a tropical rain forest. That this is so is shown by the fact
that at an elevation of 300 meters, where there is less rainfall
than at higher elevations, such a forest is well developed. While
the amount of rainfall at the base approaches the lower limits
given by Schimper for a tropical rain forest, the indications
are that this area also was originally covered by a tall rain
forest. The type of vegetation seems to be influenced more by
the distribution than by the actual amount of rainfall ; provided,
of -course, that the total precipitation is not extremely small.
This is particularly true in the Philippines as has been shown
by Brown and Matthews.* At all elevations on Mount Maquiling
the rainfall, as previously mentioned, shows a marked difference
between the dry and the rainy seasons; but the dry season is
short, and there is no long period during which there is no
rainfall. A further consideration of the effect of rainfall on
vegetation will be given in connection with soil moisture and
evaporation.

In addition to the total amount of rain that falls, it is of in-
terest to determine the amount that actually reaches the ground.
This problem was suggested particularly by the fact that at the
top of the mountain there are very frequently clouds which cause
the condensation of water on the leaves, so that water actually
drops from the trees when no rain is recorded in a gauge in
the open. In order to try to determine the amount that ac-
tually reaches the ground under the mossy forest, two rain

* Brown, W. H., and Matthews, D. M., Philippine dipterocarp forests,
I'hil Journ. Sci., Sec. A (1914), 9, 413-561.

159549 17

258

MOUNT MAQUILING

gauges were placed under the main canopy. At first it was
thought that the canopy was so even that there would be no dif-
ference in the amount of rain between two trees and near the
trunk of a tree. Rain gauges were placed in these positions,
and they showed considerable differences. The results from
the two gauges for the year 1914, and also from the gauge in the
open, are given in Table CIL For that year the gauge in the
open showed a total rainfall of 245 centimeters; that between
two trees, 310 centimeters; and that near the trunk of a tree,
150 centimeters. The average of the two gauges under the trees
was 230 centimeters, which is 15 centimeters less than the total
rainfall in the open. This would indicate that the amount of
water which reaches the ground is actually somewhat less than
that recorded in the open. The results from the two gauges are,
however, not sufficient to make this conclusion positive.

Table CII. — Total rainfall for periods of four weeks in the mossy forest
on Mount Maquiling; altitude, 1,050 meters.

[Rainfall is given in centimeters.]

Four weeks ending—

1914.

January 30

February 27

March 27

April 24

May 22

June 19

July 17

August 14

September 11

October 9

November 6 1

December 4

1915.

January 1

Total

Position of gauge.

Open.

Under trees.

Near

trunk of

large

tree.

Between

two large

trees.

5.13

3.03

16.01

3.81

1.54

9.40

2.29

1.37

7.80

15.88

9.92

15.02

6.26

7.12

10.71

37.56

24.53

87.06

23.13

16.47

27.65

21.98

12.02

17.84

89.47

63.11

75.84

8.07

4.29

5.37

8.26

2.04

5.45

14.77

2.62

11.00

8.84

1.58

20.57

245.45

149.64

309. 72

Two rain gauges were also placed in similar positions in the
midmountain forest. The results are presented in Table CIH-
In both cases the recorded rainfall was less than in the open.
The average for the two gauges under the trees for the years

RAINFALL

259

1913 and 1914 was 227 centimeters, whereas the average for
these two years in the open was 272 centimeters, a difference
of 45 centimeters.

Table CIII. — Total rainfall for periods of four weeks in the midmountain
forest on Mount Maquiling; altitude, 7U0 meters.

[Rainfall is given in centimeters.]

Position of gauge.

Four weeks ending —

Open.

26.84
20.35

Under

Near

trunk of

large

tree.

18.36

17.86

trees.

Between

two large

trees.

20.89
17.75

1912.
December 6

1913.
January 3

Total

47.19

36.22

38.64

1913.

January 31

February 28

12.75

5.06

2.57

1.76

16.57

7.22

33.25

63.25

59.45

8.87

26.36

10.04

19.69

12.70

5.98

2.20

1.38

16.45

4.91

26.65

58.70

48.11

8.84

28.40

9.55

19.09

11.30

4.97

2.01

1.48

12.15

4.96

28.28

48.20

41.68

6.29

22.25

7.87

13.83

March 28

April 25

May 23

June 20 __ ___

July 18.. _

August 15 __

September 12

October 10 ..

November 7

December 5 .-

1914.
January 2. .

Total

266.84

4.75

3.35

2.13

13.37

6.23

48.07

31.14

21.22

102.66

11.19

6.71

17.43

8.79

242.96

205.27

1914.

January 30 1

March 27...

4.54

3.03

1.36

14.71

5.62

44.80

27.51

• 18.23

97.02

12.54

4.38

15.37

8 36

3.56

2.62

1.49

7.80

5.13

38.37

21.67

20.64

81.05

7.94

2.86

7.17

3.67

April 24..

May 22 .

June 19

August 14

September 11

October 9 .

November 6

December 4

1915.
January 1..

■ ■ — - — —

Total

277. 04

9.K7 47

203 97

l

SOIL MOISTURE

MOISTURE-HOLDING CAPACITY AND MOISTURE EQUIVALENT

The percentage of moisture in the soil, on the basis of the
dry weight, at depths of 10, 20, and 30 centimeters, was de-
termined weekly from November, 1912, to December, 1913, for
the grassland area at an elevation of about 100 meters; the dip-
terocarp forest at 300 meters; the midmountain forest at 730
meters ; and the mossy forest at 1,050 meters. The results have
been presented by Brown and Arguelles.* It is important to
know not only the moisture content of the soil at different times
but also something of its water-holding capacity; and so both
the water-holding capacity and the moisture equivalent of the
soils at the various elevations have been determined. For this
purpose a composite sample, amounting in each case to 20 liters
of soil, was collected from the surface to a depth of 35 cen-
timeters at each of the elevations above mentioned. This sam-
ple was thoroughly mixed, and the smaller samples used in
making the actual determinations were obtained by the usual
method of quartering. The samples employed may, therefore,
be considered as representative. The water-holding capacity
based on the dry weight was determined according to Hilgard'sf
method ; that is, by using a column of soil 1 centimeter in height.
The pans employed were obtained from the Plant World.

When the soil on Mount Maquiling is brought to the laboratory
it contains numerous lumps which are not easily broken, but
which disintegrate readily when wet. Owing to this fact and
also to the presence of small amounts of gravel, it was thought
advisable to determine the water-holding capacity not only of the
whole sample but also of samples passed through a 2-millimeter
sieve. The results of these two sets of determinations are given
in Table CIV. An examination of this table shows that all of
the soils have a very high water-holding capacity, and that the
capacity of the whole sample and that of the sample passed

* Brown, W. H., and Arguelles, A. S., The composition and moisture
content of the soils in the types of vegetation at different elevations on
Mount Maquiling,, Phil Journ. Sci., Sec. A (1917), 12, 221-232.

fHilgard, E. W., Soils, N. Y. (1906), 209.
260

SOIL MOISTURE

261

Table CIV.— Water-holding capacity and moisture equivalents of soils at
different elevations on Mount Maquiling.

Type of vegetation.

Parang

Dipterocarp forest__
Midmountain forest .

Mossy forest

Moisture- holding
capacity.

Moisture

Altitude.

Whole
sample.

Sample
passed
through
2-mm.
sieve.

equiv-
alent of

whole
sample.

Meters.

100

89.8

91.3

48.7

300

96.3

96.6

45.9

730

96.9

97.8

45.5

1,050

170. 5

183.6

97.2 i

!

through the 2-millimeter sieve was in all cases very similar.
This would indicate that, in determining the amount of water
in the soil at any given time, errors due to variation in the size
of particles in individual samples should be negligible.

The water-holding capacity of the soil in the dipterocarp and
midmountain forests was practically the same, being, respect-
ively, 96.3 per cent and 96.9 per cent ; while that in the parang
was slightly less, 89.8 per cent. The mossy forest has a much
higher water-holding capacity, 170.5 per cent. This high capa-
city for retaining moisture is probably connected with the large
amount of organic matter contained in the soil in that region.
The composition of the various soils has been given under the
heading of chemical and physical composition of soils.

The moisture equivalent of the different soils was determined
according to the method of Briggs and Shantz;* that is, a column
of soil 0.5 centimeter in height was subjected for half an hour
to a centrifugal force equivalent to one thousand times gravity,
and the percentage of water left in the soil calculated on the
basis of the dry weight. In order to make the determination
without using the special type of centrifuge designed by these
authors, a new type of cup was devised. This consisted essen-
tially of two brass tubes, one fitting into the other but not
reaching to the bottom of the latter. The soil was placed in the
inner tube, the bottom of which was perforated with numerous
small holes so that the water thrown from the soil was held in
the outer tube. In this way the equilibrium of the machine was

* Briggs, L. J., and Shantz, H. L., The wilting coefficient for different
plants and its indirect determination, Bull. U. S. Bur. Plant Industry
<1»12), No. 230.

262 MOUNT MAQUILING

not disturbed. The bottom of the inner tube was first covered
by a fine wire gauze with 200 meshes to the inch, and this
gauze was covered by a piece of thin filter paper. The bottom
of the tube was detachable and so constructed that when screwed
onto the tube it held the wire gauze and the filter paper flat and
in position. Apparently the only objection to these tubes is that
with a column of soil 0.5 centimeter in height they hold only a
small sample. This might give rise to serious errors with soil
containing considerable quantities of gravel; but with the fine,
uniform soils of Mount Maquiling the error was negligible. In
every case duplicate determinations were made, and the results
obtained from the same soil differed by about 1 per cent. The
average results for the different soils are given in Table CIV.
As might be expected from the high water-holding capacity, the
moisture equivalents of all the soils were high, particularly so
in the case of the soil from the mossy forest.

Briggs and Shantz * have made a very careful and exact study
of the amount of water left in soils by plants when they become
permanently wilted. In their work they introduced the term
" wilting coefficient/ ' which is defined as follows:

The wilting coefficient is then defined as the moisture content of the
soil (expressed as a percentage of the dry weight) at the time when the
leaves of the plant growing in that soil first undergo a permanent reduction
in the moisture content as a result of a deficiency in the soil-moisture supply.
By a permanent reduction in the moisture content of the leaves is meant a
condition from which they can not recover their turgor in an approximately
saturated atmosphere without the addition of water to the soil.

As a result of their work they came to the following conclu-
sion :

The object of this investigation was to determine the extent of the
variation exhibited by different plants with respect to the minimum point to
which they can reduce the moisture content of the soil before permanent
wilting occurs. It has heretofore been believed that plants differ widely
in this respect and that drought resistance is in part due to the additional
supply of water which is available to some plants through the greater force
which they exert upon the soil moisture. The results of this investigation
have led us to conclude that the differences exhibited by plants in this
respect are much less than have heretofore been supposed and are so small
as to be of little practical utility from the standpoint of drought resistance.
As compared with the great range in the wilting coefficient due to soil
texture, the small differences arising from the use of different species of
plants in determining the wilting coefficient become almost insignificant.

* Briggs, L. J., and Shantz, H. L., The wilting coefficient for different
plants and its indirect determination. Bull. U. S. Bur. Plant Industry
(1912), No. 230.

Wilting coefficient

SOIL MOISTURE 263

These authors give a number of indirect methods of deter-
mining the wilting coefficient.

Txr-ix- & . j. moisture equivalent

Wilting coefficient =

1.84 (1+0.0007)

hygroscopic coefficient

0.68 (lzbO.018)

Wilting coefficient = E^E?!^^11?. capacity-21

2.90 (1±0.021)

Wilting coefficient = ?-M s^d-0.12 «ilt-0.57 clay

(1+0.025)
It will be seen that these formulas do not take into consid-
eration the atmospheric conditions. Brown,* working in Ari-
zona, found that plants wilted when the rate of evaporation was
high with a greater amount of water in the soil than when the
evaporation rate was low. Caldwell,f and Shive and Livings-
ton, % working in the same region, found that the permanent
wilting of plants occurred with varying amounts of moisture in
the soil, dependent upon the rates of evaporation, and so they
concluded that the formulas of Briggs and Shantz were not of
universal application. However, Caldwell as well as Shive and
Livingston found that, when the plants were growing in a soil
with a high water-holding capacity and were subjected to low
rates of evaporation, the amount of water left in the soil when
the plant became permanently wilted approximated that obtained
by calculation from Briggs and Shantz's formula. This is shown
by the following quotation: §

The quantitative relations holding between the magnitude given to the
calculated soil moisture residue at permanent wilting, by the Briggs and
Shantz formula, and the observed magnitudes as shown in these experi-
ments, remains to be considered. Caldwell has shown that, for lighter
soils (with low water holding powers), the observed values are always
much larger than the calculated, this discrepancy being greater, of course,
with high evaporation intensities than with lower ones. On the other
hand, the same author has established the fact that, with heavier soils (of

Brown, W. H., The relation of evaporation to the water content of
the soil at the time of wilting, Plant World (1912), 15, 121-34.

t Caldwell, J. S., The relation of environmental conditions to the phe-
nomenon of permanent wilting in plants, Physiol. Res. (1913), 1, 1-56.

t Shive, J. W., and Livingston, B. E., The relation of atmospheric evapo-
rating power to soil moisture content at permanent wilting in plants, Plant
World (1914), 17, 81-121.

§ Shive and Livingston, op. cit.

264

MOUNT MAQUILING

high water holding powers), the observed values approach much more
closely the calculated ones, being about equal to them under conditions of
low evaporation intensities. These observations of Caldwell are clearly
substantiated by the work here reported, excepting that the present experi-
ments furnish a number of cases where the observed values fall markedly
below the calculated ones (series V). As might be expected from Cald-
well's results in this connection, these cases occur with low evaporation
intensities and with the soil of highest water holding power.

The soils on Mount Maquiling, as we have seen, have a high
water-holding capacity. The rate of evaporation near the ground
in the virgin forest is moreover always low, and particularly
so at higher elevations, and nowhere under the virgin forest
does it approach the higher values that were obtained in Cald-
well's and Shive and Livingston's experiments. Owing to this
fact the wilting coefficient as obtained by the formulas of Briggs
and Shantz will, for convenience, be tentatively employed as
a rough measure of the amount of moisture that would be left
in the soil on Mount Maquiling if plants became permanently
wilted under the evaporation conditions existing near the ground.
In Table CV are shown the wilting coefficients for the various

Table CV. — Wilting coefficients of soils at different elevations on Mount

Maquiling.

Wilting coefficient.;

Type of vegetation.

Parangr

Dipterocarp forest _
Midmountain forest
Mossy forest

Calcu-

Altitude.

lated

from

water-

holding

capacity.

Meters.

100

23.7

300

26.0

730

26.2

1,050

51.6

Calcu-
lated
from
moisture

equiv-
alent.

26.5
24.9
24.7
52.8

Average
wilting
coeffi-
cient.

25.1
25. 5
25.5
52.2

soils as calculated from the water-holding capacity and from
the moisture equivalent; also, the average of these two values.
An examination of this table shows that the wilting coefficients
as calculated by these two methods are similar in every case,
and that all of the soils have a very high wilting coefficient.

In Tables CVI to CIX are given the percentages of moisture
in the soils of the parang and in the dipterocarp, midmountain,
and mossy forests for the period from November, 1912, to
December, 1913. One of the most striking peculiarities of
these tables is the similarity in the amount of moisture in any

SOIL MOISTURE

265

given soil at different depths. This is apparently due to the
fact that the dense covering of vegetation prevents the surface
soil from drying out at a much more rapid rate than the deeper
layers. The average percentages for four-week periods at a
depth of 20 centimeters in the parang and in the dipterocarp
and midmountain forests are plotted in fig. 14. In this curve

Periods of four weeks ending —

Dec.6Jan.3 Jon3l Feb.28 Mor.28 Apr.25 MayttJuneZOJuly 18 Aug. 15 5ept.ll OctIO Nov.7 QecSJanZ

&30

Fig. 14. Average weekly percentage of soil moisture on Mount Maquiling at a depth
of 20 centimeters at different altitudes.

the wilting coefficient of the soil in the dipterocarp forest is
shown as a straight line. The wilting coefficient of only one
soil has been plotted, as the coefficients for the soils in the dip-
terocarp and midmountain forests are exactly the same and that
for the parang is only 0.4 per cent lower than that of the other
two. So slight a difference is within the limits of error indi-
cated by the different values obtained by the use of the two
methods employed in calculating the coefficient. For conven-
ience in comparison, the wilting coefficient for the soil of the
dipterocarp forest may, therefore, be considered the same as
that for the other two soils.

266

MOUNT MAQUILING

SOIL MOISTURE IN THE PARANG *

In Table CVI are given the percentages of moisture in the
grassland at the base of Mount Maquiling at an altitude of 100
meters. From a comparison of this table with Table CIV it
will be seen that no determination showed at any of the depths
as great a quantity of water in the soil as 50 per cent of its
water-holding capacity. From fig. 14 and from Table CVI it

Table CVI. — Percentage of soil moisture in the grassland at the base of
Mount Maquiling ; altitude, 100 meters.

Date.

1912.

December 6

December 13 _._
December 20 .._
December 27 ._.

1913.

January 3

January 10

January 17

January 24

January 31

February 7

February 14

February 21

February 28

March 7-_

March 14

March 21

March 28

April 4

April 11

April 18.

April 25 —

Depth in centi-
meters.

30.3
34.1
35.6
36.9

38.5
38.7
34.1
37.6
34.2
30.3
33.2
35.8
35.6
35.6
31.2
27.2
25.8
25.0
24.1
29.2
30.5

20.

34.5
34.7
34.6
35.7

39.4
35.5
38.1
36.4
33.4
30.4
34.6
33.6
34.6
84.8
32.4
25.6
23.3
29.3
24.2
26.5
80.6

33.6
35.5
35.3
35.6

39.1
37.6
39.8
37.6
33.3
31.5
35.5
33.0
33.6
88.5
33.8
28.3
28.3
28.6
27.7
27.1
33.4

Depth in centi-
meters.

Date.

1913— Cont.

May 2

May 9

May 16

May 23

May 30

June 6_.

June 20 .

July 18

July 25

August 1

August 8

August 15

August 22

August 29

September 5

September 26

October 3

October 24

November 7

November 14

November 21

November 28

10.

20.

27.6

27.5

27.0

26.8

33.8

28.7

34.3

34.8

33.3

32.7

30.8

30.3

33.2

38.8

40.9

33.9

33.9

35.7

35.8

34.8

36.4

36.1

37.7

33.5

38.3

35.1

39.7

36.8

38.9

39.2

38.7

35.8

36.6

87.8

35.1

34.3

33.6

32.7

31.8

35.4

41.3

38.7

39.1

37.1

30.

27.8
27.1
30.3
32.8
33.1
31.9
29.9
85.1
36.0
35.7
35.6
34.7
36.8
35.2
40.1
40.6
36.9
33.4
31.7
34.3
42.6
38.1

will be seen that the amount of water in the soil decreased
during the dry season, beginning with January and continuing
until April, and then increased until June, after which the per-
centage was fairly constant for the remainder of the year.
During the latter part of March and the first part of April the
amount of water in the soil, at depths of 10 and 20 centimeters,
is about equal to the wilting coefficient, and only slightly higher
than the wilting coefficient at a depth of 30 centimeters. As the
rate of evaporation at this time of the year is high, it may well
be that the amount of water near the surface is not sufficient

SOIL MOISTURE

267

for the growth of plants. Even the trees have a slower rate of
growth and less-dense foliage at this time than at other times.
The low moisture content of the soil in the parang and the
high evaporation rate at this elevation would indicate that the
rapid rate of growth of plants in this area is not due to favor-
able moisture conditions, but rather to favorable illumination
and temperature. The total range of soil moisture in the grass-
land is not particularly great, as the lowest determination was
23.3 per cent at a depth of 20 centimeters on March 28, and the
highest was 42.6 per cent at a depth, of 30 centimeters on
November 21.

SOIL MOISTURE IN THE DIPTEROCARP FOREST

The percentage of moisture in the dipterocarp forest at an
elevation of 300 meters is given in Table CVII. The water-
holding capacity of this soil was 96.3 per cent, which is not much

Table CVII. — Percentage of moisture in the soil in the dipterocarp forest
on Mount Maquiling; altitude, 800 meters.

Date.

1912.
November 15 ...
November 22 .„_
November 29 .__

December 6

December 13 __.

December 20

December 27

1913.

January 3

January 10

January 17

January 24

January 31

February 7

February 14

February 21

February 28

March 7

March 14

March 21

March 28

April 4

April 11

April 18 _.

April 25

Depth in centi-
meters.

10.

57.4
57.2
57.2
55.2
53.1
54.2
60.4

20. ! 30.

57.1
59.5
57.8
57.8
54.4
52.4
54.6

55.5

54.7 .

53.8

52.2 !

51.2

47.2

53.6

57.4

54.6

54.4

47.1

45.8

47.6

50.5

55.6

52.5

44.9

48.1

47.5

52.4

45.9

46.7

39.0

45.0

40.6

44.1

42.4

41.4

41.3

42.6

52.1

49.4

42.1

47.6

56.6
56.5
58.6
56.5
52.3
56.2
54.5

57.0
54.2
54.9
60.0
56.3
51.7
53.5
48.0
47.1
51.5
47.9
50.3
48.8
44.5
44.5
49.8
44.8

Date.

1913— C

May 2

May 9 -

May 16

May 30

June 6

June 13

June 20

July 18

July 25

August 1

August 8

August 15

August 22

August 29

September 5.. .
September 12-.
September 19-.

October 3

October 24 ....
November 7 . .
November 14 _
November 21 .
November 28 _
December 12 ..
December 19 -
December 26-.

Depth in centi-
meters.

10.

44.2

45.1

50.7

51.4

46.1

42.0

54.8

53.2

56.1

52.4

54.8

53.0

58.1

64.5

55.4

54.8

57.0

55.4

56.1

| 55.2

| 55.1

i 58.4

J 55.2

| 57.2

! 59.1

! 51.2

46.2
42.9
49.4
50.8
45.4
43.5
51.7
59.8
57.3
52.9
56.2
57.8
57.2
61.2
53.9

48.1
42.4
51.0
55.4
46.6
44.7
54.4
57.9
59.4
50.0
55.1
60.0
55.8
58.8
51.2
53.8 J 55.1
61.2 59.4

57.7 56.1

54.8 ' 54.4

51.2
54.6
52.0
55.3
55.4
59.1
48.1

52.1
54.2
47.6
55.1
54.3
59.4
50.8

268

MOUNT MAQUILING

greater than that of the parang, where it was 89.8 per cent.
However, the amount of moisture in the soil in the dipterocarp
forest is always much greater than in the parang, averaging
about 20 per cent higher. The soil of the dipterocarp forest,
like that of the parang, shows the lowest water content during the
dry season. The lowest percentage of moisture observed was 39
at a depth of 10 centimeters on March 21. This percentage is
much greater than the wilting coefficient, which is 25.5 per cent.
From this it would appear that there should be sufficient mois-
ture in the soil for plants at all times; but, as has been pre-
viously noted, the rate of growth of the trees is lower and the
foliage much less dense during the dry season than at other
times. This is probably due primarily, as will be pointed out
later, to the relatively high rate of evaporation prevailing at
this time.

SOIL MOISTURE IN THE MIDMOUNTAIN FOREST

The percentage of water in the soil in the midmountain
forest at an elevation of 730 meters on Mount Maquiling is
given in Table CVIII. The water-holding capacity of the soil

Table CVIII. — Percentage of moisture in the soil in the midmountain forest
on Mount Maquiling ; altitude, 730 meters.

Date.

1912.

November 16

November 23

November 30

December 7

December 14

December 21

December 28

1913.

Depth in centi-
meters.

82.9
68.2
73.5
75.0
78.0
72.7
79.0

January 11

January 18

January25 76.8

February 1 70.2

February 8 j 69.1

February 15 70.5

February 22 73.7

March 1 74.6

March 8 70.1

March 15 57.2

March 22. 62.4

April 5 57.8

April 12 ....

April 26 ..._ 64.4

20.

30.

73.7

76.8

71.2

70.3

72.3

77.7

78.1

77.8

76.2

74.5

74.5

73.5

78.1

76.8

80.1

75.6

77.5

86.2

73.5

19. «

74.7

72 K

74.7
69.7
73.1
70.7
65.1
65.9
55.2
66.2
68.8

76.4
72.0
75.6
74.5
66.4
68.8
60.1
66.5
69.5

Date.

1913— Cont.

May3

May 10

May 17 .....

May 31

June 7-_ .

June 14

June 21

July 19

July 26

August 2

August 23

August 30

September 6

September 20

September 27

October 4

October 25

November 1

November 8

November 29

December 6

December 13

Depth in centi-
meters.

58.8

62.0

63.1

62.9

67.8

65.2

62.9

55.2

63.6

65.7

60.6

62.0

68.3

70.1

80.1

71.0

78.7

74.5

73.4

77.6

70. 5

72.7

71.7

74.6

69. 3

74.9

71.3

70.7

73. S

71.3

72. f»

71.4

78.1

64.6

66. '.)

80.4

82. 3

76.2

74.1

77.3

83. '-■

71.1

74. «>

SOIL MOISTURE 269

at this station is almost identical with that for the diptero-
carp forest, but the amount of water in the soil is always
much greater than in the dipterocarp forest, averaging about
15 to 20 per cent higher. The lowest percentage of moisture
was found during the dry season, just as was the case at
lower elevations. The lowest percentage recorded, however,
was 55.2, which is 57 per cent of the water-holding capacity
of this soil and is more than twice as great as the wilting
coefficient. The percentage of moisture in the soil is between
70 and 80 for a large portion of the year. There is, however,
no indication that this amount is excessive, as the soil is well
drained. A consideration of the amount of water in the soil
at different times of the year would seem to indicate that at
this altitude plants should always have sufficient moisture. The
rate of evaporation is low, and there is no indication that plants
suffer from adverse moisture conditions at any time. The high
moisture content of the soil and the low rate of evaporation
would appear to afford sufficient explanation of the existence
of a ground covering of shallow-rooting mesophytic herbs.

SOIL MOISTURE IN THE MOSSY FOREST

The moisture content of the soil in the mossy forest is given
in Table CIX. This table shows that the moisture content of
the soil in this forest is extremely high. There was only one
week when the determination showed less than 100 per cent
of moisture, and on that occasion this was true of only two of the
three depths. Equally striking was the variation from week
to week, and at different depths in the same week. The dif-
ferent depths frequently showed a variation of more than 100
per cent on the same day. The high moisture content seems
to be connected with the large amount of organic matter found
in this soil. The amount of organic matter apparently varies
greatly in different situations, and the variations in the water
content shown in Table CIX are probably due more to the
places from which samples were taken than to weekly change in
the moisture content of the soil as a whole. The water-holding
capacity of this soil, as determined in the laboratory, was
170.5 per cent, which is a considerably lower percentage of
moisture than was shown by most of the weekly determinations
(>f the amount of moisture in the soil. Owing to the great
variations in the water content, which are apparently due to
the difference in the soil, no great importance can be attached to
fhe actual figures obtained for the water-holding capacity. As

270

MOUNT MAQUILING

Table CIX. — Percentage of moisture in the soil in the mossy forest at the
top of Mount Maquiling ; altitude, 1,050 meters.

Depth in centi-
meters.

Depth in centi-
meters.

Date.

10.

258.1
251.5
305.0
275.9
291.0
234.5

245.0
178.6
130.5
211.1
250.5

1912.
November 16

November 23 _.

November 30 _

December 7

December 14.__ ..

December 21

1913.

January 11

January 18

February 1

February 8

February 15

February 22 _ .

March 1 .

281.8
257.2
221.2
203.6
306.3
167.4
176.5
226.4

March 8 __

March 16

March 22

March 29

April 19 _._

April 26

May 10

20.

30.

190.5

246.7

167.5

121.1

312.4

129.5

258.2

123.2

188. 1

180.5

352.8

232.0

268.2

273.0

149.5

362.3

234.3

305.8

225.2

289.0

188.0

206.0

320.2

319.9

256.0

255.5

198.8

198.6

264.9

232.1

221.8

257.2

114.6

88.2

75.1

152.0

139.2

136.8

122.0

Date.

10.

20.

30.

1913— Cont.
May 17

303. 9
224.3
260.2
159.4
209.8
212.7

214.5
185.4
246.7
161.7
226.0
171.0
137.2
211.8
207%
104.2
146.8
199.7
257.1

164.2
305.5
186.1
263.2
203.6
204.8
222.1

173 6

May 24

May 31

173.6

251 8

June 7

162 4

June 14

206 0

June 21

Julyl9.___

255. 0

August 2..

237.7
273. 8

231 8

August 9

August 16

197.7

August 23

200.1
218.3
238.0
218.8
148.1
159.9
185.7
154.2
247.3
165.3
134.6

141 2

August 30

September 27..-

142.8

October 4

173.1

October 18___ _ _

256.2

October 25

247.9

November 8

302.0

November 22

November 29

301.2
256.5

December 6.

272.1

December 13 .

the soil on which the determination was made was first brought
to the laboratory and dried, changes in the high organic content
may, of course, have caused it to lose some of its water-holding
capacity before this capacity was determined.

RELATION OF SOIL MOISTURE TO VEGETATION

The moisture content shown by the soil in the mossy and mid-
mountain forests is undoubtedly connected with the fact that the
ground covering is composed of plants that require more mois-
ture than do those found in the dipterocarp forest.

It does not seem probable, however, that the dwarfing of the
vegetation is connected with this high water content. The
great amount of water in the soil of the mossy forest is not
due to heavy rains that would cause the soil to become leached,
as the rainfall is about the same in amount here as in the area
from which the soil samples were taken in the dipterocarp
forest, and is considerably less than in the midmountain forest
and in a large proportion of tlie dipterocarp forest. The soil
of the mossy forest is, moreover, well drained, so that it must

SOIL MOISTURE 271

be well aerated, and it has a springy consistency. The figures
in Table LVIII show less acidity in the soil of the mossy forest
than in that of the dipterocarp forest. There seems, therefore,
to be no reason for considering the high moisture content of the
soil as harmful. The moisture content of the soil of the mid-
mountain forest would certainly not seem to be high enough to
be deleterious to vegetation. The fact that the trees in this
situation are much smaller than those in the dipterocarp forest
is probably due to the same factors that have resulted in the
stunted vegetation on the top of the mountain, the difference
being that these factors are more pronounced at the top.

The above discussion indicates that the moisture content of
the soil should be as favorable at high as at low altitudes, and
so cannot be connected with the dwarfing of vegetation as higher
altitudes are reached.

HUMIDITY

The relative humidity at the different elevations was meas-
ured by means of Draper recording hygrometers, which were
placed in the same cases as the thermometers. The results
are presented in Tables CX to CXXIII, in the form of weekly
maxima and minima, means, and the averages of daily maxima
and minima. The weekly figures are summarized for corre-
sponding four-week periods, as was done with the figures for
temperature. The means were obtained from the records by a
planimeter. In using the planimeter with circular Draper re-
cording hygrometer records the same error is introduced as that
described in connection with temperature. As in the former
case this error is negligible. If the humidity were 90 per cent
for one half of each day and 60 per cent for the other half, the
error due to the use of the planimeter would be less than 0.3
per cent. Such a variation in humidity was observed nowhere
except at the base station, and it was seldom greatly exceeded
at that place. The actual error for variations between 60 and
90 per cent would, of course, be much less than 0.3 per cent, as
the maximum and minimum are maintained for only very short
periods of time. We may safely conclude that the error in the
figures presented here for the mean is considerably less than
0.1 per cent; which is, of course, much less than the error in
the instrument and is within the limits of accuracy with which
the records can be read.

HUMIDITY IN THE PARANG

The recording of humidity under the second-growth trees at
the base of Mount Maquiling was begun in October, 1912, and
continued until January, 1915. The results are presented in
Table CX in the form of weekly maxima and minima, means,
and averages of daily maxima and minima. The results are
further summarized in Table CXI for corresponding four-week
periods for the entire time. The mean humidity was 82.2 per
cent; the average daily maximum, 90.7 per cent; and the aver-
age daily minimum, 68.6 per cent. The average daily range
was, therefore, 22.1 per cent. These figures indicate a compar-
atively high humidity.

272

HUMIDITY

273

TABLE CX. — Relative humidity under second-growth trees at the base of
Mount Maquiling ; altitude, 80 meters.

[Numbers give percentage of saturation.]

Week ending-

October 11 _._
October 18 .._
October 25 _._.
November 1..
November 8-_
November 15 _
November 22.
November 29.
December 6 ._.
December 13 ..
December 20 _
December 27 ..

January 3.

Average .

January 10 _ .
January 17 _ -
January 24 _ _
January 31 _ .
February 7 - _
February 14 .
February 21 _
February 28 -

March 7

March 14

March 21

March 28

April 4 .

April 11

April 18

April 25

May 2 ...

May 9

May 16

May 23

May 30

1912.

1913.

June 6
June 13

June 20

June 27

July 4_

July 18

July 25

August 1

August 8

159549 18

Maxi-
mum.

96.5
96.5
96.5
96.0
92.0
92.0
92.5
93.0
92.0
92.5
92.5
92.5

92.5

Mini-
mum.

80.5
77.5
77.0
67.0
70.0
71.0
69.0
70.0
70.0
65.0
71.5
64.5

93.0
92.5
93.0
91.5
92.5
90.5
93.0
92.0
94.0
92.0
92.5
93.5
92.5
93.0
94.0
93.0
94.0
95.0
95.0
94.0
94.5
95.0
93.0
95.0
93.5
94.0
92.5
93.0
92.0
92.0

Mean.

70.0

71.0 I

73.0
67.0
57.0
59.5
64.0
57.5
55.0
58.0
62.0
55.5
45.0
46.0
50.0
45.0
64.5
58.0
50.0
75.0
60.0
50.5
62.5
57.0
56.5
57.5
65.0
64.0
69.0
69.0
63.5
67.0

93.0
90.4
91.0
86.0
83.4
85.4
72.0
85.0
84.6
83.4
85.0
85.2

85.5

86.4
86.0
84.0
83.2
85.2
82.0
80.4
82.2
83.0
81.2
75.0
75.0
77.2
78.2
85.2
81.0
79.4
88.2
82.4
83.0
85.0
82.0
81.0
84.0
85.0
85.4
87.2
84.2
83.4
85.0

Average of daily-

Maxima. Minima,

95.7
95.8
91.3
90.6
90.1
90.8
90.9
91.3
90.4
91.0
90.9

91.5

92.0

91.1
91.8
91.5
89.6
91.1
89.6
90.6
91.3
90.7
91.0
90.0
92.4
91.6
92.1
92.9
91.1
91.9
93.3
93.4
93.2
92.7
92.8
92.4
92.9
92.6
93.0
91.6
90.9
90.4
90.4

274

MOUNT MAQUILING

Table CX. — Relative humidity under second~growth trees at the base of
Mount Maquiling; altitude, 80 meters — Continued.

Week ending —

1913.

August 16

August 22..

August 29

Septembers

September 12

September 19

September 26 -

October 8 _. ...

October 10

October 17

October 31

November 7

November 14

November 21

November 28

December 5

December 12

December 19

December 26,

1914.
January 2

Average

1914.

January 9 __'__

January 16

January 23

January 30

February 6

February 13

February 20

February 27

March 6

March 13

March 20

March 27

Aprils

April 10

April 17

April 24

May 1

May 8

May 15 _.

May 22

May 29.... ...

June 5

June 12

June 19

June 26

Maxi-
mum.

91.6
91.5
91.0
92.0
91.5
92.0
91.5
92.5
93.0
91.0
90.5
92.5
91.0
90.5
90.5
92.0
91.5
91.0
91.0

91.5

92.5

91.5
91.0
91.5
90.0
93.0
91.0
91.0
91.5
90.0
92.0
91.0
91.5
90.0
92.5
92.5
92.0
92.0
92.0
92.5
92.5
92.5
93.0
93.0
94.0
92.0

Mini-
mum.

64.0
72.0
68.0
70.0
62.0
67.5
63.5
61.0
69.5
72.0
62.0
70.5
66.5
66.5
66.0
69.5
66.5
73.5
66.0

70.0

62.6

63.0
61.0
57.0
66.6
57.5
57.0
45.0
25.0
50.6
46.5
41.5
38.0
43.5
54.0
62.0
54.0
42.0
46.0
48.6
48.5
51.0
56.0
58.0
56.6
66.5

Mean.

82.4
84.2
86.0
83.2
81.2
83.0
84.0
83.2
84.2
86.2
77.0
85.0
83.4
82.2
82.4
83.0
84.4
85.2
85.0

83.0
83.0

83.2
79.0
80.0
80.0
79.0
80.2
76.0
75.2
78.0
76.0
74.0
74.0
73.0
81.0
74.6
79.0
76.0
75.0
77.4
80.0
77.4
84.0
81.0
83.2
87.0

Average of daily-

Maxima. Minima.

90.3
90.4
90.5
90.1
90,1
90.5
90.7
90.6
90.8
90.1
88.5
90.9
88.7
89.9
88.0
89.6
88.1
90.5
89.5

88.5

87.1

89.0

87.1

89.5

89.2

88.0

90.1

87.8

89.3

89^7

88.6

88.7

89.9

89.6

90.5

90.1

90.7

91.0

91.5

90.4

91.2 |

90.9

92.1

91.6

HUMIDITY 275

Table CX. — Relative humidity under second-growth trees at the base of
Mount Maquiling; altitude, 80 meters — Continued.

Week ending-

1914.

July 3

July 10. ._

July 17

July 24

July 31

August 7

August 14

August 21

August 28

September 4 _ _
September 11 .
September 18 -
September 25 .

October 2

October 9

October 16

October 23

October 30

November 6___
November 13. .
November 20 .
November 27 _
December 4 . _ _
December 11. .
December 18. _
December 25.-

1915.

January 1

Average

Maxi-

Mini-
mum.

Mean.

Average of daily-

mum.

Maxima.

Minima.

93.0

69.5

84.0

91.2

72.6

92.5

61.0

82.4

90.5

70.6

93.0

64.0

80.0

87.9

69.8

92.5

72.5

87.0

91.7

76.6

93.0

65.0

84.0

91.1

68.6

93.0

56.0

83.0

91.6

61.1

94.5

70.0

86.0

91.8

75.0

93.0

62.0

84.0

92.5

71.1

93.0

63.5

75.4

84.6

68.4

91.5

79.5

85.2

87.1

83.2

91.5

71.5

85.2

90.2

77.7

93.0

70.0

85.0

91.2

75.0

92.0

63.0

83.0

91.4

68.5

92.0

66.0

86.0

91.7

74.2

92.0

69.5

84.2

91.0

76.3

92.0

68.0

82.0

90.0

72.1

92.0

59.0

84.2

90.7

71.5

92.5

60.0

82.2

89.9

67.8

92.5

63.0

82.2

90.5

69.0

91.5

58.5

83.0

90.2

69.0

92.5

66.0

82.2

90.9

71.7

92.5

62.5

82.0

90.8

68.5

92.5

73.5

86.0

91.3

78.7

92.5

68.0

85.0

91.1

74.2

92.0

61.0

84.2

90.9

70.9

92.5

62.5

84.0

91.0

74.4

91.5

56.0

80.4

90.2

65.5

92.1

58.4

81.1

90.1

66.5

The absolute maximum was 96.5 per cent, and the minimum
was 25 per cent The latter figure was very exceptional and
was accompanied by rather peculiar circumstances. At the
time the writer was living in a large bamboo house at the
forest station. On particularly dry days bamboo is sometimes
noticed to crack, and on this occasion there was an unusual
amount of cracking. This led to an examination of the hygro-
meter, which was recording a relative humidity of 25 per cent.
The figure was so very low that it was checked with a sling
Psychrometer and found to be correct. On examining the records
for the week at the different stations, it was found that they
all showed a remarkably low humidity on that day. This re-
cord of 25 per cent was considerably lower than any other

276

MOUNT MAQUILING

reading obtained, and there was no apparent reason to account
for it, as the temperature was not unusually high.

Table CXI. — Relative humidity for periods of four weeks from October,
1912, to January, 1915, under second-growth trees at the base of Mount
Maquiling ; altitude , 80 meters.

[Numbers give percentage of saturation.]

Four weeks ending —

January 31

February 28. _.

March 28

April 25

May 28 ._

June 20

July 18

August 15

September 12 .
October 10 ....
November 7...
December 5 ...
January 2

Average

Maxi-
mum.

93.0
93.0
94.0
94.0
95.0
95.0
94.0
94.5
93.0
93.0
96.5
93.0
92.5

3.9

Mini-
mum.

56.5
25.0
38.0
43.5
42.0
51.0
61.0
56.0
62.0
61.0
59.0
58.5
56.0

51.5

Mean.

82.8
80.1
77.1
78.7
80.2
82.2
84.7
84.4
83.1
84.1
84.4
82.6
83.7

82.2

Average of daily-

Maxima.

Minima.

89.5

70.2

90.0

63. 1

90.0

58.3

90.8

60.9

91.9

60.9

92.0

64.9

91.4

72.1

91.1

71.3

89.5

73.9

91.0

72.5

91.2

75.4

90.2

74.1

90.3

74.6

90.7

68.6

1

An examination of Table CX shows that there was no week
in which the maximum humidity was not over 90 per cent,
no week in which the average maximum was less than 84 per
cent, and only one week during which it was less than 87 per
cent. As the high humidities occur at night, it is evident that
the humidity is always high at that time. The highest mean
humidity occurred during the rainy season and the lowest dur-
ing the dry season, particularly in March and April. The aver-
age daily maximum humidity showed very little variation at
different times of the year. The average daily minimum was
lowest during the dry season, beginning with February and
ending in May. The highest average minimum, however, does
not occur in the rainy season, but during November, December,
and January, when the temperature and light intensity are both
low.

In fig. 15 are plotted the maxima, minima, average daily
maxima, average daily minima, and means for corresponding
four-week periods. The curves for the maxima and the aver-
age daily maxima have the same general form and show but
little variation with the seasons. The mean is considerably

HUMIDITY

277

lower in the dry season than at other times. The effect of
the dry season is most marked in the curves for the average
daily minima and the minima.

Periods of four weeks ending —

Jon 31 feU8 Mor.28 Apr.ZS MayE3June20Julyl8 Aug.15 SeptlZ OctlO Nov. 7 Dec 5 Jan.2

Fig. 15. Relative humidity under second-growth trees at the base of Mount Maqui-
ling ; altitude, 80 meters.

278 MOUNT MAQUILING

HUMIDITY IN THE DIPTEROCARP FOREST

The recording hygrometers in the dipterocarp forest were
placed in the same cases as the recording thermometers. The
results at an elevation of 300 meters are given in Table CXII
in the form of weekly maxima and minima, means, and aver-
age daily maxima and minima; and are summarized for the
entire period in Table CXIII in the form of maxima, minima,
means, and averages of daily maxima and minima for cor-
responding four-week periods. The humidity under the for-
est at an elevation of 300 meters is considerably higher than
in the parang at 80 meters, the mean humidity in the former
location being 89.7 per cent, and in the latter, 82.2 per cent. The
average daily maximum in the dipterocarp forest at 300 meters'
elevation was 93 per cent, and the average daily minimum, 82.9
per cent. The absolute minimum was 47.5 per cent. This
minimum occurred on the particularly dry day mentioned in
the discussion of humidity in the parang. From an examina-
tion of Tables CXII and CXIII it will be seen that, with the
exception of a very few days, the humidity in the forest at
an elevation of 300 meters was relatively high and, moreover,
fairly uniform, as the average daily variation was only 10.1
per cent. In the parang the variation was considerably
greater, being 22.1 per cent. The smaller average daily range
as well as the higher humidity in the dipterocarp forest is
perhaps due in part to the higher elevation, but probably even
more to conditions existing under the dense forest and to the
large amount of water transpired by the foliage.

It will be noticed that the mean does not change with the
seasons in exactly the same manner as does the mean at an ele-
vation of 80 meters, the highest average means occurring dur-
ing the colder months — November, December, and January —
rather than during the rainy season, from July to September.
The lowest means, however, are found during the dry season,
from March to May. The average daily maxima and minima
vary in much the same way as the means.

The maxima, minima, means, and average daily maxima and
minima are plotted in fig. 16. As in the case of the parang,
the curves for the average daily maxima and for the maxima are
very similar in form. They both, however, show the effect of
the dry season to a greater extent than the curves for the pa-
rang. Also, as in the parang, the curve for the mean shows the
effect of the dry season more than do the curves for the max-

HUMIDITY

279

ima and minima ; while this effect is again most marked for the
average daily minima and for the minima.

Table CXIL— Relative humidity in the undergrowth in the dipterocarp
forest on Mount Maquiling ; altitude, 300 meters.

[Numbers give percentage of saturation.]

Week ending-

May 30

June 6

June 13 _.

June 20

June 27

July 4..__

July 11

July 18

July 25

August 1

August 8

August 15

August 22

August 29

September 5 ..
September 12
September 19 .
September 26 .

October 3

October 10

October 17

October 24 _._.

October 31

November 7__.
November 14 ..
November 21..
November 28-.
December 5 _..
December 12 ..
December 19 __
December 26 _.

January 2

Average .

January 9

January 16. _.
January 23..
January 30. _
February 6...
February 13.
February 20..
February 27.
March 6

1914.

axi-

Mini-

um.

mum.

96.0

79.0

96.0

75.5

97.0

73.5

96.0

74.0

95.0

83.0

94.5

82.5

96.0

84.5

93.0

85.0

93.0

84.5

93.0

78.0

93.0

80.0

93.5

80.0

94.5

85.0

93.0

86.0

93.9

85.0

95.0

77.0

94.0

82.0

94.0

82.0

94.0

79.0

96.0

86.0

95.0

84.0

95.5

83.0

96.0

75.0

96.0

89.0

96.5

86.5

97.0

86.0

97.0

86.5

96.5

87.0

96.0

87.0

96.5

92.0

96.5

86.0

97.0
95.2

95.0
95.0
95.0
97.0
93.5
93.6
94.0
93.0
93.0

87.0

86.0
82.0
82.0
80.0
80.0
80.0
66.0
47.5
70.0

Mean.

90.2
91.5
89.3
91.3
90.7
92.0
92.0
91.4
90.1
89.4
90.2
89.4
90.2
89.0
91.4
90.2
90.0
92.0
91.0
93.2
93.0
93.3
89.6
93.3
92.0
94.2
94.3
93.2
94.1
94.4
94.2

91.7

Average of daily-

Maxima. Minima

94.1
95.1
95.3
95.1
93.7
93.9
93.8
92.0
91.8
91.0
91.5
91.8
92.4
92.1
92.1
93.0
93.1
93.0
93.0
94.3
94.3
94.5
94.1
94.9
94.2
96.3
96.3
95.8
95.5
95.5
95.8

93.2

94.6

92.2

94.7

92.0

93.9

93.4

96.1

89.2

92.5

89.5

92.9

87.4

93.0

86.0

92.2

89.0

92.0

84.3
81.1
76.4
82.9
86.8
87.0
88.3
89.3
85.8
85.5
85.3
83.6
88.0
87.5
86.3
84.7
85.6
87.0
85.1
88.5
89.2
88.0
84.2
91.7
88.9
91.5
91.5
90.0
91.8
94.0
92.3

91.0

87.5
84.0
87.7
82.9
84.6
76.9
72.1
80.9

280

MOUNT MAQUILING

Tables CXIL— Relative humidity in the undergrowth in the dipterocarp
forest on Mount Maquiling; altitude, 300 meters— Continued.

Week ending-

March 13

March 20

March 27

Aprils

April 10

April 17..

April 24..

Mayl- -

May 8

May 15

May 22

May 29 -

June 5

June 12

June 19

June 26

July 3..

July 10-„

July 17

July 24

July 31

August 7

August 14

August 21

August 28

September 4...
September 11.
September 18.
September 25-

October2

October 9

October 23

October 30

November 6__.
November 13—
November 20—
November 27—
December 4 —
December 11—
December 18—
December 26..

1914.

Maxi-
mum.

1915.

January 1

Average .

92.0

92.0

91.5

91.5

92.0

91.0

91.0

91.9

92.5

92.0

91.5

92.0

92.0

92.0

93.0

93.0

93.0

92.5

93.0

93.0

94.0

93.5

94.5

94.5

94.5

94.0

94.5

94.5

94.5

94.0

94.0

95.0

96.0

95.0

95.0

95.5

97.0

98.0

96.0

95.5

95.5

96.5

Mini-
mum.

65.5

57.5

57.0

60.0

73.0

69.0

70.0

58.5

61.0

63.6

62.0

66.0

73.5

72.0

71.0

82.0

83.0

76.0

78.0

86.5

82.5

76.0

80.5

76.8

75.5

78.0

82.5

84.0

77.0

83.6

84.0

80.0

79.0

85.0

82.0

84.5

82.0

91.5

91.0

84.8

81.0

81.0

Mean.

86.0

84.2

84.0

82.0

87.2

86.0

86.2

84.0

83.4

86.0

85.4

86.0

89.0

88.0

89.4

90.0

89.4

88.4

87.0

92.0

89.4

88.4

90.4

89.0

85.0

92.0

91.2

91.4

90.4

91.2

91.4

92.4

91.2

91.4

92.0

92.2

93.0

94.2

94.0

93.2

93.2

92.4

Average of daily-

Maxima. Minima.

89.3

91.3

91.6

90.6

91.0

91.2

89.9

89.7

90.9

91.4

91.2

91.1

91.1

91.1

91.7

91.6

92.3

92.2

91.0

90.8

92.6

92.9

93.1

92.9

93.1

88.8

93.1

92.8

93.7

93.2

93.2

93.1

94.3

93.0

94.5

94.3

94.5

95.7

95.6

95.6

94.8

94.6

93.7

92.7

73.2

70.4

68.1 |

67.4 j

80.9

75.8

76.9

65.9

70.4

71.8

74.3

71.8

83.5

80.8

82.3

86.7

85.9

83.6

83.0

88.9

84.1

78.9

86.1

83.3

79.9

87.1

86.8

88.2

85.0

87.1

88.9

88.6

86.6

87.9

87.8,

88.9

88.2

93.7

92.3

89.4

90.3

86.3 |

HUMIDITY 281

Table CXIIL— -Relative humidity for periods of four weeks from May,
191$, to January, 1915, in the undergrowth in the dipterocarp forest
on Mount Maquiling; altitude, 800 meters.

[Numbers give percentage of saturation.]

Four weeks ending-

Maxi-
mum.

Mini-
mum.

Mean.

Average of daily-

Maxima.

Minima.

January 30

97.0
94.0
93.0
92.0
92.5
97.0
96.0
94.5
95.0
96.0
96.0
98.0
97.0

80.0
47.5
57.0
60.0
58.5
66.0
76.0
76.0
75.5
77.0
75.0
82.0
81.0

92.7
88.0
85.8
85.3
84.7
89.4
90.1
89.9
89.8
91.3
92.0
93.1
93.7

94.8
92.6
91.4
90.4
91.1
93.2
92.5
92.2
92.2
93.4
94.2
95.4
95.2

87.1
79.1
73.1
75.2
70.6
80.4
86.3
84.8
85.5
86.9
88.0
90.1
91.0

82.9

February 27 ._

March 27

April 24

May 22

June 19

July 17

August 14 .

September 11

October 9

November 6

December 4

January 1

Average .

95.2

70.1

89.7

93.0

- - ■

The weekly records of humidity at an elevation of 450
meters are given in Table CXIV, and the figures are sum-
marized in Table CXV. The humidity in the forest at 450
meters' elevation is very similar to that at 300 meters' elevation,
but is slightly lower, the mean at 450 meters being 1.9 per cent
lower than at 300 meters. The hygrometer at 450 meters' ele-
vation was, however, on a more exposed ridge than that at an
altitude of 300 meters. The mean humidity and the average
daily minimum vary in much the same way at 450 meters as
at 300 meters' elevation. The average daily maximum, however,
does not appear to be any lower during the dry season than at
other times.

At 450 meters' elevation a recording hygrometer was also
placed in the open in the same case as the thermometer. This,
however, was run only from the last week in April, 1914,
to November 27, 1914. Even in this short period there were
four weeks during which records were not obtained, as the
machine was an old one and the clock did not work well. The
weekly results are given in Table CXVI and are summarized
in Table CXVII. Table CXVII presents some rather interest-
ing features. For the sake of comparing the humidity in the

282

MOUNT MAQUILING

Periods of four weeks ending —

JanJOFeb.27 Man27Apr.2+ May22 June 19 July 17 Ai/g.14 Septll Oct.9 Nov.6 Dec A Jan. I

Fig. 16. Relative humidity in undergrowth in dipterocarp forest ; altitude, 300 meters.

Table CXIV.: — Relative humidity in the undergrowth in the dipterocarp
forest on Mount Maquiling; altitude, 450 meters.

[Numbers give percentage of

saturation.]

Week ending—

Maxi-
mum.

Mini-
mum.

84.0
73.5
74.6
83.0
82.0
83.5
78.0
75.5

Mean.

Average of daily-

Maxima.

Minima

1913.
August 1 _ _ _ .

91.0
91.0
93.0
91.5
92.0
92.0
93.0
93.0

86.2
87.0
86.0
88.0
87.8
88.0
86.0
87.4

89.2
89.9
90.5
90.7
90.6
91.0
90.3
91.3

85.8
81.4
81.3
85.7
84.7
86.0
83.7
82.3

August 8 .__ ..

August 15

August 22 _

August 29

Septembers ._

September 12

September 19

HUMIDITY

283

Table CXIV.— Relative humidity in the undergrowth in the dipterocarp
forest on Mount Maquiling ; altitude, A50 meters— Continued.

Week ending-

September 26 _

October 3

October 10

October 17

October 24

October 31

November 7 ...
November 14 .
November 21 __
November 28 _

December 5

December 12 __
December 19. _
December 26 ..

January 2

Average .

January 9-__
January 16 __
January 23 ._
January 30...
February 6 . _
February 13.
February 20.
February 27.

March 6

March 13

March 20

March 27

April 3

April 10

April 17

April 24

May 1

May 8

May 15

May 22

May 29

June 5

June 12

June 19

June 26 ......

July 3

July 10

July 17

July 24.

1918.

1914.

Maxi-

Mini-
mum.

Mean.

" ' " ' 1

Average of daily-

mum.

Maxima.

Minima.

93.0

77.5

88.6

91.4

84.1

92.5

71.0

85.0

91.3

78.8

93.0

77.5

88.,4

91.6

82.9

92.0

78.0

88.4

90.8

85.6

j 92.0

76.0

88.2

90.8

83.2

93.5

64.0

85.4

91.6

77.7

94.0

83.0

90.2

91.1

86.6

93.5

79.0

91.2

92.4

86.4

94.0

78.5

90.4

93.5

86.3

94.5

78.0

91.2

93.1

87.5

94.5

83.0

91.6

93.6

87.9

, 94.5

85.0

91.6

93.0

89.9

94.5

90.0

91.6

93.1

90.7

94.5

88.0

92.0

93.1

90.4

93.4

85.5

91.0

92.2

89.5

93.0

79.5

88.7

91.6

85.1

94.0

83.0

90.4

92.3

86.5

94.0

76.0

89.2

92.5

82.9

97.9

77.0

92.0

97.1

84.3

94.0

76.5

89.0

92.6

79.6

95.0

74.0

88.4

93.5

79.6

94.0

77.0

89.0

92.5

84.7

93.0

59.5

85.0

91.1

70.9

96.0

45.0

84.4

93.3

70.7

93.0

66.0

88.0

92.1

79.5

92.0

54.0

84.2

91.5

70.5

99.0

54.0

82.2

93.4

68.2

94.0

53.0

84.0

93.0

66.6

98.0 ,

59.5

81.2

92.5

67.1

93.0 |

74.2

89.0

92.4

81.5

93.0 |

71.0

86.2

91.9

76.5

93.0

63.0

87.2

91.5

76.8

91.5

56.5

81.0

90.4

64.6

94.9

65.0

84.6

93.1

72.2

94.9

62.1

87.0

93.3

72.6

95.0

65.5

87.2

93.1

77.3

95.0

66.0

85.0

93.0

72.1

95.0

73.5

89.4

92.5

84.1

93.5

74.2

87.0

92.3

79.1

94.0

68.0

90.0

92.6

81.8

93.0

79.5

89.4

91.9

85.8

93.5

82.0

89.0

92.5

86.6

92.5

80.0

89.0

90.8

86.6

93.5

78.5

88.2

92.0

85.0

93.0

88.0

90.2

91.7

89.1 .

284

MOUNT MAQUILING

Table CXIV. — Relative humidity in the undergrowth in the dipterocar},
forest on Mount Maquiling ; altitude, 450 meters — Continued.

Week ending -

Maxi-
mum.

1914.

July 81 ._

August 7

August 14

August 21

August 28

September 4...
September 11.
September 18 _
September 25 _.

October 2

October 9

October 16 ....
October 23 ....
October 30 ....
November 6 ...
November 13 ..
November 20..
November 27..

December 4

December 11 .
December 18 .
December 25. _

1915.

January 1

Average .

94.5
93.9
92.5
94.5
95.5
92.0
92.5
93.5
93.0
93.0
93.0
93.0
93.0
92.5
92.5
93.0
93.0
93.0
92.0
92.0
91.5
92.0

93.7

Mini-
mum.

72.0
72.0
82.0
75.1
78.0
82.0
87.5
76.0
79.5
82.0
82.2
81.5
77.0
78.0
84.0
79.0
83.2
78.0
87.5
87.5
80.0
84.0

74.0

Mean.

88.0
87.0
90.4
88.4
86.0
90.0
90.4
89.4
88.0
90.2
90.0
88.0
90.0
89.0
89.2
89.4
89.2
88.0
90.0
90.0
89.0
88.4

88.0

Average of daily-

Maxima. I Minima.

91.5

79.8

93.1

77.1

91.8

86.9

92.3

83.5

90.3

82.1

91.1

88.6

90.8

88.5

92.4

82.0

91.2

84.1

92.3

87.7

91.9

87.2

91.1

85.4

91.9

86.8

91.6

85.8

91.4

85.5

92.1

85.6

92.0

86.5

92.1

86.6

91.4

89.8

91.5

89.1

91.0

86.8

91.4

88.8

87.9

92.1 ! 81.3

open with that in the forest, Table CXVIII has been construct-
ed, to show the relative humidity under the forest for the same
four-week periods in 1914 as are covered by Table CXVII for
humidity in the open. A comparison of these two tables shows
that during the eight four-week periods the maximum humid-
ity was greatest in the open for five periods, the same in
both situations for one period, and greatest in the forest for
two periods. The minimum for the four-week periods was al-
ways lower in the open than in the forest. The mean was
higher sometimes in the forest and sometimes in the open. The
average daily maximum was higher in the open for five periods,
the same in both situations for one period, and higher in the
forest for two periods. The average daily minimum was al-
ways considerably less in the open than in the forest. The
lower minima in the open would appear to be due to the removal
of the forest canopy, admitting of the freer movement of the

HUMIDITY 285

wind, which allowed the drier air above the tops of the trees
to strike the hygrometer. That the maximum should be greater
in some cas.es in the open and in others in the forest is probably-
due to various local conditions. When clouds come down from
higher elevations, they lose some of their water content in pass-
ing through the canopy before they reach the hygrometer
under the forest, whereas they have direct access to the hygrom-
eter in the open. When, on the other hand, there was no
such movement, the cooling at night of the humid air under
the forest would produce a higher humidity than the cooling
of the drier air which reached the hygrometer in the open.

Table CXV. — Relative humidity for periods of four weeks from July, 1913,
to January, 1915, in the undergrowth in the dipterocarp forest on
Mount Maquilincr; altitude, 450 meters.

[Numbers give percentage of saturation.]

Pour weeks ending-

January 30

February 27_._

March 27

April 24

May 22

June 19

July 17

August 14

September 11 _.

October 9

November 6

December 4

January 1

Average .

Maxi-
mum.

Mini-
mum.

Mean.

Average of daily—

__.

Maxima. Minima.

97.9

76.0

90.1

93.8

83.3

96.0

45.0

86.7

92.6

76.6

99.0

53.0

84.6

92.5

71.2

98.0

59.5

85.9

92.1

75.5

95.0

56.5

84.9

92.5

71.7

95.0

66.0

87.8

92.6

79.3

93.5

78.5

88.9

91.8

86.0

94.5

72.0

87.7

91.0

83.0

95.5

75.1

88.1

90.9

85.4

93.5

71.0

88.4

91.7

83.7

94.0

64.0

88.5

91.3

84.6

94.5

78.0

90.1

92.6

87.1

94.5

77.5

90.2

92.1

88.4

95.5

67.1

87.8

92.1

81.2

HUMIDITY IN THE MIDMOUNTAIN FOREST

A recording hygrometer was also placed in the case with the
recording thermometer at an elevation of 740 meters in the
midmountain forest. The records are given in the form of
weekly maxima, minima, means, and average daily maxima and
minima in Table CXIX; and the results are summarized for
corresponding four-week periods in Table CXX. The humid-
ity at this elevation is slightly higher than in the dipterocarp
forest at 450 meters' elevation. The mean humidity for the
entire period in the midmountain forest was 90.4 per cent,
and in the dipterocarp, 87.8 per cent, a difference of 2.6 per
cent. The absolute maximum in the midmountain forest was
$9.2 per cent, and the absolute minimum, 54.5 per cent. The

286 . MOUNT MAQUILING

Table CXVI. — Relative humidity for weekly periods in the open on Mount
Maguiling ; altitude, 450 meters.

[Numbers give percentage of saturation.]

Week ending-

1914.

Mayl

May8

May 15.—

May 22

June 12 ___

June 19

June 26

July 3

July 10-

July 17

July 24

July 31

August 7

August 14

August 21

September 11

September 18

September 25

October 2

October 9

October 16 ..

October 23

October 30

November 6.__

November 13 __

November 20

November 27

Maxi-
mum.

94.3
93.0
96.5
96.0
92.0
92.5
92.0
93.5
92.5
94.5
93.5
94.5
94.5
94.5
95.0
88.5
94.5
96.5
9'7.0
97.0
98.5
98.5
98.9
98.0
98.0
98.7

Mini-
mum.

54.5

60.5

58.0

58.0

60.0

63.5

66.5

72.5

69.0

64.5

73.6

66.0

63.0

74.0

64.0

85.5

68.0

70.5

73.0

73.5

72.0

68.0

71.0

76.2 j

73.8

76.0

69.5

83.2
85.0
86.4
86.4
82.0
85.2
86.4
87.2
87.4
87.0
89.2
87.0
85.0
91.2
87.4

Average of daily-

Maxima Minima

85.4 |

84.5 j
86.7 |
87.3 |
92.0 ;
94.5
93.0
92.7
98.3
93.1
92.5

95.5
95.7
96.7
96.6
91.0
90.7
91.4
92.8
91.1
93.1
92.7
92.9
93:9
93.4
93.7
88.5
89.3
89.6
90.9
91.7
96.8
97.5
97.6
97.4
97.6
97.5
96.0

61.3
66.8
67.4
67.4
66.1
71.9
75.0
76.3
78.9
76.0
78.0
73.0
66.6
81.1
76.1
85.5
77.1
74.6
78.8
80.2
78.6
82.3
79.4
79.4
79.3
80.6
79.6

Table CXVII. — Relative humidity for periods of four weeks in the open on

Mount Maquiling; altitude, 450 meters.

[Numbers give percentage of saturation.]

Four weeks ending-

1914.

May 22

June 19

July 17

August 14

September 11

October 9...

November 6

December 4..

Average

Maxi-
mum.

Mini-
mum.

Mean.

Average

Df daily—

Maxima.

Minima

96.5

54.5

85.3

96.1

65.7

92.5

60.0

83.6

90.9

69.0

94.5

64.5

87.0

92.1

76.6

94.5

63.0

88.1

93.2

74.7

95.0

64.0

87.4

91.1

80.8

97.0

68.0

86.0

90.4

77.7

98.9

68.0

93.1

97.3

79.9

98.8

69.5

93.0

97.0

79.8

96.0

63.9

87.9

93.5

75.5

HUMIDITY ' 287

Table CXVIIL— < Relative humidity for periods of four weeks in the under-
growth in the dipterocarp forest on Mount Maquiling; altitude, WO
meters.

[Numbers give percentage of saturation.]

Four weeks ending-

May 22

June 19

July 17

August 14

September 11.

October 9

November 6

December 4

Average.

Maxi-
mum.

!

Mini-
mum, i

Mean.

Average of daily-
Maxima. 1 Minima.

95.0

56.5

84.9

92.5

71.7

95.0

66.0 j

87.8

92.6

79.3

93.5

78.5 j

88.9

91.8

86.0

94.5

72.0 |

88.9

92.0 83.2

95.5

75.1 |

88.7

91.1

85.7

93.5

76.0 ;

89.4

92.0

85. 3

93.0

77.0 !

89.0

91.5

85.9

93.0

78.0

89.1

91.9

87.1

88.3

91.9

83.0

average daily maximum was 93.5 per cent, and the average
daily minimum, 85.7 per cent, a difference of 7.8 per cent, which
is less than the average daily variation at 450 meters' ele-
vation, where the average daily range was 10.9 per cent. The
figures in Tables CXIX and CXX show that with the exception
of short periods of a few days the humidity in the midmountain
forest was always high and was, moreover, very even.

Table CXIX. — Relative humidity in the midmountain forest on Mount Ma-
quiling; altitude, 740 meters.

[Numbers give percentage of saturation.]

Week ending—

Maxi-
mum.

Mini-
mum.

76.0
78.5
75.5
74.0
85.5
84.0
91.2
84.5
82.0
83.0
81.0
80.2
79.0
77.5
79.5
83.5

Mean.

89.2
92.2
91.4
89.0
94.0
93.2
93.4
93.2
91.3
91.4
91.2
91.2
91.1
90.2
89.1
93.0

Average <
Maxima.

96.1
96.7
97.4
91.1
95.6
95.5
94.7
95.2
93.1
94.7
93.8
94.4
94.5
93.5
94.8
95.8

>f daily-
Minima.

1913.

June 13

June 20

97.5
97.6
99.2
92.5
98.0
97.5
95.5
96.5
94.5
96.3
95.5
96.0
97.0
96.5
96.5
97.2

77.7
84 5

June 27

83 5

July 4 ..

83 9

July 11 _ _

90 9

July 18

90 7

July 25 _

93 1

August 1 ..

89.6

August 8

86 8

August 15

85 3

August 22

August 29 ._

86.8
86 5

September 5

September 12

87.5
86 0

September 19

85 9

September 26

88.9

288

MOUNT MAQUILING

Table CXIX. — Relative humidity in the midmountwin forest on Mount Ma-
quiling; altitude, 740 meters— Continued.

Week ending-

October 3

October 10...
October VI ...
October 24...
October 31...
November 7...
November 14.
November 21.
November 28.
December 5...
December 12..
December 19..
December 26..

January 2.

Averag-e .

January 9___
January 16 ..
January 23 ..
January 30. _
February 6 ._
February 13 .
February 20 .
February 27 .

March 6

March 13

March 20

March 27 ....

April 3

April 10 .....

April 17

April 24

Mayl

May 8

May 15

May 22

May 29

June 6

June 12

June 19

June 26

JulyS

July 10.

July 17 .

July 24.......

July 81.-...

1913.

1914.

1914.

Maxi-
mum.

93.5
94.5
95.5
94.7
94.5
94.5
98.0
96.5
95.0
95.0
93.5
95.0
95.5

94.5

95.8.

Mini-
mum.

69.3
88.0
81.8
88.0
75.0
71.6
91.0
89.0
87.5
89.7
89.5
90.3

90.0

Mean.

82.6

86.2
90.6
91.0
92.2
91.0
91.4
92.6
93.0
92.2
92.0
92.2
92.0
92.2

90.2

91.4

Averag-e of daily-

Maxima. Minima.

91.4
93.3
93.7
93.6
93.8
92.5
*94.6
94.5
93.3
93.2
92.3
93.4
93.4

92.6

94.1

93.5

85.0

91.2

92.6

94.0

87.0

92.0

92.6

93.0

85.0

91.2

92.3

94.5

86.9

92.3

92.9

94.5

85.5

91.1

93.2

95.0

84.5

91.4

93.3

94.0

70.0

87.3

92.5

95.0

54.5

87.2

93.9

93.5

83.0

90.0

92.3

94.8

55.0

87.0

93.6

95.5

57.0

89.4

93.8

94.5

64.5

89.4

93.6

95.0

66.0

89.0

93.7

94.0

82.0

89.4

93.2

94.0

79.0

89.3

93.0

94.5

75.0

89.2

92.8

94.0

62.2

86.4

93.3

95.0

66.1

89.0

93.7

95.0

72.5

89.2

93.9

96.0

67.2

89.0

93.2

95.5

73.1

89.0

94.4

95.5

80.0

91.0

93.0

95.5

77.0

90.0

94.2

95.0

73.1

90.4

93.7

93.0

80.0

90.0

92.8

94.0

79.5

89.2

93.1

94.0

82.0

89.4

92.3

92.5

81.0

90.0

91.9

95.5

85.5

92.4

94.6

97.0

65.0

89.2

94.6 1

HUMIDITY 289

Table CXIX. — Relative humidity in the midmountain forest on Mount Ma-
quiling; altitude, 7U0 meters — Continued.

Week ending-

1914.

August 7

August 14

August 21

August 28

September 4 _.
September 11 .
September 18 .
September 25 .

October 9

October 16 _—
October 23 .__.
October 30 ....
November 6...
November 13..
November 20—
November 27..
December 4 __.
December 11 _.
December 18 _.
December 25 ..

1915.

January 1

Average .

Maxi-
mum.

98.2
96.3
95.0
94.0
93.0
94.0
98.0
96.0
95.5
94.5
94.0
93.0
93.0
93.0
93.0
92.0
92.0
93.0
92.0

94.0

Mini-
mum.

Mean.

76.0
85.0
76.1
84.0
89.0
89.1
67.0
74.0
89.0
86.0
85.2
85.5
89.0
86.5
87.5
84.0
88.0
87.0
86.0
80.0

86.0

94.4

78.5

Average of daily -

Maxima. Minima.

90.0
92.0
91.2
91.0
91.4
92.0
88.2
91.0
93.2
92.2
91.4
91.0
91.4
91.0
91.4
91.2
91.0
89.2
89.2
90.0

91.0

90.2

95.6
96.1
95.0
93.8
93.1
92.4
92.9
95.7
94.8
93.9
93.3
92.5
92.4
92.4
91.9
91.7
91.5
90.6
90.9
91.1

92.2
93.2

80.8
90.0
86.0
88.5
91.0
91.2
80.0
82.9
91.2
89.3

90.1
89.4
89.9
88.4
90.0
89.1
87.9
87.9

87.7

85.5

Tabls CXX. — Relative humidity for periods of four weeks from June, 1918,
to January, 1915, in the midmountain forest on Mount Maquiling;
altitude, 740 meters,

[Numbers give percentage of saturation.]

Pour weeks ending-

Maxi-
mum.

94.5
95.0
95.5
95.0
96.0
97.6
99.2
98.2
97.0
98.0
95.5
98.0
95.5

Mini-
mum.

Mean.

Average of daily-

Maxima.

Minima.

January 30 _

85.0
54.5
55.0
66.0
62,2
73.1
74.0
65.0
76.1
67.0
71.6
84.0
80f.O

91.7
89.2
88.9
89.2
88.4
90.4
90.8
91.6
91.2
90.3
91.5
91.8
90.7

92.6
93.2
93.3
93.1
93.5
95.1
93.7
94.8
93.8
94.2
93.2
92.9
92.1

89.5
83.3
80.6
84.3
77.7
82.2
86.9
87,0
88.0
85.1
88.6
90.8
89.7

February 27 _

March 27 _

April 24

May 22

June 19

July 17

August 14

September 11

October 9

November 6

December 4

January 1

Average . . . . .

90.4

93.5

85.7

159549 19

290

MOUNT MAQUILING

Periods of four weeks ending —

Ja30 kb.17 Hail ,\pr.tt MaySJunelSJulyU^M Sept./ 1 Oct 3 Nov.6 Dec A Jan I

38

54

82

\18

74

70 -\

66

62

58

fM

^

--^

3e —

r

\ \

\

V

\

__.\.
\

\\

1
i
1

\
- \ -i

>-4

___..c:
5

—

\

US ...

;

0:- /

r

X

f

....

r--^— - —

_^cr ^.c

* -

\

/

X

f

—

t

L

~"5

i

/

\
\
V

, . ...

1 i

■ ! [■■

!

A.

/

t-. .. i

'

- ~l i

! t -

«'

l

/

i

- - -itA-iflWlir

i-._. : /

/

i

/

\

/

i
i

—

/
/

\._.

\

/

i
i
-j—
i

\

/

i

i
i

f

1

\

/ T

: :
/

i

1

i

/

\

c

i

i \

1
i

— <r

h— /

.-. c

—

f"""

—

J_

/

i

i

—

—

i

i

~ r

i
c

i
i

i

Fig. 17. Relative humidity in midmountain forest ; altitude, 740 meters.

HUMIDITY

291

The maxima, minima, means, and average daily maxima and
minima for four-week periods are plotted in fig. 17. These
carves are similar in form to those for the lower elevations,
but are more irregular.

HUMIDITY IN THE MOSSY FOREST

As at lower elevations, a recording hygrometer was placed
in the case with the recording thermometer in the mossy
forest at the top of Mount Maquiling. This hygrometer re-
corded 100 per cent humidity for practically the entire period,
and there would be months at a time when the records did not

Table CXXI. — Average daily maximum of relative humidity for periods of
four weeks from May, 1913, to January, 1915, at different elevations
on Mount Maquiling.

[Numbers ;.;ive percentage of saturation.]

Four weeks ending-

January 30

February 27__.

March 27

April 24

May 22

June 19

July 17

August 14

September 11 .

October 9

November 6...
December 4 ___
January 1

Average

Elevation in meters.

80.

300. ;

i

88.0

94.8 \

89.2

92.6

88.9

91.4

89.7

90.4 ;

90.8

91.1 !

92.0

' 93.2

91.4

92.5 !

91.1

92.2

89.5,

92.2

91.0

93.4

90.1 i
90.0 j
90.0 |

94.2
95. 4
95.2

Forest.

93.6
92.6
92.5
92.1
92.5
92.6
91.8
91.0
90.9
91.7
91.3
92.6
92.1

Open.

96. 1
90.9
92.1

93.2 !
91.1 |
90.4 |

97.3 j
97.0 i

92.6
93.2
93. 3
93. 1
93. 5
95.1
93. 7
94.8
93.8
91.2
93. 2
92. 9
92.1

90.1

93.0 |

92.1

93. E

indicate less than 100 per cent. This shows that the humidity
at the top of the mountain was constantly high, but does not
mean that the atmosphere under the forest was continually sat-
urated, as the top of the mountain is in the cloud belt. The
clouds not only cause the hygrometer to register 100 per cent,
but also wet the hairs of the instrument so that, before it can
record a lower humidity, the hairs must dry out to some extent.
Ah the rate of evaporation is very low, short periods during
which the air is not saturated may pass, and the top of the
mountain again becomes bathed in clouds before the hairs have
f}Hed out sufficiently to record a humidity of less than 100

292

MOUNT MAQUILING

Periods of four weeks ending:-

JonJO Feb.27 ManZ7 Apr.24May2ZJunel9Ju(yl7 Aug.l4Septll Oct. 3 Nov.6 DecA Jan. i

Fig. 18. Mean relative humidity under forest at different altitudes on Mount
Maquiling.

per cent. The lowest humidity recorded by this instrument w's
91 per cent. This occurred on only one day, and on no othor
occasion was anything like so low a humidity recorded. As tin1

HUMIDITY

293

! able CXXII. — Average daily minimum of relative humidity for periods
of four weeks from May, 1913, to January, 1915, at different elevations
on Mount Maquiling.

[Numbers give percentage of saturation.]

Four weeks ending-

Elevation in meters,

Forest. Open.

.January 80

February 27

March 27

April 24

May 22

June 19

July 17

August 14

September 11

October 9

November 6.

December 4

January 1

07. (

58. 6

55. t

59. 1
55. (
64. i
72.]
71.;

7;}». <

Average

87.1
79. 1
73.1
75.2

70.6

80.4 \
86. 3

84.8 .

85.5 ;

86.9 '
88.0 .
90.1
91.0 i

82. 9 I

83.3
76. 5
71.2
75.5

71.7
79.3

86. 0
83.0 J
85.4 |
83.7 I
84.6
87.1
88.4

81.2

65.7 !
69.0 |

76.6 I

.,j

80.8 J

77.7 |

79.9 |

79.8 ;

89. 5
83. 3
80. 5
81.3
77.7
82. 2
86. 9
87.0
88.0
85. 1
88. 6
90. 3
89.7

sr>. 7

['able CXXIII. — Mean relative humidity for periods of four weeks from
May, 1913, to January, 1915, under the forest at different elevations on
Mount Maquiling .

[Numbers give percentage of saturation.]

1 Elevation in meters.

Four weeks ending

450.

January 30 „. _

February 27,

March 27

April 24

May 22

June 19

July 17

August 14

September 11 -_

October 9

November 6

December 4

January 1

Average .

Forest. | Open.

80. 6

92.7

90. 1 L

91.7

77. 6

88. 0

K6.7 |..

89.2

75. 5

85.8

84.6 L.

88. 9

76. 9

85. 3

85.9 L

89. 2

77.1

84.7 :

84.9

85.3

88.4

82.2 ■

89.4

87.8

83.6

90. 4

84.7 ■

90. 1

88.9 i

87. 0

90. 8 !

84.4 J

89.9

87.7 1

88. 1 '

91.6 |

83. 1 :

89.8

88. 1 '

87.4

91.2

84. 1

91.3

88.4 ;

86.0

90. 3 !

82.7

92. 0

88.5 !

93.1

91.5

83. 0

93. 1

90.1 |

93. 0

91.8

83.9

93. 7

90.2 !.

90. 7

81.2

89.7

87.8 1

87.9

90.4

294

MOUNT MAQUILING

records indicate a humidity of 100 per cent at almost all times
and as they are inaccurate in the manner described, they are
not presented, although they were taken for the entire period
from October, 1912, to January, 1915. From the records we
may conclude that the atmosphere under the forest is saturated
or nearly saturated at almost all times.

HUMIDITY AT DIFFERENT ELEVATIONS

The average daily maxima, the average daily minima, and
the mean humidities for four-week periods at the different ele-
vations are shown in Tables CXXI, CXXII, and CXXIII. The
means are plotted in fig. 18. An examination of this figure
shows that the curves for all the different elevations have fht

100

200

Elevation in meters
300 400

500

6U0

700

>£

*fc%

1 :
j 1

j j

$2

0>^O — -*.

- - i-

i

..«ff.* ..

1 _!_-

,--- €

<y

A^2

!

i i

u.J-J-J

88

"1^

/
/

*

>
/

/

/

/
/

)

i ...

,

M

/

/

/

,**•*

80

o'

1

1
- f - -

1

76

I

/

-io

-

~4

— — ~

—

68

-

/

d

1 1

fiA

Fig. 19. Average daily maxima and minima and mean relative humidity at different
altitudes on Mount Maquiling.

HUMIDITY 295

same general form. The difference between the dry and the wet
seasons is very evident. Table CXXIII shows that the mean
humidity at elevations of from 300 to 740 meters is very
much higher than at 80 meters, but that there is comparatively
little difference under the forest at the different elevations. The
difference between the mean humidity at 300 meters and that
at 740 meters is only 0.7 per cent.. In fig. 19 the average daily
minima, average daily maxima, and means for the different ele-
vations are plotted for the entire period. This figure shows
very clearly that the mean humidity increases considerably
between elevations of 80 and 300 meters, but that there is very
little difference in the mean at different elevations in the vir-
gin forest up to 740 meters. The curve for the average daily
minima shows an even greater difference between the humidity
in the virgin forest and the humidity in the second-growth
than does the curve for the mean. The average daily maxima
are, however, not very different in the several cases. Humidity
influences vegetation largely through its effect on evaporation,
and so the discussion of the effect of humidity on vegetation
will be deferred and given in connection with the discussion of
evaporation.

EVAPORATION

Evaporation was measured by means of a Livingston rain-
correcting atmometer, and all readings were reduced to the
standard used by Livingston.* This form of atmometer con-
sists essentially of a porous clay cup from which water is evap-
orated. The cup is so connected, by means of rubber stoppers
and glass tubes, with a bottle containing water that the cup is
kept constantly filled, the water that is evaporated from the
moist surface being replaced by water from the bottle; while
the backward flow of water from the cup is prevented by the
insertion of a mercury valve.

The rates of evaporation were measured at the different
stations in the tops of trees; near the ground, both on ridges
and in ravines; and in some cases in the open. In the dip-
terocarp and the midmountain forests measurements were also
taken in second-story trees. When an atmometer was placed
in the top of a tree the end of the main stem was cut off and
the crown trimmed as described in the discussion on temper-
ature. An attempt was made to place these atmometers in such
positions that they would be exposed to the same rates of evap-
oration as the upper surface of the crowns of the trees. To
accomplish this exactly is very difficult, particularly as the trees
are always growing and continual trimming is necessary. Va-
riations in the shape of the crowns of the trees in which the
instruments were placed probably caused some irregularities in
the readings, but the general consistency of the results in-
dicates that these were not serious. The glass bottles from
which the atmometer cups obtained water were always inclosed
in a perforated box, so that they might be screened from the
direct action of sunlight. The cups which measured the rate
of evaporation under the forest or in the open were placed
about 25 centimeters above the soil surface. All cups were
restandardized at frequent intervals.

Readings of the rates of evaporation were begun in Novem-
ber, 1912, and continued until January 1, 1915. In nearly all
cases the results represent the average readings from two evap-

* Livingston, B. E., Atmometry and the porous cup atmometer, Plavt
World (1915), 18, 21.
296

EVAPORATION 297

orimeters and in some cases from more. A single evaporimeter
was only used in ravines and in some cases near the ground
under the trees.

EVAPORATION IN THE PARANG

All readings of evaporation in the parang were made weekly
until July, 1913. Thereafter evaporation was measured daily
in the top of a fairly tall second-growth tree, under the second-
growth forest, in the lawn at the forest station, at the top of
a small patch of Saccharum, and near the ground under the
Saccharum. The atmometers at the top of the Saccharum were
so placed as to give them the same exposure as that to which
the tips of the leaves of the grass were subjected. As no
such complete series of daily measurements of evaporation in
the tropics are available, it has been thought worth while to
give these readings in full, and they are presented in Table
CXXIV. The measurements extend from July 1, 1913, to Jan-
uary 1, 1915. There were some days when it was impossible
to take readings and these appear in the table as blanks, the
evaporation for the following day being the summation for two
days. In order that these figures may be considered conve-
niently, they are presented in a series of tables in the form of
average daily rates, and maximum and minimum rates for
corresponding four-week periods for the entire time. Such
data for the top of the second-growth tree and the lawn aro
given in Table CXXV. The average daily evaporation for the
entire period in the top of the tall tree was 21.1 cubic centime-
ters; the maximum, 51 cubic centimeters; and the minimum,
0.0. Zero readings appear in this table for the four-week
periods ending July 17, September 11, and December 4. Refer-
ence to Table CXXIV will show that no evaporation was re-
corded on November 20, 1913; June 20, 1914; and September
4, 1914. The absence of any recorded evaporation on these
days was due to periods of very rainy weather.

The average daily evaporation on the lawn was 19.7 cubic
centimeters, or very little less than in the top of the second-
growth tree. The atmometer in the lawn was, however, at tho
top of a small ridge and was about as fully exposed to the
action of sun and wind as was the one in the top of the second-
growth tree. The maximum in the lawn was 52.1 cubic centi-
meters, which is slightly greater than the maximum in the
top of the second-growth tree. The minimum in the lawn was
0.0. On the same days on which no evaporation was recorded
m the top of the second-growth tree the atmometer in the

298

MOUNT MAQUILING

Table CXXIV. — Average daily evaporation in different situations near the
base of Mount Maqutting; altitude, 80 meters.

L Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

July 2

July 3

July 4

July 5

July 6

July 7— ...

July 8

July 9

July 10

July 11

July 12

July 13

July 14

July 15

July 16

July 17

July 18

July 19

July 20

July 21

July 22

July 28

July 24

July 25

July 26

July 27

July 28

July 29

July 80

July 31., ...
August 1- -
August 2...
August 3—.
August 4. ..
August 5...
August 6...
August 7—
August 8..
August 9„
August 10 .
August 11-.
August 12.
August 13.
Augtist 14.
August 15.
August 16-

Date.

Top of a
tall tree

in
second -
growth
forest.

25.7
17.9
21.8

17.7

37.0

13.1

22.0

17.5

18.2

12.2

14.2

12.2

14.2

5.2

9.6

7.4

14.0

19.2

7.3

5.5

19.4

21.2

13.3

20.9

29.6

12.2

26.2
24.5
14.0
15.4
17.6
12.4
4.1
13.1
22.4
21.9
28.0
41.9
26.6
24.5
14.9
15.5
12.5
89.6

In small patch of
Saceharum.

Lawn.

At top
of

18.0
10.5
14.2
"9.7

26.2

8.7

16.8

14.6 |

13.8 I

8.7 |

7.3

11.6

9.5

1.4

4.3

3.9

6.5

14.4

5.0

1.4

14.4

18.0

7.5"

14.4

23.7

7.1

1.4

5.3

13.8

7.4

9.9

11.4

8.5

2.1

9.2

9.9

15.4

19.1

82. 6

21.3

16.4

10.0

10.6

7.7

26.2

21.7

6.0

14.2

10.5

10.5

7.5

5.6

9.0

9.6

1.1

4.4

3.7

5.9

11.8

4.4

1.8

18.5

14.8

13.7

13.1

20.7

3.7

0.7

4.4

13.8

6.6

8.0

9.5

7.3

1.4

7.3

8.7

13.9

17.4

29.9

19.9

15.3

10.2

10.5

7.6

25.6

On
ground
under

2.2

0.0

4.4

2.2

0.0

0.0

0.7

0.0

2.2

0.0

0.7

1.5

3.7

2.2

2.2

8.1

1.8

0.0

0.0

1.4

0.7

1.1

1.8

1.4

0.0

0.7

2.5

2.9

2.9

1.1

6.6

6.6

1.4

1.4

0.03

7.2

Near
ground

under
second-
growth
forest.

EVAPORATION

299

Table CXXIV. — Average daily evaporation in different situations near the
base of Mount Maquiling; altitude, 80 meters — Continued.

Date.

Top of a
tall tree

in

second-

; growth

forest.

1913.

August 17

August 18

August 19

August 20

August 21. __

August 22

August 23 _

August 24 ___.

August 25. __

August 26

August 27-_

August 28--,.

August 29

August 30--

August 31._

September 1 _._

September 2 ___

September 3 ...

September 4

Septembers

September 6 _._

September 7

September8

September 9

September 10 _.

September 11

September 12

September 13

September 14 _ ...

September 15

September 16

September 17

September 18

Septembers

September 20

September 21

September 22

September 23

September 24

September 25

September 26 _

September 27 ___

September 28

September 29

September 30

October 1

October 2

In small patch of
Saccharum.

Lawn.

18.6

11.0

19.1

13.9

19.1

14.5

9.8

5.0

10.5

5.5

14.7

10.9

15.1

9.3

13.6

10.1

17.0

10.2

8.6

5.2

17.1

12.1

16.3

10.7

14.1

11.1

21.1

13.5

21.2

14.3

21.0

14.9

11.4

10.1

34.4

20.6

31.0

24.8

33.7

24.3

31.2

21.7

25.2

19.5

37.5

28.1

12.5

9.5

1.2

1.5

11.1

•7.0

18.7

12.9

23.8

17.3

22.5

16.0

35.5

26.6

20.9

16.6

20.8

15.2

16.2

12.4

15.8

12.8

21.7

16.1

23.2

18.5

19.9

15.6

20.8

16.7

13.5

9.8

5.3

2.6

14.3

10.3

21.3

16.0

21.0

13.4

16.6

11.9

22.9

19.4

24.5

18.9

At top

of
grass.

3.1]

11.0 !

15.3 J

16.3 !

4.5 ;

6.0 ;

9.2 I

9.9 j

9.5 j

8.9 |

3.9 !

10.5 |
10.8 j

8.7 j

13.6 j
13.5 !
15.3 '

8.7
17.9
20.6
20.2
19.4
15.9
24.1

6.4

0.4

5.1
11.5
16.1
14.4
22.9
13.5
13.2
11.7
11.3
14.8
16.4
14.2
15.0

7.1

1.3

8.0
14.5
14.6
11.0
17.6
17.3

On
ground
under
grass.

1.4
1.4
2.1
5.0
0.0
1.4
5.0
5.0
0.7
0.1
0.0
0.8
1.2
0.9
2.5
4.1
4.3
1.3
2.5
5.5
4.5
8.4
5.7
6.6
1.4
0.0
0.0
1.7
4.1
4.8
9.0
4.8
2.5
2.6
1.3
2.3
4.4
4.0
4.3
0.0
0.0
0.0
0.0
1.2
2.6
3.8
5.1

Near
ground

under
second-
growth
forest.

1.1
1.5
4.5
3.4
0.0
1.6
2.2
1.9
1.7
1.3
0.0
1.6
1.6
1.9
2.0
3.2
1.6
1.4
3.0
4.4
4.6
4.6
3.8
4.3
0.6
0.0
0.0
1.7
3.4
2.5
5.8
2.3
1.9
3.3
0.1
2.4
3.9
3.3
3.7
0.0
0.0
0.0
0.0
6.0
1.7
3.8
3.6

300

MOUNT MAQUILING

Table CXXIV. — Average daily evaporation in different situations near the
base of Mount Maquiling; altitude, 80 meters — Continued.

Date.

October 3

October 4

October 5

October 6

October 7

October 8

October 9

October 10 ...

October 11

October 12 ....
October 13 ....

October 14

October 15

October 16 .._.

October 17

October 18 ....
October 19 ....
October 20 ....
October 21 .__.
October 22 ...
October 23 ....
October 24 ....
October 25 ....
October 26 ....
October 27 ...
October 28 ....
October 29 ....
October 30 ...
October 31 ...
November 1__
November 2._
November 3...
November 4._.
November 5...
November 6__
November 7__.
November 8._
November S.-
November 10.
November 11..
November 12..
November 13..
November 14 ..
November 15..
November 16.
November 17.
November 18.

Top of a
tall tree

in
second-
growth
forest.

Lawn.

17.5
12.9
16.1
12.1
11.4
12.9
17.2
15.8
12.8
0.0
1.3

17.

24.9

10.9
19.6

6.6
16.9
14.3
12.2
13.8
15.0
16.5
11.5
21.6
20.3
20.2
17.8
17.0
19.5
21.9

8.3
11.9
12.7
12.8

2.9

4.3
15.8

7.1

5.1
12.5

5.1
14.0
19.8
15.8
22.5

In small patch of
Saccharum.

27.6
20.2

At top
of

17.6
11.9
12.4
9.6
9.9
11.7
15.7
15.6
11.3
0.0
1.4

10.1

18.4

6.7

17.0

12.8

12.1

12.0

14.6

17.1

16.2

17.9

17.1

18.1

16.8

14.8

17.8

21.0

6.8

9.2

11.3

11.7

1.6

2.5

12.1

4.3

2.6

9.6

1.5

9.8

15.4

10.6

16.0

20.5
17.6

On
ground
under
grass.

4.6
0.9
1.7
0.0
2.5
1.5
2.2
2.7
2.1
0.0
0.0
0.0
0.0
1.8
0.0
2.6
2.2
2.0
2.8
3.3
4.5

4.8
4.3
5.8
3.4
3.1
3.7
5.0
1.0
2.3
2.7
1.7
0.0
0.0
1.0
0.0
0.0
0.0
0.0
0.0
0.8
1.6
1.6

Near
ground I

under
second- j
growth i
forest. I

2.4
2.5

EVAPORATION

301

Table CXXIV.— - Average daily evaporation in different situations near the
base of Mount Maquiling; altitude, 80 meters— Continued.

November 19-
November 20.
November 21.
November 22.
November 23.
November 24-
November 25.
November 26.
Nov ember 27-.
November 28-
November 29_
November 30-.
December 1 __.
December 2 ...
December 3 ...
December 4 __.
December 5 ...
December 6 __.
December 7 __.
December 8 ._.
December 9 _..
December 10 - .
December 11 _.
December 12 ..
December 13 - .
December 14 ..
December 15 ..
December 16 -.
December 17 . .
December 18 .
December 19 . .
December 20 ..
December 21 ..
December 22 ..
December 23 ..
December 24-.
December 25 >.
December 26 ..
December 27 ..
December 28..
December 29 . .
December 30. .
December 31..

Date.

1913.

1914.

Top of a
tall tree

in
second-
growth
forest.

19.5
0.0
11.4
14.3
9.4
19.8
18.1
22.3
26.8
1.8
16.7

30.8
23.1
16.9
21.2
14.5
8.5
9.3
19.1
10.5
14.9
21.4
13.8
17.9
10.6
5.3
4.5
18.0
13.2
3.3
6.9
11.6
14.4
15.1
13.1

28.4
27.1

January 1.
January 2.
January 3.

32.9
15.7
12.4

16.1
16.1
13.3

Lawn.

16.7
0.0
8.5
11.6
5.4
17.6
14.1
19.2
20.8
0.0
10.1

19.5
14.5
11.3
14.6
10.3
5.9
6.2
13.1
7.4
10.7
15.1
10.4
12.8
7.1
3.3
3.4
12.3
9.6
2.4
5.5
9.2
9.5
11.2
9.7

In small patch of
Saccharum.

At top

of
grass.

13.4
0.0
4.5
6.6
1.0

10.6
8.3

13.8

18.1
0.0

10.2

On

ground
under
grass.

2.7
0.0
0.0
0.0
0.5
1.2
0.8
1.7
2.7
0.0
0.0

16.6
13.0 j
11.6
14.5

9.1

4.5

5.6
10.3

4.5

7.2
11.7

8.6
11.5

4.6

2.4

1.4
10.1

6.9

2.0

4.9

6.0

7.3

9.9

9.0

Near j
ground

under !
second- !
growth
forest.

6.3
0.0
0.0
0.0
0.5
4.9
3.0
4.3
5.6
0.0
0.0

1.7
1.0
2.2

2.3

0.0 j
0.7 |
0.0 !

0.9 ;
o.o I
o.o !

0.0 !
1.9 I
1.3 j
0.0 \
0.0 j

o.o I

0.0 !
0.0 ;
0.0 ,

0.0 j
0.6 j
0.9 j
1.0 I

0.7 j

20.1

15.9

1.6

19.6

20.0

6.8

20.2

19.3

5.2

13.8

11.0

3.1

9.4

6.1

0.8

14.2

9.2

3.0

12.7

9.7

3.7

12.3

7.6

1.9

6.2
3.8
3.1
4.1
1.8
0.9
1.0
2.4
0.8
2.1
4.1
1.7
3.0
1.1
0.0
0.0
2.3
1.2
0.0
0.0
1.2
2.6
3.1
2.7

4.4
4.9

6.5
3.3
2.3

4.0
4.1
3.1

302

MOUNT MAQUILING

Table CXXIV. — Average daily evaporation in different situations near the
base of Mount Maquiling ; altitude, 80 meters — Continued.

January 4

January 6

January 6

January 7

January 8

January 9

January 10. ..
January 11. __
January 12._.
January 13...
January 14. _.
January 15. __
January 16.__
January 17. _.
January 18™
January 19...
January 20__.
January 21. _.
January 22...
January 23-..
January 24...
January 25--.
January 26.. .
January 27...
January 28—.
January 29. _.
January 30...
January 31__.
February 1...
February 2...
February 3...
February 4...
February B.-
February 6...
February 7...
February 8...
February 9...
February 10 _.
February 11.
February 12.
February 13.
February 14-
February 15..
February 16.
February 17.
February 18. .
February 19..

Date.

Top of a
tall tree

in
second-
growth
forest.

8.
15.
19.
20.
21.
11.
34.
20.
19.
20.
14.
17.
19.

50.
16.
20.
21.
10.
11.
19.

Lawn.

6.8
12.2
16.1
14.9
15.8

9.3
27.5
12.7
16.9
17.3
11.9
12.6
17.3
27.1

40.0
14.4
17.8
18.4
10.1
10.3
16.6

39.1

37.2
17.7
21.4
21.4
23.8
19.8
21.2
9.1
22.1
24.0

41.4
19.0
14.3
19.6
10.2
14.5
17.3
26.2
33.1
18.9
31.5

In small patch of
ScLccharum,

At top
of

grass.

2.8
8.9
13.7
13.7
18.7
5.2
18.4
10.4
13.0
13.1

12,8
20.2

38.3
11.4
13.4
14.0
5.8
5.8
12.4

On
ground
under
grass.

35.8

29.6
14.0
17.4
14.7
19.3
13.8
15.3
5.7
16,. 7
18.1

30.9
13.5
10.0
13.2
6.3
9.6
11.1
19.5
23.7
15.6
22.8

0.0
1.9
4.4
3.1
3.1
0.0
5.6
3.9
4.6
4.2
2.6
2.9
4.7
5.6

11.2
4.3
3.5
4.1
1.4
5.9
3.2

10.5
4.2
5.7
4.4
6.6
4.1
5.4
1.4
3.3
5.9

8.5
4.9
3.8
3.5
1.2
2.8
3.2
6.8
9.1
5.5
9.5

Near
ground

under
second-
growth
forest.

EVAPORATION

303

TABLE CXXIV.— Average daily evaporation in different situations near the
base of Mount Maquiling; altitude, 80 meters— Continued. "

Top of a
tall tree

in
second-
growth
forest.

Lawn.

In small patch of
Saccharum.

Near
ground

under
second-
growth

forest.

6.6

12.8

Date.

At top

of
grass.

On
ground
under
grass.

7.2
9.8

1914.
February 20. __,.__ _.

29.0
41.7

26.1
30.5

19.7
22.6

February 21

February 22

February 23 ...

60.7
22.8
25.9
33.1
13.7
31.3

57.3
22.8
24.1
30.6
11.7
23.6

42.3
19.0
18.9
24.3
8.7
. 21.2

18.0
6.0
7.4

10.8
3.0
7.5

25.1
8.7
9.9

13.3
4.4

10-1

February 24 _

February 25

February 26. _.

February 27

February 28 ... _

March 1

March 2

46.6
23.0
36.1
21.9
22.9
32.7
25.7
21.2
28.5
32.1
32.9
32.5

44.3
19.6
35.5
22.1
21.1
28.9
26.9
22.3
28.9
33.2
35.1
34.1

32.1
13.7
24.3
15.8
16.0
27.6
21.7
15.7
22.2
24.3
27.4
26.8

13.2

5.3

12.1

7.1

5.9

12.4

9.7

6.5

9.6

13.6

12.7

14.2

18.6

8.8

14.6

8.8

9.6

13.1

10.9

8.8

13.1

15.3

17.2

18.2

March 3

March 4

March 5

March 6

March 7 :

March 8-__

March 9

March 10. _ _

March 11

March 12.._ _

March 13 ..__ _

March 15

March 16

53.9
31.7
25.7
32.7
38.9
28.7
36.7
27.9
33.4
29.5
38.2
25.4

56.6
32.6
27.9
35.8
43.4
36.3
40.8
33.3
88.0
33.9
44.1
28.6

42.4
21.1
19.5
25.8
30.5
23.7
30.4
23.4
27.0
23.8
31.0
19.5

18.3
10.4
10.9
14.5
13.9
12.4
15.1
12.8
14.5
11.6
16.8
13.3

27.4
11.2
11.3
15.7
20.4
17.2
20.4
16.0
19.0
18.2
22.6
13.8

March 17

March 18

March 19_._ .

March 20

March 21

March 22...

March 23

March 24

March 25

March 26

March 27

March 29

March 30

75.0
28.9
32.7
30.5
35.7
21.3

88.1
33.2
40.2
35.5
46.6
26.2

62.7
24.1
29.2
24.9
31.2
17.2

30.5
13.9
14.5
12.2
16.8
12.0

46.0
17,9
21.2
18.2
20.4
11.3

March 31

April 1

April 2

April 3... .

April 4

April 5

April 6 ._

32.3
22.5

40.5
28.1

30.3
20.2

13.2
10.0

20.0
13.8

April 7

304

MOUNT MAQUILING

Table CXXIV. — Average daily evaporation in different situations near the
base of Mount Maquiling; altitude, 80 meters — Continued.

April S.-
April 9 ..
April 10 .
April 11 .
April 12 .
April 13 .
April 14 .
April 15 _
April 16 _
April 17 .
April 18 .
April 19 .
April 20 .
April 21 .
April 22 .
April 23 .
April 24 -
April 25 -
April 26 .
April 27 .
April 28 .
April 29 .
April 30 -
May 1 ...
May 2 .._
May 3 ...
May 4 ___
May 5 -__
May 6 —
May 7 —
May 8 —
May 9 —
May 10 _.
May 11. _
May 12 ._
May 13 „
May 14 ..
May 15 ._
May 16. .
May 17-
May 18 -
May 19 ._
May 20 ..
May 21 -
May 22 ..
May 23 „
May 24 ..

Date.

1914.

Top of a
tall tree

in
second-
growth
forest.

Lawn.

30.2
85.6
9.6
24.4
37.0
34.9
22.0
27.1
17.1
28.7
28.6

62. 6
18.3
31.8
9.2
31.0

56.8
34.4
34.4
34.9
38.5
43.8
41.4
42.0
36.3
37.7
43.0
37.6
33.8
31.5
17.7
23.0
37.6
41.9
44.5
39.7
28.8
39.5
31.8
26.8
15.3
16.3
27.8

In small patch of
Saccharum.

At top

of
grass.

25.1
25.0
8.5
18.7
28.8
26.2
16.5
23.8
14.8
23.7
22.3

49.2
11.9
22.7
5.6
28.0
32.5

48.6
29.5
34.6

28.4

On

ground
under
grass.

-I.

11.7
14,3
2.5
7.7
13.7
12.8
7.4
8.1
5.8
10.3
10.8

24.5
3.1

EVAPORATION

305

Table CXXIV.— Average daily evaporation in different situations near the
base of Mount Maquiling; altitude,. 80 meters-— Continued.

i

Top of a
tall tree

in
second-
growth
forest.

64.2
36.7
25.3
34.6
23.6
20.9

Lawn.

68.1
37.0
29.1
36.4
29.8
23.3

In small patch of
Saccharum.

Near
ground

under
second-
growth
forest.

J Date.

At top

of
grass.

On

ground
under
grass.

1914.
May 25

23.0
13.6
9.5
12.4
9.5
8.4

May 26 .._

May 27 ._

May 28

May 29

May 30 -_

May31.__ ._._

June 1

48.6
13.4
2.0
3.3
23.6
28.3
22.6
27.2
24.0
24.2
32.8
24.4
28.5
19.7
26.3
33.1
9.6
24.5
5.7
0.0

51.2
15.0
2.2
1.3
20.6
27.3
21.1
26.1
23.9
24.5
31.6
26.5
21.3
17.5
26.4
35.0
8.8
24.6
4.2
0.0

15.3
4.4
9.0
0.0
5.1
8.0
5.8
9.6
5.4
8.0
8.0
5.8
4.4
4.4
6.9

10.9
2.5
5.8
0.0
0.0

June 2

June 8

June 4 .__

June 6

June 6 _.

June 7

June 8 ._

June 9_-_ _ _

June 10

June 11

June 13___,

June 15-

June 17

June 19

i

""""I

June 21

1

7.5
14.5

17.8
20.4
17.6
18.1
19.0
17.1
19.1
13.2
15.8
11.8

13.3
13.1

16.5
18.4
17.1
17.6
18.6
15.8
18.1
13.2
16.1
12.2

1

2.2
1.5

3.0
6.5
5.1
5.1
4.7
4.4
5.5
3.1
3.9
2.0

June 23

June 25

June 27__ _

June 29

July l._

July 3

July5

18.2
14.0
19.4
19.5
40.9

16.1
12.2
16.5
26.0
32.9

0.8
2.4
1.2
6.8
9.5

July 7

July 9

159649 20

306

MOUNT MAQUILING

TABLE CXXIV. — Average daily evaporation in different situations near the
base of Mount Maquiling; altitude, 80 meters — Continued.

July 11

July 12

July 13

July 14

July 15

July 16

July 17

July 18

Julyl9._._.

July 20

July 21

July 22

July 23

July 24

July 25

July 26

July 27

July 28

July 29

July 30

July 31

August 1 __
August 2 __
August 3 __
August 4 _ .
August 5 ..
August 6 —
August 7 . .
August 8 ._
August 9 __
August 10 _
August 11 -
August 12 .
August 13 .
August 14.
August 15 _
August 16 .
August 17.
August 18 _
August 19.
August 20 .
August 21 _
August 22 .
August 23 .
August 24-
August 25.
August 26 .

Date.

1914.

. Top of a
tall tree

in
second-
growth
forest.

40.2

41.4
27.9
10.1
8.7
8.4
15.9
11.4
12.2
13.4
9.4
8.1
7.3
15.6
19.5
16.6
19.8
22.3
17.4
19.9
22.
20.7
18.6
28.2
20.7
18.5
18.3

17.9
5.1

Lawn.

9.7

In small patch of
Saccharwm.

At top

of
grass.

92.2
44.3
33.1
11.2

7.6

8.1
15.8

9.9
10.7
10.2

9.1
11.3

6.4
15.5
18.5
15.3
17.7
21.6
15.2
18.5
22.2
21.2
17.6
26.5
22.8
19.3
18.2

16.3
4.7

34.4 J
10.7 j
23.2 |
20.6 j
20.8
14.5
20.0
9.9
31.4
24.0
11.8
26.0
41.1
51.0

35.2
9.6
19.4
20.3
20.4
14.2
16.3
10.3
25.3
23.2
11.5
25.0
20.5
51.6

On

ground
under
grass.

EVAPORATION

307

Table CXXIV.— Average daily evaporation in different situations near the
base of Mount Maquiling; altitude, 80 meters— Continued.

Top of a
tall tree

in
second -
growth
forest.

50.9
50.4
34.4

In small patch of
Saccharum.

Near

Date.

Lawn.

50.0
52.1
34.3

■

At top

of
grass.

On

ground
under
grass.

under
second-
growth
forest.

1914.
August 27

17.4
17.4
7.9

August 28

August 29 .

--,

August 30 _

|

August 31

59.8

11.6

2.3

3.1

0.0

3.1

9.5

19.9

7.5

1.0

5.4

26.6

29.0

4.3

8.1

13.5

17.7

13.2

15.8

21.4

22.2

20.6
17.5
24.8
17.6
17.2
11.8
15.7
9.0
10.5
12.1
18.1
21.1

61.3
11.0
2.9
3.0
0.0
1.6
8.6
19.3
7.4
2.8
4.4
26.0
30.1
3.3
7.2
11.3
14.8
11.3
12.0
19.6
19.6

19.0
17.3
22.3
15.6
15.9
12.1
13.8
8.0
8.3
9.7
16.9
18.6

!

September 1 __

3.9

0 0

September 2

September 3 _

i

0.0
0 0

September 4

Septembers __.-

0.0
1 6

September 6

September 7

2 4

September 8

0 0

September 9 .

0 0

September 10

0.0
7.9
6.3
0.0
1 2

September 11

September 12

September 13 .

September 14

i

September 15

1

1 6

September 16 .

i

4 7

September 17

2 4

September 18

3 1

September 19

4 7

September 20 __. __.

5 5

3 9

September 22

i

4.7

September 23

5.5
5.5
3.9
3.9
1.6
2.4
2.4
0.0
1.6
3.1
4.7

September 24

j

September 25

"1

September 26 .

September 27

September 28

September 29 _

1

September 30

I

October 1

I

October 2

1

October 3

!

October 4

i

October 5

29.2
23.7
13.7
8.6
18.6
19.3
22.7
21.3

24.9
20.2
10.5
6.4
14.0
15.1
18.9
19.5

1

3.9

October 6-

I

4.3

October 7 _

|

3 1

October 8 ...

\—

!

0 0

October 9 _

2 0

October 10 __

3.1

October 11

3 9

October 12

4.7

308

MOUNT MAQUILING

Table CXXIV. — Average daily evaporation in different situations near the
base of Mount Maquiling; altitude, 80 me ters— Continued.

Date.

Top of a
tall tree

in
second-
growth
forest.

Lawn.

17.9
22.2
17.9
14.4
12.6

In small patch of
Saccharum.

Near
ground

under
second -
growth
forest.

At top

of
grass.

On

ground
under
grass.

1914.
October 13 -

22.5
23.6
21.9
16.9
14.0

3.9
6.7
5.9
4.7
4.7

October 14 —

October 16 _ .

October 17

October 18

October 19 _ _

24.7
10.7
21.3
14.7
21.3
28.4

22.3
10.3
17.7
13.2
16.7
26.0

3.9
1.6
3.1
3.1
1.6
7.1

October 20 _ _

October 21 __.__

October 22 ._

October 23 —

October 24

October 25

October 26

39.3
25.1
21.1
12.6
19.8
29.4
24.4
14.5
25.0
21.3
19.1
16.8
17.2

35.2
20.6
19.2
10.8
16.7
26.9
24.0
14.3
34.5
19.9
17.6
20.5
17.4

6.3

October 27 _

4.7

October 28 _

1.6
2.4
3.9
3.5
3.6
3.1
3.9

October 29 .__ ___

October 30

October 31

November 1

November 2

November 3

November 4

4.7

November 5

4.7

November 6 _

3.1

November 7

3.9

November 8

.

November 9

25.4

26.1
23.3
18.0
23.4

21.5

25.4
20.3
17.7
22.3

3.9

2.4

November 11

November 12_.

7.1

3.1

November 13-___ _

3.9

November 14 __

3.9
3.9

3.9

4.6
5.5
6.3
5.5

November 15

November 16

42.0
14.0
16.9
22.1
16.0
17.7

38.6
14.0
15.1
19.9
14.5
18.1

November 17 .___.

November 18.- _. .

November 19 __

November 20 _.

November 21 : _

6.5

November 23

44.0

20.8
12.1
15.0
14.8

42.5

22.1
23.5
15.9
10.8

7.1

4.7

November 25

6.2

November 26

7.9

November 27 _ _>

4.7

November 28

0.0

EVAPORATION

309

Table CXXIV. — Average daily evaporation in different situations near the
base of Mount Maquiling; attitude, 80 meters — Continued.

Top of a
tall tree

in
second-
growth
forest.

Lawn.

In small patch of
Saccharum.

Near
ground

under
second-
growth
forest.

Date.

At top

of
grass.

On
ground
under
grass.

1914.
November 29

14.3

8.8

6.8

10.8

9.1

15.3

11.3

10.8

17.1

19.5

10.4

7.9

17.7

12.6

7.1

15.5

21.3

13.6

10.9

23.0

23.3

17.9

11.5

15.4

13.1

20.5

7.1

13.7

10.7

0.8
0.0
1.6
0.0
0.6
1.6
0.8
1.7
3.3
3.9
1.6
0.0
3.1
1.6
1.6
2.2
• 4.7
3.1
3.1
5.5
5.5
6.3
3.1
3.1
4.7
7.1
1.6
2.4

November 30 .'-__.' _

8.8
7.2

December 1

December 2 __ _

10.2
8.5
16.0

December 3 _..

December 4

December 5

10.2
10.3
15.3
17.2

8.1

6.1
15.9
41. 5

5.1
13.2
19.5
12.7

9.8
19.2
18.7
15.8
10.7
13.0
12.0
19.0

5.7
11.0

December 6 _._ _

December 7 _„ _

December 8

December 9 ._.'. __

December 10

December 11 __

December 12

December 13 __

December 14

December 15 ...

December 16

1

December 17

December 18

December 19 ___ _. .

December 20 _. _

December 21 _ _._

December 22 ._ ._

December 23 _ _

December 24

December 25 ._

December 26

December 27

December 28 ._

45.8
26.6
22.1
12.5

22.5-

39.7
21.6
19.9
10.5

19.6

12.6
7.1
7.9
1.6

6.3

December 29 __

December 30

December 31

1915.

lawn showed no evaporation. On October 12, 1913, when there
was an evaporation of 1.8 cubic centimeters in the top of the
second-growth tree, there was no evaporation from the instru-
ment in the lawn.

From Table CXXV it will be seen very clearly that the
highest average rates of evaporation occur during the dry sea-
son. The highest average rates for four- week periods occurred

310

MOUNT MAQUILING

Table CXXV. — Daily evaporation for periods of four weeks from July,
1918, to January, 1915, in different situations near the base of Mount
Maquiling ; altitude, 80 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Four weeks ending —

January 30

February 27

March 27

April 24 _

May22__._

June 19 ._

July 17

August 14

September 11 __

October 9

November 6

December 4

January 1

Average _

Top of tall tree in second -
growth forest.

Average.

19.3

24.2
29.6
25.1
30.8
23.4
18.2
16.7
19.9
17.9
18.4
16.5
14.9

21.1

Maxi-
mum.

34.1
41.7
38.9
37.5
41.0
36.7
44.4
41.9
51.0
35.5
31.6
26.8
27.1

Min-
mum.

8.3

12.3

21.2

9.4

12.9

2.0

0.0

4.1

0.0

4.3

1.8

0.0

3.3

In lawn.

Average, i

Maxi-
mum.

37.6

6.1

16.2
21.2
30.8
29.2
33.7
23.6
15.8
13.3
16.3
14.6
15.5
14.3
11.9

19.7 !

Mini-
mum.

27.5

6.8

33.1

9.1

44.1

19.6

46.6

9.2

44.5

15.3

37.0

1.3

46.1

0.0

32.6

1.4

52.1

0.0

30.1

2.6

34.5

0.0

25.4

0.0

21.6

2.4

36.6 j

5.2

between January 30 and June 19, and particularly during March,
April, and May. After June the rates were very much lower
than during the dry season and reached the minimum in De-
cember. The high rates in the dry season are probably the
result of the combined action of intense light, low humidity,
and high wind velocity; while the lowest rates occur at the
time when the temperature is lowest and the humidity greatest.
The highest minimum daily rates also occur in the dry season;
and the lowest, during the latter part of the year. The maxi-
mum daily rates, however, bear no such relation to the alter-
nating dry and wet seasons as do the average and the minimum
rates. The absolute maximum in both cases occurred during the
last week of August, 1914, which is during the middle of the
rainy season. Moreover, the maximum daily rates in the top of
the tree for the four weeks ending July 17, August 14, and Sep-
tember 11, respectively, are all higher than any of the maximum
rates for the dry season. These high rates were observed to be
coincident with high wind velocity during typhoon periods, when
there was little or no rain. Despite the fact that these very
high rates are found during the rainy or typhoon season, the
average rates at this time are much lower than during the dry
season.

EVAPORATION

311

^n°, J r L~Datly e™P°™ti<>n for periods of four weeks from July
1918, to January, 1915, near the ground under the second-growth forest
near the base of Mount Maquiling; altitude, 80 meters.

™™her* BiVe evM>°rati™ »» <="bic centimeters from a Livingston atmometer.]

Four weeks ending-

January 30 __
February 27 _

March 27

April 24

May 22

June 19

July 17

August 14 ___
September 11..

October 9

November 6 __
December 4 _ _ .
January 1

Average.

Maxi-
mum.

8.9

Mini-
mum.

5.3

1.0

8.1

13.9

2.3

14.2

22.6

8.8

14.7

23.0

2.3

13.8

20.4

2.5

6.9

13.5

0.0

4.5

16.6

©.0

2.6

- 9.5

0.0 !

3.8

17.4

0.0

2.8

6.3

0.0

3.3

7.1

0.0

3.0

7.9

0.0

3.0

7.9

0.0

Average .

6.6 I

13.5

The rates of . evaporation under the second-growth trees are
given in Table CXXVI. It will be seen that the average daily
evaporation is 6.6 cubic centimeters, which is only 31 per cent
of the rate in the top of the tree. The maximum daily evap-
oration was 23 cubic centimeters, which is less than half the
maximum rate either in the top of the second-story tree or in
the lawn. The minimum rate was 0.0 and occurred during all
the four-week periods beginning with the one ending June 19
and terminating with that ending January 1. The maximum
daily evaporation occurred in the dry season and not in the rainy,
as did the maximum in the second-growth tree and in the lawn.
This is very probably due to the fact that the atmometer under
the trees was protected to a considerable extent from the winds
that caused these very high rates in the other two situations.
The highest average and the highest maximum and minimum
under the trees are all found to occur during the dry season
when humidity is lowest.

The rates of evaporation for a small grass area are given in
Table CXXVIL The average daily evaporation in the top of
the grass was 13.5 cubic centimeters. This indicates that the
tops of the grass cut down the evaporation found in the lawn
by 31 per cent. The maximum at the top of the grass was
31.4 cubic centimeters and the minimum, as might be expected,
0-0. The average daily evaporation under the grass was 4
cubic centimeters, which is 61 per cent of that under the forest

312

MOUNT MAQUILING

and 19 per cent of that in the top of the second-growth tree.
That the rate under the grass is less than, under the trees is
probably due to the fact that the grass lessened the movement
of the wind more than did the second-growth forest. The
maximum under the grass was 16.8 cubic centimeters, and the
minimum, 0.0.

Table CXXVII. — Daily evaporation for periods of four weeks from July,
1913, to January, 1915, in a small patch of Saccharum near the base
of Mount Maquiling ; altitude, 80 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

At top of grass.

Near ground under grass.

Four weeks ending-

Average.

Maxi-
mum.

Mini-
mum.

2.8
5.7
13.7
5.6
1.1
0.7
0.4
1.3
0.0
0.0
1.4

Average.

3.8
5.6
11.0
9.9
1.4
2.0
2.8
2.7
2.3
1.0
1.2

Maxi-
mum.

5.9
10.8
16.8
16.8

4.4
8.1
8.4
9.0
5.8
2.7
6.8

Mini-
mum.

January 30 _

12.6
16.2
22.4
21.9
10.1
10.7
12.0
13.3
11.7
9.3
7.9

20.2
24.3
31.0
31.4
21.7
29.9
25.6
22.9
21.0
18.1
20.0

0 0

February 27 _. __ .... _

1 2

March 27

5 3

April 24

2 2

July 17

0 0

August 14 ,_ . __

0 0

September 11 .

0 0

October 9 __ _

0 0

November 6

December 4 _.

0.0
0 0

January 1

00

13.5

24.2

3.0

4.0

8.7

0 8

In addition to daily readings the rate of evaporation was
also measured weekly in the top of the second-growth tree
and under the second-growth forest from November 22, 1912,
until July, 1913. Weekly readings were also taken in the crown
of a second-growth tree, at the top of a large area of Saccharum
spontaneum, and near the ground under the Saccharum.

The weekly results in these five situations for the period from
November 22, 1912, to January 1, 1915, are given in Table
CXXVIII, and summarized for corresponding four-week pe-
riods in Table CXXIX. The average rate of evaporation in
the top of the second-growth tree for the entire period is very
similar to that for the shorter period previously discussed.
Near the ground under the second-growth forest the rate of evap-
oration for the longer period was slightly lower than for the
shorter one. The rate in the crown of the second-growth tree
was intermediate between that under the forest and that in the
top of the tree, but was much nearer the rate under the tree
than that in the top. The average daily rate in the top of the tree

EVAPORATION

313

Table CXXVIIL— Average daily evaporation for weekly periods in dif-
ferent situations near the base of Mount Maquiling; altitude, about
100 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Week ending—

1912.

November 22.
November 29.
December 6 ...
December 13 _.
December 20 _.
December 27 _.

January 3___
January 10 ._
January 17 ..
January 24..
January 31..
February 1 ...
February 14.
February 21.
February 28.

March 7

March 14

March 28

April 4__

April 11

April 18

April 25

May 2

May 9

May 16

May 23

May 30

June 6

June 13

June 20

June 27

July 4

July 11

July 18

July 25

August 1

August 8

August 15

August 22

August 29

September 5 .
September 12
September 19

1913.

Top of
second-
growth
tree.

2
2
March 21 35>3

2

31.
30.
32.
18.
28.
36.
18.
27.
28.
23.
33.
36.
27.
21.
18.
17.
10.
14.
18.
15.
23.
18.
14.
22.
21.
22.

In Under
second- second-
growth : growth
tree. tree.

6.9

6.3 J

6.4 j

7.5 i

7.1 I

6.4 I

4.1
5.3

5.5

7.0

6.0

9.0

10.2

9.2

8.9

7.8

11.0

17.4

14.6

19.0

18.4

9.3

13.0

19.4 |

7.9 |

11.2 ,

11.7

6.7

14.7 j

16.9 !

12.6 !

7.8 ;

8.8 |

5.9 j
3.5 j
5.8 |
6.1 |
5.6

10.0
7.0
4.7
7.6
8.8
8.5

3.1
1.8
2.8

2.2 !
1.4 I

0.7
1.9
1.8
4.1

2.7 ;

3.8 |

5.3 :
5.4
4.9
2.6
6.0

12.9
12.2 j

15.1 !

8.6 |

5.4 ;
8.8 \

12.5 I
1.7'
8.2!

7.1 :

6.0 j

11.2 I
14.7

6.1 ;

4.2 |

6.7 j

3.1 ;

1.5 !

1.0 ;
1.3 :
1.6 ;
3.7 ;

2.6 :

1.6 I

2.5 j

2.6 I
3.0

Grass area.

(Saceharum sjwn-

taneum.)

Top of
grass.

10.3

8.4
9.3
9.6
10.2
9.2

1.1
8.5
7.1
10.3
2.7
9.5
12.9
12.5
14.2

12.1 j

14.2 j

23.5 !
22.2 j
20.1 j
13.1 j

7.7 !

12.8 :

12.7 :

4.6 !
13.4 j

15.0 ;

14.2

17.1 ;

21.6 '

16.2 i

11.2 !

10.7 !

9.3 j

6.8 ;

8.2 i

8.7 I

8.4 j
13.1 !

10.3 j

7.8 j

8.9 !

12.8 j

15.4 j

Under
grass.

1.2

2.3
1.1

0.8
1.5
1.4
2.9
1.5
3.6
4.1
4.3
5.5
11.0
5.1
20.3
12.3
10.3
10.5
3.9
6.9
11.3
0.5
6.5
6.0
4.2
7.6
9.6
5.1
4.1
2.4
1.6
1.6
0.4
0.7
0.0
0.0
0.0
0.0
0.0
0.2
0.9

314

MOUNT MAQUILING

Table CXXVIII. — Average daily evaporation for weekly periods in dif-
ferent situations near the base of Mount Maquiling ; altitude , about
100 meters — Continued.

September 26 .

October 3

October 10...
October 17 ....
October 24 ....
October 31 ....
November 7...
November 14-
November 21.
November 28.
December 5 ...
December 12 .
December 19 .
December 26 ..

January 2

January 9

January 16...
January 23...
January 30. __
February 6...
February 13 _.
February 20 .
February 27..

March 6

March 13

March 20

March 27

April 3 __

April 10

April 17

April 24

May 1___

May 8

May 15

May 22

May 29

June 5._

June 12

June 19

June 26

July 3

July 10.

July 17

July 24

July 31

Top of ^
second-
growth
tree.

In

second-
growth
tree.

Under
second-
growth
tree.

Grass area.

(Saccharum spon-

taneum.)

Top of
grass.

Under
grass.

1913.

17.2
20.6
17.7
9.5
20.5
26.2
12.3
14.2
16.4
16.1
17.6
13.9
10.4
12.8

17.2
15.7
20.9
21.9
18.8
22.8
19.8
25.9
28.3
26.0
29.4
31.4
31.-4
33.1
18.9
23.6
24.6
32.3
35.5
31.3
24.2
30.4
16.0
26.2
21.1
12.1
17.1
17.7
31.0
11.3
16.9

5.3
6.1
5.3
6.9
7.2
9.0
4.3
5.7
6.9
6.1
6.0
4.9
3.6
4.0

5.8

5.3

6.9

7.4

8.0

8.0

7.9

10.4

10.9

10.5

13.4

15.9

17.0

18.4

10.9

13.0

12.6

15.9

18.4

14.4

12.6

14.4

8.2

11.7

9.2

5.6

8.6

8.9

16.1

5.0

8.9

1.9
2.6
2.1
1.1
3.2
5.1
1.8
1.5
2.8
2.6
2.7
1.9
1.1
2.0

3.6

3.2

5.5

6.2

6.4

6.5

6.6

8.6

10.6

10.0

13.8

14.8

18.2

19.7

12.1

14.8

12.1

15.5

16.8

12.6

10.3

10.8

4.7

7.2

5.0

2.6

4.3

3.2

10.2

1.1

3.2

12.1

11.6

10.6

3.3

11.2

12.4

6.1

5.5

5.8

5.5

6.2

6.4

3.6

6.0

6.0
6.7
9.1
10.6
10.1
6.7
10.1
13.8
14.9
16.6
19.7
20.3
20.9
22.6
13.9
19.4
20.9
24.9
26.9
22.4
18.4
15.4
11.5
19.3
13.0
9.1
14.1
10.8
23.7
8.0
11.6

0.0

2.5

2.1

0.8

2.4

4.9
2.1

1.1

2.8

1.4

1.0
0.7

0.6

i.6

1914.

1.5

1.7

2.6

4.2

3.7

4.4

4.5

6.4

7.2

6.4

9.2

10.0

11.8

EVAPORATION

315

Table CXXVIIL— Average daily evaporation for weekly periods in dif-
ferent situations near the base of Mount Maquiling; altitude about
1 00 meters — Continued. '

Week ending-

August 7

August 14

August 21--__-

August 28

September 4 ._
September 11 .
September 18 _
September 25 .

October 2

October 9

October 16 :___

October 23

October 30

November 6.__
November 13 ._
November 20 ._
November 27 __

December 4

December 11 ._
December 18 ._
December 25 __

1914.

1915.

January 1_

Top of
second-
growth
tree.

21.3
12.3
20.1
36.4
15.9
10.4
14.5
20.7
13.5
16.4
21.2
15.2
20.9
21.5
38.7
19.2
17.9
11.4
13.5
14.9
15.5

20.5

In
second-
growth
tree.

Under
second-
growth
tree.

12.0
6.3
9.6

18.7
8.6
5.9

6.6 |

9.1 ;
5.4 |
6.9 i
8.1 |

5.7 J
7.4 !
7.6 |
6.9 !

6.8
2.0
4.3
11.0
4.1
1.7
2.8
4.8
2.1
2.6
4.7
2.6
3.7
3.7
3.5

6.7

4.8

7.6

5.3

4.3

0.7

5.0

2.1

5.9

3.1

6.4

4.5

7.9

5.4

Grass area.

(Saccharum 8pon-

taneum.)

Top of
grass.

Under
grass.

18.0

9.0

5.9

0.6

12.4

2.9

21.9

6.9

9.4

1.5

4.4

0.2

7.9

1.8

14.6

4.2

8.3

1.6

8.5

1.1

11.2

2.5

6.7

0.4

9.4

1.8

10.7

2.7

9.1

1.7

9.6
9.9
4.1
7.3
7.9
9.3

11.3

2.7
3.2

0.2
0.6
1.6
1.9

was 21.6 cubic centimeters; in the crown of the second-growth
tree, 9.2 cubic centimeters ; and under the forest, 5.8 cubic centi-
meters. The rates of evaporation in the large grass area are
very similar to those in the smaller area. The average daily
rate at the top of the grass in the large area was 12.1 cubic
centimeters, and in the smaller, 13.5 cubic centimeters. This
difference may be accounted for by the fact that the grass in
the smaller area did not interfere as much with .the wind move-
ment as did the grass in the large space. The rates under the
grass are practically the same in the two cases, being 4 cubic
centimeters in the small patch and 3.9 cubic centimeters in the
large one.
Yapp * measured the rate of evaporation at different eleva-

*Yapp, R. H., On stratification in the vegetation of a marsh, and its
relations to evaporation and temperature, Ann. Bot. (1909), 23, 275-319.

316

MOUNT MAQUILING

tions in a sedge marsh and found that above the sedge it was
more than fifteen times that in the lowest stratum.

Table CXXIX. — Average daily evaporation for periods of four weeks from
November, 1912, to January, 1915, in different situations near the base
of Mount Maquiling ; altitude, about 100 meters,

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Four weeks ending-

January 31

February 28

March 28

April 25

May 23--_-

June 20

July 18

August 15

September 12 ..

October 10

November 7

December 5

January 2

Average .

Top of

In

second-

second-

growth

growth

tree.

tree.

19.7

6.5

25.5

9.3

28.7

13.5

26.4

14.3

29.2

14.0

26.9

11.8

18.4

* 8.2

16.7
19.9
17.9
18.4
17.7
15.9

21.6

7.5

8.9
6.7

7.1
6.4
5.7

9.2

Under
second-
growth
forest.

4.0
6.5
11.3
12.1
10.6
8.2
4.5
2.6
3.8
2.8
3.3
2.8
2.6

5.8

Grass area.
(Saccharum spon-

taneum.) j

Top of
grass.

Under '
grass.

8.2

2.5 |

11.9

5.0 !

18.7

10.8 !

16.3

7.9 i

17.3

6.1 |

16.1

6.6 !

12.0

2.4 j

10.3

0.3 j

11.0

1.5 !

11.1

1.8 i

8.9

2.3 \

7.8

1.8 !

7.3

1.3 !

Daehnowski * has measured the rates of evaporation at dif-
ferent heights in an Ohio bog and found that the evaporation at
5 feet above the ground was twice that at 3 inches above the
soil.

Sherff f observed similar conditions in a bog in Illinois, where
he found that evaporation was ten times as great 175 centi-
meters above the soil as at its surface.

Dachnowski's figures for evaporation near the ground and at
greater heights do not differ so much as do those in the grass
areas on Mount Maquiling, but the differences found by Sherff
and Yapp are greater than those at the base of Mount Ma-
quiling. This may well be due to the fact that the substrata
are moister in the marsh and bog than in the grass area.

In fig. 20 are plotted the rates of evaporation for four-week
periods at the top of the second-growth tree, in the crown of

* Daehnowski, A., The vegetation of Cranberry Island (Ohio) and its
relations to the substratum, temperature, and evaporation. II, Bot. Gaz.
(1911), 52, 126-150.

f Sherff, E. E., Evaporation conditions at Skokie marsh, Plant World
(1913), 16, 154-160.

EVAPORATION

317

Periods of four weeks ending —

Jandl FebI8Mar.2d AprE5Mqy23June?0Julyt8 AugJ5Sept.l2 0ct.IO Nov. 7 Dec: 5. Jon.2

Fig. 20. Average daily evaporation in different situations near the base of Mount
Maquiling; altitude, about 100 meters.

the second-growth tree, under the second-growth tree, at the top
of the grass, and under the grass. All of these curves have
approximately the same form and show clearly the high rate of
evaporation during the dry season. After the dry season, which
is most pronounced during March and April, there was a rapid

318

MOUNT MAQUILING

fall in the rate of evaporation until the four-week period ending
July 18, after which there was a slight rise followed by another
fall, the lowest rate in every case occurring during the four
weeks ending January 2. The greater difference between the
rate in the top of the tree and that in the tree than between
the rate in the tree and that under the trees is emphasized.
At the top of the grass, as might be expected, the rate during
every period is shown to be next to that in the top of the tree.
The rate for every period is less under the grass than under the
trees.

Table CXXX gives the weekly evaporation in the lawn and on
the bare ground in an area that was slightly protected from
wind by surrounding trees and a low ridge. The results are
summarized in Table CXXXI. The average daily evaporation

Table CXXX. — Average daily evaporation for weekly periods, about 25
centimeters above the ground, near the base of Mount Maquiling ; alti-
tude, 80 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.l

Week ending—

1913.

April 4

April 11

April 18

April 25

May2

May 9__

May 16

May 23

May 30-..

June 6 u._

June 13

June 20

June 27

July 4

July 11

July 18

July 25

August 1

August 8

August 15

August 22

August 29

September 5...
September 12..
September 19. .
September 26..
October 3

Near
ground
in pro-
tected

area.

16.0

16.9

14.6

20.0

30.4

8.0

20.6

22.3

18.1

29.3

31.4

23.0

13.1

15.3

9.2

6.1

8.9

6.2

6.6

15.1

11.4

9.3

11.9

12.1

12.6

12.9

14.1

In lawn

on an

exposed

. ridge.

Week ending—

16.4 t|

13.3 ;j

6.7 ;|
i

9.6 !

10.4 ||
9.5 j|

16.8 j|
11.4 '!

9.8 i|

15.6 !

15.9 ||

16.7 ;

13.2 jj

15.3 Si

1913.

October 10

October 17

October 24

October 31.

November 7 . ...
November 14 . _ .
November 21.- .
November 28. ..

December 5

December 12...
December 19-..
December 26. ..

1914.

January 2

January 9

January 16

January 23

January 30

February 6

February 13 .__
February 20 __.
February 27 ...

March 6

March 13

March 20

March 27

April 3

Near
ground
in pro-
tected

area.

In lawn

on an
exposed j

ridge.

12.9 ;

2.9 |
15.4 i
17.2

8.0 |

10.7 !
8.7 i
9.5 j

10.8 |
9.0 I
5.7
7.7 '

11.6

10.0 j

12.1 i

13.9 |

13.0 j

14.1 (
13.4 !
15.9
16.7
16.4
21.3
22.4
22.6
23.2

14.1

7.8
14.3
19.8
9.8
11.3
13.6
12.7
11.5
9.8
7.3
9.3

12.8
12.5
16.6
18.3
17.3
17.0
18.4
23.9
25.3
23.7
29.9
33. 3
36.4
39.4

EVAPORATION

319-

TABLE CXXX.— Average daily evaporation for weekly periods, about 25
centimeters above the ground, near the base of Mount Maquiling ; alti-
tude, 80 meters — Continued.

Week ending-

Near
ground
in pro-
tected

area.

1914.

April 10

April 17

April 24

May 1 ...

May 8

May 15

May 22

May 29

June 5

June 12

June 19

June 26

July 3

July 10

July 17

July 24

July 31

August 7

August 14

August 21

19.5
15.7
19.4
23.1
28.6
21.7
21.1
25.0
12.6
19.6
14.1

8.4
12.4
12.6
22.3

7.9
12.7
23.3

8.5
15.1

In lawn
on an

exposed
ridge.

Week ending—

Near
ground
in pro-
tected

area.

In lawn
on an

exposed
ridge.

j

1914.

24.3 j

27.3

25.9

August 28.-.

23.1
9.9
6.1

33 4

September 4..

16 1

September 11

10.0

33.3
40.3

September 18- —

9.9
18.9

12 9

September 25

19. 0

32.9 j

October 2

9.4

12.1

28.2 :

October 9

10.6

13.5

32.6
16.2 '
25.9
19.7 j

October 16

14.9
9.1
13.1
15.7

18 0

October 23

13 3

October 30

18 4

November 6

22.5

12.0
16.6
16.6
32.6

November 13 .

12.9
13.1
13.7
7.2

17.4

November 20

17 8

November 27 -_.

19.4

December 4

10.3

10.7
15.7
21.2
12.0

December 11-

9.1
10.4
10.7

11.9

December 18 .

13.0

December 25 . . .

13.6

1915.

18.0

January 1 __

13.3

17. 5

Table CXXXI. — Average daily evaporation for periods of four weeks from
April, 1913, to January, 1915, in the open, about 25 centimeters above
the ground, near the base of Mount Maquiling ; altitude, 80 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.l

Four weeks ending-

January 30 .
February 27
March 27 ...

April 24

May 22

June 19

July 17

In some-
what
shelt-
ered
area.

In lawn
on an

exposed
ridge.

12.3

16.2

15.0

21.2

20.7

30.8

18.2

29.2 \

22.0

33.7 |

21.7

23.6

12.4

15.8 '

Four weeks ending-

August 14

September 11-

October 9

November 6 ..
December 4-__
January 1

Average

1

In some-
what
shelt-
ered

11.2
12.4
12.7
12.1

10.8 i
9.7 i

14.7 |

In lawn

on an
exposed j

ridge. •

13. 3
16.3
14.6
15.5
14.3
11.9

19.7

in the lawn for the entire period was 19.7 cubic centimeters,
and on the bare ground in a sheltered area, 14.7 cubic centi-
meters. In this table, as in other previous tables, it will be
noticed that the highest average rates of evaporation occur in

320

MOUNT MAQUILING

the dry season, from March to June; and the lowest in Decem-
ber, when the humidity is high and the temperature low.

As the canopy of the second-growth forest varies greatly in
different places, it was thought advisable to measure the rate
in several different situations. Readings were made weekly
at three sites under the second-growth forest. ^The results are
given in Table CXXXII. Evaporation was also measured in a

Table CXXXII. — Average daily evaporation for weekly periods under trees
near the base of Mount Maquiling ; altitude, about 100 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Week ending—

Under second-growth forest.'

Under

culled

forest on

slope of

ravine.

Site 1.

Site 2.

Site 3.

1913.
April 4 __ _.

15.1
8.6
5.4
8.8

12.5
1.7

.8.2
7.1
6.0

11.2

14.7
6.1
4.2
6.7
3.1
1.5
1.0
1.3
1.6
3.7
2.6
1.5
2.5
2.6
3.0
1.9
2.6
2.1
1.1
3.2
5.1
1.8
1.5
2.8
2.6
2.7
1.9

6.6
15.4
7.7
8,3
15.6
4.2
8.9
11.1
7.1
11.9
16.9
8.7
8.1
6.3
3.3
1.9
1.0
1.0
0.8
1.9
1.4
0.7
1.4
1.3
1.7
1.9
1.4
0.5
3.0
6.8
8.8
3.4
2.6
4.2
2.8
3.1
1.9

9.6
13.1
6.3
10.9
14.6
3.5
9.0
9.4
6.7
11.7
13.1
9.9
4.8
5.5
3.3
1.7
2.2
2.1
2.1
0.5
3.3
1.6
3.1
3.4
3.7
2.1
2.6
1.9
1.5
4.2
5.6
1.6
1.6
2.5
2.3
2.0
1.4

April 11

April 18

April 25... . . _

May2 _

May 9 _ _. .

May 16 „_

May23

May30.._ .

June 6

June 13 •_ .

June20 _.

June27. .. . _._

July4

3.1

July 11 .

1.5

July 18

t.%

July 25

2.4

August 1__ _ _

3.#

August 8 . _.

0.7

August 15 .__

§.4

August22 .

2.1

August 29

1.1

September 5

3.6

September 12 _ ___ _

4.1

September 19

4.2

September 26

1.6

October 3 _ __ . __

2.1

October 10 _

1.6

October 17 _ _

1.4

October 24 _-___

2.4

October 31

3.1

November 7 _ __

1.0

November 14

0.6

November 21 _

1.2

November 28 __ _ ._ ___

0.8

December 5 _

0.9

December 12 „ ___ ___

1.7

EVAPORATION 321

Table CXXXIL— Average daily evaporation for weekly periods under trees
near the base of Mount Maquiling; altitude, about 100 meters — Cont.

Week ending-

December 19.
December 26.

January 2 ...
January 9 ...
January 16 _.
January 23 ._.
January 30 ...
February B.-
February 13.
February 20 ^
February 27.

March 6

March 13

March 20

March 27

April 3

April 10

April 17

April 24

May 1

May8

May 15

May 22

May 29

June 5

June 12

June 19

June 26

July 3

July 10

July 17

July 24

July 31

August 7

August 14

August 21

August 28

September 4 ___
September 11 ._
September 18 .-
September 25 ._

October 2

October 9

October 16

October 23

October 30

November 6 ...
159549-

er second-growth forest.
i 1. Site 2. Site 3.

Under
culled
forest on
slope of
ravine.

1.1 i

1.1

J
0.5

0.2

2.0 ; 2.8

!

1.2

0.5

3.6

2.6

2.0

0.9

3.2

2.6

2.0 ! 0.9

5.5

4.3 |

3.0 | 1.5

6.2

5.2

3.6 | 2.1

6.4 \ 5.0

4.0

1.4

6.5 i 5.8

4.0

1.2

6.6 5.4

4.2

1.0

8.6 i 9.6

6.1

3.4

10.6 12.3

7.8

5.1

10.0 1 11.2

6.5

3.2

13.8 8.1

9.9

6.6

14.8 j 8.4

12.3

5.4

18.2 | 17.2

15. 6 j 9. 1

19. 7 19. 1

15.1 9.3

12.1 12.1

10.9 6.3

14.8 j 12.5

11.9

3.7

12.1 | 12.1

| 11.0

4.7

15.5 i 14.6

! 14.6

6.1

16.8 ! 18.2

19.7 j 10.5

12.6 I 14.2

13.7 ; 6.0

10.3 ; 12.4

12.9 4.6

10.8 ! 14.4

14.6

6.9

4.7 | 5.9

6.0

0.3

7.2 1 10.7

9.9

1.6

5.0 ! 9.0

6.2

1.4

2.6 ! 5.4

3.2

0.5

4.5 | 7.2

5.3

0.0

3.2 5.0

2.5

4.1

10.2 ! 11.4

12.3

11.4

1.1

5.1

2.2

0.8

3.2

6.8

4.9

4.5

6.8

12.3

10.7

4.7

2.0

3.5

1.1

1.4

4.3

6.3

5.5! 7.1

11.0

10.6

18.3 ! 10.7

4.1

4.7

3.2

2.1

1.7

3.1

0.8

2.3

2.8 5.9

3.8

1.8

4.8

7.9

8.4

2.7

2.1

5.1

4.5

0.8

2.6 ! 5.5

4.9

1.1

4.7 ! 6.5

6.4 ! 2.3

2.6 3.1

2.7 | 3.0

3.7 | 7.3

3.0 | 1.7

3.7

i 7.6

3.9

1 1.9

-21

322

MOUNT MAQUILING

Table CXXXII. — Average daily evaporation for weekly periods under trees
near the base of Mount Maquiling; altitude , about 100 meters — Cont.

Week ending—

1914.

November 13
November 20
November 27
December 4 __
December 11 .
December 18 .
December 25 .

January 1 .__

Under second-growth forest.

Site 1.

Site 2.

3.5

6.9

4.8

7.5

5.3

8.1

0.7

4.4

2.1

6.9

3.1

7.1

4.5

10.6

5.4

12.7

Site 3.

2.4
2.2
5.9
3.0
3.1
3.8
2.3

4.2

Under '.

culled
forest on
slope of |
ravine.

1.4
2.1
4.1
1.4
0.5
0.6
1.4

ravine under a badly culled forest at the lower edge of the dip-
terocarp forest at an elevation of approximately 100 meters.
The results of these measurements are also given in Table
CXXXII. The figures in Table CXXXII are summarized in Ta-
ble CXXXIII. An examination of Table CXXXII shows that
from week to week there were considerable variations in the
rates at different situations under the second-growth forest;
but Table CXXXIII shows that the average daily rates for the
entire period are very similar, being in the different cases 6.3
cubic centimeters, 7.1 cubic centimeters, and 6 cubic centimeters.
Evaporation in the ravine was considerably lower, the average
daily rate for the entire period being only 3.3 cubic centimeters.

All the grass areas previously discussed, except the lawn,
were covered with Saccharum, Weekly measurements were al-
so made of the evaporation at the top of the grass in a large
patch of Imp erata exaltata, beginning April 11, 1913, and extend-
ing to January 1, 1915. The results are so similar to those from
the large patch of Saccharum that they have not been presented
in detail; but in Table CXXXIV the rates of evaporation in
the tall-grass areas are brought together for the sake of compar-
ison. In this table it will be seen that the average daily rate
of evaporation in the large area of Imperata was 12.7 cubic
centimeters, and in the large patch of Saccharum, 12.1 cubic
centimeters. This table shows, as do the previous tables, that
the highest rate of evaporation occurred between March and
June, and the lowest, in December.

It is very striking that neither the highest average humidity
nor the lowest average rate of evaporation occurred during the

EVAPORATION

323

Table CXXXIIL— Average daily evaporation for periods of four weeks
from April, 1913, to January, 1915, under trees "near the base of Mount
Maquiling; altitude, 100 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Four weeks ending —

January 30 _
February 27....

March 27

April 24

May 22

June 19

July 17

August 14

September 11 .

October 9

November 6._.
December 4 __
January 1

Average

Under second-growth forest, i Under j
' culled !

- ^ , forest on'

n. '' i slope of

Site 1. Site 2. ! Site 3. i ravine.

5.3

8.1

14.2

12.1

10.6 |

8.2 |

4.5 |

2.6 |

3.8 !

2.8

3.3 !

3.0 !

3.0 ;

6.3

4.3

3.2

1.5

8.3

5.5

2.7

11.2

11.1

6.1

11.8

11.1

6.0

12.5

12.2

6.8

10.6

9.8

2.6

6.1

4.8

4.0

4.1

3.2

2.3

3.7

4.3

4.2

3.8

4.0

2.0

5.8

3.6

2.1

5.0

2.8

1.6

5.7

2.4

0.9

7.1

6.0

3.3

Table CXXXIV. — Average daily evaporation for jjeriods of four weeks from
November, 1912, to January, 1915, in tall-grass areas at the base of
Mount Maquiling ; altitude, about 100 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Top of grass.

Four weeks ending-

January 31

February 28

March 28

April 25

May 23

-Tune 20

July 18

August 15

September 12 ...

October 10

November 7

December 5

January 2

Average .

Saccharum.

In small
area.

12.6 |

16.2 j
22.4 !
21.9 !
24.8 !

10.1 j

10.7 J
12.0 j

13.3 i
11.7 ;

9.3
7.9

14.4

Ini-
perata.

In large i In large
area. I area.

8.2
11.9
18.7
16.3
17.3
16.1
12.0
10.3
11.0
11.1
8.9 j
7.8 |
7.3 |

i2.i :

8.8 I

13.3 j

20.6 j

19.4 \

19.7 j
17.9 j
12.4 j

9.6 |
10.3 |

8.5 |
10.2 j

7.9 ;

6.9 '■
12.7

On ground under
Saccharum .

In small
area.

3.8
5.6
11.0
9.9

1.4
2.0
2.8
2.7
2.3
1.0
1.2

In large j
area.

2.6
5.0
10.8
7.9
6.1
6.6
2.4
0.3
1.5
1.8
2.3
1.8
1.3

3.9

324

MOUNT MAQUILING

rainy months from July to September, but occurred instead dur-
ing the months of ' November, December, and January, when
temperature and light intensity were lowest. During the dry
season the intense illumination, high temperature, low humid-
ity, and great wind velocity all combine to increase evaporation ;
and the effect is seen very clearly in all the tables in which evap-
oration is recorded. During the latter part of the year the
temperature is low, and the humidity is high, while the wind
velocity is not usually great; also, the light is less intense than
at any other time except for limited periods during the rainy
season. All these factors combined produce a low rate of evap-
oration and appear to be more influential in this respect than
are the large amounts of rain that fall between the months of
June and September.

EVAPORATION IN THE DIPTEROCARP FOREST AT 300 METERS'

ELEVATION

In the dipterocarp forest evaporation # was measured in the
top of a dominant Parashorea; in the crown of a second-story
tree, Dillenia philippinensis ; near the ground on a forested
ridge; and in a ravine under the forest. In the last case the
instrument, as previously mentioned, was placed on the bank of
Molauin River at an elevation of about 300 meters and at some
little distance from the other instruments. The results of the
weekly readings between October, 1912, and January 1, 1915,
are given in Table CXXXV and are summarized for correspond-

Table CXXXV. — Average daily evaporation for iveekly periods in different
situations in the dipterocarp forest on Mount Maquiling; altitude, SOO
meters.

T2Jr [Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Week ending —

[n top of

dominant

tree.

7.5
8.9
14.7
9.7
7.5
9.1
5.1
9.1
10.0
11.4
8.7

In
second-
story
tree.

Near
ground

under
forest.

In ravine
under
forest.

October 18

1912.

October 25

1.4
1.7
1.8
1.4
1.1
1.2
1.0
1.0
1.1
1.1

1.1

0.9

November 22 _ _

s

1,0

November 29 -~ __ _

3.1
2.6
2.6
1.9
2.0

1.1

December 6

0.9

December 13

1.0

December 20 _

0.8

December 27

0.7

EVAPORATION

325

Table CXXXV.— Average daily evaporation for toeekly periods in different
situations in the dipterocarp forest on Mount Maquiling; altitude 300
meters — Continued. * '

Week ending-

1913.

January 3

January 10 .-.
January 17 ...
January 24 __.
January 31 ._.
February 7 _ _ .
February 14 _.
February 21 ..
February 28 _.

March 7 .

March 14

March 21

March 28 .__■__

April 4

April 11

April 18

April 25

May 2

May 9

May 16

May 23...

May 30

June 6

June 13

June 20

June 27

July 4

July 11

July 18

July 25

August 1

August 8

August 15

August 22

August 29

September 5__
September 12 _
September 19 _
September 26 _

October 3

October 10

October 17

October 24

October 31

November 7 ._
November 14 .
November 21 _

op of
inant
•ee. -

In

second-
story
tree.

Near
ground
under
forest.

In ravine
under
forest.

5.2

0.9

0.4

0.4

7.8

1.7

1.0

9.9

2.7

1.4

0.5

9.0

3.3

1.7

1.5

7.1

2.6

1.4

1.0

12.5

5.0

0.2

3.3

16.3

5.9

2.4

1.4

17.3

6.4

3.0

1.8

15.8

5.0

2.6

1.8

11.7

3.3

1.1

6.4

18.2

6.3

3.2

2.5

26.1

10.7

6.2

1.9

21.5

9.6

6.4

4.3

16.9

8.9

8.1

5.0

25.6

i 9.0

6.2

3.6

13.4

4.4

2.1

1.1

20.6

7.7

4.7

2.2

24.4

9.6

6.4

3.0

8.0

2.6

0.9

1.1

21.4

7.0

3.6

2.0

19.6

7.1
7.3
9.4
12.0
7.1
5.0

3.6
3.3
5.1
7.6
3.6
2.4

18.4

23.3

27.7

19.0

17.0

1.4

14.9

4.7

2.1

12.1

3.6

1.6

10.9

1.9

0.4

21.3

6.7

0.4

17.7

6.3

0.6

0.5

10.4

6.0

1.0

0.7

19.7

9.1

4.7

0.7

13.0

3.3

1.0

0.5

12.4

3.3

1.4

0.6

21.0

5.3

2.3

1.1

21.0

8.1

2.9

1.3

19.6

5.9

2.6

1.1

12.7

3.1

1.9

0.9

15.0

4.7

2.1

0.6

13.1

3.0

1.7

0.8

11.2

4.1

0.9

0.3

14.3

4.5

1.9

0.4

17.5

7.6

3.0

0.4

7.4

2.8

0.9

0.0

10.4

2.4

0.9

0.0

10.9

3.4

1.4

0.2

326

MOUNT MAQUILING

Table CXXXV. — Average daily evaporation for weekly periods in different
situations in the dipterocarp forest on Mount Maquiling; altitude, 300
meters — Continued.

Week ending—

1913.

November 28

December 5

December 12 _.

December 19...

December 26

1914.

January 2

January 9

January 16

January 23

January 30 i__

February 6

February 13

February 20

February 27

March 6

March 13

March 20 ..

March 27

April 3

April 10

April 17

April 24

May 1

May 8

May 16

May 22

May 29

June 5

June 12

June 19

June 26

July 3

July 10 _

July 17

July 24

July 31

August 7 _ __

August 14 ..

August 21 __

August 28_

September 4 _.

September 11

September 18.__ ._.

September 25

October 2

In top of

dominant

tree.

In
second-
story
tree.

11.1

3.4

10.4

2.8

8.2

1.9

5.6

1.3

7.0

1.1

10.4

3.1

9.9

2.7

11.8

4.1

12.9

4.7

14.4

5.1

14.6

5.1

11.9

4.6

18.3

7.2

19.5

7.7

15.6

6.4

21.4

9.4

23.0

9.1

21.7

9.5

23.5

. 10.6

13.7

5.1

16.0

5.0

18.6

6.0

24.4

9.9

23.8

11.1

23.8

8.5

18.6

8.1

25.7

8.1

14.1

5.2

28.8

6.7

16.0

4.4

10.9

1.9

19.5

4.0

19.1

4.7

33.2

9.6

7.5

1.1

23.9

6.8

20.6

5.0

13.7

2.6

24.1

5.6

41.9

12.3

15.3

3.7

14.9

2.7

17.4

2.0

20.7

3.6

15.0

3.3

Near
ground
under
forest.

1.4
1.0
0.4
0.4
0.4

1.4
1.1
1.7
2.4
2.4
2.3
2.3
3.6
4.6
3.4
5.6
6.6
6.1
7.1
3.7
3.6
3.6
7.0
7.4
4.8
6.1
4.4
1.0
3.9
2.6
0.8
0.9
2.4
6.8
2.6
3.3
3.4
1.1
3.1
3.9
2.1
0.8
1.5
2.5
1.2

EVAPORATION

327

Table CXXXV.— Average daily evaporation for weekly periods in different
situations in the dipterocarp forest on Mount Maquiling; altitude, SOO
meters — Continued.

Week ending-

October 9

1914.

October 16. .;

October 23

October 30. _.

November 6

November 13 _.

November 20

November 27

December 4

December 11

December 18

December 25 .

January 1 __ __

1915.

In top of

dominant

tree.

13.6
19.5
14.9
19.9
19.8
17.8
16.6
18.7
11.1
13.0
13.5
14.0

In
second

19.8

1

nd-
ry
e.

Near
ground

under
forest.

2.1

1.1

4.1

2.1

2.0

1.0

3.9

1.9

4.9

2.0

3.3

1.4

3.1

1.6

3.8

2.0

0.6

0.0

1.5

0.9

2.2

0.9

2.4

1.6

3.4

1.9

In ravine
under
forest. \

0.4
0.8
0.3
0.5
2.6
1.8
2.6
1.5
0.2
0.4
0.9
0.9

ing four-week periods in Table CXXXVI. The figures in this
table are slightly different from those given by Brown and Mat-
thews. This is due to the use by Brown and Matthews of figures
from only one instrument, whereas the figures here given are

Table CXXXVI. — Average daily evaporation for periods of four weeks
from October, 1912, to January, 1915, in different situations in the
dipterocarp forest on Mount Maquiling; altitude, SOO meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Four weeks ending-

In top of

dominant

tree.

10.4
15.8
19.9
18.6
20.6
21.7
17.2
16.9
20.5
15.9
13.8
11.5
10.6

In
second-
story
tree.

3.4
5.9
8.1
7.1
8.0
7.6
4.5
5.3
5.6
3.5
4.3
2.9
2.1

Near
ground
under
forest.

1.7
2.7
4.7
4.9
4.9
4.0
2.2
2.2
2.2
1.9
1.7
1.2
1.0

In ravine
under
forest.

1.2
1.3
2.8
2.6
3.7
1.4
1.1
0.9
0.8
0.8
0.7
0.9
0.7

January 31 _.

February 28 fc

March 2S .__ .

April 25

May 23 ...

June 20_ _ .

July 18 ._

August 15

September 12 .__

October 10

November 7 ._ ___

Decembers

January 2 _ _

Average

16.4

5.3

2.7

1.5

328 MOUNT MAQUILING

averages from several. The figures in Table CXXXVI are
plotted in fig. 21. From Table CXXXVI it will be seen that
the average daily evaporation in the top of the dominant tree
was 16.4 cubic centimeters, which is somewhat lower than in the
top of the second-growth tree at an elevation of 80 meters, where
the average was 21.6 cubic centimeters. The daily rate of evap-
oration in the crown of the second-story tree was very consid-
erably lower, being 5.3 cubic centimeters, or 32 per cent of that
in the top of the dominant tree. On the ground under the
forest it was lower still, being 2.7 cubic centimeters, or 16 per
cent of the amount in the top of the dominant tree. The evap-
oration in the ravine was even lower than near the ground
on a ridge, being only 1.5 cubic centimeters, or 9 per cent of
that in the top of the dominant tree. It will thus be seen that
the rate of evaporation varies greatly in different situations
within the dipterocarp forest, being about eleven times as great
in the top of the dominant tree as in the ravine. The differ-
ences in the rates of evaporation in the different situations are
shown very clearly in fig. 21. The curves for the dipterocarp
forest show the same general character as do those for the pa-
rang, the lowest rate, except in the case of the dominant tree,
occurring during the four weeks ending January 2. In the dom-
inant tree the rate for this period was slightly higher than for
that ending January 31.

The maximum daily evaporation for any one-week period
in the top of the dominant tree was 41.9 cubic centimeters, and
the minimum, 5.1. In the second-story tree the maximum was
12.3 cubic centimeters, and the minimum, 0.6. Near the ground
on the ridge the maximum was 8.1 cubic centimeters, and in
the ravine, 6.4. The minimum in the last two cases was 0.0,

It is interesting to note that the greatest amount of epiphytic
vegetation occurs in the tops of the trees, where the rate of evap-
oration is high. These epiphytes being on the larger branches
are of course not exposed to so high a rate of evaporation
as is the uppermost portion of the dominant canopy, but they
are exposed to rates that are higher than those at lower levels
in the forest. These epiphytes are for the most part provided
with water-storage tissue, and all have leathery, xerophytic
leaves. They are thus constituted to stand the high rates of
evaporation, while they are exposed advantageously for the re-
ception of light and rain. The absence of phanerogamic epi-
phytes at lower levels in the forest is probably connected to a
large extent with the decreased light intensity in these situations.

EVAPORATION

329

Periods of four weeks ending —

JonSI kb.ZdMoc28Apr.25 M„y25June?QJulyl8 Auq.l5 Septl2 Oct. 10 Nov.7 Dec. 5 Jon. 2

x

IV, -,. ,

%H vnde^/^L-—.^ A\—M- _1\-

TV

tf/

'n?-

JfTr2**

oV .......

\

s

A

r /

J5h:.-&:.

1.

^

6....

>-t

•6~.,

<^-<y- :•■«■ <y:-

<

Fig. 21. Average daily rate of evaporation in different situations in the dip-
terocarp forest, Mount Maquiling ; altitude, 300 meters.

330

MOUNT MAQUILING

Though the evaporation rates appear to be fairly low under
the forest, they do not seem, as will be shown later, to be
low enough for the development there of a thick covering of
mosslike plants. The atmosphere in this forest is probably
rarely saturated with moisture, and the absence of clouds from
which water would be condensed on mosslike plants is probably
as important as evaporation in preventing the development of
a thick covering of such plants. Epiphytes on the trunks of the
trees are very scarce in this forest.

Table CXXXVII. — Average daily evaporation for weekly periods in dif-
ferent situations in the dipterocarp forest on Mount Maquiling; altitude,
450 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer ]

Week ending —

August 15

August 22

August 29

September 5 . .
September 12 .
September 19 .
September 26 .

October 3

October 10

October 17

October 24

October 31

November 7-_.
November 14 . .
November 21..
November 28 - .
December 5 ...
December 12 _.
December 19 _.
December 26 _ .

January 2 .__

January 9

January 16 ...
January 23...
January 30. _.
„ February 6__
February 13-
February 20..
February 27-

March6

March 13

1914.

In top of

dominant

tree.

16.0

12.5

11.3

10.0

20.7

13.2

10.9

13.6

11.9

9.4

12.4

14.6

5.3

8.0

9.5

10.2

9.6

6.4

3.5

6.1

7.3
8.5
10.2
12.3
13.7
14.2
13.1
18.3
20.3
13.6
21.9

In
second-
story
tree.

12.8
3.3
5.2
5.4

13.1
9.4
5.1
6.7
5.0
5.6
5.7
8.7
1.9
3.3
5.3
4.5
5.1
2.7
1.0
1.3

2.9
3.4
3.9
5.3
6.0
6.5
5.4
10.1
11.8
6.1
10.4

Near ground un-
der forest.

Top of
ridge.

4.8
1.7
1.7
1.8
4.6
3.9
2.7
4.3
2.9
0.8
3.2
5.8
1.4
2.8
2.7
3.4
3.5
1.5
0.8
0.7

1.6
1.7
3.4
2.6
3.0
4.7
3.0
5.0
4.6
4.1
6.7

Side
of ridge.

1.9
1.4
1.5
1.2
3.3
3.0
1.8
2.3
1.7
1.4
2.4
1.8
0.9
1.4
1.9
1.8
1.7
0.6
0.4
0.5

0.8
1.3
2.2
2.5
2.7
2.6
2.1
3.4
1.3
2.8
5.8

Near
ground
in open.

8.9
5.6
5.7
5.2
6.5
6.3
7.3

10.3
9.3
3.0
9.5

10.9
3.6
4.9
6.4
5.9
3.7
1.9
1.1
1.7

2.1

2.8
3.8
4.9
6.3
7.0
4.0
9.4

12.0
7.1

13. «

EVAPORATION

331

Table CXXXVII. — Average daily evaporation for weekly periods in dif-
ferent situations in the dipterocarp forest on Mount Maquiling ; altitude ,
450 meters* — Continued.

Week ending-—

March 20

March 27

April 3

April 10

April 17 -

April 24

May 1--- -

May8

May 15

May 22

May 29

June 5

June 12

June 19

June 26

July 3

July 10

July 17

July 24

July 31

August 7

August 14

August 21 ._

August 28

September 4 __
September 11 .
September 18 .
September 25 _

October 2

October 9

October 16

October 23

October 30

November 6...
November 13 ..
November 20. _
November 27-.
December 4 .--
December 11 —
December 18 _ .
December 25 _ _

1914. •

1915.

January 1.

In top of

dominant

tree.

In
second-
story
tree.

Near grc
der fc

Top of
ridge.

>und un-
rest.

Side of
ridge.

Near
ground
in open.

0

20.9

12.1

8.0

5.6

12.1

20.1

11.9

5.3

6.9

12.6

21.9

11.3

10.0

7.8

14.6

11.2

4.4

4.0

3.3

7.1

19.1

5.8

4.0

4.5

9.4

17.3

6.0

3.8

3.9

7.5

25.2

10.9

5.4

7.8

13.8

20.0

10.8

7.3

3.6

13.4

19.0

9.8

5.7

5.3

12.4

20.4

9.5

5.0

6.6

11.4

22.1

10.1

5.9

6.8

14.2

14.9

7.1

2.4

4.4

6.8

19.9

8.5

3.9

5.7

8.6

13.8

6.1

2.9

3.7

5.7

10.5

3.2

1.2

1.6

3.5

17.9

8.3

2.5

3.8

3.9

16.0

7.8

2.1

1.1

2.5

19.7

10.6

3.6

5.3

5.6

11.4

2.9

0.3

1.1

5.8

17.5

9.1

3.5

5.0

5.5

20.1

8.1

3.2

5.3

11.0

9.2

4.5

0.7

1.3

1.4

20.2

9.4
12.6

2.9

5.8

4.0

7.6

7.0

23.5

10.6

6.8

3.2

0.9

1.1

2.7

6.0

2.2

0.4

0.7

0.9

15.7

6.5

2.4

2.9

3.4

19.5

7.8

3.2

2.6

3.9

15.8

7.6

2.2

2.8

4.8

10.4

4.0

1.5

2.1

3.3

14. .8

6.8

3.2

4.4

6.3

10.1

4.0

1.3

1.7

4.6

13.6

5.6

2.4

2.6

6.9

14.0

5.9

2.4

3.1

7.3

12.2

4.8

1.8

2.6

5.4

12.5

5.3

2.1

3.1

6.4

14.0

6.1

2.3

2.9

7.9

4.5

9.9

0.3

0.7

11.4

6.3

1.8

0.5

0.3

3.4

10.0

2.8

1.0

1.8

4.9

9.7

3.3

0.8

1.2

4.0

14.8

6.2

2.4

2.9

7.4

332

MOUNT MAQUILING

EVAPORATION IN THE DIPTEROCARP FOREST AT 450 METERS'

ELEVATION

The rates of evaporation at an altitude of 450 meters were
recorded in the top of a dominant tree ; in the crown of a second-
story tree; under the forest on the top and at the side
of a ridge; also near the ground in the center of a clearing
made by removing the' trees from the plot used for detailed
measurements of vegetation at this elevation. Readings were
begun in August, 1913, and continued until January, 1915. The
weekly results are presented in Table CXXXVII and are sum-
marized in Table CXXXVIII for corresponding four-week pe-
riods. The rates of evaporation for four-week periods in dif-
ferent situations are shown graphically in fig. 22. In the top
of the dominant tree the daily rates are somewhat lower than

Table CXXXVIII. — Average daily evaporation for periods of four weeks
from August, 1913, to January, 1915, in different situations in the
dipterocarp forest on Mount Maquiling ; altitude, 450 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.j

Four weeks ending-

January 30 ._.
February 27 ..

March 27

April 24

May 22

June 19. _

July 17

August 14

September 11 .

October 9

November 6 ._
December 4...
January 1

Average . .

In top of

dominant

tree.

In

second-
story
tree.

4.7
8.5

10.1
6.9

10.3
8.0
7.5
6.2
6.9
6.6
5.6
5.6
2.8

Near ground un-
der forest.

_L

Top of
ridge.

2 7
4.3
6.0
5.5
5.9
3.8
2.4
1.9
2.5
2.9
2.6
2.4
1.2

Side of
ridge.

Near-
ground
in open.

2.2

4.5

2.4

8.1

5.3

11.2

4.9

9.7

5.8

12.8

5.2

8.8

3.0

3.9

3.2

5.9

2.7

5.6

2.4

6.1

2.3

6.6

2.0

6.5

1.0

3.3

14.7 !

6.9 j

3.4

at 300 meters' elevation, averaging 14.7 cubic centimeters at 450
meters and 16.4 at 300. The instrument in the second-story
tree was near the top of the crown and in a rather exposed po-
sition. It showed a daily rate of evaporation of 6.9 cubic cen-
timeters, which is 1.6 cubic centimeters more than the rate In
the second-story tree at 300 meters' elevation. This difference is
due to the position of the instruments in the two cases, as at 300

EVAPORATION 333

meters the atmometer was placed in the center of the crown
under a dense canopy. An examination of Table CXXXVII
shows that the rate near the ground on the top and at the
side of the ridge varied considerably from week to week. The
same difference is also evident in the four-week periods given
in Table C XXXVIII. The average daily rates for the entire
period are very similar, however, being 3.4 cubic centimeters
in one case and 3.3 in the other. Both of these averages are
higher than the average rate near the ground at 300 meters'
elevation. The difference is probably due to exposure, as the
station at 450 meters' elevation was on a sloping ridge, while
that at 300 meters' elevation was on more even ground. More-
over, the ridge at 450 meters was more exposed than that at
300 meters. At 450 meters the evaporation near the ground was
23 per cent of that in the top of the tree. The evaporation
near the ground in the open was less than half that in the
top of the dominant tree. This at first might seem strange,
particularly in view of the fact that at 80 meters' elevation the
rate of evaporation in the lawn was only very slightly less
than that in the top of the second-growth tree. However, al-
though the clearing at 450 meters was on a ridge, in an open
situation, so that the surrounding country could be seen from
the place where the atmometer was located, it is still probable
that the instrument was not so much exposed to the action of
the wind as was that in the top of the tree. The differences in
the rates of evaporation in the different situations are brought
out very clearly in fig. 22. From the curves in this figure it
will be seen that the lowest rate of evaporation occurred m every
case during the period ending January 1. The similarity m
the rates of evaporation under the forest on the top and at the
side of the ridge is shown clearly. Moreover, these curves show
that the rates near the ground in the open and in the top of the
second-story tree were not very different, while the rate was
much higher in the top of the dominant tree than in any other

situation. . ,. , . ,

The maximum daily evaporation in the top of the dominant
tree for a one-week period was 25.2 cubic centimeters, and
the minimum, 3.5 cubic centimeters. Near the ground on the
ridge the maximum was 10.0 cubic centimeters, and the mm -
mum, 0.3. Near the ground on the side of the ridge the maxi-
mum was 7.8 cubic centimeters, and the minimum, 0^3. Near
the ground in the open the maximum was 14.6 cubic centi-
meters, and the minimum, 0.9.

334

MOUNT MAQUILING

Periods of four weeks ending —

Jan. 30 kb.27 Mar.27 Apr. 2^ May22JunelSJulyl7 Aug. It Septll Oct 3 Nov. 6 Dec 4- Jon. I

21
20
IS
IB
17
16
15
/4
13
12
II

/0i
9
8
7
6
5
4-
3
I
I

f-M/t- ^-r\^ -ft- --1 - \\

0

-\t>-

\

KDr«5

._■*<£_.

-\

3

FIG. 22. Average daily rate of evaporation in different situations in the diptero-
carp forest, Mount Maquiling ; altitude", 450 meters.

EVAPORATION

335

EVAPORATION IN THE MIDMOUNTAIN FOREST AT 740
METERS' ELEVATION

The rates of evaporation at this elevation were recorded in
the top of a dominant tree, in the crown of a second-story tree,
near the ground under the forest, and under the forest in a
ravine at the side of a ridge. The weekly readings from No-
vember, 1912, to January 1, 1915, are given in Table CXXXIX

Table CXXXIX. — Average daily evaporation for weekly periods in dif-
ferent situations in the midmountain forest on Mount Maquiling;
altitude, 7h0 "meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

November 8 _.
November 15 .
November 22 .
November 29 .
December 6._.
December 13-.
December 20_.
December 27.-

January 3 • ...
January 10 _.
January 17 ._
January 24 ._
January 31 ._
February 7 —
February 14 -
February 21.
February 28 -

March 7

March 14

March 21

March 28

April 4

April 11

April 18

April 25

May 2

May 9

May 16

May 23 _

May 30

June 6-

June 13

June 20_..__.

June 27

July 4

Week ending-

In top of

dominant

tree.

In
second-
story
tree.

Near
ground
under
forest.

In rav'ne
under
forest.

3.2
3.9

0.2
0.2

0.3

4.0

0.3

0.2

2.9

0.2

0.0

6.8

4.4

0.9

4.1

2.9

0.7

0.5

0.2

5.3

1.0

1.4

0.3

3.4

0.5

0.4

0.2

1.0

0.3

0.1

0. 03

2.5

0.5

0.2

0.3

4.0

1.1

0.6

0.3

6.9

1.0

0.9

0.0

2.0

1.0

0.7

0.0

3.9

1.1

0.5

0.5

6.2

0.7

0.7

0.0

7.6

2.7

1.4

0.3

6.3

3.3

1.8

0.3

3.2

1.5

0.4

0.0

9.9

3.0

1.9

0.6

16.7

6.2

4.3

0.2

13.7

6.0

4.5

1.9

10.8

7.8

3.6

1.6

12.0

4.7
1.2
2.0
2.5
0.0
4.4

2.1

3.6

0.6
1.1
1.5

0.0
2.0

8.5

11.3

1 9

14.5

11.0

2.8
2.5

3.1
2.1

9.9

13.6

l

4.2

1.7

16 6

6.2

2.7

11.4

3.6

1.1

11.3

5.2
1.3

1.2

0.6

8.3

4.6

336

MOUNT MAQUILING

Table CXXXIX. — Average daily evaporation for weekly periods in dif-
ferent situations in the midmmmtain forest on Mount MaquiHng;
altitude, 7^0 meters — Continued.

Week ending: —

July 11

July 18

July 25

August 1

August 8

August 15

August 22—-

August 29

September 5._.
September 12
September 19. .
September 26.

October 3

October 10

October 17

October 24.. _.

October 31

November 1 ...
November 14 .
November 21 _
November 28 ..
Decembers —
December 12.-
December 19--
December 26.-

January 2 ..
January 9 —
January 16 ..
January 23 ..
January 30 ..
February 6 ..
February 13 .
February 20 .
February 27 .

March 6

March 13 ....
March 20 — .
March 27 „. .

Aprils

April 10

April 17

April 24

May 1

May 8

May 15

May 22

1913.

1914.

In top of

dominant

tree.

In
second-
story
tree.

Near
ground

under
forest.

In ravin<
under
forest.

6.8

4.3

3.5

1.2

2.9

2.2

1.2

o.e

1.7

0.8

0.3

0.0

2.0

1.6

1.5

0.2

5.2

3.8

2.6

0.2

8.3

6.2

4.6

0.6

7.2

5.2

2.9

0.3

5.3

4.2

2.0

0.5

5.3

5.4

3.0

0.3

7.4

6.4

3.5

0.5

7.7

6.6

4.0

0.6

5.6

3.7

1.4

0.4

8.0

6.2

2.1

0.5

7.1

4.7

1.8

0.5

4.6

4.1

3.2

0.5

6.0

3.7

1.3

0.4

6.8

4.9

1.6

0.4

1.5

0.6

0.2

0.1

3.7

2.3

0.4

0.1

3.2

1.5

0.4

0.04

4.5

2.8

0.7

0.1

4.2

2.1

0.4

0.1

2.0

0.8

0.0

0.0

0.7

0.1

0.0

0.0

3.5

2.8

0.7

0.3

1.1

0.5

0.3

0.2

4.9

2.7

0.5

0.3

5.7

2.6

0.6

0.3

5.0

3.4

0.6

0.3

7.5

5.4

0.9

0.4

6.7

5.4

1.2

0.3

4.0

3.1

. 0.8

0.1

10.7

9.9

3.0

1.4

11.1

8.7

3.9

1.7

3.5

5.0

1.1

1.6

12.7

11.6

4.0

0.9

10.7

7.8

2.6

0.9

9.8

7.3

3.0

1.4

11.5

9.1

4.2

1.1

5.3

2.9

0.9

0.4

9.6

7.9

2.7

0.7

8.6

6.0

2.0

0.4

14.3

11.0

4.3

0.7

10.7

7.4

3.5

1-7

11.0

8.1

3.0

1.7

9.9

9.1

4.1

2.4

EVAPORATION

337

Table CXXXIX.— Average daily evaporation for weekly periods in dif-
ferent situations in the midmountain forest on Mount Maquilinq-
altitude, 7UO meters — Continued.

Week ending-

1914.

May 29 ..
June 5...
June 12..
June 19_
June 26..
July 3 —

July 10

July 17

July 24 _

July 31

August 7

August 14

August 21

August 28

September 4__
September 11.
September 18.
September 25.

October2

October 9

October 16

October 23

October 30

November 6 __.
November 13 .
November 20 _
November 27 _

December 4

December 11. _
December 18 _ ..
December 25..

1915.

January 1 .

In top of

dominant

tree.

In
second-
story
tree.

Near
ground
under
forest.

In ravine
under
forest.

13.8

10.2

4.6

1.4

6.7

5.4

1.9

1.3

11.6

8.6

3.4

1.9

6.6

2.4

1.6

0.5

7.3

4.1

1.6

0.5

9.1

7.4

4.1

1.7

4.5

3.4

1.6

0.4

6.8

5.3

1.9

0.7

5.3

3.2

1.0

0.3

10.5

9.4

4.1

1.4

15.9

7.2

2.9

0.9

3.6

2.6

0.8

0.3

9.6

9.1

3.8

0.9

7.1

5.8

1.8

0.6

0.3

0.5

0.0

0.0

1.0

0.4

0.3

0.0

13.7

10.1

5.6

0.7

12.0

9.5

4.6

0.5

10.1

7.9

2.1

0.6

9.6

3.1

0.9

0.2

6.8

4.1

1.4

0.4

5.2

2.6

0.3

0.04

5.4

3.2

0.5

0.3

6.6

3.8

0.4

0.1

5.3

3.2

0.4

0.5

5.8

3.8

0.2

0.0

5.9

4.5

0.6

0.0

1.2

0.5

0.0

0.0

2.4

0.9

0.0

0.0

3.6

3.8

0.3

0.1 |

4.8

3.3

0.6

0.8 j

5.7

5.5

0.5

0.3

and are summarized for corresponding four-week periods in
Table CXL. The rates were very much lower at this eleva-
tion than in the dipterocarp forest. The average daily rate in
the top of the dominant tree was 7.2 cubic centimeters, which
is 49 per cent of that in the top of the tree at an elevation of
450 meters, an4 44 per cent of that at 300 meters' elevation.
In this forest the atmometer in the second-story tree was placed
in the lower part of the crown of a DiUenia reifferscheidia.
In spite of the fact that the atmometer in the second-story

159549 22

338

MOUNT MAQUILING

Table CXL. — Average daily evaporation for periods of four weeks from
November, 1912, to January, 1915, in different situations in the mid-
mountain forest on Mount Maquiling ; altitude, 71*0 meters,

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Four weeks ending —

January 31- __ _.._ ._.

In top of

dominant

tree.

4.9
7.1

10.1
8.8

10.6
, 11.3
7.1
6.6
5.4
9.3
5.4
4.3
3.0

In

second-
story
tree.

2.2
4.4
6.1
7.2
8.9
6.7
4.7
4.4
4.7
6.5
3.4
2.6
1.7

Near
ground
under
forest.

0.7
1.7
2.8
2.7
3.1

In ravine
under
forest.

0.3

February 28 - _.

0.6

March 28

April 25

May 23 .

1.0
1.1
1.7

June 20 :

3.5 1 1.6

July 18

2.6 i 0.8

August 15 _ . . _. . _ __ . __ _

2.3 ! 0.5

September 12. .__ _

2.2 ! 0.4

October 10—

2.8 ! 0.5

November 7

December 5 __. . _ _ _ _

1.2 0.3

0.4 | 0.4

January 2. _ . . _

0.4 i 0.2

2.0 ! 0.7

Average _. . _._. ._ . __ _

7.2

4.9

tree was in the lower portion of the crown, there was nothing
like so great a difference here between the rate in the second-
story tree and that in the top of the dominant tree as there
was at lower elevations. This would seem to be very evidently
connected with the more open character of the canopy in the
midmountain forest. The average daily rate for the entire
period in the second-story tree was 4.9 cubic centimeters, which
is 68 per cent of that in the top of the dominant tree. The
average daily rate near the ground under the forest was 2 cubic
centimeters, or 28 per cent of that in the top of the dominant
tree. At an elevation of 300 meters the rate on the ground
was 16 per cent of that in the top of the dominant tree, and
at 450 meters it was 23 per cent. The rate in the ravine was
much less than that near the ground on the top of the ridge.
In the ravine the average daily rate was 0.7 cubic centimeter,
which is 35 per cent of that on the ridge and 10 per cent of
that in the top of the dominant tree. The rates of evaporation
under the forest are considerably less than those in similar
situations at lower elevations. This probably accounts in large
part for the greater development of epiphytes, particularly cryp-
togamic ones, on the trunks of the trees in the midmountain
forest than in the dipterocarp forest. Fogs, which are of more
frequent occurrence here than at lower altitudes, may be a con-
tributing factor.

EVAPORATION

339

The rates of evaporation for four-week periods in the dif-
ferent situations are plotted in fig. 23. A comparison of this
curve with the curves for lower elevations emphasizes the fact
that the difference between the rates of evaporation in the top
of a dominant tree and those in the second-story tree is not so
great as at lower altitudes. These curves, like those for lower al-
titudes, show very strikingly the high rates of evaporation
during the dry season. In this case the high rates were partic-
ularly marked in April and May. A second or lower maxi-
mum is shown even more strikingly than at lower elevations.
In the midmountain forest the second maximum is very defi-
nite for the period ending October 10. All the curves show
a lower rate during the rainy season than either immediately
before or immediately after it. In every case the lowest average
minimum for a four-week period occurs during the period end-
ing January 2.

The maximum daily evaporation for a one-week period in
the top of the dominant tree was 16.7 cubic centimeters, and
the minimum, 0.3.

In the second-story tree the maximum was 11.6 cubic centi-
meters, and the minimum, 0.1. Near the ground under the
forest the maximum was 6.2 cubic centimeters, and in the ra-
vine, 4.1. In both of the last situations the minimum was 0.0.

EVAPORATION IN THE MOSSY FOREST

In the mossy forest evaporation was measured at the sum-
mit of the east peak on Mount Maquiling for the period from
October, 1912, to January, 1915. Atmometers were placed in
the top of a dominant tree, in the crown of a dominant tree,
near the ground under the forest, in a shallow ravine near
the summit of the peak, and also on a pole the top of which
was at about the level of the forest. The weekly readings of
these atmometers are given in Table CXLI and are summarized
for corresponding four-week periods for the entire time in
Table CXLII.

The maximum daily rates for a one-week period were: in
the top of the dominant tree, 21.6 cubic centimeters; on the
Pole, 14.4 ; near the ground under the forest, 2.5 ; in the ravine,
1-9; and in the crown of a dominant tree, 4.7. In all cases the
minimum was 0.0.

An examination of Table CXLII shows that, while the rates
]n the top of the tree and on the pole varied from time to
t]me, the average rate for the entire period was very similar

340

MOUNT MAQUILING

Periods of four weeks ending —

Jon J/ FebZd Mar.?8 Aptf5.ffay23June20July/8 Aug.15 5eptl2 Oct. 10 Hov. 7 Dec.5 Jan2

II

10

.5 7 —

.5 6

.. .

i

1

I

l/

/

/

c

/

/

\
\

1

<t

\
\

\ \

t

V

V

\

>

/ /

C

/
/

\

\

/ /

f /

\ \

\ \
\ J

/

*7

\
\

NT

1

/

\

(

\

A

*

i

\

1

}

X

Y

\

I

>

s

\

#

1

1

i

\

i

1
1
1 —

>

***{

k.

/

\

\

\

vt

^*«— /

'A

\

\

A

^

x

\
\

^

if

*

„ , t

Ke4

/

\
C

I

US

7

{

X..

v

\
\

\.

H

y~*<

* fi

n

Pig. 23. Average daily rate of evaporation in different situations in
the midmountain forest, Mount Maquiling ; altitude, 740 meters.

EVAPORATION

341

Table CXLL— Average daily evaporation for weekly periods in different
situations in the mossy forest at the top of Mount Maquiling; altitude
1,050 meters. '

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Week ending-

October 18...
October 25 ...
November 1_-
November 8__.
November 15.
November 22_
November 29_ .
December 6 _ . .
December 13 -
December 20 _
December 27.

January 3

January 10. _
January 17 ..
January 24..
January 31..
February 7__
February 14.
February 21.
February 28..

March 7

March 14

March 21

March 28

April 4

April 11

April 18

April 25

May 2._

May 9

May 16

May 23

May 30

June 6

June 13

June 20

June 27

July 4

July 11. _

July 18__

July 25

August 1

August 8

August 15.__.

August 22

August 29 ....

1912.

In top of

dominant

tree,

0.4
2.1
1.7

0.2
2.2
3.5
3.8
1.0
2.2
3.6
3.6
4.0
1.4
7.5

10.5

10.6
9.5

13.7
2.6
6.6
6.7
0.6

11.4
9.3
6.9
9.4

12.2
9.9
7.2
8.7
3.4
2.3
0.4
0.9
0.8
1.5
3.2
3.2

On pole.

2.1

2.5

In crown
of domi-
nant tree.

Near
ground
under
forest.

2.4
4.6
1.9
4.4
3.1

0.3

2.9

3.9

4.1

1.2

2.7

3.9

3.4

3.1

2.4

9.3

11.5

12.2

10.5

13.3

3.1

5.1

10.8

0.9

14.4

9.2

8.0

10.1

13.1

10.6 \

8.2

9.4 j

4.8 |

2.7 1

0.4 !

0.9 !

0.7 ;

1.6
6.8
3.2

0.0
0.4
0.0
0.4
0.1

0.01

0.0

0.5

0.3

0.0

0.0

0.6

0.0

0.0

0.2

0.8

1.1

1.0

1.0

2.3

0.5

0.5

0.3

0.0

2.2

0.9

0.6

1.0

2.2

1.4

1.4

4.7

0.3

0.0

0.2

0.0

0.0

0.04

0.1

0.0

In ravine
under
forest.

0.3 i

0.1 |

0.1 |

0.2 L__

o.o L .......

o.o L__

°-° ! -

0.3

0. 0 0. 2

0. 0 0. 0

0. 1 0. 03

0. 1

0.0

0.0

0.3

0.0

0.0

0.3

0.0

0.0

0.2

0.4

0.5

0.7

0.5

2.5

0.5

0.4

0.04

0.0

1.3

0.5

0.4

0.8

1.7

0.8

1.0

0.2

0.2

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0
0.0
0.0
0.0
0.0
0.0
0.3
0.0
0.0
0.0
0.3
0.4
0.4
0.2
0.9
0.2
0.2
0.0
0.0
1.6
0.3
0.4
0.4
1.5
0.7
1.0
0.6
0.5
0.0
0.0
0.1
0.0
0.0

o.o I

0. 0 S

342

MOUNT MAQUILING

Table CXLI. — Average daily evaporation for weekly periods in different
situations in the mossy forest at the top of Mount Maquiling; altitude,
1,050 meters — Continued.

Week ending-

In top of

dominant

tree.

1913.

September 5 ..
September 12 .
September 19 .
September 26 .

October 3

October 10

October 17 ..__

October 24

October 31

November 7._.
November 14-.
November 21_.
November 28 _.
December 5 ...
December 12 _.
December 19 ..
December 26 _ .

January 2

January 9

January 16 ._.
January 28—
January 30...
February 6 . _ .
February 13.
February 20-
February 27.

March 6

March 13

March 20

March 27

April 3-

April 10

April 17

April 24

May 1-

May 8

JVIay 15

May 22

May 29-—-

June 5

June 12

June 19

June 26

July 3. -

July 10.

July 17

1914.

3.2
3.8
5.2
5.6
7.6
6.8
2.4
4.8
5.0
0.9
3.0
3.4
2.1
2.7
0.7
0.2
2.0

0.4

3.2

2.6

3.4

5.1

5.1

2.8
10.3
10.8

3.3
13.2

9.4

7.4

9.2

3.4

8.0

7.0
12.5
21.6

9.2

8.8
13.1

4.7
11.2

5.1

6.6

4.4

0.9

1.5 I

On pole.

4.1
4.6
4.9
6.4
7.4
7.4
2.3
6.3
6.8
2.1
4.0
2.1
2.4
4.1
1.4
0.7
3.0

0.6
2.8
3.3
4.4
4.1
5.2
2.6
7.0
6.7
4.2
9.3
8.1
7.5
9.3
4.1
6.6
6.5
8.9
7.1
6.6
7.4
9.2
4.1
8.6
4.9
7.2
3.0
0.7
2.1

In crown
of domi-
nant tree.

0.5

0.2

0.3

0.0

0.0

0.6

0.4

0.4

0.0

0.0

0.0

0.0

0.0

0.04

0.1

0.0

0.0

0.1

0.2

0.1

0.0

0.0

0.0

0.4

0.9'

3.0

0.0

4.6

1.4

1.5

0.9

0.0

1.7

0.6

2.4

0.8

0.3

1.2

0.9

0.

1.3

0.4
0.0
0.0
0.0

Near
ground
under
forest.

In ravine!
under
forest. '

0.04
0.04
0.1
0.0
0.0
0.4
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.1
0.0
0.0

0.0

0.2

0.04

0.0

0.2

0.0

0.0

0.6

0.2

0.04

2.5

0.6

0.5

0.7

0.0

2.5

0.4

2.0

0.7

0.7

1.1

1.1

0.4

0.1

0.0

0.4

0.0

0.0

0.0

EVAPORATION

343

Table CXLL— - Average daily evaporation for weekly periods in different
situations in the mossy forest at the top of Mount Maquilinp; altitude,
1,050 meters — Continued.

Week ending-

July 24

July 31

August 7

August 14

August 21

August 28- _-.
September 4__
September 11 _
September 18 _
September 25 _

October 2

October 9

October 16

October 23

October 30 ....
November 6__.
November 13 ..
November 20 _.
November 27 _.
December 4 _ _ .
December 11 ..
December 18 ..
December 25 _.

1914.

1915.

January 1.

In top of

dominant

tree.

3.4
7.3
9.0
1.5
4.6
1.9
0.0
0.6
8.1
9.5
7.6
4.3
3.6
3.5
2.7
4.4
4.0
4.8
3.6
0.6
1.2
3.9
2.9

In crown
On pole. | of dom
jnanttree.

3.8 ;

7.7 !
6.5 i
1.4 i

4.3 !
1.7 ;
0.0 |
0.0 i

8.9 |
9.1 j
7.6
5.5
6.1

5.4 |
4.4 j
6.3
5.6
9.0
6.0
2.4
3.0
5.7
4.0

6.9 i

0.0
1.9
1.2
0.0
0.0
0.0
0.0
0.0
2.1
1.5
1.3
0.2
0.0
0.1
0.1
0.0
0.0
0.3
0.0
0.0
0.0
0.0
0.04

0.2

ground
under
forest.

In ravine
under
forest.

0.0

0.0

0.9

0.2

0.0

0.4

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

2.1

0.4

0.8

0.3

0.8

0.2

0.1

0.1

0.0

0.0

0.0

0.0

0.1

0.2

0.04

0.0

0.0

0.0

0.04

0.2

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.3

0.0

0.3

. 0.2

in the two cases. In the top of the dominant tree the average
daily rate was 5.3 cubic centimeters, and on the pole, 5.4.
These two situations may very well be taken to represent read-
ings in two different places in the main canopy.

The average daily evaporation in the top of the dominant
tree, 5.3 cubic centimeters, was 1.9 less than in the midmoun-
tain forest. The rate in the crown of the dominant tree was
very much lower than in the top of the tree and approached
the rate on the ground. The average daily rate in the crown
of the dominant tree was 0.6 cubic centimeter, which is only
11 per cent of that in the top of the dominant tree. This dif-
ference is greater than that between the rate of evaporation in
the top of the dominant tree and the rate in the second-story
tree at any of the lower elevations.

The average daily evaporation near the ground was 0.4 cu-

344

MOUNT MAQUILING

Table CXLII. — Average daily evaporation for periods of four weeks from
November, 1912, to January, 1915, in different situations in the mossy
forest at the top of Mount Maquiling; altitude*, 1,050 meters.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Four weeks ending —

In top of

dominant

tree.

On pole.

3.4
4.4
8.1
7.3
8.2
8.6
4.8
2.9
3.1
7.2
5.0
4.1
2.7

In crown
of domi-
nant tree.

0.2
0.7
1.4
1.0
1.1
1.0
0.9
0.5
0.1
0.8
0.2
0.1
0.1

Near
ground
under
forest.

In ravine
under
forest.

January 31 __. _ ._

3.1
5.4
7.9
7.5
10.0
9.1
4.4
3.1
2.6
6.9
3.5
3.1
1.7

0.1

0.2

0.7

1.0

0.8

0.7

0.3

0.1

0.01

0.6

0.1

0.04

0.1

0.02
0 2

February 28

March 28

0.5
0.5
0 6

April 25

May 23

June 20

0.7
0.3
0 1

July 18 _

August 15 _ _ _

September 12

0 05

October 10

0.3

0.05
0 2

November 7 . .._ _

December 5 _. ..

January 2

0 1

Average-

5.3

5.4

0.6

0.4

0.3

bic centimeter, which is only 8 per cent of that in the top of
the dominant tree. This difference between the rate near the
ground and that in the top of the dominant tree is very much
greater than at lower elevations. In the ravine the average
daily evaporation was still lower, being only 0.3 cubic centimeter,
or 6 per cent of what it was in the top of the dominant
tree. The low rates of evaporation in the crown of the tree
and near the ground, as compared with those in the top of
the dominant tree, would seem to be sufficient to explain the
presence of the dense covering of filmy ferns, liverworts, and
delicate mosses on the trunks of the trees and their much less
abundance on exposed branches and leaves. An examination
of Table CXLI shows that there were many weeks during which
no evaporation was recorded in the crown of the dominant
tree, near the ground, or in the ravine. Beginning with Oc-
tober 17, 1913, there were eight consecutive weeks when there
was no evaporation near the ground under the forest, while
in a number of other cases there was no evaporation for con-
siderable periods. The rates of evaporation in the various situa-
tions are plotted for four-week periods in fig. 24. The great
difference between the rates in the top of the trees and those
in the other situations is shown very clearly. The variations
in the seasonal rates are similar to those for lower elevations

EVAPORATION

345

Periods of four weeks ending —

Jon.31 Feb. 28 Mar. 28 Apr. 25 Moy23Junt20Julyi8 A'ug.15 5epU2 OcUO Nov. 7 0et5 Jan. 2

■

.S 5

^i

r

V

\

*»•<

Fig. 24. Average daily rate of evaporation in different situations in mossy forest,
Mount Maquiling; altitude, 1,050 meters.

346

MOUNT MAQUILING
EVAPORATION AT DIFFERENT ELEVATIONS

For convenience in comparing the rates of evaporation at
different elevations, the average daily rates in the tops of the
trees at these different elevations are brought together for four-
week periods in Table CXLIII and are plotted in fig. 25. The

Periods of four weeks ending —

Jan. 3/ Feb.Z8 Mar.Z8 Apr.25 '.May 23 June 20 July 18 Ay. 15 SeptJ2 Oct 10 Nov, 7 Dec. 5 Jan.2

Z8
26
24
12
20
18
16
/4

12

10

8

6

l

I!

i

&

/ *>=

«

VM-Nt

/£/>

"-c:

y~7

«s

Fig. 26. Average daily rate of evaporation in the tops of dominant trees at different
altitudes on Mount Maquiling.

rates near the ground are treated in a similar manner in Table
CXLIV and fig. 26. An examination of fig. 25 shows that the
curves for seasonal variations at different altitudes have very
similar forms, which would indicate that these variations

EVAPORATION

347

Periods of four weeks ending—

Jm- 31 M. £8 Mdfflfyr.15 Moy?3Ju/7e?0Julyl8 Aug.15 Septll OcUO Nov.7 Dec.5 Jon.2

Fig. 26; Average daily rate of evaporation under the forest at different
altitudes on Mount Maquiling.

348

MOUNT MAQUILING

Table CXLIIL— Average daily evaporation for periods of four weeks in
tops of dominant trees from October, 1912, to January, 1915, at differ-
ent elevations on Mount Maquiling.

[Numbers give evaporation in cubic centimeters

from a Livingston

atmometer.]

Four weeks ending —

Elevation in meters.

80.

30J.

450.

740.

1,050.

January 31 _

19.7
25.5
28.7
26.4
29.2
26.9
18.4
16.7
19.9
17.9
18.5
17.7
15.9

10.4
15.8
19.9
18.6
20.6
21.7
17.2
16.9
20.5
15.9
13.8
11.5
10.6

11.2
16.5
19.1
17.4
21.2
17.7
16.0
13.9
13.9
13.9
11.8
10.1
8.0

4.9
7.1
10.1
8.8
10.6
11.3
7.1
6.6
5.4
9.3
5.4
4.3
3.0

8.1
5.4

7.9
7.5
10.0
9.1
4.4
3.1
2.6
6.9
3.5
3.1
1.7

February 28

March 28 _

April 25

May 23

June20._.

July 18. . ._.

August 15

September 12

October 10

November 7 ._-

December5 _. _

January 2 ..

Average _ __

21.6

16.4

14.7 | 7.2

5.3

TABLE CXLIV. — Average daily evaporation for periods of four weeks from
October, 1912, to January, 1915, under the forest at different elevations
on Mount Maquiling.

[Numbers give evaporation in cubic centimeters from a Livingston atmometer.]

Four weeks ending-

January 31 . _
February 28 .

March 28

April 25

May 23

June 20

July 18

August 15-._
September 12
October 10_..
November 7 .
December 5 _
January 2 ...

Average

4.0
6.5
11.3
12.1
10.6
8.2
4.5
2.6
3.8
2.8
3.3
2.8
2.6

I

5.8

Elevation in meters.

300. 450.

1.7
2.7
4.7
4.9
4.9
4.0
2.2
2.2
2.2
1.9
1.7
1.2
1.0

2.7

2.7
4.3
6.0
5.5
5.9
3.8
2.4
1.9
2.5
2.9
2.6
2.4
1.2

740. 900. 1,050.

0.7
1.7
2.8
2.7
3.1
3.5
2.6
2.3
2.2
2.8
1.2
0.4
0.4

0.2
1.0
1.2
1.2
2.0
2.0
0.9
0.5
0.5
1.0
0.5
0.2
0.1

2.0

0.9

0.1

0.2

0.7

1.0

0.8

0.7

0.3

0.1

0.01

0.6

0.1

0.04

0.1

0.4

are brought about by similar sets of factors in the different
situations. It has been previously noted that the curves for
rainfall, temperature, humidity, and light all show similar
variations at different altitudes. Table CXLIII and fig. 25 show

EVAPORATION 049

sf^^^rr rates of evaporation deci-ease with

rising elevations. This decrease in the rate of evaporation
accompanied by an increase in the moisture content ofthe son
wou Id certainly be sufficient to account for the greater deve op-
ment of herbaceous vegetation as higher elevations are reached
Likewise the decrease m evaporation, accompanied by the greater
cloudiness, should account for the greater development of crypto-
gamic epiphytes at higher elevations

An examination of Table CXLIV shows that the rate of
evaporation near the ground under the forest- also decreases
steadily with increasing altitudes. A comparison of fig 26
with fig 25 shows that the rates vary in much the same way
under the trees as in the tops of the trees. The difference in
rates of evaporation at different elevations was relatively greater
near the ground than in the tops of the trees, as will be seen by
a comparison of Tables CXLIII and CXLIV. The rate in the
tops of the trees in the mossy forest was 25 per cent of that in the
top of the second-growth tree at the base, while the rate near
the ground under the mossy forest was only 7 per cent of that
under the second-growth trees at an elevation of 80 meters
The evaporation at the top of the trees in the mossy forest was
32 per cent of that in the dipterocarp forest at an elevation of
300 meters, while the rate near the ground in the mossy forest
was 12 per cent of that near the ground in the dipterocarp forest
at an elevation of 450 meters.

Shreve* repeatedly emphasizes the fact that in the rain
forests of the Blue Mountains in Jamaica xerophytes and ex-
treme hygrophytes may live together in the closest proximity.
This is also more or less true of the vegetation at all altitudes
on Maquiling. In the grass areas at the base a delicate Riccia
and a Selaginella live on ground that is covered by coarse grasses.
In the dipterocarp forest mesophytic ferns are found in the
ravines, and very xerophytic epiphytes grow in the tops of the
trees. In the midmountain forest the xerophytes again occur
in the trees, and delicate, filmy ferns and liverworts in ravines.
In the mossy forest orchids of xerophytic appearance are found
near the tops of the branches, and filmy ferns, liverworts, and
mosses on the trunks.

If we examine the rates of evaporation in the tops of the
trees and in situations near the ground under the forest, it
will be seen that the plants at the tops of the trees live in an

Shreve, F., A montane rain-forest, Pub. Carnegie Inst, of Washington
fl»14), No. 199.

350 MOUNT MAQUILING

environment which is very different from that under the forest.
This is true as regards not only evaporation but also tempera-
ture, as the variations in temperature are much greater in the
tops of the trees than under the forest.

The aVerage rate of evaporation in the tops of the second-
growth trees at the base of the mountain was seventy two times
that in the ravine near the summit. So great a difference would
seem to be sufficient to explain the differences in the epiphytes
in the two situations. In the ravine near the summit there is
an extensive development of delicate liverworts and filmy ferns,
while in the parang epiphytes other than crustaceous lichens
are almost entirely absent. It is interesting to note that even
the small difference between the rate of evaporation near the
ground on the ridge at the top of the mountain and that in the
ravine near the top is accompanied by an evident difference in
the epiphytic vegetation as delicate filmy ferns are much more
developed in the ravine than on the ridge.

The difference in the rates of evaporation in the two situa-
tions just discussed is relatively much greater than that between
the rate near the ground in mesophytic forests in the United
States and in the open in the Arizona desert. Gates * found
an average daily evaporation of 4.4 cubic centimeters in a
beech-maple forest in Michigan. This is a lower rate than that
observed in mesophytic forests by Fuller,f Transeau, t or Wea-
ver. § Livingston l| gives the average weekly rate of evap-
oration at Tucson, Arizona, from May 25 to September 1, 1908,
as 373 cubic centimeters. This is only twelve times as great
as the low rate recorded by Gates. The rate in the tops of the
trees in the mossy forest is eighteen times that in the ravine
at the same elevation. In the dipterocarp forest at 300 meters7
elevation the rate in the tops of the trees is eleven times that
in the ravine.

While the effect of the different rates of evaporation on the

* Gates, F. C, The relation between evaporation and plant succession in
a given area, Am. Journ. Bot. (1917), 4, 161-178.

t Fuller, G. D., Evaporation and soil moisture in relation to the suc-
cession of plant associations, Bot. Gaz. (1914), 58, 193-234.

| Transeau, E. N., The relation of plant societies to evaporation, Bot.
Gaz. (1908), 45, 217-231.

§ Weaver, J. E., A study of the vegetation of southeastern Washington
and adjacent Idaho, University of Nebraska Studies (1917), 17, 1-133.

|| Livingston, B. E., A study of the relation between summer evap-
oration intensity and centers of plant distribution in the United States,
Plant World (1911), 14/ 205-222.

EVAPORATION oci

ground covering and on the development of epiphytes is fairly
clear, it is not clear m regard to the height of the forests and
rates of growth. It will be noted that both the height of ve-
getation and the rates of growth decrease with lower rates of
evaporation This is quite contrary to what has usually been
observed to be the case with temperate vegetation. This point
will be discussed later.

COMPARISON OF RATES OF EVAPORATION ON MOUNT MAQUILING
WITH THOSE IN OTHER LOCALITIES

All of the rates of evaporation mentioned in the following
discussion were obtained from a Livingston atmometer and re-
duced to the standard used by Livingston. With one excep-
tion the rates to be compared with those on Mount Maquiling
appear to have been recorded by instruments not provided with
rain-correcting attachments. There is no means of estimating
the error thus introduced, but the rates for these localities would
undoubtedly have been higher had they been taken in the same
manner as were those for Mount Maquiling.

Fuller * found that the average daily rate of evaporation near
the ground in a beech-maple forest in Indiana was 8 cubic cen-
timeters. Transeauf observed1 an average daily rate of 8.5
cubic centimeters from June 6 to July 2, 1907, in a mesophytic
forest on Long Island, New York. Weaver % found the rate of
evaporation in a Thuja climax forest only slightly greater (0.5
cubic centimeter daily in 1913) than Fuller's figures for the
beech-maple forest of Indiana.

The rates of evaporation in a mesophytic forest in Florida
have been measured by Gano and McNeill § with a Livingston
rain-correcting atmometer, from January to May, 1913. The
average daily rate for this period was 8.5 cubic centimeters,
which is very similar to the results obtained in northern meso-
phytic forests by Fuller, Transeau, and Weaver. All of these
rates are higher than the average daily rate under the second-
growth forest at the base of Mount Maquiling, and several

Fuller, G. D., Evaporation and soil moisture in relation to the succes-
sion of plant associations, Bot. Gaz. (1914), 58, 193-234.

f Transeau, E. N., The relation of plant societies to evaporation, Bot.
Gn*. (1908), 45, 217-231.

t Weaver, J. E., A study of the vegetation of southeastern Washington
*ftd adjacent Idaho, University of Nebraska Studies (1917), 17, 1-133.

§ Gano, L., and McNeill, J., Evaporation records from the gulf coast,
B"t Gaz. (1917), 64, 318-329.

352 - MOUNT MAQUILING

times as great as that under the dipterocarp forest. They are,
moreover, considerably higher than the average for any four-
week period in the dipterocarp forest. Fuller's figures for evap-
oration in the beech-maple forest indicate a rate twenty times
as great as that under the mossy forest.

Fuller * found an average daily evaporation of 13.5 cubic
centimeters at a height of 2 meters above the forest floor in a
beech-maple forest in Indiana. This rate is much higher than
that at the top of the trees at an elevation of 740 meters and is
only 1.2 cubic centimeters less than the average daily rate in the
top of the dominant tree at 450 meters' elevation. The rate
observed by Fuller was practically twice that in the second-
story tree at the latter elevation.

In a beech-maple forest in Michigan Gates f has found a much
lower rate than any of those mentioned above. He says that
the average daily rate for the normal density of this forest was
4.4 cubic centimeters. The highest average daily rate obtained
in open ground was 14.7 cubic centimeters. The average daily
rate under the forest was, however, considerably higher than
that under the virgin forest at any elevation on Mount Ma-
quiling. The rate in the open was very similar to that in the
top of the tree at 450 meters' elevation.

The above comparisons would seem to indicate that the rates
of evaporation under the forest on Mount Maquiling are much
lower at all elevations, except under the second-growth forest,
than in an average mesophytic temperate forest. The average
daily rate of evaporation under the second-growth trees for
the four-week periods ending March 28, April 25, and May 23.
was 11 cubic centimeters, which is higher than any of the summer
rates just mentioned for a mesophytic forest. It should be re-
membered, however, that a second-growth forest is very low
and by no means a climax type. These high rates for the
second-growth forest are similar to those obtained by Fuller t
during the summer months in an oak-dune association in In-
diana, where the average for three seasons was 11 cubic cen-
timeters, exactly the same as under the second-growth trees
during the driest months.

* Fuller, G. D., Evaporation and the stratification of vegetation, Bot. Goz.
(1912), 54, 424-426.

f Gates, F. C., The relation between evaporation and plant succession in
a given area, Am. Journ. Bot. (1917), 4, 161-178.

t Fuller, G. D., Evaporation and soil moisture in relation to the succt—
sion of plant associations, Bot. Gaz. (1914), 58, 207.

EVAPORATION „-q

Livingston * gives the rate of evaporation ^
stations in the United States fori? T,* & nUmber of
September 7, 1908. HesaysT P6n°d fr°m Mav 25 *o

The deciduous forest of the middle ***+ ~

cc, often over 150 and e^oTct.TLZT^ & ^'^ ** °™ 10°
_ C-' as the mean weekly summer rate,

these rates were obtained in the ™™ •« /,
cups 15 centimeters above "the so it r£ce Th 'a* ^ °f J*6
rates in the two open areas at the lZ Jt^M^Z
were respectively, 103 and 138 centimeters. This comnari nn
would mdicate that the rate of evaporation at the baSe of

ro^uSire:rlar to that * the ---"

e evation of about 1,525 meters. One of the statfons wa t
the open at Cinchona, another on a forested ridge, and the third
m a forested ravine. The average daily evaporation I tit
ravine for the period from September 6 to October 11 re-
duced to Livingston's standard, was 0.6 cubic centimeter, which
is somewhat less than the average daily rate for the ravine in
the midmountain forest at an elevation slightly below 740 me-
ters. Brown % also measured the evaporation from May 22
to June 16, 1910, in the same ravine in Jamaica with a rain-
correcting atmometer and found an average daily rate of 0 77
cubic centimeter. This figure is larger than Shreve's. Shreve's
instrument did not have a rain-correcting attachment but was
protected from rain by a glass plate, which did not, however,
protect it from the fogs, and so Shreve's rate may be slightly
too low. The average rate obtained by Brown is greater than
the average rate in the ravine in the midmountain forest of
Mount Maquiling. While Brown's and Shreve's records in Ja-
maica cover too short a period to make them strictly compar-
able with the records on Maquiling, it seems not improbable
that the rates in the ravine in the Jamaican forest and in
the midmountain forest are very similar. Shreve found an
average daily evaporation on the forested ridge of 3 cubic cen-

Livingston, B. E., A study of the relation between summer evaporation
intensity and centers of plant distribution in the United States, Plant
World (1911), 14, 205-222.

f Shreve, F., A montane rain-forest, Pub. Carnegie Inst. Washington
'1914). No. 199.

•I Brown, W. H., Evaporation and plant habitats in Jamaica, Plant
World (1910), 13, 79-82.

169649 23

354 MOUNT MAQUILING

timeters. This is a higher daily rate than was observed near
the ground in the virgin forest on Mount Maquiling, except in
the dipterocarp forest at an elevation of 450 meters, where
the average daily rate was 3.4 cubic centimeters. The average
of the two stations in the dipterocarp forest gives practically
the same rate as Shreve's figures give for the forested ridge
in the Blue Mountains of Jamaica. In the open at Cinchona
Shreve's figures give an average daily rate of 6.8 cubic cen-
timeters for the period between June 20 and November 22.
Brown's figure for the same station for the period between
May 22 and June 16 was 8.2. From these figures it would
appear that the rate in the open at Cinchona is not very dif-
ferent from the rate in the tops of the trees at an elevation of
740 meters, or the rate near the ground in the opening in the dip-
terocarp forest at an elevation of 450 meters. According to these
figures it would appear that the rates obtained by Shreve are
higher than those in the midmountain forest, except in the
ravine. According to the writer's recollection the physical type
of the forest on the Blue Mountains of Jamaica at an eleva-
tion slightly greater than 1,500 meters is more similar to that of
the midmountain than any of the other forest formations on
Mount Maquiling. In very damp ravines, however, the mossy
covering in the Jamaican forest approaches that in the mossy for-
est on Mount Maquiling. In the montane forest in Jamaica fogs
are of very frequent occurrence; a fact that is emphasized by
Shreve as having great influence on the vegetation. It seems
not unlikely that these frequent fogs are largely responsible
for the mossiness of the forest in the wet ravines.

The rates of evaporation in the montane forest of Jamaica,
according to the records of Shreve and Brown, do not appear to
be anything like as low as the rates in the mossy forest on
Mount Maquiling. Concerning the humidity in the Jamaican
forest Shreve says:

After repeated observations with the hygrograph and sling psychro-
meter, I am convinced that saturation, or even humidities as high as 97
to 99 per cent, are extremely transitory states of the atmosphere in the most
moist situations in the rain-forest. Saturation must precede precipitation;
and the condensation of moisture on the foliage of plants often takes place
in the deep forest. As soon as precipitation or condensation occurs, there
is a fall in the humidity and it naturally rises again but slowly, f°r
although the extent of wet surfaces capable of adding by evaporation to
the moisture of the air is very great, the high humidity itself retards such
evaporation. Cloudiness is an important factor in influencing humility
as well as is fog. The passage of small clouds over the face of the sun

EVAPORATION 355

causes immediate and pronounced rises in humidity, due in great measure
to the sudden fall of temperature which may be too transitory to affect
the sluggish thermograph.

In the midmountain forest of Mount Maquiling, although
the humidity is high, the air is probably seldom saturated, but
in the mossy forest the atmosphere under the forest appears
to be practically saturated a large part of the time. From my
own observations in Jamaica and on Mount Maquiling, and
from Shreve's discussion of the forest in Jamaica, I am convinced
that fogs are of much more frequent occurrence and persist
for very much longer periods near the top of Mount Maqui-
ling than in the forest on the Blue Mountains in Jamaica. The
much lower rate of evaporation in the mossy forest of Mount
Maquiling than that obtaining in the Jamaican montane forest
as well as the greater prevalence of fogs in the former location
probably account for the fact that the mossy covering has
developed near the summit of Mount Maquiling, even on the
ridges, to an. extent approached only in the moister ravines
in the Jamaican forest.

It may be of interest to compare the lowest rate of evapora-
tion observed on Mount Maquiling with high rates reported
from the United States. According to Livingston,* the average
weekly rate of evaporation at Tucson, Arizona, from May 25
to September 1, 1908, was 373 cubic centimeters. This is one
hundred seventy-eight times as great as the average rate in the
ravine in the mossy forest near the top of Mount Maquiling.
The average weekly rate at Reno, Nevada, for seven weeks
between June 29 and September 1, 1908, was, according to
Livingston, 437 cubic centimeters. This is two hundred eight
times the average rate in the ravine near the top of Mount
Maquiling. The rate in Arizona is seventy-seven times that in
the ravine in the midmountain forest on Mount Maquiling lhis
ratio is only slightly greater than that between the rate of evap-
oration in the ravine in the mossy forest of Moun Maquiling
and that at the top of the second-growth tree, the latter being
seventy-two times as great as the former.

The relation of evaporation to plant succession has of late
received considerable attention.^ Fulter,t J* _a result of his

intensity and centers of plant distribution in the United States, Plant WotUt

(1911) 14, 205-222. . . 1 ,. , +v.p .ucces-

t Fuller, G. D., Evaporation and soil moisture m relation to the succes
of plant associations, Bot. Gaz, (1914), 58, 193-^4.

sion

356 MOUNT MAQUILING

studies in Indiana, says that the variations in evaporation in
different types of vegetation were great enough to be efficient
factors in causing succession. Weaver, * in discussing the ve-
getation of southeastern Washington and adjacent Idaho, says:

A study of the differences of the rates of evaporation in the various
plant communities shows that these differences are sufficient to be im-
portant factors in causing succession, at least through the earlier stages,
where light does not play an important role.

Gates f has studied the rates of evaporation in a limited area
in Michigan. The rates here were apparently lower than those
dealt with by Fuller and Weaver. Concerning the effect of
evaporation on vegetation Gates says :

The complete range of evaporation conditions present in this region,
namely, from bare ground to the mature forest, is completely within the
physiological limits of the seedlings! of Acer saccharurn, Pinus strobus,
Pinus resinosa, and Thuja occidentalis. Given suitable soil conditions,
maple seedlings will develop under evaporation conditions at least 337
per cent more xerophytic than the normal hardwood forest, or 400 per
cent more xerophytic than the very dense forest.

From this he concludes that the changes in the rates of evap-
oration due to vegetation are not essential for succession.

At the base of Mount Maquiling where the original forest
has been removed there are evidences that the area was orig-
inally covered by a tall dipterocarp forest. In the area are
scattered large individuals of Parashorea malaanonan which
regularly produce large numbers of seeds, but these do not
grow into seedlings even in the second-growth forest. In the
same area Dr. F. W. Foxworthy has attempted to grow seed-
lings of Parashorea and other dipterocarps in plantations, but
^without success. However, as might be expected, such seed-
lings did grow at slightly higher elevations within the dip-
terocarp forest. From these observations it would appear that
Parashorea seedlings cannot succeed in the cleared area for-
merly occupied by this species. The most obvious explanation
of this would seem to be that the high evaporation rate and
low moisture content of the soil, resulting from the removal of
the dense forest, are at least the chief factors in killing the
seedlings of Parashorea and, further, that a fairly dense forest
must be established in this area before the dipterocarps can
enter. In this case it would seem that a low rate of evapo-

* Weaver, J. E., A study of the vegetation of southeastern Washington
and adjacent Idaho, Univ. Nebraska Studies (1917), 17, 36.

f Gates, F. C, The relation between evaporation and plant succession
in a given area, Am. Journ. Bot. (1917), 4, 161-178.

EVAPORATION o-r,

ration caused by a forest cover may be instrumental in pro
ducmg further succession. p °"

?lMrSnMariVdeS J6 f°rest has been amoved at an ele-
vation of 500 meters. This area appears to be much moister
than that at the base of Mount Maquiling. The dipte^ocarn
seeds that have been scattered over the cleared awfSSS
well and have produced vigorous plants which grow rapid!y
and look as though they would reach maturity

The evaporation conditions in the open on Mount Mariveles
at an altitude of 500 meters are not severe enough to exclude
seedlings of the dominant species of the dense forest. It would
appear, therefore, that in some cases either a lower rate of
evaporation or a higher moisture content of the soil, or probably
both, resulting from the growth of vegetation, may be efficient
factors m succession while in other cases a lower rate of evap-
oration is not essential. The two cases just mentioned have
been discussed at some length by Brown and Matthews.*

RELATION OF EVAPORATION TO VEGETATION

On Mount Maquiling the best-developed vegetation is found
at the base of the mountain, and the poorest, at the top; in other
words, among the natural climax types the best-developed
vegetation occurs in a situation where there is the highest evap-
oration, and the poorest, where there is the lowest. This is
quite different from conditions ordinarily found in temperate
countries, where the tall climax types occur in situations with
the lower rates of evaporation. One of the most prominent
features of the vegetation is the change from desert to prairie,
and then to forest, with decreasing rates of evaporation.
Fuller t found that, as vegetation developed from dune asso-
ciations to the beech-maple forest, the rate of evaporation
decreased. Weaver i has also found a decreasing rate of evap-
oration from the desert scrub formation to the climax cedar
forest. On Mount Maquiling, however, as has been previously
Pointed out, the rates of evaporation even in the dipterocarp
forest appear to be lower than in the mesophytic forest of the
United States.

* Brown, W. H. and Matthews, D. M., Philippine dipterocarp forests,
phil. Journ. Sci, Sec. A (1914), 9, 413-561.

T Fuller, G. D., Evaporation and soil moisture in relation to the succes-
S1°n of plant associations, Bot. Gaz. (1914), 58, 193-234.

I Weaver, J. W., A study of the vegetation of southeastern Washington
an<* adjacent Idaho, Univ. Nebraska Studies (1917), 17, 1-133.

358 MOUNT MAQUILING

It seems to be the general consensus of physiologists that
the transpiration stream is very important for the movement
of dissolved salts from the roots to the leaves of plants. This
opinion is expressed very clearly by Pf eff er * and by Jostf
Burgerstein $ emphasizes this view in a critical discussion of
work done previous to the publication of his book, and he seems
to have shown very clearly that the earlier work presented no
conclusive evidence in favor of the view that transpiration was
a necessary evil. Barnes, § while admitting the possibility that
transpiration is of advantage for the transport of mineral salts,
was inclined to the view that it is a necessary evil. He makes
the following statement:

In the rain forests of Ceylon (and doubtless elsewhere) there are regions
of luxuriant vegetation where for months at a time the rain ceases only
to be replaced by a mist. In such conditions evaporation is almost im-
possible. It cannot, therefore, be necessary to an adequate supply of
solutes in the soil.

This is not in agreement with what the writer has been able
to learn from his own observations and from descriptions of
forests in the Malayan region.

Hasselbring || has found that tobacco plants growing under
shade transpire less, but give more ash, than plants growing in
the open. This writer was evidently working with compara-
tively high rates of evaporation. In another paper fl he says
that tobacco plants in the open transpired more than those un-
der shade, but that the total amount of dry substance produced
was practically the same in both cases. These experiments were
also performed with comparatively high rates of evaporation.
Very high rates of evaporation and low percentages of moisture
in the soil are undoubtedly detrimental to vegetation, but it
does not follow from this that very low rates of evaporation
might not also be unfavorable. The present status of this

* Pfeffer, W., The Physiology of Plants. English translation by A. J.
Ewart. Oxford (1900).

f Jost, L., Lectures on Plant Physiology. English translation by R. J-
H. Gibson. Oxford (1907).

t Burgerstein, Die Transpiration der Pflanzen. Jena (1904).

§ Barnes, C. R., in Coulter, Barnes, and Cowles, Text Book of Botany
(1910), 317.

|| Hasselbring, H., The relation between the transpiration stream and the
absorption of salts, Bot. Gaz. (1914), 57, 72-73.

U Hasselbring, H., The effect of shading on the transpiration and assim-
ilation of the tobacco plant in Cuba, Bot. Gaz. (1914), 57, 257.

EVAPORATION 359

question seems to be very well summed up in the following
quotation from Livingston: *

The question as to what rates of transpiration are necessary to elevate
the requisite amount of salts in tall plants deserves further attention at
the hands of experimenters. It appears clear enough, on a priori grounds,
that some transpiration must generally give better growth than none at
all, but the rates generally experienced by ordinary plants are probably
much higher than the optimum.

The rate of transpiration depends, of course, in a large
measure, upon the evaporating power of air. Shreve, t who
made a very detailed study of transpiration rates in the montane
rain forest of Jamaica, found, as pointed out previously, that
the rate of evaporation was very low in this forest and that the
rate of* transpiration was also extremely low. In comparing
the rates found in the forest in Jamaica with those of plants
in Arizona, he says:

* * * The rates of relative transpiration in Jamaican rain-forest
plants and in plants of the Arizona desert are found to be of the same
general order of magnitude1. This is merely saying that the rates of tran-
spiration in the two regions are proportional to the rates of evaporation
which prevail in them. While the plants of the rain-forest are capable of
losing much more water per unit area than are the plants of the desert
if the two kinds of plants are brought under the same conditions, it is
nevertheless true that as each set of plants exists, under its own climate,
the desert plant loses far more water in transpiration per unit area than
does the plant of the rain-forest.

It has, of course, been clearly established that high rates of
evaporation are harmful to plants ; but, in order that there may
be any transpiration, there must be an appreciable rate of evap-
oration. It would seem, therefore, that there may be minimum
and optimum rates of evaporation for plant growth, even though
the optimum rates may be comparatively low. Such low
rates as occur at high elevations on Mount Maquiling may be
below the optimum; but, in view of the present state of our
knowledge, we can only speculate concerning this point. Still,
it may be of interest to compare the rates of evaporation with
the heights of the trees at different elevations on Mount Maqui-
ling. Such a comparison is made in Table CXLV. In the sec-
ond column of Table CXLV the average rates of evaporation
in the tops of the dominant trees are given in centimeters, and

* Palladin, V. I., Plant Physiology, edited by B. E. Livingston. Phila-
delphia (1918), 136.

t Shreve, F., A montane rain-forest, Pub. Carnegie Inst. Washington

(1914), No. 199.

360

MOUNT MAQUILING

the last column gives the heights of the trees. In order to
have the evaporation rates of the same general magnitude as
the heights of the trees, they have been multiplied by 2.64
and the results given in column 3. The figures in column 3
are in fairly close agreement with the heights of the vegetation,
although not so close as the ratios of the temperature-light
indices. It is very natural that evaporation should show the
same general sort of curve as the temperature-light indices, as
temperature and light are largely responsible for the differences
in rates of evaporation at different elevations on Mount Ma-
quiling. The general agreement between the ratios of evap-
oration and the heights, of trees may, therefore, be accidental.
If we were to assume that the rates of evaporation in the
virgin forest are below the optimum and that the size of the

Table CXLV. — Comparison of evaporation rates and heights of vegetation
at different elevations on Mount Maquiling.

Altitude. !

j Average
daily
evapor-
ation.

80 !
300 |

450 I
740 ;
1,050

21.6
16.4
14.7
7.2

5.3

Average
daily

evapor-
ation

X 2.64.

57.0
42.7
39.8
19.0
14.0

Height of

trees.

38
36
22

8-14

trees would be directly proportional to the rate of evaporation,
then the differences in the rates of evaporation at the different
elevations would be sufficient to account for the differences in the
heights of the trees, except perhaps at an altitude of 740 meters.
However, if we attempt to explain the heights of the vegetation
as due to evaporation, it would be necessary to assume that
the evaporation rates at 80 and 300 meters are higher than
the optimum and high enough to be detrimental; otherwise,
there would be no explanation of the fact that at these eleva-
tions the ratios for the heights of vegetation are much lower
than those for evaporation. In comparing the ratios of the
temperature-light indices with the height of the vegetation, it
has been shown that the temperature-light ratios are also higher
than those for the vegetation at the lower elevations.

A very, logical explanation of the heights of the vegetation
at different elevations is obtained if we assume that the de-

EVAPORATION ofil

crease in the height of the trees with increasing elevations is
due to decreasing temperature and light intensity TdtTtte
rates of evaporation at 80 and 300 meters are too Wgh for he
best development of the vegetation and so account for the fart

nl ulr* Z l^ l0Ter Part °f the diPterocarp forest are no
so tall as would be indicated by the temperature-light indices
The rates of evaporation at the highest elevations may be
too low for rapid growth, and may have some effect in causing
the dwarfing of vegetation; but, as before mentioned, we have
no real evidence on which to base an opinion. A combination
of temperature light intensity, and evaporation rates would
certainly seem to be sufficient to account for the observed dif-
ferences m vegetation, and it might perhaps be more reasonable
to ascribe to differences in temperature and light rather than
to evaporation at least the major part, if not all, of the varia-
tions m the height of the vegetation. This is particularly so
since the high rates of evaporation in the dry season appear to
have a very decidedly detrimental influence on the vegetation in
the parang and in the dipterocarp forest. As will be shown later
it is during the dry season that trees at the base of the mountain
make their slowest growth. At this time many of the second-
growth trees are deciduous for a considerable period. Para-
shorea malaanonan at an elevation of 300 meters also makes its
slowest growth during the dry season; and at this time, though
the trees are not deciduous, the foliage is much less dense than
at other times. During the dry season the ground in the dip-
terocarp forest, particularly in the lower part, is literally cov-
ered with dead leaves.

The writer has made too few measurements of seasonal growth
in the midmountain and mossy forests for them to be conclusive,
but those made seem to point to the conclusion that trees near
the top of the mountain also grow more slowly during the dry
season than at other times.

The moisture conditions on the ridges in the dipterocarp
forest would appear to be unfavorable for the development of
herbaceous plants. In the discussion of vegetation it was shown
that such plants were scarce on the plots in the dipterocarp
forest and very abundant in the midmountain forest. In the
dipterocarp forest at an elevation of about 500 meters there is
a very considerable development of various speciss of Elatos-
tema. These are small herbaceous plants, and in this region
they frequently cover the ground over considerable areas, even
°n the ridges. During the dry season all of the plants of these

362 MOUNT MAQUILING

species on the ridges at elevations slightly above 500 meters are
very frequently found wilted. Evidently at such times the com-
bination of the relatively low moisture content of the soil and
the relatively high evaporation rates is unfavorable for these
species. As they frequently wilt at high elevations in the dip-
terocarp forest, it is not surprising that they do not occur on
the ridges at low altitudes, as the soil moisture decreases and
evaporation increases at lower elevations.

As previously mentioned, the dipterocarp forest is much bet-
ter developed in regions where there are no distinct wet and
dry seasons and where there is an evener distribution of rain-
fall than prevails on Mount Maquiling.

The dry season certainly has a very detrimental effect on cul-
tivated plants at elevations of from 50 to 80 meters. Good
growth can only be obtained during this season by means of
irrigation.

There thus appears to be considerable evidence to indicate
that at least during the dry season the rate of evaporation in
the dipterocarp forest is too high for the best development of
plants. This question will be considered again in discussing
seasonal rates of growth.

The effect of evaporation on the ground covering and on the
epiphytic vegetation has been discussed previously.

WIND VELOCITY

The velocity of the wind at different elevations on Mount Ma-
quiling was measured by gauges obtained from Julien P. Friez
Baltimore, Maryland. The type of instrument used was operated
by four cups, so placed as to catch the wind from any direction.
The instrument used read only a thousand miles; as the wind
frequently exceeded that rate within a week, particularly at
the higher altitudes, it was impracticable to obtain weekly read-
ings at all elevations. However, a sufficient number of compa-
risons were obtained at different elevations to indicate that wind
velocity, as might be expected, increases with altitude.

Daily readings were taken in the top of a second-growth
tree in the parang from July, 1913, to January, 1915. The
instrument was elevated on a pole so as to expose it above the
foliage. The results of the daily readings are given in Table
CXLVI and are summarized for corresponding four-week pe-
riods in Table CXLVII. The latter figures are plotted in fig.
27. An examination of this figure shows that there were two pe-
riods of high wind velocity ; one during the dry season and due

Table CXLVI. — Daily wind velocity at the base of Mount Maquiling; alti-
tude, 80 meters.

[Numbers give wind velocity in miles.]

Date.

I--..

1913.

2.. .

3

4....

5..

6__

7...

8._

9.

10.

11.

12.

13... j

14. ._ !

15.. i

Ifi.. _ I

17 """ i

18.. |

19.. "~|

July.

_

i

! August.

■■

Septem-
ber.

October.

Novem-
ber.

Decem-
ber.

82.0
88.0

113. 7
72.0

58.8
59.4

61.7
89.7

158.2

62.9

87.0

33.7

83.0

79.4

80.2

84.5

109.0

48.8

62.5

355.0

69.7

90.8

29.3

46.3

55.2

266.5

90.2

45.0

79.1

| 118. 1

J 77.8
1 78.5

219.7
107.6

65.8
62.0

67.6
104.2

62.3
100.3

65.8

91.0

56.2

16.7

83.4

100.3

53.4

98.4

148.7

108.9

85.6

112.1

54.7

136.7

191.4

58.2

99.7

130.4

56.3

95.9

99.5

136.6

94.9

117.3

32.0

64.4

143.3 !

61.5

110.2

88.2

6.6

63.3

73.6

55.5

111.6

87.7

107.4

104.1

83.5

338.0

96.7

97.6

66.2

10.9

116.7 i

89.5

109.9

101.5

137.3
115.9

29.8
73.0

198.3
92.7

106.5
41.3

• 180. 1

f 51.7
I 87. 8

86.8

8.5

91.1

113.7

84.8

156.5

65.0

36.1

70.2

87.4

79.4

36

47.0

3

364

MOUNT MAQUILING

Table CXLVI. — Daily wind velocity at the base of Mount Maquiling ;
tude, 80 meters — Continued.

alti-

Date.

July.

98.7
70.2
59.0
70.7
68.5
62.0
112.1
91.6
71.6
104.8
268.2
174.8

August.

115.1
56.3
66.2
54.6

77.4
45.3
98.7
129.8
79.8
63.1
52.6
67. 5

Septem-
ber.

74.7
53.1
81.7
81.3
56.7
74.1
107.5
36.8
53.6
79.9
63.3

October.

78.2
71.0
64.9
73.7
95.6

113.8

101.4
74. .0

131.0
56.4

101.3
91.8

Novem-
ber.

Decem-
ber.

1913.

20

75.3
71.0
107.2
104.3
120.7
113.9
81.0

94.1

95.9
71 5

21

22

23

66 3

24

47 4

25 ;

26

} 181.1

27

102 9 140 2

28

29

118. 2 j 190 g
62.7 j

30

114 3

31

97.5
88. 5

June.

Average

Date.

80.3

"""

January.

127. 1
109.8
103.8
140.4
105.7
80.6
59.2
75.7
128.3
195.1
103.6
87.4
96.9
88.8
90.2

155.3

| 206.2

69.7
82.6
97.7
107.6
97.2
83.7

1 271.4

226.6

78.2
128.3

72.4

Febru-
ary.

92.7
91.6
93.2

119.2
76.1
80.7

133.8

) 157.0

112.4
102.4
123.7
88.1
99.1
99.6
138.1
153.7
J 65.9
1 18.6
124.2
196.2

1 216. 1

74.7

80.7

| 80.9

j 72.3

I 131. 2

111.4

88.8

90.9

March.

| 209. 4

126.2
168. 7

67.0

124.8

113.8

| 84.6

I ' 86.4

95.2
119.5
114.9

80.6

90.1

I 184. 2

160.2

112.9

120.6

138.2

80.8

[ 109. 3

1 99.5

123.2

120.0

117.5

128.1

144.6

1

> 308. 4

85.0

April.

[ 102. 4

1 124. 6

134.2

77.3

| 174. 2

80.0

66.7

138.6

98.2

102.8

99.0

97.1

86.4

f 62.7

I 62. 4

77.4

83.1

i 176. 7

56.0
130.3
865.6
299.7

81.5

| 154. 3

86.8
J 91.0
I 114. 0

May.

1914.
1 _ . _

172.5 88 1

2

44.9 161.3

3

4

101.8

98.8

f 121. 9

1 91. 2

85.5

182. 3
109.1

5 „

125. 3

6 __.

94.7

7. *...

81.3

8 ._ __

103.6 ! 65.3

9

107.6
112.5
44.9

68.1

10

57.8

11

67.4

12

66.9 ! 62.7

13

106.8 i 43.8

109.0 ! 78.5

15 _ _.

115.4

89.4
75.1

82.2

17 __

> 290. :.;

18

19

f 76.0 220.2

20

I 88.1 1 220.2

6L8;[ i47.o

114.0 ij
41.9 57.fi
) i ! 83 '?

21 _. _

22 _

23

24 .

25—

( 137-2i 69. 2
f 67 8' 87.1

26

27___

1 72.5 34.7
79 4 i 67.0

28 _. ._

29 .

61.4 | 92. T»

30

68.8 | 99- :"'

81

70.1 !

Average

107.3

100.8

113.3

124.1

86 1 1 89. 4

WIND VELOCITY

365

TABLE CXLVI.-Daily wind velocity at the base of Mount Maquilina ■ alti
tude, 80 meters— Continued.

11.

12.

13-

14-

15-

16-

17-

18-

19-

20-.

21-

22

23-

24..

25-

26..

27-

28-.

29-

30..

31.

Date.

1914.

July. August.

212.3

276.
276.
119.
109.
10.

756.

203.

89.

50.

56.

57.

39.

51.

106.

2.

57.

49.

70.
140.
114.

60.

81.

75.

47.

Septem- ^ . ,
^er October.

109.
49.
60.
51.
67.
57.
54.
51.

239.

128.

66.

65.

54.
105.

60.

41.
195.
199.
131.

71.
167.
283.
305.
339.
284.

167.4
159.8
109.2
62.4
136.8
195.6
219.3
126.3
101.2
90.6
195.1
123.2
42.5
55.7
67.8
60.0
64.3
44.3
67.2
72.1
78.9
64.2
44.4
71.4
112.7
22.1
69.6
51.4
57.1
64.2

68.7
63.7
60.8
64.1
36.5
68.2
40.4
78.7
49.9
64.6
85.3
81.3
47.9
80.3
73.3
70.5
62.4
59.4
71.3
57.9
62.2
50.3
109. 2
104.7
83.3
170. 8
102.8
82.9
62.4
93.6
115.4

Novem-
ber.

128.9
65.7

102.8
77.1
40.2
64.7

65.3 !
5.3 !

102.7 :

28.1 !
103.6 i
108.2 !

70.8 |

76.4 !

61.9 j
98.6 j
67.8 |

46.2 1
100.6 !

55.4
67.1
72.9
79.0
70.4
62.2
94.1
84.3
84.7
121.1
66.5

Average.

121.7

93.2

74.9 I

Decem-
ber.

73.0
76.6

58. 0
86.8
62.9
42.2
51.2

136.6
91.2
85.7
93.6

101.7
62.7

105. 6
97.7
68.8
51. 7
81.7
74.4

113.2
78.2
63.8
49.8
71.2
65.7

55. 1
106.8

85.5
101. 1
98. 8
74.1

79.5

to the northeastern monsoon, and the other during the period
ending September 11, which is in the typhoon season. From
Table CXLVI it will be seen that the high average velocity
during the latter period was due to comparatively short inter-
vals of heavy winds, which occurred during typhoon weather.
The high average velocity during the dry season is a result of
fairly constant, high daily velocities during the season of the
northeastern monsoon.

366

MOUNT MAQUILING
Periods of four weeks ending-

Jon.

30 ted.

27 Mar

W Apr.

MMa\

tZZ Jut

ieI9Jub

ti7 Apa

/¥ Sep

til Oct

.y Nov

6 Dec,

4 Jan

130

C

)

IZO

_

110

lUU

90

.

80

'

FIG. 27. Average daily wind velocity at the base of Mount Maquiling ; altitude, 80

meters.

The most obvious effects of wind on vegetation are due to the
increased evaporation resulting from high wind velocity. An
examination of the tables for evaporation shows that at the base
of the mountain the highest daily evaporation rates in the tops
of the trees occurred simultaneously with some of the high wind
velocities that were due to typhoons. The highest average rate
of evaporation, however, occurred during the period of the north-
eastern monsoon when the daily wind velocity was constantly
fairly high.

There is no evidence that the trees on Mount Maquiling are
injured by the mechanical action of the wind, except that leaves
are torn off during^ typhoons. The writer has observed the ef-
fects of a number of typhoons and has always found that the

WIND VELOCITY 367

greatest damage due to wind occurred in the dipterocarp
forest and not at high elevations, although of course there may-
be times when the reverse is the case. Since the high wind
velocities at the greater altitudes do not cause high rates of
evaporation, there is little reason for assuming that differences
in wind velocities have any marked influence in producing the
dwarfing found near the top.

Table CXLVII. — Average daily wind velocity for periods of four iveeks,
from July, 1913, to January, 1915, at the base of Mount Maquiling;
altitude, 80 meters.

Four weeks ending— Miles.

January 30 105.8

February 27 100-7

March 27 nl-°

'April 24 133-4

May 22 92^

June 19 85*5

July 17 *>*

August 14 ld'9

September 11 129,2

October 9 ™.l

November 6 °^°

December 4 N '
January 1

96 7
Average

The high wind velocities at the summit of the mountain are
probably responsible for the fact that hydrophytic epiphytes
are not so well developed in the tops of the trees as on the trunks.
The effect of high evaporation on epiphytic vegetation is very
evident where an opening occurs in the canopy, as in such
places the hydrophytic epiphytes die when exposed to the wind.
The greatest development of epiphytes occurs, however, near
the top of the mountain where the wind velocities are greatest
While the high wind velocity at the top of the mountain would
tend to cause rapid evaporation, the very moist condition of the
air counteracts this tendency to such an extent that the rate ot
evaporation is, as we have seen, very low.

INTERRELATION OF ENVIRONMENTAL CONDITIONS

Seasonal changes in environmental conditions in the Mount
Maquiling region can be traced to wind direction and the posi-
tion of the sun. The northeastern monsoon strikes the Islands
on the western coast and deposits a large part of its moisture
on the divide between Laguna de Bay and the Pacific Ocean
before it reaches Mount Maquiling. The result is that when it
does reach Mount Maquiling it is a drying wind and produces a
distinct dry season, which is most pronounced from February
to May. The southwestern monsoon is not nearly so strong a
wind, and a large part of tlie rain that falls at this season of
the year is the result of cyclonic disturbances (typhoons) . Dur-
ing this monsoon rains are deposited on all parts of the Islands,
and at this time there is in the Mount Maquiling region a dis-
tinct rainy season, when the skies are overcast by clouds for
a considerable portion of the time. The season of heaviest rains
is usually from July to September.

Light intensity is influenced greatly by the degree of cloudi-
ness. The sun is overhead during the latter part of April and
again about the middle of August. Between April and August
it is in the north and is farthest south in the latter part of
December. If the degree of cloudiness were the same at all
times, we would expect two periods of maximum insolation, co-
incident with the times when the sun is overhead ; and a period
of minimum insolation during December. During the latter part
of April, when the sun is overhead, the dry season is at its
height, and this is the period of maximum insolation. When the
sun gets to be farther north, the light intensity naturally de-
creases. The return to the overhead position does not, however,
bring an increase in light intensity, as by this time the rainy
season has set in, and instead of an increase in the intensity
there is a decrease until the latter part of the rainy season.
After the passing of the cloudiness that accompanies the rainy
season, there is a rise in light intensity, followed by a fall as
the sun gets to be still farther south, the average intensity
reaching a minimum during the latter part of December, when
the sun is farthest south.

The temperature follows the light intensity fairly closely.
The highest temperatures occur during the dry season, when
the light is most intense. After this the temperature decreases
368

INTERRELATION OF ENVIRONMENTAL CONDITIONS 369

until the latter part of the rainy season, when there is a slight
rise, coincident with the rise in light intensity. Following this
there is another fall until the end of the year, when the light
intensity is lowest.

The rate of evaporation is greatest about April, during the
height of the dry season, when light intensity and temperature
are both high. The rate falls during the rainy season but does
not reach a minimum until the end of the year, when the tem-
perature and light intensity are both at a minimum. It thus
appears that temperature and light intensity have more effect
on the rate of evaporation than does the amount of rainfall.

Humidity is lowest in the dry season and highest at the end
of the year, when the light intensity and temperature are both
low. Thus humidity, like evaporation, appears to be regulated
more by temperature and light intensity than by rainfall.

The seasonal variations in the environmental conditions are
similar at all altitudes; although, of course, the intensity of va-
rious factors varies at different elevations.

SEASONAL RATES OF GROWTH

Measurements of rates of growth for various seasons were
made on a number of the same trees that were used for yearly
measurements. In making the seasonal measurements it was
not practicable to use similar periods in every case; and so, in
order to have the results for different lengths of time compar-
able, all of the rates of growth have been calculated for periods
of thirty days. All the measurements of seasonal growth, like
those of annual growth, are diameter measurements. Rates of
diameter growth are probably as good measurements of rates of
growth of trees as the rates of any other single dimension, and
it is of course impracticable to get the total growth of trees. The
seasonal rates of growth do not, however, necessarily represent
the actual amount of material manufactured in the period con-
cerned. This objection does not appear to be nearly so serious
in the case of tropical as it would be for temperate-zone trees;
but it must be borne in mind that there may be periods when
trees are accumulating and storing food much more rapidly than
is indicated by the growth of any single dimension.

SEASONAL GROWTH IN THE PARANG

Seasonal measurements of diameter growth were taken on the
small specimens of Parashorea growing in the open at an eleva-
tion of about 100 meters. The results are presented in Table
CXLVIII and are plotted for different diameter classes in fig.

Table CXLVIII. — Seasonal diameter growth of Parashorea malaanonan
(bagtican lawan) in the open at the base of Mount Maquiling ; altitude,
about 100 meters.

[Rates of growth are reduced to rates in centimeters for 30 days.]

Diameter.

Jan. 29

to
Mar. 26.

era.

4.95

0.000

4.175

0.010

4.14

0.016

3.60

0.092

3.74

0.016

4.29

0.026

3.30

0.010

4.625

0.016

3.43

0.000

Mar. 26 | Apr. 29

to | to
Apr. 29. j June 2.

0.000
0.013
0.000
0.029
0.029
0.000
0.000
0.013
0.013

0.029
0.029
0.070
0.086
0.070
0.111
0.029
0.210
0.057

June 2

to
July 24.

0.074
0.054
0.073
0.156
0.092
0.137
0.045
0.019
0.073

July 24 I Oct. 13

to I to
Oct. 13. j Dec. 10.

0.095
0.089
0.073
0.150
0.064
0.229
0.080
0.000
0.010

0.073
0.000
0.032
0.108
0.083
0.089
0.057
0.057
0.000

Dec. 10

to
Jan. 29.

0.069
0.045
0.025
0.000
0.051
0.175
0.045
0.045
0.026

370

SEASONAL RATES OF GROWTH

371

TABLE CXLVllL-Seasonal diameter growth of Parashorea malaanonan
(bagtican lauan) in the open at the base of Mount Maqnilinq ; altitude
about 100 meters — Continued. * ' '

Diameter.

Jan. 29
» to
Mar. 26.

Mar. 26

to
Apr. 29.

Apr. 29

to
June 2.

June 2

to
July 24.

July 24

to
Oct. 13. ,

Oct. 13

to !
Dec. 10. i

Dec. 10

to
Jan. 29.

era.
4.35

0.025

0.000

0.057

0.054

0.086

1
0.067 '

0. 069

4.70

0.041

0.029

0. 070

0. 054

0. 080

0.099

0.035 !

4.925

0.010

0.029

0.111

0. 092

0. 038

0.016

0.016 1

4.875

0.035

0.000

0.099

0. 083

0. 086

0.032

0. 035

Average

0.023

0.012

0.079

0.077

0. 083
0.127

0.055
0.165

0. 049

7.105

0.016

0.029

0.099

0. 083

0.069

7.605

0.010
0.000

0.013
0.041

0.013
0.057

0.092
0.054

0. 025

6.15

0. 073

0. 073

o. 051 :

5.15

0.016

0.000

0. 000

0.102

0.143

0. 067

0. 095 '

6.04

0.000

0.000

0.041

0.127

0. 089

0.000

0. 051 i

5.39

0.000

0.041

0.000

0.073

0. 137

0. 057

0. 061

6.95

0.000

0.000

0.086

0.054

0.048

0.010

0. 061

6.105

0.000

0.041

0.029

0.038

0.057

0.016

0.035 '

5.15

0.000

0.013

0.070

0.054

0.073

0. 057

0. 025 l

5.06

0.016

0.013

0.029

0.111

0.150

0. 032

0. 085

7.35

0.010

0.000

0.041

0.083

0.105

0. 099

0.069 '

7.37

0.016

0.057

0.070

0.156

0.064

0. 172

0. 105

6.16

0. 000

0.000

0.057

0.045

0. 102

0.099

0. 051

5.425

0.041

0.000

0.041

0.029

0. 073

0. 000

0. 051

6.00

0.016

0. 000

0.057

0.054

0. 041

0. 041

0.061

6.405

0.010

0.013

0.041

0. 064

0. 095

0.073

0. 061

5.04

0.000

0.013

0.086

0.064

0. 054

0. 000

0. 105

6.695

0.025

0.000

0.041

0.092

0.095

0.099

0.069

5.75

0.035

0.013

0.070

0.064

0.080

0.083

0.051

5.51

0.035

0.029

0.099

0.045

0.086

0. 067

0. 025

5.02

0.102

0.029

0.181

0.102

0. 127

0. 073

0.051

6.63

0.067

0.000

0.013

0. 184

0. 105

0.067

0. 051

5.90

0.086

0.029

0.127

0.102

0.127

0. 114

0. 082

9.00

0.000

0.000

0.029

0.038

0.064

0. 051

0. 016

9.2

0.092

0.029

0.156

0.146

0.137

0. 073

0.061

7.97

0.086

0.000

0.127

0.102

0.073

0. 057

0. 061

9.3

0.051

0.029

0.111

0.102

0.073

0. 073
0.066

0.025

Average

0.027

0.016

0.066

0.084

0. 092

0.058

10.05

0.000 i

0.000

0.041

13.6

0.016 !

0.000

0.099

13.8

0.010

0.000

0.156 |

10.95

0.086

0.057

0.140

10.24

0.060 !

0. 041

0. 181

10.88

0.067

0.057

0. 127

11.10

0.095

0.070

0.127

Average

0.048 j

0.032

0. 124

0. 064

0. 165 !

0.032 |

0.035

0. 092

0. 169 j

0. 114 !

0. 051

0. 083

0.150

0. 089

0. 016

0. 102

0.134 1

0.010

0. 156

0. Ill

0.073

0.051

0. 025

0. 064

0.095

0.051

0.035

0. Ill

0. 118

0.016 ;

0. 069

0. 052

28. An examination of this figure shows that the slowest growth
was made during the dry season, and the most rapid, during the
rainy period. An attempt was made to correlate the seasonal

372

MOUNT MAQUILING

rates with changes in climatic factors. It is very clear that the
variations in rates of growth do not follow the variations in any
single factor. Thus, temperature and light intensity are high
when growth is slowest, while growth is also slow when tern-

Periods of four weeks ending —

Jan.29 Mar,?6 AprXB June2 JulyZt-

Oct 13

De&/0

Fig. 28. Seasonal diameter growth of Parashorea malaanonan (bag-dean lauan) in
the open at the base of Mount Maquiling ; altitude, about 100 meters.

perature and light intensity are lowest. When evaporation is
greatest the rates of growth are slowest; but, at the end of the
year, when the rate of evaporation is lowest and the moisture
content of the soil high, there is also a period of slow growth.
Moreover, no combination of different factors has been found
which varied in the same manner as do the rates of growth.

SEASONAL BATES OF GROWTH 373

This may be due in part to growth not being coincident with
the elaboration of food materials, and to the fact that we have
no means of estimating the relation of evaporation and soil
moisture to the rates of growth. In the introductory para-
graphs in the discussion of growth it was pointed out that
high transpiration during the day is accompanied by a decrease
in the diameter of the tree trunks, these returning to their
original size at night. It was also mentioned that Petch * had
found that trees of Hevea brasiliensis might shrink as much as 3
millimeters during the dry season. It is not at all improbable
that, in taking seasonal measurements, variations in diameter
due to swelling and shrinking may play a considerable role in
causing the changes observed, and this may also account in part
for the lack of agreement between rates of growth and seasonal
changes of environment.

Despite these facts there seems to be a general sort of relation
between environment and rates of growth. At the height of
the dry season, when the soil moisture is lowest and the evapora-
tion highest, the adverse effect of dry conditions upon the trees
is shown in loss of foliage and in the slowest rate of growth for
the entire year being made at that time. With the advent of
heavier rains growth becomes more rapid, and it is during the
rainy season that the most rapid growth takes place. Follow-
ing this there is a period at the end of the year when, although
the rate of evaporation is low and the moisture content of the
soil high, there is a slow rate of growth. At this time, however,
the light intensity and temperature both reach a minimum,
which may account for this slow rate of growth. After Jan-
uary the light intensity and temperature increase rapidly, but
by this time the dry season has set in, and the rate of evapora-
tion reaches a maximum during the time that light intensity
and temperature would appear to be most favorable The high
rate of evaporation and the lower moisture conten of the soil ^at
this time apparently more than offset the favorable temperature

and light intensity. , mflrjp

Measurements of seasonal rates of growth were also made
on one hundred twenty-one individuals of secon d-gr owl th tr x*
A summary of the results is given in Table CXLIXanc^«
plotted in fig. 29. This curve, while not agreeing in detail with
the curves for Parashorea, shows the Bame genera J*^Jj£
chief difference is that the rate of growth rftoejecon^gro^

~ * Fetch, T., The girth i^^T^Heve. brasiHensis, Ann. Roy. Bat.
Gardens, Peradeniya (1916), 6, 1-10.

374

MOUNT MAQUILING

Table CXLIX. — Average seasonal diameter growth of 121 second-growth
trees near the base of Mount MaquUing ; altitude, about 80 meters. All
figures are reduced to rates in centimeters for SO days.

Period.

Rate of growth.

x January 15 to February 16 0.200

February 16 to March 24 0.178

March 24 to April 28 0.155

April 28 to June 18 0.183

June 18 to July 24 0.252

July 24 to October 8 0.252

. October 8 to December 1 0.197

December 1 to January 15 0.162

Periods ending —

Jan. 15 Feb. 16 Har.Z* Apr. 28 June 18 July 24- Oct. 8 Dec.

„cn

250

4

o

o

Pi

>> 230

o

CO

S-t

o

s

s ISO

%
g

bo

I 1-70

«

150

Fig. 29. Average seasonal diameter growth of 121 second-growth trees near the
base of Mount Mao.uiling ; altitude, 80 meters.

trees from April 28 to June 28 was slow, whereas Parashorea
made a rapid growth between April 29 and June 2. Like Para-
shorea the second-growth trees showed the slowest rate of growth
during the dry season and the most rapid rate during the rainy
period; and an intermediate rate at the end of the year, when
moisture conditions would appear to have been favorable, but
when light intensity and temperature were lowest.

SEASONAL RATES OF GROWTH
SEASONAL GROWTH IN THE DIPTEROCARP FOREST

375

Seasonal rates of growth of Parashorea mdtaawman in the
virgin forest at an altitude of about 300 meters were measured
by Brown and Matthews.* The results are presented in detail
in their publication and are plotted in their fig. 12. This figure
is here reproduced as fig. 30. The curves in fig. 30 also show
the slowest rate of growth at the height of the dry season, the

Period.

Ju(y23
Oft. 13

Oct/3
Dae JO

D*CM
JoaZi

Fig.

30. Seasonal rates of diameter growth of Parashorea malaunonan in diptero-
carp forest; altitude, about 300 meters.

most rapid growth during the rainy period, and an intermediate
rate at the end of the year. There are, however, some striking
differences between these curves for the virgin forest and those
for the trees near the base of the mountain. The period from
the first part of October to the first of December was one during
which the trees at 80 meters' elevation showed a slow rate of

* Brown, W. BL, and Matthews, D. M., Philippine dipterocarp forests.
Phil. Joum. SeL, Sec. A (1914), 9, 451.

376 MOUNT MAQUILING

growth, but during which Parashorea in the forest made a very-
rapid growth. The period from the last of July to the first
part of October was one of rapid growth at an elevation of
80 meters and of slow growth for Parashorea in the virgin
forest. During this period the light intensity in the virgin
forest was less than during either the preceding or the following
period; and it may be that with the diminished light at this
altitude the great amount of cloudiness during the rainy sea-
son was responsible for this slow rate in the virgin forest.
It is interesting to note that the rate at this time is not very
different from that at the end of the year, and that the light
intensity, as measured by the difference in evaporation from
the white and the radio-atmometers, was similar during the two
periods. The changes in rate of growth in the virgin forest
would seem to be best explained by assuming that the slow rate of
growth during the dry season was due to high evaporation rates
and low moisture content of the soil, and that as moisture con-
ditions became more favorable the rate of growth increased.
However, when moisture conditions during the rainy season
were still very favorable the low light intensity was apparently
responsible for a decreased rate of growth. As the light in-
tensity again increased the rate of growth increased, while at
the end of the year, when both light intensity and temperature
were low, the rate of growth again decreased.

A consideration of the rates of seasonal growth in the parang
and in the lower portion of the dipterocarp forest would indicate
that the rates of growth are influenced by changes in light in-
tensity, temperature, and evaporation. This is what might be
expected from the discussion previously given under the heading
Of Light, where it was shown that variations in temperature and
light appeared to be sufficient to account for the changes in
height from the tall forest at lower elevations to the dwarfed
one at higher altitudes. In the same discussion it was pointed
out that the trees in the lower part of the dipterocarp forest
were not so tall as would be indicated by the temperature-light
indices, and it was suggested that this difference might be due
to high rates of evaporation, particularly during the dry season.

Variations in light apparently show a greater effect on sea-
sonal rates of growth of trees in the virgin forest than upon
those at an elevation of 80 meters, where growth appears to be
more largely controlled by moisture conditions. This again is
in harmony with the view previously expressed that trees that
formerly existed in the latter area were probably not nearly so

SEASONAL RATES OF GROWTH 377

tall as would be indicated by the temperature-light indices, while
those growing in a virgin forest in regions with a more evenly
distributed rainfall do reach the heights indicated by the temper-
ature-light indices for the base of Mount Maquiling.

As the high rates of evaporation obtaining during the dry
season in the lower part of the dipterocarp forest and in the
parang appear to have such adverse effects on the rates of
growth, it seems probable that the lower rates of evaporation
occurring at higher elevations should be favorable, rather than
detrimental, to the development of a tall forest. This consider-
ation suggests that it is the low light intensity and temperature,
rather than the low rates of evaporation, that are responsible
for the dwarfing of the trees at higher elevations. This idea
is in harmony with the view previously expressed in the dis-
cussion on Evaporation.

CLASSIFICATION OF LEAVES

CLASSIFICATION ACCORDING TO RAUNKIAER'S LEAF SIZES

A system of classifying the leaves in different plant habitats
has been devised by Raunkiaer.* An abbreviated translation of
this work has been presented by Fuller and Bakke.f According
to Raunkiaer's system, leaves smaller than 25 square millimeters
are leptophylls; those from 25 to 225 square millimeters, nano-
phylls; 225 to 2,025, microphylls; 2,025 to 18,225, mesophylls;

Table CL. — Classification of erect woody plants on Mount Maquiling ac-
cording to Raunkiaer' s leaf sizes. (Ferns and palms are omitted.)

PLANTS OVER 2 METERS IN HEIGHT ON 0.25 HECTARE IN VIRGIN DIPTEROCARP
FOREST; ALTITUDE, 450 METERS.

Species.

Individuals.

Micro-
phyll;

Meso-
phyll.

Macro-
phyll.

Micro-
phyll.

Meso-
phyll.

Macro-
phyll.

1
3

21

34

20

4

1

8fi

Second-story species

5
4

6 140

22
16

Third-story species

63
6

Undergrowth species -

Total .-_

4

HEIGHT
SEA ASS

79

9

. 7

295

MIDMOU
700 MET

38

NTAIN
ERS.

PLANTS OVER 1 METER IN
FOREST (QUERCUS-NEOLIT

ON 0.25 HECTARE IN
OCIATION) ; ALTITUDE,

First-story species

Second-story species

2
2

32

28
1

1

4

10
5

117

412

1

1
17

Shrubs ,

Total

4

61

5

15

530

18

PLANTS MORE THAN 1 METER IN HE
EST ; ALTITUD

IGHT ON 0.05 HE
E, 1,000 METERS.

CTARE IN MOSS1

r FOR-

8

8

57 I 5«

* Raunkiaer, C, Om Bladstorrelsens Anvendelse i den biologiske Plante-
geografi, Bot. Tidsk. (1916), 33, 225-240.

f Fuller, G. D., and Bakke, A. L., Raunkiaer's "Life Forms," "Leaf-Size
Classes," and statistical methods, Plant World (1918), 21, 25.
378

CLASSIFICATION OF LEAVES 379

^ t0T 16T4^f> ^crophylls; while larger leaves are mega-
phylls In Table CL the erect w6ody dicotyledonous plants on
the plots previously described, at different altitudes on Moun"
Maquihng, are classified according to Raunkiaer's system, both
by number of individuals and by number of species. In this
table the sizes given for compound leaves refer to the leaflets
An examination of the table shows that only three of Raun-
kiaer s leaf sizes were represented on these plots in the virgin
forests ; these were microphylls, mesophylls, and macrophylls.
In the dipterocarp and midmountain forests the leaves were pre-
dominantly mesophylls, although in both cases there were some
species with microphylls and some with macrophylls. In the
mossy forest there were only two leaf sizes, microphylls and
mesophylls. These were represented by the same number of
species, while there was one more individual with microphylls
than with mesophylls. This shows at once that the leaves in the
mossy forest were smaller than those at lower elevations. In the
midmountain forest there was, moreover, a smaller percentage
of macrophylls and a slightly larger percentage of microphylls
than in the dipterocarp forest, which might indicate that the
leaves in the midmountain forest are smaller than in the dip-
terocarp forest. However, since such a large proportion of the
leaves were mesophylls, it would appear that this class covers too
large a range to allow an accurate comparison to be made of the
sizes of leaves in the midmountain and dipterocarp forests.

CLASSIFICATION ACCORDING TO LENGTH AND BREADTH

In order to compare the leaf sizes at different altitudes more
closely and also to see whether changes in length and breadth
are proportional at different altitudes, the leaves have been
classified according to length and breadth in a series of tables.
These tables are similar in form. The leaves are classified ac-
cording to length classes of 10 centimeters and width classes
of 5 centimeters. The measurements of simple and compound
leaves are presented separately. The sizes of the compound
leaves are for the whole leaves and not for the leaflets as in
Table CL. The species and individuals are also classified ac-
cording to the character of the margins. Such data for the erect
woody dicotyledonous plants in the culled dipterocarp forest are
given in Table CLI; for those in the virgin dipterocarp forest,
in Table CLII; for those in the midmountain forest, in Table

380

MOUNT MAQUILING

Table CLI. — Leaf characters of trees over 1 meter in height on 0.25 hectare
in the culled dipterocarp forest on Mount Maquiling; altitude, 200
meters*

SIMPLE LEAVES.

Length in centimeters.

Width in centimeters.

0 to 10.

10 to 20.

20 to 30.

0 to 5.

5 to 10.

10 to 15.

15 to 20.

Spe-
cies.

Indi-
vid-
uals.

Spe-
cies.

3
12
46
17

2

80

Indi-
vid-
uals.

81

240

268

61

13

663

Spe-
cies.

1
Indi- c. „
vid-S.pe-
uals.|cies-

Indi-
vid-
uals.

Spe-
cies.

3

9

30

12

Indi-
vid-
uals.

Spe-
cies.

Indi-
vid-
uals.

Spe-
cies.

Indi
vid

uals

First-story species:
Dipterocarp s

81

|

Miscellaneous

4
6
3

9
19
5

1
5
1

2
51
3

7
16
7
2

32

14
43
12
13

235
173
51

1 2

Second-story species ._
Third-story species

7
2

76
6

4 I 46

Undergrowth species _

Total

~H

33

7

56

54

540

82

9

82

5

48

COMPOUND LEAVES.

First-story species: |
Dipterocarps '

!

|

Miscellaneous

2

8
2

4

31

8

4
4
4

6
57
16

1

2

1

i

i

8

2
43

s! 5

Second-story species _ -

4 ■■ 45

Third-story species

1

3

1

3

1
6 I 24

Undergrowth species _

i

1

3

43

12

79

2

5

1

i

9

45

Total ___.

12

13 ! 74

CHARACTER OF MARGIN OF ALL LEAVES.

First- story species:

Dipterocarps

Miscellaneous

Second-story species _ .

Third-story species —

Undergrowth species.

Total

Entire.

Species.

103

Indi-
viduals.

81

256

409

66

13

Not entire.

Species.

825

22

Indi-
viduals.

17
30

a Five undetermined individuals and 5 palms are not included in this table.

CLASSIFICATION OP LEAVES

381

Table CLIL-W characters of erect, woody plants over 2 meters in height
on 0.25 hectare in the virgin divterofiam **<*<>«+ ™ m™.-* »#—....«„...

altitude, U50 meters.1

he virgin dipterocarp forest on Mount Maquiling;

SIMPLE LEAVES.

i

Length in centimeters.

Width in centimeters

0 to 10.

10 to 20.

20 to 30. 1

.i

0to5.

5 to 10.

10 to 15.

15 to 20.

Spe-
cies,

Indi-
vid-
uals.

Spe-
cies.

2

Indi-
vid-
uals,

33

25

80

38

5

181

Spe-
cies.

Indi-
vid-
uals.

Spe-
cies.

1
4
10
6
2

Indi-
vid-
uals.

1

18
28
7
4

58

Spe-
cies.

2

7
18
10

2

39

Indi-
vid-
uals.

Spe-lIn.?-

ciesJv,f
uals.

SpeJ11*1"

c,es'|ual8.

First-story species:

Dipterocarps

Miscellaneous

Second-story species ._

Third-story species

Undergrowth species..

Total

1
2

7

2

► 1

13

1

33
12

. '. __ j

■■ 1 i

5 j 9
14 19
3 i 14

-jJ_l

24 j 47

1

8
4

4

37
18

1 1 4

75
35
2

157

4
2

26
2

2 ! 2
2 j 15

13

59 ;

23

7

32

4 1 17

First-story species:
Di pterocarps

■—

COMPOI

j

rND

LEA^

fES.

r

Miscellaneous _■

3 6

5 i 27

4
2

13
9

!

2 5 ^

5
23

3
3
3

9
13
20

Second-story species ..
Third-story species

.....

4

1

3

20 i

Undergrowth species. .

[ ""

Total

8

38 9

42

2

5

6

98

9

42

C

HARACTER 0

FMi

VRGIN OF AL

L LE

AVE

S.

|

i

Entire.

Not entire.

-

i
Species.

3
15
34
14

Individ-
uals.

34
45
137
50
4

Spe

cies.

Individ-
uals.

First-story species:
DipterocarpB

Miscellaneous

4

7
9
2

8
30
29

2

Second-story species __

Third-story species -

Undergrowth species ._

2

Total

fi8

270

22

69

1 Livistona sp., a palm represented by 13 plants, and 1 undetermined individual, are not

included in this table.

382

MOUNT MAQUILING

Table CLIII. — Leaf characters of trees over 1 meter in height on 035 hec-
tare in the midmountain forest (Quercus-Neolitsea association) on
Mount Maquiling ; altitude, TOO meters?

SIMPLE LEAVES.

First-story species ...
Second-story species _

Total

Length in centimeters.

0 to 10.

Spe-
cies.

Indi-
vid-
uals.

34

10 to 20.

20 to 30+.

Spe-
cies.

Indi-
vid-
uals.

43

372

458

Spe-
cies,

Indi-
vid-
uals.

Width in centimeters.

0to5.

Spe-
cies.

23

Indi-
vid-
uals.

54
199

253

<2«^ Indi-
S.pe" vid-
cies-uals.

227

10 to 15.

Spe-
cies,

Indi-
vid-
uals.

15+.

Spe-
cies.

Indi-
vid-
uals.

12

10 I 3 i 12

COMPOUND LEAVES.

First-story species _..
Second-story species .

Total

CHARACTER OF MARGIN OF ALL LEAVES.

First-story species .__
Second-story species _

Total

Entire.

Species.

49

Individ-
uals.

107
311

Not entire.

Species-.

418

19

Individ-
uals.

21
122

143

* Cyathea caudata, a tree fern ; Pinanga, a palm ; and 1 undetermined specimen are not
included in this table.

Table CLIV. — Leaf characters of erect, woody plants more than 1 meter
in height on 0,05 hectare in the mossy forest on Mount Maquiling; al-
titude 1,100 meters*

SIMPLE LEAVES.

Lengrth in centimeters.

OtolO.

Spe-
cies

Indi-
vid-
uals.

10 to 20.

Spe-
cies.

Indi-
vid-
uals.

34

20 to 30.

Spe-
cies.

Indi-
vid-
uals.

Width in centimeters.

0to5.

Spe-
cies.

12

Indi-
vid-
uals.

5 to 10.

Spe-
cies.

Indi-
vid-
uals.

10 to 15.

Spe-

Indi-
vid-
uals.

15 to 20.

Spe-
cies.

Indi-
vid-
uals.

CLASSIFICATION OF LEAVES

383

TABLE CLIV.— - Leaf characters of erect, woody plants more than 1 meter
in height on 0.05 hectare in the mossy forest on Mount Maquiling; al-
titude 1,100 meters — Continued.

CHARACTER OF MARGIN OF ALL LEAVES.

Entire.

Not entire.

Species.

Individ- ! Sl>ecies Individ-
uals. | &*>ec,e8- ualB%

8 Cyathea caudata, a tree fern, represented by 44 individuals, is not included in this table.

Table CLV. — Leaf characters of plants less than 1 meter in height on plot
10 meters square in culled dipterocarp forest on Mount Maquiling;
altitude 200 meters.

Trees-
Herbs .
Vines..

SIMPLE LEAVES.
Length in centimeters.

OtolO.

Spe-
cies.

Indi-
vid-
uals.

10 to 20.

Spe-
cies.

Indi-
vid-
uals.

3 to 30 +

Spe-
cies.

Indi-
vid-
uals.

Width in centimeters.

0to5.

Spe-
cies.

Indi-
vid-
uals.

5 to 10.

Spe-
cies.

Indi-
vid-
uals.

10 to IB.

~ 1

Ilndi-

Spe-|
cies.i,

vid-
uals.

15 to 20+.

Spe-
cies.

Indi-
vid-
uals.

Total— 3 13 18 63 1 11

18 11 69

COMPOUND LEAVES.

Trees

2

2

3

18

■I

! 2 j 2

3

18

Herbs

1 |

Vines-

2
5

4
22

j |

2

4

Total

2

2

! 2 | 2

5 I 22

_-

rr-r-rr.

L_i

CHARACTER OF MARGIN OF ALL LEAVES.

Entire.

i

17 59

2 j 23

Not entire.

Species.

2
1
2

Individ-
uals.

Treesa__„____

2

Herbs..

23

Vines

4

Total

19 82

5

29

* One undetermined individual is not included.

384

MOUNT MAQUILING

Table CLVI. — Leaf characters of plants on a plot 10 meters square in the
dipterocarp forest on Mount Maquiling ; altitude, 450 meters.

SIMPLE LEAVES.

Trees »_.
Shrubs .
Herbs -.
Vines *> .

Total .

Trees*..
Shrubs .
Herbs _.
Vines b .

Total.

Length in centimeters.

0 to 10.

Spe-
cies.

Indi-
vid-
uals.

36

10 to 20.

Spe-
cies.

Indi-
vid-
uals.

22

133

20+.

Spe-
cies.

Indi-
vid-
uals,

11

Width in centimeters.

0to5.

Spe-
cies.

Indi-
vid-
uals,

15

5 to 10.

Spe-
cies.

Indi-
vid-
uals.

133

10 to 15.

Spe-
cies.

Indi-
vid-
uals.

15+.

Spe-
cies.

Indi-
vid-
uals.

COMPOUND LEAVES.

Trees* __

2

13

5

12

3

14

4

11

Shrubs

2
2

2

82

96

2
2

8

2

Vines b

1

53

1
4

53

67

8?.

Total

3

66

9

%

CHARACTER OF MARGIN OF ALL LEAVES.

Entire.

Species.

27
1
5
6

Individ-
uals.

118

1

45

63

227

Not entire.

Species.

14

Individ-
uals.

25
21

132

a Undetermined individuals and palms are not included.
b Undetermined individuals are not included.

CLIII ; and for those in the mossy forest, in Table CLIV. Similar
data for the plots 10 meters square, on which all plants were
measured, are given in Tables CLV to CLVII. In order to
present these figures in a more convenient form they have been
converted into percentages and set forth in Tables CLVIII to
CLXIII. '"

Table CLVIII gives the percentages of simple-leaved plants
with leaves less than 5 centimeters in width. This table shows
very clearly that the number of plants with leaves less than 5

CLASSIFICATION OF LEAVES

385

TABLE ChVll.-Leaf characters of plants on a plot 10 meters square in the
midmountam-forest formation on Mount Maquilmg; altitude, 700 meters.

SIMPLE LEAVES.

Width in centimeters.

CHARACTER OF MARGIN OF ALL LEAVES.

Trees

Herbs

Vines

Total

Entire.

Species.

Indi-
viduals.

Ill
137
29

Not entire.

Species, j

Indi-

5 1 11

3 | 1,208

4 j 134

12 i 1,353

centimeters in width increases rapidly with rising elevations.
This change is marked in the first- and second-story trees and
in the herbs. In Table CLIX are presented the percentages of
simple-leaved plants with leaves less than 10 centimeters in
length. The data in this table agree in general with the data
in Table CLVIII in showing that the number of plants with
small leaves is greater at higher than at lower elevations.

In Table CLX are given the percentages of simple-leaved plants
with leaves more than 10 centimeters in width. An examination
of this table shows that the number of both species and indivi-
duals with such leaves is greater in the dipterocarp than in the
ftiidmountain forest, while not one is found in the mossy forest.
Table CLXI gives the percentages of simple-leaved plants with
leaves more than 20 centimeters in length. The virgin dipter-

159549-

-25

386

MOUNT MAQUILING

Table CLVIII. — Percentages of simple-leaved plants on Mount Maquiling
with leaves less than 5 centimeters in width.

BY INDIVIDUALS.

First-
story
species.

Second-
story
species.

Third-
story
species.

Herbs.

All erect

woody

plants

more

than 1 or

2 meters

in height.

Culled dipterocarp forest ..
Virgin dipterocarp forest.

Midmountain forest

Mossy forest

BY SPECIES.

Culled dipterocarp forest .
Virgin dipterocarp forest.

Midmoun tain forest

Mossy forest

11
22

50
75

35

28

33

33

33

29

30

50

31

50

57

75

32
32
40
75

Table CLIX. — Percentages of simple-leaved plants on Mount Maquiling
with leaves less than 10 centimeters in length.

BY INDIVIDUALS.

Culled dipterocarp forest _
Virgin dipterocarp forest.

Midmountain forest

Mossy forest

First-
story
species.

Second-
story
species.

Third-
story
species.

Herbs.

All erect

woody

plants

more

than 1 or

2 meters

in height.

BY SPECIES.

Culled dipterocarp forest ..
Virgin dipterocarp forest.

Midmountain forest

Mossy forest --

20

11

14

0

13

20

21

10

33

18

28

7

29

18

69

69

ocarp forest shows distinctly larger percentages of these long
leaves than does the midmountain forest, while not one is
present in the mossy forest.

From the data in the four tables just discussed it would seem
clear that the percentage of large leaves decreases while the per-
centage of small ones increases with rising elevations. The ex-
planation of this is not obvious. It can hardly be due to moisture

CLASSIFICATION OF LEAVES

387

TABLE CLX.— Percentages of simple-leaved plants on Mount Maquiling with
leaves more than 10 centimeters in width.

BY INDIVIDUALS.

First-
story
species.

0.6
6
3
0

Second-
story
species.

36
21
5

Third-
story
species.

9
29

Herbs.

0
16
0

All erect

woody

plants

more

than 1 or

2 meters

in heigrht.

Culled dipterocarp forest .

17
19
4
0

Virgin dipterocarp forest

Midmountain forest

Mossy forest ..__

BY SPECIES.

Culled dipterocarp forest

5

7
7
0

19
18
18

10
20

0
17
0

14
15
12
0

Virgin dipterocarp forest

Midmountain forest

Mossy forest ___

Table CLXI. — Percentages of simple-leaved plants on Mount Maquiling
with leaves more than 20 centimeters in length.

BY INDIVIDUALS.

First-
story
species.

0.6
6

0.9
0

Second-
story
species.

Third-
story
species.

Herbs.

All erect

woody

plants

more

than 1 or

2 meters

in height.

Culled dipterocarp forest _.

15

28
2

4

31

24

17
0.9

7

22
2
0

Virgin dipterocarp forest _ _

Midmountain forest

Mossy forest _.

BY S

PECIES.

Culled dipterocarp forest

5
7
3
0

9
24

11

5

20

33
33
29

7
18
7
"0

Virgin dipterocarp forest

' Midmountain forest

Mossy forest

conditions, as the rate of evaporation decreases and the percent-
age of soil moisture rises with increasing altitudes. Moreover,
there is a greater proportion of large leaves in the parang than at
higher elevations, while in the parang the rate of evaporation is
higher and the percentage of soil moisture lower than anywhere
in the virgin forest. Wind may afford a partial explanation, as
wind velocity is greater at high than at low altitudes, and a tree

388 MOUNT MAQUILING

with large leaves would probably be more likely to be defoliated
by high wind velocities than would one with small leaves. It
may be, however, that the small size of leaves at high elevations
is simply an expression of the poor conditions for growth that
result in the conspicuous dwarfing of trees. Raunkiaer in his
studies found the smallest leaves on the area with the lowest
vegetation. In the second-growth forest at the base of Mount
Maquiling the trees are of small size, but this is not due to
poor growth conditions. As just mentioned, these trees have
a greater percentage of large leaves than those in the virgin
forest.

The second-story trees in the dipterocarp and midmountain
forests do not appear to have smaller leaves than the first-story
trees. From Table CLVIII, in which are given the percentages
of simple-leaved plants with leaves less than 5 centimeters in
width, it will be seen that a smaller percentage of such leaves
is found in the second than in the first story of the dipterocarp
forest, while the percentage is only slightly greater in the
second story than in the first story of the midmountain forest.
The percentage of plants with leaves less than 10 centimeters
in length is much less in the second story of the midmountain
forest than in the first, and only slightly greater in the second
story of the virgin dipterocarp forest than in the first story.
While the percentage of small leaves appears to be about the
same in the first and second stories, the number of large leaves
is considerably greater in the lower stories than in the first, as
an examination of Tables CLX and CLXI will show. The oc-
currence of this high percentage of large leaves in the under-
stories may be connected with lessened wind movement or lower
evaporation. It will be noticed that the number of plants with
leaves more than 10 centimeters in width and with leaves more
than 20 centimeters in length is greater in the third story than
in the second of the dipterocarp forest, and considerably greater
in either of these stories than in the second story of the mid-
mountain forest. The smaller percentage in the midmountain
forest can hardly be due to rates of evaporation.

CLASSIFICATION ACCORDING TO WHETHER SIMPLE OR COMPOUND

In Table CLXII are given the percentages of plants with com-
pound leaves. The number of individuals with compound leaves
is less in the culled dipterocarp forest than in the virgin dipter-
ocarp forest. The number of both species and individuals with
compound leaves is much less in the midmountain than in the
virgin dipterocarp forest, while there are no individuals with

CLASSIFICATION OF LEAVES

389

TABLE CLX1I.— Percentages of plants on Mount Maquiling with compound

leaves.

BY INDIVIDUALS.

Culled dipterocarp forest .
Virgin dipterocarp forest.

Midmountain forest

Mossy forest

Culled dipterocarp forest ..
Virgin dipterocarp forest.
Midmountain forest

Mossy forest

First-
story
species. !

3 i

22 |

9j
0 I

BY SPECIES.

Second-
story
species.

21

22
11

Third-
story
species.

28 ;

25

23

17

25

32

17

13

17

15

0

Herbs.

I All erect '
I woody j
j plants |
j more |
1 than 1 or,
2 meters i
in heigrht.|

0
3

0.1
0

0 j

20

25 |

19

13 j

16

0

0

Table CLXIII. — Percentages of plants on Mount Maquiling which kai
leaves with entire margins.

BY INDIVIDUALS.

First-
story
species.

99
91

84

78

'ECIES.

88
82
77
69

Second-
story
species.

96
82
72

84
83
67

Third-
story
species.

69
63

71

61 !

Herbs.

50
68
10

67
63
63

All erect

woody

plants

more

than 1 or

2 meters

in height.

Culled dipterocarp forest . __

94

Virgin dipterocarp forest

80

Midmountain forest _ __

75

Mossy forest

78

BY SI

Culled dipterocarp forest ._ ...

82

Virgin dipterocarp forest. _ __ . ... _

76

Midmountain forest

Mossy forest

72
69

compound leaves in the mossy forest. In the virgin dipterocarp
and the midmountain forests the percentage of individuals with
compound leaves is approximately the same in the different
stories. In the virgin dipterocarp forest the number of species
with compound leaves is greatest in the first story and least in
the third.

390 MOUNT MAQUILING

CLASSIFICATION ACCORDING TO CHARACTER OF MARGINS

The percentage of leaves with entire margins is given in
Table CLXIII. It will be seen that the percentage of both in-
dividuals and species decreases with rising elevations and that
in general the percentage of entire margins is smaller in the
nnderstories than in the first story. The lowest percentage in
any of the tree stories in the dipterocarp forest is in the third
story. The number of individuals, not only of woody species
but also of herbs with entire margins, is less in the midmountain
forest than in the virgin dipterocarp forest.

The changes in leaf margins at different elevations may per-
haps be connected with moisture conditions, as the smallest per-
centage with entire margins is found in the mossy forest where
fogs are of frequent occurrence and the rate of evaporation is
low, and the greatest percentage in the dipterocarp forest where
the rate of evaporation is very much higher. Water appears
to run from leaves without entire margins more readily than
from those with entire margins, and so nonentire margins may
be of advantage to plants growing in places where the rate of
evaporation is low. That the lower stories have a smaller per-
centage of entire margins than the first story is in keeping with
this view.

Bailey and Sinnott * have made a study of the distribution of
entire and nonentire margins as related to climatic conditions.
This work was based on various floras. The following quotation
from their summary is in general agreement with the results
just given:

Leaves and leaflets with entire margins are overwhelmingly predominant
in lowland-tropical regions; those with non-entire margins in mesophytic
cold-temperate areas.

In the tropical zones, non-entire margins are favored by moist uplands,
equable environments, and protected, comparatively cool habitats; in the
cold-temperate zones, entire margins are favored by arid environments
and other physiologically dry habitats.

* Bailey, I. W., and Sinnott, E. W., The climatic distribution of certain
types of angiosperm leaves, Am. Journ. Bot. (1916), 3, 24-39.

MOUNT BANAHAO

GENERAL DESCRIPTION

. WhZ *? Tk °" M°Unt Ma<*uilinS was finished, it seemed
desirable to obtain some measurements of climatic factors on
another mountain with a somewhat different type of vegetation,
and to compare the results with those obtained on Mount Ma-
quilmg. Mount Banahao offered the best possibilities for such
a study.

Mount Banahao is one of three extinct volcanic cones which
form an isolated mountain mass on the boundary between La-
guna and Tayabas Provinces. It is the largest of the three
and has an elevation of about 2,300 meters. The next in height
is Mount Cristobal, which lies to the west of Mount Banahao
and is connected with the latter by a narrow saddle. The other
peak, Lukban Peak, is a small cone on the northeastern side of
Mount Banahao. All three peaks are regular cones. Mount
Banahao has a large crater which opens toward the south. The
sides of the crater are very steep, while the rim is narrow and
knifelike. The part of the mountain under discussion is on the
northern slope, along the trail leading from Majayjay to the sum-
mit. On this side the. mountain rises from the plains at U-uvi
barrio at an elevation of about 450 meters.

The rainfall on the northern and northeastern slopes of Mount
Banahao is distributed throughout all the months of the year,
and there are no distinct wet and dry seasons.

The northeastern monsoon strikes the Islands on the eastern
coast and deposits a large part of its moisture before passing
over the mountain masses. As there are no high mountain
masses northeast of Mount Banahao, this monsoon brings heavy
rains to the northern and northeastern slopes of the mountain.
The southwestern monsoon is not nearly so strong a wind as the
northeastern monsoon and, although it brings rains on the west-
ern side of the Archipelago, a large part of the rains that come
at this season of the year are the result of cyclonic disturbances
(typhoons), which cause the deposition of rains on both sides
of the Islands. Therefore, also during this monsoon, heavy
rains occur on the northern slopes of Mount Banahao.

VEGETATION

Along the trail from Majayjay to the top of Mount Banahao
the original forest vegetation has been almost entirely removed

391

392 MOUNT BANAHAO

to an elevation of about 650 meters, and even for some distance
beyond this the forest has been culled of the trees most valuable
for commercial purposes.

In describing the vegetation of Mount Banahao, it will be
most convenient to give an account of the forest occurring at
selected elevations.

At altitudes slightly above 650 meters the forest has been
very badly culled. A number of the tallest trees" were measured,
and the greatest height was found to be about 17 meters. In
this situation the diameters of the trees are rather large, com-
pared with their heights. The greatest diameter recorded
was 95 centimeters. The original forest was probably taller
than that now found at this elevation. The development of
epiphytes is rather scanty; the most frequent are Aglaomorpha
and Asplenium nidus. On the trees are also found some mosses
and a few orchids. The most conspicuous herbs on the ground
are Strobilanthes pluriformis, Elatostema longifolium, and Sela-
ginella. Climbing bamboos are conspicuous, and climbing palms
(rattans) are rather numerous.

At 1,000 meters' elevation the tallest tree measured was 20
meters high, and the greatest diameter was 1.05 meters. The
undergrowth here is very dense and consists largely of tree
seedlings. The development of epiphytes is perhaps slightly
greater than at lower elevations. Piper 'longivaginans, a liane,
is abundant and conspicuous. Plate XL, fig. 1, shows a view in
this forest.

The forest at an elevation of 1,500 meters is very open. The
tallest trees are about 18 meters in height. Lianes are abundant
and consist largely of species of Freycinetia. Owing to their
abundance and the striking character of their foliage these form
one of the most conspicuous elements in the vegetation. Among
the most prominent trees are species of Querctcs. Epiphytes
are abundant but not enough so to influence materially the ap-
pearance of the vegetation. The most conspicuous epiphytes are
orchids, the prominent species being Bulbophyllum vagans, Den-
drochilum pwmilum, and Phreatea.

The greatest development of epiphytes occurs at an elevation
of about 1,800 meters. At this elevation there is a broad, shal-
low ravine which runs across the trail up the mountain. The
trees are perhaps smaller in this ravine than at lower altitudes
and are densely covered with thick layers of moss and mosslike
plants. Plate XL, fig. 2, shows a view of this mossy forest. In
exposed situations at this altitude the epiphytic covering is not
particularly heavy.

VEGETATION oqo

The crater rim at the point under discussion, has an eleva
tion of approximately 2,100 meters. The forest is Lrly open
and consists of two stories of trees Thp fw T • "
story is composed almost entirely^ ZJ^J;^™^
Besides this species there are a few specimens of Podo a™
co*U*s. The tallest individuals of Podocarpus imbriccZ^
heights of about 14 meters, while the average height of the ma n
canopy is about 12 meters. Many of the trees have a tend™ y
to lean downhill. The second story is composed of a few species
of dicotyledonous trees, the most prominent of which isSyZ
plocos whitfordu. Among the other prominent species are
Drimys ptperita,HonmUnthuS alpinus, Clethra lancifolia, Rho-
dodendron kochn, Symplocos luzoniensis, and Ilex crenata The
undergrowth is scanty, giving the forest a fairly open appear-
ance. The most important element in the undergrowth is a
semiwoody herb, Strobilanthes piriformis. The ground is
largely bare. In places a small creping plant, Nertera depress
iorms conspicuous patches. Mosses, filmy ferns, and a few liver-
worts are scattered here and there. Epiphytic mosses and other
epiphytes are rather scarce. The most prominent epiphyte is
a small but showy orchid, Dendrochilum venustulum. Plate
XXXIX shows two views in this forest.

From the foregoing discussion it will be seen that the vege-
tation on Mount Banahao differs strikingly from that on Mount.
Maquiling. At an elevation of 1,000 meters on Mount Banahao
the tallest trees were 20 meters in height and the greatest dia-
meter measured was 1.05 meters. At 1,500 meters the tallest
trees were about 18 meters high. This is in striking contrast
with the sizes of the trees at the top of the east peak of Mount
Maquiling at an elevation of 1,050 meters, where the tallest trees
were about 8 meters in height. Even at the top of Mount
Banahao at an altitude of about 2,100 meters the tallest trees
were about 14 meters in height, which is a much greater height
than that of trees at the top of Maquiling. The dwarfing on
Mount Banahao, while very perceptible, was therefore much
less striking than on Mount Maquiling and much less in pro-
portion to the altitude. At no elevation were epiphytes de-
veloped on ridges to a much greater extent than in the lower
Portion of the midmountain forest on Mount Maquiling.

There is a great difference between the species on Banahao
Jmd those on Maquiling, but perhaps the most striking floristic
difference is the development, at the top of Mount Banahao, of
a coniferous forest. A discussion of the rates of growth of

394 MOUNT BANAHAO

Podocarpus at the top of Mount Banahao has been presented
previously.*

MEASUREMENTS OF ENVIRONMENTAL FACTORS

After completing the work on Mount Maquiling the writer
became connected with the University of the Philippines in
Manila and it was, therefore, impossible for him to live in the
neighborhood of Mount Banahao and obtain a set of readings
such as was obtained on Mount Maquiling. The trip from
Manila to the top of Mount Banahao and back, without taking
into consideration the time required for securing extensive meas-
urements, cannot be made in much less than four days. These
conditions made it necessary to have the readings taken by some
one else, and this work was largely done by an assistant, Ma-
cario Ocampo, who had had no scientific training. It seemed
inadvisable under the circumstances, to use atmometers, as a
man without scientific training could hardly be expected to
obtain accurate results with them. The only instruments em-
ployed were rain gauges, recording thermometers, and record-
ing hygrometers. Owing to the simplicity of the rain gauge
there seemed to be little chance of error in the use of this in-
strument, which opinion was borne out by the fact that the
distribution of rainfall obtained at the various altitudes cor-
responds well with the distribution as recorded by the Weather
Bureau stations near the coast in this region. With the slight
changes in temperature found to obtain on Mount Banahao, there
was practically no necessity for correcting the thermometers,
and so the records of the temperature may be regarded as fairly
accurate. The recording hygrometer presents greater difficulties,
but even this instrument requires comparatively little correction
under the fairly constant conditions obtaining on Mount Banahao.
However, both the recording thermometers and the recording
hygrometers were checked a number of times by the writer,
and the slight corrections found necessary were made in the
records. The results obtained from these several instruments
are, therefore, probably about as accurate as could be expected
from them.

The rain gauges were placed in the tops of trees, except at
the two lower elevations, where they were on the ground in
the open.

* Brown, W. H., The rate of growth' of Podocarpus imbricatus at the
top of Mount Banahao, Luzon, Philippine Islands, Phil. Journ. Sci., Sec
C (1917), 12, 317-328.

MEASUREMENTS OF ENVIRONMENTAL FACTORS 395

At first instruments were installed only at an altitiirt* of
1,550 meters and at the top of the mountain It an aSde
2,100 meters. In these two situations the three types of instru-
ments were operated from November 3, 1915, to November 3

f;,^"311; gaUgf W6re installed at ^des of 430,'
660, and 1,015 meters. At an altitude of about 660 meters there
are large clearings in the forest, and the rain gauge at this
altitude was placed in such a clearing. The rain gauge at an
altitude of 430 meters, which is considerably below the limits
of the forest, was placed in an open field. Recording hygro-
meters and recording thermometers were also placed in the
forest at elevations of 660 and 1,015 meters, and were operated
from March, 1916, to November 1, 1916. The recording hy-
grometer at 1,015 meters did not run well during the latter part
of the period, and so the records for this time have been omitted
The thermometers at the lower elevations were old and the clock
works did not operate well, usually stopping before the end of
the week, and sometimes running for only two or three days.
The thermometer part of the instruments, however, worked ac-
curately. Owing to the breaks in the records the maximum and
minimum temperatures are not given in the tables for these
elevations. The mean temperatures in both cases were cal-
culated by adding together the average daily maximum and
minimum and dividing by two.

TEMPERATURE

The temperature for the year in question at an altitude of
1,550 meters is summarized for four-week periods in Table
CLXIV, and for the top of the mountain at an altitude of about
2,100 meters, in Table CLXV. The mean temperature at about
1,550 meters was 16.5°, which is 1.3° lower than at the top
of Mount Maquiling. The mean temperature at the top of
Mount Banahao was 14.6°, which is 3.2° lower than at the top of
Mount Maquiling. Since the trees at an elevation of 1,550 meters
and at the top of Mount Banahao are taller than at the top of
Mount Maquiling, it would appear that temperature alone cannot
explain the difference in the size of the trees on the two moun-
tains. This is in agreement with the conclusion reached in the
discussion of temperature on Mount Maquiling.

The average daily maximum temperature at 1,550 meters was
•7.7°, and the average minimum, 15.4°, the average daily varia-
tion being 2.3°, which is less than the average variation at the
top of Mount Maquiling, where it was 2.4°. As the average
(iai]y variation was less at the top of Mount Maquiling than at

396

MOUNT BANAHAO

Table CLXIV. — Temperature for periods of four weeks in undergrowth in-
forest on Mount Banahao; altitude, about 1,550 meters.

[Numbers give degrees centigrade.]

Four weeks ending-

December 1

December 29 ._.

January 26

February 23

March 22

April 19

May 17

June 14

July 12.

August 9

September 6 __.

October 4

November 1

Average .

1916.

Maxi-
mum.

Mini-
mum.

13.3

9.4

9.9
11.2
12.0
12.8
14.9
15.5
15.0
15.3
13.9
13.6
13.9

Average of daily-

Mean.

Maxi-
ma.

Mini-
ma.

16.0

16.7

15.2

14.7

16.1

14.1

14.9

15.8

13. 8

15.1

16.2

14.3

15.2

16.8

14.2

16.1

17.4

14.9

17.6

18.5

16.6

17.8

19.1

16.6

17.7

19.1

16.3

17.5

19.1

16.1

17.5

18.8

16.2

16.8

17.9

15.6

18.0

19.0

16.9

16.5

17.7

15.4

Table CLXV. — Temperature for periods of four weeks in forest at the top
of Mount Banahao; altitude, about 2,100 meters.

[Numbers give degrees centigrade.]

Four weeks ending —

1915.
December 1 _. _ __ .

17.7
17.1

16.5
15.8
17.8
17.1
19.2
18.9
22.7
23.6
19.2
17.1
17.1

10.6
10.0

8.3
7.7
5.0
10.3
11.1
14.3
12.5
9.2
12.2
12.2
14.5

14.9
13.8

13.4
13.2
13.5
13.5
15.0
15.1
15.7
15.2
14.9
15.8
15.6

15.9
14.7

14.6
14.2
15.0
14.5
16.2
17.6
17.4
16.7
16.1

December 29 __

1916.
January 26

February 23

March 22

April 19

May 17

June 14 __

July 12

August 9

September 6 _.

October 4 _

15.6 i

November 1

15.9

Average _.

14.6

15.7

Maxi-
mum.

Mini-
mum.

Average of daily-

j Maxima. ! Minima.

13.3
13.1

12. 0
12.0
12.2
12.4

13.8
15.2

14.*
14.1

14. 6

14.2

14.?

13. «

the other elevations, it would appear that the average daily
variation at 1,550 meters on Banahao is less than anywhere on
Maquiling. The average daily maximum at the top of Mount

Measurements of environmental factors 397

Banahao was 15.7° and the average daily minimum, 13 6° the
average daily variation being 2.1°, which is slight^ eSs ihan

•n srsr on and probabiy iess th- - a- —

The highest mean temperature for any four-week period at

3 3° At the tT ?k and ^ l0W6St' H-7°' a differ— 0
3.3 At the top of the mountain the highest mean for a four-
week period was 15.8°, and the lowest, 13.2°, a difference of
2.6 . The absolute range for the entire year at 1 550 meters
was 12.5° and at the top, 18.6°. From these figures't S be

rVi n t6mperature under the ^rest at high elevations
on Mount Banahao is very uniform. The records for tem-
perature at elevations of 660 and 1,015 meters are riven in
Tables CLXVI and CLXVII. The mean temperature at aTe.eva-
Table CLXV I. -Temperature for periods of four weeks in forest on Mount
Banahao; elevation, 660 meters.

[Numbers give decrees centigrade.

Four weeks ending-

Mean.

Average of daily-

! Maxima. Minima.

April 19

May 17

June 14

July 12

September 6.
October4

Average .

20.5 !

20.9 !

20.1

22.6 :

23.6 ]

21.5

21. 1 ;

22.9 !

19.2

20.5 !

22. 3 !

18.6

20.6

21.8 1

19.3

20.8

22.2 J

19.3

21.0

22.3 1

19.7

Table CLXVII.— Temperature for periods of four weeks in forest on Mount
Banahao; elevation, about 1,015 meters.

[Numbers give degrees centigrade.]

Four weeks ending-

Mean.

| Average of daily-

! Maxima. Minima.

1916.

April 19 17 0

May 17 " " 190

June14— 18.5

JuIyi2____ 18-4

August 9 193

Septembers 19.5

October 4 lg#7

November 1 i jg. \

Average 18.6

18.1 ;

20.2 |
19.9 |

20.0 ;

20.7 i
20.5 j
19.4 ;
19.4 !

19.8 !

15.8
17.8
17.0
16.7
17.9
18.5
18.0
16.7

17.3

398

MOUNT BANAHAO

tion of 1,015 meters from March, 1916, to November 1, 1916,
was 18.6°. At 660 meters' elevation the mean temperature from
March, 1916, to October, 1916, was 21°. At both of these al-
titudes the average daily range was slight, being 2.5° at 1,015
meters and 2.6° at 660 meters.

RAINFALL

The rainfall for weekly periods at different elevations is given
in Table CLXVIII and is summarized for four- week periods
in Table CLXIX. An examination of these tables will show
that at elevations of 1,550 and 2,100 meters, the only stations

Table CLXVIII.— -^Rainfall at different elevations on Mount Banahao.

[Numbers give rainfall in centimeters.]

Week ending-

November 10.
November 17_
November 24.
December 1 __.
December 8 . .
December 15 -
December 22 .
December 29 .

January 5 —
January 12- ..
January 19. _.
January 26_-
February 2.-
February 9__
February 16.
February23.

March 1

March 8

March 15

March 22—
March 29_ —

April 5

April 12

April 19 — -

April 26

May 3

May 10

May 17

May 24

May 31

June 7 ------

June 14

June 21

June 28

1915.

1916.

Approximate altitude in meters.

430.

660. 1,015. 1,550. 2,100.

1.62
3.82
3.16
7.12
2.13
2.88

45.6
10.5

9; 8

13.1
7.05
9.9

20.9
1.73

11.2
0.00

31.9
4.3
6.5

22.8
8.1

10.1
1.75

12.6
49.2
38.1
30.5
15.7
10.9
11.1
47.5

27.5

13.2

29.1

24.2

30.3
0.65

14.6
8.5
7.1

13.8
4.15
2.12
1.65
8.4

21.1

13.3

29.3
8.16

10.1

12.6
5.05
5.09
9.6
7.01
13.8
3.41

8.5
27.1
28.5
22.1
16.3
14.0

9.4
30.1

18.8
9.2
14.6
47.6
59.8
0.23
10.6
15.2
6.5
9.6
3.15
2.65
15.7
0.52
13.6
10.5
19.8
10.1
7.15
27.0
17.1
6.01
14.3
13.0
6.01
9.6

MEASUREMENTS OF ENVIRONMENTAL FACTORS 399

TABLE CLXVIIL— Rainfall at different elevations on Mount Banahao—Ctd.

Week ending-

1916.

July 5

July 12 .

July 19

July 26

August 2

August 9

August 16

August 23

August 30

September 6 _.
September 13 .
September 20 .
September 27 .

October 4

October 11

October 18

October 25

November 3 ■ .

Approximate altitude in meters.

430.

6.12
13.0
10.1
10.2
5.2
3.75
8.3
8.0
4.9
1.7
6.8
16.9
19.7
18.5
5.4
18.4
15.7
25.1

1,015.

I

9.2
16.7
6.2
7.5
2.77
1.9
6.8
3.8
2.3
0.9
3.85
11.8
15.9
13.6
4.43
19.9
18.7
32.3

meter

3.

550.

2,100.

4.09

9.8

16.9

26.4

8.0

8.0

9.2

7.01

6.3

3.45

3.93

2.2

9.8

4.81

2.15

4.07

3.25

3.95

2.3

4.2

8.4

5.11

19.5

18.4

17.4

17.8

20.5
5.05
17.9
14.8
25.1

21.5

7.8
20.5
18.10
41.2

a Nine days.

Table CLXIX. — Rainfall for periods of four weeks at different elevations

on Mount Banahao.

[Numbers give rainfall in centimeters.]

Four weeks ending—

1915.

December 1 _.
December 29 .

January 26....
February 23..

March 22

April 19

May 17

June 14

July 12.

August 9

September 6 .
October 4—1.
November 8..

1916.

Total, November 3, 1915, to November 3,
1916 _• -

Total, May 17, 1916, to November 3, 1916.

Approximate altitude in meters.

430.

15.72
14.60
19.49
14.73
50.71
49.00

660. 1,015. 1,550. 2,100.

79.00
39.58
30.32
29.25
22.90
61.90
64.60

41.70
37.75
18.37
13.80
45.15
75.33

130.40

86.20

85.20

69.80

94.00

89.60

54.05

85.78

27.17

21.80

44.45

40.82

60.16

64.05

26.75

49.41

38.20

51.81

27.43

20.66

17.50

17.08

65.80

62.81

62.85

87.60

733.96 746.82

164.25 248.55

,2.10 I 238.53 289. J

400

MOUNT BANAHAO

for which there are continuous records for the year, the rain-
fall was heavy and was evenly distributed throughout the year.
At the top of the mountain the total rainfall was 746.8 cen-
timeters and there was no four-week period during which there
was not more than 17 centimeters of rain. The total rainfall
at 1,550 meters was 734 centimeters, and again there was no
four-week period with less than 17 centimeters of rain. A com-
parison of the amounts of rain for similar periods at elevations
from 660 to 2,100 meters would seem to indicate that there should
be a very heavy rainfall at all altitudes in the virgin forest.

. No measurements were made of the water content of the
soil, but the soil always appeared moist, as would be expected
%from the heavy rainfall.

HUMIDITY

The relative humidity at an elevation of 1,550 meters is
given in Table CLXX. The mean humidity for the entire year
was 89.1 ; the average daily maximum, 92.6 ; and the average

Table CLXX. — Relative humidity for periods of four weeks in undergrowth
in the forest on Mount Banahao; altitude, about 1,550 meters.

[Numbers give percentage of saturation.]

Four weeks ending —

Maxi-
mum.

92.0
95.0

92.0
99.5
99.0
99.0
99.0
98.0
97.0
95. 0
97.5
97.0
95.8

Mini-
mum.

Mean.

"'"•"*"

88.6
88.1

87.8
84.6
91.9
89.5
89.7
90.9
91.7
89.5
89.5
88.8
87.3

Average of daily-

Maxima.

90.0
90.5

90.1
94.4
96.3
93.6
93.1
94.3
94.3
92.2
92.8
92.9
89.3

Minima.

1915.
December 1

76.0

77.8

31.0
57.0
39.3
59.0
71.5
70.0
83.0
72.0
68.3
72.5
76.0

85 8

December 29 __

86 4

1916.
January 26 __ ...

82.9
84 1

February 23 __.

March 22

81.4
82.8
82.8
85.8
87.3
83.9
84.2
83.9
83.6

April 19

May 17

June 14 . _ __

July 12. ._ _. _ .

August 9_.

September 6 _ _

October 4 _. .

November 1___

Average

89.1

92.6

84 2 ;

daily minimum, 84.2. There was no four-week period in which
the average daily maximum was less than 89 per cent or the
average daily minimum less than 81 per cent. During the en-
tire year there was no period during which a maximum of 100
was registered by the instrument, and there was only one four-

MEASUREMENTS OF ENVIRONMENTAL FACTORS 401

week period during which the average daily maximum was more
than 94.4. It would thus appear that absolute saturation must
be relatively rare in this forest. The absolute minimum for the
entire period was 31 per cent, showing that, although the average
humidity is high, there may be periods of comparatively low
humidity. The humidity for the top of the mountain is given in
Table CLXXI. Here the average humidity was slightly higher

TABLE CLXXI.— Relative humidity for periods of four weeks in the forest at
the top of Mount Banahao; altitude, about 2,100 meters.

[Numbers give percentage of saturation.]

Four weeks ending-

December 1 >.
December 29 .

January 26 . . .
February 23..

March 22

April 19

May 17

June 14

July 12

August 9

September 6_.

October 4

November 1 _ .

1916.

Average.

Maxi-
mum.

93.0
97.5

94.0
99.0
100.0
100.0
97.0
97.0
99.5
100.0
99.0
100.0
100.0

Mini-

81.5
85.0

Average of daily-

Mean.

I I

I Maxima. Minima.

91.1
91.7

71.0 j

90.4

91.7 !

72.0 ;

91.2

93.6 i

51.0

93.0

96.9 j

62.0 !

94.9

97.9 |

85.5 ]

92.3

94.9

87.0 !

93.1

95.0 !

86.0 i

93.6

96.0 j

71.0 !

91.9

94.7 |

79.0 j

92.5

93.9 |

88.5 |

95.4

96.8 ;

91.5 j

96.8

98.2 ;

94.8 |

88.4
88.3

87.2
87.8
86.3
91.0
89.6
91.0
91.7
88.0
89.0
93.8
90.7

89.4

than at 1,550 meters, being 92.7 per cent. The average daily
maximum and average daily minimum were also higher, the
former being 94.8, and the latter, 89.4 per cent. The lowest hu-
midity recorded was 51 per cent, while 100 per cent was reg-
istered during five four-week periods. The relative humidity
at an elevation of 1,015 meters is given in Table CLXXII, and
at an elevation of 660 meters in Table CLXXIII.

In Table CLXXIV is given the mean relative humidity at the
different altitudes from March, 1916, to November 1, 1916. From
this table it would appear that there is comparatively little dif-
ference in the percentage of humidity at different elevations.
The lowest average humidity occurred at 1,550 meters and the
highest at the top, the difference being 4.2 per cent. No record
°f 100 per cent humidity is shown in Table CLXXIII for an

159549 26

402

MOUNT BANAHAO

Table CLXXII. — Relative humidity for periods of four weeks in under-
growth in the forest on Mount Banahao; altitude, about 1,015 meters.

[Numbers give percentage of saturation.]

Four weeks ending —

1916.

April 19

May 17

June 14

July 12

August 9

September 6 __.

Average .

Maxi-
mum.

95.0
96.5
97.0
96.0
99.0
100.0

Mini-
mum.

33.0
71.0
79.0
66.0
60.5
80.0

Mean.

89.6
89.7
91.8
90.3
91.6
94.2

Average of daily— |

Maxima. Minima.

93.0 |

93.3 |

94.4 |

93.4 I
94.3 J

97.5 i

83.4

82.0
87.6
83.7
86.6
88.6

91.2

94.3 j

Table CLXXIII. — Relative humidity for periods of four weeks in the forest
on Mount Banahao; altitude, about 660 meters.

[Numbers give percentage of saturation.]

Four weeks ending —

1916.

April 19

May 17

June 14

July 12

August 9

September 6

October 4

November 1

Average

Maxi-
mum.

93.5
95.5
95.0
95.5
96.5
99.7 I
99.0 j
97.6 i

Mini-
mum.

77.0
70.0
80.0
62.0
62.8
76.0
88.3
86.5

99.7

62.0

Average of daily—

Mean.

Maxima.

Minima.

89.3

91.6

85.6

88.5

92.6

81.9

90.8

92.9

86.4

89.7

92.7

83.1

88.7

92.3

85.7

90.9

97.1

88.6

93.7

97.3

92.1

92.0

96.4

90.3

90.4

94.1

86.7

Table CLXXIV. — Mean humidity for periods of four weeks in undergrowth
in the forest at different elevations on Mount Banahao.

[Numbers give percentage of saturation.]

Four weeks ending —

660.

Elevation
1, 015.

in meters.
1, 550.

89.5
89.7
90.9
91.7
89.5
89.5
88.8
87.3

2, 100.

April 19

1916.

89.3

88.5
90.8
89.7
88.7
90.9
93.7
92.0

89.6
89.7
91.8
90.3
91.6
94.2

94.9

May 17. __ 1

92. H

June 14

93.1

July 12

93. f>

August 9

91.9

September 6 - __

92. 5

October 4

95.4

November 1 _ _ _ ____

96. X

Average -

90.4

91.2

89.6

93.*

CORRELATION OP ENVIRONMENT AND VEGETATION 403

elevation of 660 meters whiia inn

only one period at 1015 meters ^ *** ^ rCC°rded for

CORRELATION OP ENVIRONMENT AND VEGETATION

An examination of the tables fnr roia+i„ u
elevations w„uW seem to Z&t*£SZ2gg«Z
at no altitude is there a dense mossv mm™
situation. The rarity with whLThLT^ y ^ So^TSS
recorded indicates that fogs which cause a condensation ^f water
an the vegetation must be comparatively rare, as such fo^s if
of long duration, would probably wet the hairs of the Wro
meters and cause them to register complete saturation The"
mean relative humidity at the three lower elevations is very
similar to that in the midmountain forest on Moun t MaqXg7
while the mean relative humidity at the cop 0f Mount Banahao
is only 2.8 per cent higher than that in the'midmountain "ores
at 740 meters on Mount Maquiling. At the top of Mount Ma-
quiling the vegetation drips with moisture for a large part of
the time. The writer has not observed such a condition on
Mount Banahao except during or immediately following rains
At other times the leaves do not appear to be wet. We would
therefore, expect evaporation to be much more rapid at the dif-
ferent elevations on Mount Banahao than at the top of Mount
Maquiling. The lack of fogs and the probably higher evapo-
ration rates prevailing on Mount Banahao thus seem to explain
the lack of a mossy forest in exposed situations there, even though
the rainfall is much heavier than at any altitude on Mount
Maquiling.

The comparative scarcity of complete saturation on Mount
Banahao would indicate that cloudiness is not nearly so preva-
lent there as at the top of Mount Maquiling, so that the light
intensity at all elevations is probably considerably greater than
at the top of Maquiling. The similar relative humidity at ele-
vations of 660, 1,015, and 1,550 meters may, moreover, indicate
that the degree of cloudiness is much more uniform at these
different elevations than on Mount Maquiling. This is in agree-
ment with casual observations of the weather made by the writer
on Mount Banahao. Owing to this and to the slighter degree of
dwarfing with rising altitudes than obtains on Mount Maquiling,
!t would seem probable that the lower temperature at higher
elevations is more largely responsible for dwarfing on Mount
Banahao than is the case on Mount Maquiling. In order to
determine the possible relation of temperature to dwarfing on
^ount Banahao, temperature indices have been calculated for

404

MOUNT BANAHAO

altitudes of 1,015, 1,550, and 2,100 meters. That these indices
for the different altitudes might be comparable, they have been
calculated only for the period from March to November, 1916.
The results are given in Table CLXXV. In the first column of

Table CLXXV. — Comparison of temperature indices and heights of trees
at different elevations on Mount Banahao.

Elevation.

Meters.
1,015
1,650
2,100

Physiologi-
cal temper-
ature in-
dex.

35.3
28.1

18.2

Pisum-

tempera-

ture index.

I Physiologi-
cal temper-
ature in-
dex -*- 1. 56.

17.4
16.1 |
13.3

22.6

18

11.7

Pisum-
tempera-
ture index

X 1. 12.

19.5

18

14.9

Height

of tallest

trees.

Meters.
20
18
14

this table is shown the elevation in meters, and in the second
column the temperature indices according to Livingston's phy-
siological system.* These indices were calculated for the dif-
ferent four-week periods and then averaged for the entire time.
In the third column are given the Piswm-temperature indices.
These were calculated from Leitch's paper on the relation of
temperature to rates of growth of roots of Pisum.f In making
these calculations Leitch's curve for rates of growth of Pisum
for twenty-two and a half hours was drawn on a large scale, and
the rates of growth corresponding to the different mean tem-
peratures for four-week periods were taken as the growth indices
for these temperatures. The various temperature indices are, of
course, simply ratios. In order to have them comparable with
the heights of the trees as given in column 6, the physiological
temperature indices have been divided by 1.56 and the Pisum
indices multiplied by 1.12, the results being given in columns
4 and 5. An examination of culumn 5 shows that the ratios
for the Pisum indices are fairly similar to those for the
heights of the trees but that, according to this system, varia-
tions of temperature would not be quite sufficient to account for
the differences in height. The ratios for the physiological tem-
perature indices are not so similar to the heights of the trees
as are those of the Pisum indices; but, according to the phy-
siological indices, variations in temperature would be more than

* Livingston, B. E., Physiological temperature indices for the study o(
plant growth in relation to climatic conditions, Physiological Researches
(1916), 1, 399-420.

f Leitch, L, Some experiments on the influence of temperature on the
rate of growth in Pisum sativum, Ann. Bot. (1916), 30, 25-46.

CORRELATION OF ENVIRONMENT AND VEGETATION 405

sufficient to account for the differences in height. A considera-
tion of the ratios obtained by these two systems would, there-
fore, indicate that temperature may be largely responsible for
the differences in the heights of the trees at different elevations
on Mount Banahao, and that variations in light intensity are
not nearly so important in causing variations in height here as
on Mount Maquiling. The greater heights of the trees on Mount
Banahao than at similar elevations on Mount Maquiling may,
therefore, be due largely to a greater light intensity on Mount
Banahao, though the more even distribution of rainfall may have
a contributing effect.

LIST OF SPECIES MENTIONED IN THE TEXT, WITH
AUTHORITIES, LOCAL NAMES, AND FAMILIES

Acacia famesiana Willd. (aroma). Leguminosae.
Agelaea sp. Connaraceae.

Aglaia diffusa Merr. (salaquin pula). Meliaceae.
Aglaia harmsiana Perk, (malasaging) . Meliaceae.
Aglaia iloilo Merr. = A. argentea Blume (iloilo). Meliaceae.
Aglaia llanosiana C. DC. (alupag). Meliaceae.
Aglaia sp. (malasaging) . Meliaceae.
Aglaomorpha meyeniana Schott. Polypodiaceae.
Ahernia glandulosa Merr. Flacourtiaceae.
Alangium longiflorum Merr. Cornaceae.
Alangium meyeri Merr. (putian). Cornaceae.
Albizzia procera Benth. (acleng parang). Leguminosae.
Allophylus grossedentatus F.-Vill. Sapindaceae.
Alocasia macrorrhiza Schott. Araceae.
Alphonsea arborea Merr. Annonaceae.
Alpinia brevilabris Presl. Zingiberaceae.
Alstonia scholaris R. Br. (dita). Apocynaceae.
Altingia excelsa Noronha. Hamamelidaceae.
Alyxia monilifera Vid. Apocynaceae.

Amoora cumingiana C. DC. Meliaceae. *

Amoora sp. Meliaceae.

Anaxagorea luzonensis A. Gray. Annonaceae.
Angiopteris angustifolia Presl. Marattiaceae.
Annona muricata Linn. Annonaceae.

Antidesma ghaesembilla Gaertn. (binayuyu). Euphorbiaceae.
Antidesma pleuricum Tul. Euphorbiaceae.
Ardisia boissieri A. DC. (tagpo). Myrsinaceae.
Ardisia perrottetiana A. DC. Myrsinaceae.
Ardisia serrata Pers. Myrsinaceae.
Areca wendlandiana Seheff. Palmae.

Arenga pinnata Merr. = A. saccharifera Labill. (cabo negro). Palmae.
Argostemma wallichii Walp. Rubiaceae.
Artocarpus cumingiana Tree, (anubing). Moraceae.
Artocarpus rubrovenia Warb. (anubing). Moraceae
Artocarpus woodii Merr. Moraceae.
Asplenium nidus Linn. Polypodiaceae.
Astronia lagunensis Merr. Melastomataceae.
Astronia pulchra Vid. Melastomataceae.
Astronia rolfei Vid. (dungao). Melastomataceae.
Astronia williamsii Merr. (dungao). Melastomataceae.
Bambusa spinosa Roxb. (cauayan). Gramineae.
Barring tonia sp. Lecythidaceae.

Bauhinia malabarica Roxb. (alibangbang). Leguminosae.
Begonia aequata A. Gray. Begoniaceae.
Biophytum sensitivum DC. Oxalidaceae.
Bischofia javanica Bl. (tuai) . Euphorbiaceae.
406

LIST OF SPECIES MENTIONED IN THE TEXT 407

Blumea balsamifera DC. (sambong) . Compositae.
Bridelia minutiflora Hook, f . Euphorbiaceae.
Buchanania arborescens Blume (balinghasay) . Anacardiaceae.
Bulbophyllum vagans Ames & Rolfe. Orchidaceae.
Calamus spp. (bejuco). Palmae.
Calanthe triplicata Ames. Orchidaceae.
Callicarpa erioclona Schauer (palis). Verbenaceae.
Calyptrocalyx spicatus Blume. Palmae.
Canarium ahemianum Merr. Burseraceae.
Canarium lucidum Perk. Burseraceae.
Canarium luzonicum A. Gray (pili) . Burseraceae.
Canarium villosum F.-Vill. (pagsahing). Burseraceae.
Canarium sp. (isangjuac). Burseraceae.
Carica papaya Linn. Caricaceae.
Caryota ciimingii Lodd. (pugahan). Palmae.
Caryota sp. (pugahan). Palmae.
Casearia sp. (malatapai) . Flacourtiaceae.
Castanospermum sp. Leguminosae.

Ceiba pentandra DC. = Eriodendron anfractuosum DC. (kapok). Bomba-
caceae.

Celtis philippensis Blanco (malaicmo). Ulmaceae.

Ceratostylis senilis Reichb. f. Orchidaceae.

Chisocheton mmvngianus C. DC. (salaquing puti). Meliaceae.

Chisocheton pentandrus Merr. (catang macsin or salaquing pula). Melia-
ceae.

Chisocheton sp. (salaquing pula). Meliaceae.

Chloranthus officinalis Bl. Chloranthaceae.

Christisonia wightii Elm. Orobanchaceae.

Cinchona succirubra Pav. Rubiaceae.

Cinnamomum mercadoi Vid. (calingag). Lauraceae.

Cissus trifolia K. Sch. Vitaceae.

Citrus hystrix DC. (cabuyao). Rutaceae.

Cleidion javanicum Blume. Euphorbiaceae.

Clerodendron quadriloculare Merr. Verbenaceae.

Clethra lancifolia Turcz. Clethraceae.

Coleus multiflorus Benth. Labiatae.

Columbia serratifolia DC. (anilao). Tiliaceae.

Commelina nudiflora Linn. Commelinaceae.

Cordia myxa Linn, (anonang). Boraginaceae.

Corysanthes merrillii Ames. Orchidaceae.

Cotylanthera tenuis Bl. Gentianaceae.

Cratoxylon blancoi Blume. Guttiferae.

Cratoxylon celebicum Blume (guyong-guyong). Cuttiterae.

Crotorc consangumeus Muell. Euphorbiaceae.

Oo*(m leiophyllus Muell. Euphorbiaceae.

Cryptocarya lauriflora Merr. Lauraceae.

Cyaft** Wafca Copel. Cyatheaceae Euphorbiaceae.

Cyclostemon maquilmgensis Merr. (tinaan pantai;. i^up

Cyrtandra incisa Clarke. Gesneriaceae.

Daemonorops spp. (bejuco). Palmae.

Decaspermum paniculatum Lindl. Myrtaceae.

Dendrochilum glumaceum Lindl. Orchidaceae.

408 VEGETATION OF PHILIPPINE MOUNTAINS

Dendrochilum pumilum Reichb. f. Orchidaceae.

Dendrochilum venustulum Pfitz. Orchidaceae.

Desmodium jmlchellum Benth. Leguminosae.

Dichrotrichum chorisepalum Clarke. Gesneriaceae.

Dillenia philippinensis Rolfe (catmon). Dilleniaceae.

Dillenia reifferscheidia F.-Vill. (catmon). Dilleniaceae.

Dimorphocalyx longipes Merr. Euphorbiaceae.

Dimorphocalyx luzoniensis Merr. Euphorbiaceae.

Diospyros ahernii Merr. (anang). Ebenaceae.

Diospyros discolor Willd. (camagon). Ebenaceae.

Diospyros pilosanthera Blanco (bolongeta). Ebenaceae.

Diplodiscus paniculatus Turez. (balobo). Tiliaceae.

Dischidia purpurea Merr. Asclepiadaceae.

Dischidia sp. Asclepiadaceae.

Donax cannaeformis K. Schum. Marantaceae.

Dracontomelum dao Merr. & Rolfe (dao). Anacardiaceae.

Drimys piperita Hook, f . Magnoliaceae.

Drynaria quercifolia J. Sm. Polypodiaceae.

Dysoxylum decandrum Merr. Meliaceae.

Dysoxylum pauciflorum Merr. Meliaceae.

Dysoxylum rubrum Merr. Meliaceae.

Dysoxylum turczaninown C. DC. Meliaceae.

Elaeocarpus argenteus Merr. Elaeocarpaceae.

Elaeocarpus calomala Merr. Elaeocarpaceae.

Elaphoglossum sp. Polypodiaceae.

Elatostema carinoi W. R. Shaw. Urticaceae.

Elatostema longifolium Wedd. Urticaceae.

Elatostema viridescens Elm. Urticaceae.

Enterolobium saman Benth. Leguminosae.

Epirixanthes cylindrica Blume. Polygalaceae.

Eria sp. Orchidaceae.

Eriobotrya japonica Lindl. Rosaceae.

Eugenia arcuatinervia Merr. Myrtaceae.

Eugenia astronioides C. B. Rob. Myrtaceae.

Eugenia calubcob C. B. Rob. (calubcob). Myrtaceae

Eugenia crassipes C. B. Rob. (calubcob). Myrtaceae.

Eugenia cumini (Linn.) Merr. (duhat). Myrtaceae.

Eugenia longiflora F.-Vill. Myrtaceae.

Eugenia luzonensis Merr. (malaruhat puti). Myrtaceae.

Eugenia mananquil Blanco. Myrtaceae.

Eugenia robertii Merr. Myrtaceae.

Eugenia saligna C. B. Rob. Myrtaceae.

Eugenia similis Merr. (malaruhat). Myrtaceae.

Eugenia sp. (malabayabas). Myrtaceae.

Eulophui exaltata Reichb. f . Orchidaceae*

Euonymus javanica Bl. Celastraceae.

Euonymus vibumifolia Merr. Celastraceae.

Euphoria cinerea Radlk. (alupag). Sapindaceae.

Eurya acuminata DC. Theaceae.

Evodia glabra Blume. Rutaceae.

Evodia semecarpi folia Merr. Rutaceae.

Evodia villamilii Merr. Rutaceae.

LIST OF SPECIES MENTIONED IN THE TEXT 409

Evodia sp. Rutaceae.

Ficus ampelos Burm. f. (malaisis). Moraceae.

Ficus banahaensis Elm. Moraceae.

Ficus bamesii Merr. Moraceae.

Ficus dementis Merr. Moraceae.

Ficus elastica Roxb. Moraceae.

Ficus gareiae Elm. Moraceae.

Ficus hauill Blanco (hauili). Moraceae.

Ficus linearifolia Elm. (auymit). Moraceae.

Ficus manilensis Warb. (isis). Moraceae.

Ficus minahassae Miq. (hagimit). Moraceae.

Ficus nervosa Heyne (agusus) . Moraceae.

Ficus nota Merr. (tibig). Moraceae.

Ficus paucinervia Merr. (tangisang biauac). Moraceae.

Ficus ribes Reinw. (auymit). Moraceae.

Ficus satterthwaitei Elm. Moraceae.

Ficus ulmifolia Lam. (isis). Moraceae.

Ficus validicaudata Merr. Moraceae.

Ficus variegata Blume (tangisang biauac) . Moraceae.

Ficus warburgii Elm. Moraceae.

Flacourtia sp. Flacourtiaceae.

Forrestia philippinensis Merr. Commelinaceae.

Freycinetia robinsonii Merr. Pandanaeeae.

Freycinetia williamsii Merr. Pandanaeeae.

Freycinetia sp. Pandanaeeae.

Galeola hydra Reichb. f. Orchidaceae.

Garcinia binucao Choisy (binucao). Guttiferae.

Garcinia rubra Merr. Guttiferae.

Garcinia venulosa Choisy (gatasan). Guttiferae.

Garcinia spp. Guttiferae.

GlochiMon album Boerl. (magna). Euphorbiaceae.

Glochidion lancifolmm C. B. Rob. Euphorbiaceae.

GlochiMon merrillii C. B. Rob. Euphorbiaceae.

Glochidion philippicum C. B. Rob. Euphorbiaceae.

Glochidion reticulatum Elm. Euphorbiaceae.

Gfc>c^cm trichogynum Muell. (bogna). Euphorbiaceae.

Glochidion williarmii C. B. Rob. Euphorbiaceae.

Goniothalamus amuyon Merr. (amuyong). Annonaceae.

Goniothalamus elmeri Merr. Annonaceae.

Oewm stylocarpa Warb. (susumbic). Tiliaceae.

(tontuuwahJ? i*mie^ Warb. (tambulao). Mynsticaceae.

Hedyotis philippensis Merr. Rubiaceae.

Hemigraphis strigosa F.-Vill. Acanthaceae.

Heterospathe elata Scheff. Palmae.

tfevea brasiliensis Muell. Euphorbiaceae.

Histopteris incisa J. Sm. Polypodiaceae.

Homalanthus alpinus Elm. Euphorbiaceae.

Homalanthus fastuosus Pax. Euphorbiaceae.

Htmatonthus po^neus Pax (balanti). »r^

Hopea ummtoto Merr. (dalingdingan). Dipterocarpaceae.

Hoy a odorata Schltr. Asclepiadaceae.

Hydnophytum sp. Rubiaceae.

410 VEGETATION OF PHILIPPINE MOUNTAINS

Hymenophyllum javanicum Blume. Hymenophyllaceae.

Ilex crenata Thunb. Ilieineae.

Ilex foxworthyi Merr. Aquifoliaceae.

Imperata exaltata Brongn. (cogon). Gramineae.

Ipomoea triloba Linn. Convolvulaceae.

Itea maesaefolia Elm. Saxifragaceae.

Ixora longistipula Merr. Rubiaceae.

Ixora macrophylla Bartl. Rubiaceae.

Knema glomerata Merr. = K. heterophylla Warb. (tambalao). Myristi-

caceae.
Koordersiodendron pinnatum Merr. (amugis). Anacardiaceae.
Laportea subclausa C. B. Rob. (lipa). Urticaceae.
Leea aculeata Blume. Vitaceae.
Leea manillensis Walp. Vitaceae.
Leea philippinensis Merr. Vitaceae.
Leea quadrifida Merr. Vitaceae.
Lepisanthes schizolepis Radlk. Sapindaceae.
Leucaena glauca Benth. (ipil ipil). Leguminosae.
Leucosyke capitellata Wedd. (lagasi). Urticaceae.
Litsea garciae Vid. Lauraceae.

Litsea glutinosa C. B. Rob. (puso puso) . Lauraceae.
Litsea luzonica F.-Vill. Lauraceae.
Litsea perrottetii F.-Vill. (marang). Lauraceae.
Livistona sp. (anahau). Palmae.

Lophopetalum toxicum Loher (cala-tumbago). Celastraceae.
Lygodium circinnatum Sw. Schizaeaceae.

Macaranga bicolor Muell.-Arg. (hamindang). Euphorbiaceae.
Macaranga grandifolia Merr. (taquip asin). Euphorbiaceae.
Macaranga tanarius Muell.-Arg. (binunga) . Euphorbiaceae.
Macaranga spp. (binunga). Euphorbiaceae.
Machilus philippinensis Merr. Lauraceae.
Mallotus moluccanus Muell.-Arg. (alim). Euphorbiaceae.
Mallotus philippensis Muell.-Arg. (banato). Euphorbiaceae.
Mallotus ricinoides Muell.-Arg. (hinlaumo, alim). Euphorbiaceae.
Mangifera indica Linn. Anacardiaceae.
Mastixia philippinensis Wang, (tapulao). Cornaceae.
Medinilla astronioides Triana. Melastomataceae.
Medinilla multiflora Merr. Melastomataceae.
Medinilla myrtiformis Triana. Melastomataceae.
Medinilla venosa Triana. Melastomataceae.
Melastoma polyanthum Blume. Melastomataceae.
Metiosma macrophylla Merr. Sabiaceae.
Meliosma sylvatica Elm. Sabiaceae.
Melochia umbellata Stapf (labayo). Sterculiaceae.
Memecylon paniculatum Jack (culis). Melastomataceae.
Merremia hastata Hallier f. Convolvulaceae.
Merremia umbellata Hallier f. Convolvulaceae.
Mimosa pudica Linn. Leguminosae.
Mussaenda philippica Rich, (cahoy dalaga). Rubiaceae.
My ristica philippensis I jam. (duguan). Myristicaceae.
Myrmecodia sp. Rubiaceae.
Nauclea junghuhnii Merr. (mambog). Rubiaceae.

LIST OF SPECIES MENTIONED IN THE TEXT 4H

Nauclea orientalis Linn.= Sarcocephalus orientalis (bancal). Rubiaceae.

Meolitsea villosa Merr. Lauraceae.

TJeonauclea calycina Merr. (uisac) . Rubiaceae.

Neonauclea media Merr. Rubiaceae.

Neotrewia cumingii Pax & Hoffm. (bato-bato) . Euphorbiaceae.

Nepenthes alata Blanco. Nepenthaceae.

Mephelium mutabile Blume (bulala) . Sapindaceae.

Nertera depressa Banks & Soland. Rubiaceae.

Octomeles sumatrana Miq. Datiscaceae.

Oleandra colubrina Copel. Polypodiaceae.

Operculina turpethum S. Manso. Convolvulaceae.

Oreocnide trinervis Miq. (malatuba). Urticaceae.

Oreodoxa regia H. B. K. Palmae.

Oroxy ium indicum Vent, (pincapincahan). Bignoniaceae.

Osmelia conferta Benth. (malatapai). Flacourtiaceae.

Osmelia philippinensis Benth. Flacourtiaceae.

Palaquium merrillii Dubard. Sapotaceae.

Palaquium philippense C. B. Rob. (palac-palac). Sapotaceae.

Palaquium tenuvpetiolatum Merr. (palac-palac or manicmc). Sapotaceae

Pandanus gracilis Blanco. Pandanaceae.

Pandanus luzonensis Merr. Pandanaceae.

Papualthia lanceolata Merr. = Poly althia lanceolate Vidal (lanutan)

ParaZlZ^malaanonan Merr. = P. p/tcafa Brandis (bagtican lauan)

^^^5^2^^=^ ***"*«* DC. (cupang). Leguminosae.

Pentctcme contorta M. & R. (white lauan). Dipterocarpaceae.

Phacelophrynium sp. Marantaceae.

Phaius sp. Orchidaceae.

Phalaenopsis amabilis Blume. Orchidaceae.

Phreatea. Orchidaceae.

Pinanga bamesii Becc. Palmae.

Pinanga insignis Becc. Palmae.

Prnws insularis Endl. Pinaceae.

Piper lonqivaginans C. DC. Piperaceae.

Pipturua arborescens C. B. Rob. (dalunot). Urticaceae.

Pisonia umbellifera Seem, (anuling). Nyctagmaceae.

Pithecolobium subacutum Benth. Leguminosae.

Planchonia spectabilis Merr. (lamog). Lecythidaceae.

Plumeria acutifolia Poir. Apocynaceae.

Podocarpus costalis Presl. Taxaceae.

Podocarpus imbricatus Blume. Taxaceae.

Polyalthia cumingiana Merr. Annonaceae.

Polyalthia sp. Annonaceae.

Polypodium sinuatum Wall. Polypodiaceae.

Polyscias nodosa Seem. Araliaceae.

Pometm pmnata Forst. (malugay). Sapindaceae.

Pothos sp. Araceae. , e

/Vemna cumtw^towo Schauer (maguili). Verbenace .

/Vemna odorata Blanco. Verbenaceae.

Psidmm guajava Linn, (guava). Myrtaceae.

Psychotria sp. Rubiaceae.

412 VEGETATION OF PHILIPPINE MOUNTAINS

Pteris quadriaurita Retz. Polypodiaceae.

Pterocarpus indicus Willd. (narra). Leguminosae.

Pterocymbium Unctorium Merr. (taluto). Sterculiaceae.

Pterospermum diversifolium Blume (spp.) (bayog). Sterculiaceae.

Pygeum preslii Merr. (uto-uto). Rosaceae.

Quercus robinsonii Merr. (oayan). Fagaceae.

Quercus soleriana Vid. (cataban). Fagaceae.

Radermachera sp. Bignoniaceae.

Rafflesia manillana Teschem. Rafflesiaceae.

Rapanea philippinensis Mez. Myrsinaceae.

Rhododendron kochii Stein. Ericaceae.

Rhododendron quadrasianum Vid. Ericaceae.

Riccia sj). Hepaticae.

Rourea volubilis Merr. Connaraceae.

Rubus fraxinif olius Poir. Rosaceae.

Rungia sp. Acanthaceae.

Saccharum spontaneum L. (talahib). Gramineae.

Sambucus javanica Bl. Caprifoliaceae.

Sapindus saponaria Linn. Sapindaceae.

Saurauia latebracteata Choisy. Dilleniaceae.

Saurauia luzoniensis Merr. Dilleniaceae.

Saurauia whitfordii Merr. Dilleniaceae.

Schefflera sp. Araliaceae.

Schizostachyum diffusum Merr. Gramineae.

Schizostachyum mucronatum Hack, (boho) . Gramineae.

Schizostachyum sp. (boho). Gramineae.

Selaginella belangeri Spring. Selaginellaceae.

Selaginella maquiliensis Hieron. Selaginellaceae.

Selaginella pennula Spring. Selaginellaceae.

Semecarpus gdgantifolia F.-Vill. (ligas). Anacardiaceae.

Semecarpus philippinensis Engl, (ligas) . Anacardiaceae.

Shorea guiso Blume (guijo) . Dipterocarpaceae.

Shorea polyspermia Merr. (tangili). Dipterocarpaceae.

Sida javensis Cav. Malvaceae.

Sideroxylon sp. (white nato). Sapotaceae.

Siphonodon celastrineus Griff. Celastraceae.

Sterculia crassiramea Merr. Sterculiaceae.

Sterculia cuneata R. Br. Sterculiaceae.

Sterculia foetida Linn. Sterculiaceae.

Sterculia oblongata R. Br. (malacacao). Sterculiaceae.

Sterculia sp. (lapnit). Sterculiaceae.

Streptocaulon baumii Decne. Asclepiadaceae.

Strobilanthes pluriformis C. B. Clarke. Acanthaceae.

Strornbosia philippinensis Rolfe (tamayuan). Olacaceae.

Strongylodon macrobotrys A. Gray. Leguminosae.

Symphorema luzonicum F.-Vill. Verbenaceae.

Symplocos ahernii Brand. Symplocaceae.

Symplocos floridissirna Brand. Symplocaceae.

Symplocos luzoniensis Rolfe. Styraceae.

Symplocos merrilliana Brand. Symplocaceae.

Symplocos villarii Vid. Symplocaceae.

Symplocos whitfordii Brand. Styraceae.

LIST OP SPECIES MENTIONED IN THE TEXT

413

Synedrella nodiflora Gaertn. Compositae.

Tabemaemontana pandacaqui Poir. (pandacaqui). Apocynaceae.

Taeniophyllum philippinense Reichb. f. Orchidaceae.

Tectaria sp. Polypodiaceae.

Terminalia edulis Blanco (calumpit). Combretaceae.

Terminalia nitens Presl. Combretaceae.

Terminalia pellucida Presl (calumpit or talisay-gubat) . Combretaceae,

Thea montana Merr. Theaceae.

Trema orientalis Blume (anabion). Ulmaceae.

Trickomanes apiifolium Presl. Hymenophyllaceae.

Trichomanes pluma J. Sm. Hymenophyllaceae.

Trickomanes proliferum Bl. Hymenophyllaceae.

Trichosanthes quinquangulata A. Gray (cabalonga). Cucurbitaceae.

Trichosporum philippinenses 0. Ktze. Gesneriaceae.

Turpinia pomifera DC. (malabago) . Staphyleaceae.

Urandra luzoniensis Merr. (tapulao). Icacinaceae.

Urophyllum banahaense Elm. Rubiaceae.

Utricularia rosulata Be'nj. Lentibularieae.

Vernonia lancifolia Merr. Compositae.

Voacanga globosa Merr. (bayag-usa). Apocynaceae.

Weinmannia luzoniensis Vid. Cunoniaceae.

Wickstroemia meyeniana Warb. Thymelaeaceae.

GENERAL SUMMARY AND CONCLUSIONS

MOUNT MAQUILING

The vegetation on Mount Maquiling shows a gradation from
a tall forest at the base of the mountain to a dwarfed mossy
one at the summit.

Between elevations of about 100 and 600 meters there is a
tall dipterocarp forest, a type of Schimper's tropical rain forest,
characteristic of the lowlands in the Philippines and in many
other parts of the Indo-Malayan region. This forest consists
of three stories of trees, each composed of different species.
The first, or tallest, story is dominated by members of the family
Dipterocarpaceae. At middle elevations the forest consists of
two stories composed of different tree species. At the top of
the mountain there is only one story of trees. These trees are
dwarfed and very peculiarly shaped and are thickly covered
with mosses and mosslike plants. Mossy forests are frequently
found on high mountains in the Philippines and elsewhere in
the tropics.

The ground covering in the dipterocarp forest is composed
largely of tree seedlings and, at higher elevations, of herbaceous
plants.

The epiphytes in the dipterocarp forest are largely phanero-
gams and are confined chiefly to the largest branches "of the
tallest trees. At middle elevations epiphytes are more numerous
and cryptogams are more conspicuous. Mosses and liverworts
may form a thin covering over a considerable portion of the
trunks of trees. The greatest development of epiphytes is at
the top of the mountain in the mossy foxest, where the lower
branches and the trunks of the trees are thickly covered with
mosses and mosslike plants, in which grow a number of larger
plants, including phanerogams. On the smaller branches epi-
phytes are also numerous, but less so than on the trunks.

The original vegetation around the base of the mountain
has been removed, and the land that is not now cultivated is
covered with a mixture of grass and second-growth forest
composed of small trees.

Humidity is fairly high at all elevations but increases with
rising elevations, and at the top of the mountain the atmosphere
under the forest is practically saturated most of the time.

414

GENERAL SUMMARY AND CONCLUSIONS 415

The increase in humidity at high elevations is accompanied
by an increase in cloudiness and a lower light intensity.
Temperature gradually decreases with rising elevations.
The decrease in temperature and light intensity and the in-
crease in humidity with rising elevations result in a rapid
decrease in the rate of evaporation from the base to the summit.
There is a pronounced, though not very severe, dry season in
the Maquiling region.

The amount of water in the soil increases with rising eleva-
tions, and only at low elevations does it appear to decrease suffi-
ciently during the dry season to have a harmful effect on the
vegetation.

Except at the lower elevations the heights of the trees at
different altitudes agree very closely with the light-temperature
indices— that is, with the product of the light intensity mul-
tiplied by temperature indices for growth. This indicates that
the decrease in light intensity and temperature, as high eleva-
tions are reached, is responsible for the dwarfing of the trees.
The heights of the trees at the lower elevations are not so great
as would be indicated by the temperature-light indices, but at
these elevations the rate of evaporation is evidently sufficiently
high at times to be harmful. It is probable that this high
rate is responsible for the fact that the trees are not so tall as
would be indicated by the temperature-light indices ; particularly,
as in the lowlands, in regions where there is ™ Pronoune^ diy
season, trees do reach the heights indicated by the temperature-
light indices for the base of Mount Maquiling.

The rates of growth of trees at different elevations agree fa.rly
closely with the temperature-light indices.

The increase in epiphytic vegetation, particularly ciyptogam ^
with rising elevations is apparently due to ^Z^
evaporation and the presence of fogs. A thick covering
mosses and mosslike plants seems to be dependent on <z j^c c^U
saturated condition of the atmosphere or on the frequent

ThVpecXr shapes of the trees in the mo.y forest at ^the

top of Mount ^^^ri^^^^^
aerial roots, which seem to be favored by tne n

obtaining in this forest. elevations is

The increase in herbaceous plants with rismg

apparently due to an increased moisture content ot

a lower rate of evaporation. atrikinglv bizarre

On Mount Maquiling are found ^^.^f^^Lte are

plant genera of the Indo-Malayan region, but such pi §

416 VEGETATION OF PHILIPPINE MOUNTAINS

rare here, as in other places in this region, and have very little
effect on the appearance of the vegetation.

MOUNT BANAHAO

On Mount Banahao the dwarfing of the vegetation is much
more gradual than on Mount Maquiling. The trees at the sum-
mit at an altitude of about 2,100 meters are taller than those at
the summit of the east peak of Mount Maquiling at an altitude
of 1,050 meters. Variations in temperature on Mount Banahao
appear to be sufficient to account for all, or nearly all, of the
dwarfing.

As the vegetation on Mount Maquiling and Mount Banahao
is typical of many mountains in moist tropical regions it seems
not improbable that, when the dwarfing is gradual on such moun-
tains, it is due largely to a decrease in temperature; but where
it occurs at lower elevations, as on Mount Maquiling, decrease
in light intensity may play an important role.

The humidity on Mount Banahao is high at all elevations,
but at no altitude is the atmosphere practically saturated most
of the time as at the top of Mount Maquiling.

Epiphytic vegetation is not developed at any elevation to
the same extent as at the top of Mount Maquiling, although the
rainfall at high elevations on Mount Banahao is several times
as great as at the top of Mount Maquiling and is more evenly
distributed. It would appear, therefore, that heavy rains are
not sufficient to produce a dense covering of mosses and mosslike
plants, unless they are accompanied by very high humidity or
frequent fogs.

APPENDIX

It is usual to give records of temperature and relative humidity
according to calendar months. As the data from Mount Maqui-
ling are presented for periods of four weeks rather than for
calendar months, it has seemed desirable, for purposes of com-
parison, to present summary tables of the data obtained from
the recording instruments in the more usual form of calendar
months. Such tables have been prepared by Mr. Evaristo Ad-
lauan from the writer's original records and are here presented.

Table CLXXVI.— Tempera ture from October, 1911, to January, 1915, under
second-growth trees near the base of Mount Maqniling; altitude, <so
meters. .

[Numbers give degrees centigrade.]

Period.

January

February

March

April

May

June

July

i August

| September

I October

1 November

December

Entire period
159549 27

Average of (

aily

Maxi-
mum, j

Mini-
mum.

Mean.

Maxima. M

nirna.

29.0 |

19.4

24.2

2*;. s

21.7

31.9 !

19.8 :

24.7

2s. 1

21.8

33.7 ;

20.7 !

26.8

30.7 ;

23. 0

34.0 !

19.6 !

27.4

31.2 i

23. 5

34.6

22.3 |

27.7

31. K !

24. 2

33.9 !

' 21.9 I

26.9

31.0 1

23. '.<

32.1 !

20.9

26.3

29. 2

24. 2

31.0 !

20.2

26.1

28.6

23. :»

31.0 !

20.3

25. 9

28.9 ■

23. /

32.3

21.0

25.8

28.7 |

23. 6

31.1 \

19.9

25.7

28.1 '

23. 4

31.9

19.9

24. K

27.6 |

22. 0

34.6 ;

19.4

29.2 i

417

418

APPENDIX

Table CLXXVII. — Temperature from January, 1913, to January, 1915, in
undergrowth in the dipterocarp forest, Mount Maquiling; altitude, 300
meters.

[Numbers give degrees centigrade.]

Period.

January

February ..*

March

April

May

June

July

August

September

October

November

December

Entire period

Maxi-
mum.

Mini-
mum.

Mean.

24.8

16.6

21.2

25.6

17.4

21.6

' 27.7

18.9

23.0

29.0

19.4

24.1

29.4

20.5

24.7

29.7

20.5

24.6

28.0

19.4

23.8

28.0

20.5

23.7

27.5

'19.7

23.3

27.7

19.4

22.8

25.9

19.4

22.6

25.0

19.7

22.0

29.7

16.6

23.1

Average of daily -

Maxima.

Minima

22.6

20.1

23.2

20.0

25.9

21.7

26.8

22.1

27.4

22.7

27.1

22.6

25.4

22.5

25.6

22.5

25.3

21.9

24.7

21.5

24.0

21.6

23.2

21.0

25.1

21.7

.

Table CLXXVIII. — Temperature from August, 1913, to January, 1915, in
undergrowth in the dipterocarp forest, Mount Maquiling; altitude, 450

meters.

[Numbers give degrees centigrade.]

Period.

Maxi-
mum.

Mini-
mum.

17.2
18.6
19.7
21.1
22.5
20.5
21.4
20.7
20.0
20.0
19.7
19.4

Mean.

20.1
20.7
22.9
23.9
. 25.0
24.1
23.5
23.3
23.2
22.6
22.1
21.6

Average of daily-

Maxima.

21.6
22.4
24.9
25.9
27.0
25.4
24.6
24.7
24.6
24.2
23.6
22.6

Minima.

■
January _... _

23.3
24.5
27.2
27.5
28.6
27.2
26.4
26.7
26.6
27.5
25.6
23.9

19 3

February _ _

19 5

March. _ __

21.1

April ._

22.4

May___ „ ___ ___

23.4

June _

22.7

July..

22.6

August __ _ ._ . . _

22.4

September ._ _

22.0

October

21.7

November __

21. 5

December _

20. S

Entire period

28.6

17.2

22.8

24.3

21.6

APPENDIX

419

TABLE CLXXIX .-Temperature from November, 1912, to January 1915 in
undergrowth m the mtdnwuntain forest, Mount Maquiling; altitude, V.JO

[Numbers give degrees centigrade.]

Period.

January

February

March

April

May 1

June

July

August

September

October

November

December

Entire period

Maxi-
mum.

22.7

Mini-
mum.

Mean.

Average of daily

i Maxin

15.6 ;

16.6 |
18.0 |
18.3 !
20.0 !

18.3 !

19.4 |

19.4 I

19.7 I
18.9 !

15.5 |
16.3 I

15.5

19.3 !

19.4 |
21.3
22.1
23.1
22.9
22.0

2i.9 ;

22.2 j
21.4

20. 8
20.0 |

21.4

20.7
**20. 9
23.3
24.0
25.1
25.0
23.4
23.5
23.6
23.0
22.1
21.4
23. 0

18.6

18. 2
19.7
20.6
21.7
21.7
21.3
21.0
21.1
20. 5
20. 1
19.6

20. 3

Table CLXXX. — Temperature from November, 1912, to January, 1915,
under the mossy forest at the top of Mount Maquiling; altitude, 1,050
meters.

[Numbers give degrees centigrade.]

Period.

Maxi-
mum.

Mini-
mum.

Mean .

Average

>f daily-!

20.3

15.9

Maxima.
17.2

Minima.

January

12.2

15.3

February

20.3

12.8

15.9

17.4

15.4

March

22.2

13.9

17.1

18.8

16.3

April

22.3

13.3

18.2

19.8

17.0 j

May... _ _._

23.9
23.9
26.1

17.0
16.6
14.2

19.4
19.6

18.7

21.1
21.6
20. 6

18.1 ]

June

18.3 !

July..

19.4 !

August __

21.7

14.8

17.9

19.5

17.1 !

September .

23.7
22.0

13.7
15.3

18.2
17.4

19.8

IB. 8

17.3 i

October

16. 8

November ___

21.4

13.8

17. 5

18.6

37.1

December

Entire period

20.3

13.9

17.0

18.0
19. 3

16.3

26.1

12.2

17.7

17.0

420

APPENDIX

Table CLXXXI. — Relative humidity from October, 1912, to January, 1915,
under second-growth trees near the base of Mount Maquiling; altitude,
80 meters.

[Numbers give percentage of saturation.]

Period.

Maxi-
mum.

Mini-
mum.

Mean.

82.9
80.1
76.8
78.9
81.0
83.6
84.3
83.4
83.9
85.7
82.5
84.3

Average of daily-

Maxima.

Minima.

January

93.0
93.0
94.0

56.5
25.0
38 0

89.6
89.9
89.9
91.0
92.0
92.1
90.8
90.1
90.6
91.7
90.3
' 90.4

71.1
63.1
57 9

February ---■*-- -,

March

April

94.0 43.0
95.0 42.0
95.0 | 56.0
94.0 61.0
94.5 56.0
93. 0 62. 0

60 4

May

62.8

June _.

67 6

July

72.8
71.5
73.3
.76.1
74.2
74.0

August

September __

October

96.5

59.0

November

93.0
92.5

58.5
56.0

December ._ _

Entire period _

96.5

25.0

82.3

90.7

68.7

Table CLXXXII. — Relative humidity from May, 1918, to January, 1915, in
undergrowth in the dipterocarp forest, Mount Maquiling ; altitude, 300
meters.

[Numbers give percentage of saturation.]

Period.

January

February

March

April

May.

June i

July

August -

September

October

November __.

December

Entire period

Maxi-
mum.

97.0
94.0
93.0
92.0
96.0
97.0
96.0
94.5
95.0
96.0
97.5
98.0

98.0

Mini-
mum.

80.0
47.5
57.0
58.5
58.0
71.0
76.0
75.5
77.0
75.0
82.0
81.0

47.5

Mean.

92.6

88.0
85.2
85.5
87.8
90.0
90.1
89.2
91.1
91.7
92.9
93.7

89.8

APPENDIX

421

TABLE CLXXXIII.— Relative humidity from July, 1913, to January 191-, .•„
undergrowth m the dipterocarp forest, Mount Maquiling; altitude \so
meters. ' * ~

[Numbers give percentage of saturation.]

January

February _ _

March

April

May

June

July

August

September .

October

November. _
December _ .

Period.

Entire period .

Maxi-
mum.

Mini- ;
mum.

Mean.

97.9

76.0

90.1

96.0

45.0 '

86.7

99.0

-53.0

84.1

98. 0

58.0

85.5

95.0

56.5 !

86.0

95.0

68.0 :

88.9

94.5

72.0

88.9

95.5

72.0

87.7

93.5

74.0

88.3

93.5

64.0 ;

88.3

94.5

78.0

89.9

94.5

77.5

90.3

99.0

45.0

87.9

Table CLXXXIV. — Relative humidity from June, 1913, to January , 1915, in
undergrowth in the midmountain forest, Mount Maquiling; altitude, 740
meters.

[Numbers give percentage of saturation.]

r>™-,wi i Maxi- Mini- M .

Period. ^„«, «,„«» Mean.

j mum. | mum.

__ . _; |

January • 94.5 | 85.0 91.6

February | 95.0 j 54.5 89.2 }

March.. __. .._.! 95.5 1 55.0: 88.9 !

April ! 94.5; 62.2; 88.7 ;

May ! 96.0; 66.1; 89.1

June - -! 99.2 ; 73.1; 90.7

July ' 98.0 ; 65. 0 j 91.5

August 98.2 j 76.0 j 91.2

September 98.0 ' 67-(» i 9°-4

October ... ! 96.0 69.3 j 91.3

November..-. ' 9B.0 71.6 | 91.8

December-.. - - j 95^ SflLOJ 90.9

Entireperiod - 99.2 M-5 | *>'*

INDEX

Abella y Casariego, D. E., work of, 15, 175.
Acacia farnesiana, 21, 23, 406.
Acanthaceae, 409, 412.
Acer saccharum, 356.
Acleng parang, 406.
Aerial gardens, 37.

roots in mossy forest, Plate XXII.
Agelaea sp., 60, 406.
Aglaia argentea, 406.

diffusa, 44, 49, 64, 74, 406.
harmsiana, 64, 85, 89, 406.
iloilo, 64, 74, 406.
llanosiana, 64, 71, 72, 406.
spp., 38, 44, 49, 54, 58, 59, 64, 96, 406.
Aglaomorpha, 81, 392.

meyeniana, 81, 406.
Agusus, 70, 72, 409.
Ahernia glandulosa, 64, 406.
Alangium longiflorum, 64, 71, 406.

meyeri, 44, 49, 54, 58, 59, 64, 406.
Albizzia procera, 406.
Alibangbang, 21, 23, 131, 138, 139, 406.
Alim, 23, 138, 139, 150, 410.
Allophylus grossedentatus, 64, 71, 72, 406.
Alocasia macrorrhiza, 84, 86, 90, 406.
Alphonsea arborea, 63, 406.
Alpine region of tropical mountains, 113.
Alpinia brevilabris, 60, 74, 96, 406.
Alstonia seholaris, 23, 137, 188, 139, 406.
Altingia excelsa, 104, 170, 406.
Alupag, 46, 50, 66, 72, 406, 408.
Alyxia monilifera, 60, 100, 406.
Amoora cumingiana, 64, 85, 89, 406.

sp., 44, 49, 406.
Amugis, 28, 68* 410.
Amuyong, 409.

Anabion^ 23, 24, 132, 188, 139, 413.
Anacardiaceae, 407, 408, 410, 412.
Anahau, 46, 60, 54, 410.
Analysis, chemical, of soils, 172.

mechanical, of soils, 173.
Anang, 32, 64, 408.

Anaxagorea luzonensis, 62, 66, 74, 406.
Angiopteris angustifolia, 37, 406.
Anilao, 23, 130, 138, 139, 407.
Anisoptera-Stromboeia formation, 33.
Annonaceae, 406, 409, 411.
Annona muricata, 119, 120, 406.
Anonang, 23, 187, 188, 189, 407.
Antidesma ghaesembilla, 21, 23, 137, 138, 406.

plewricum, 64, 85, 89, 93, 406.
Anubing, 64, 186, 188, 189, 406.

Anuling, 45, 60, 65, 71, 72, 411.
Apocynaceae, 406, 411, 413.
Aquifoliaceae, 410.
Araceae, 60, 406, 411.
Araliaceae, 411, 412.

Ardisia boissieri, 44, 49, 54, 68, 59, 64, 86,
89, 93, 406.
perrottetiana, 44, 59, 406.
serrata, 64, 406.
sp., 44, 49, 59, 85, 89, 93.
Areca wendlandiana, 119, 406.
Arenga pinnata, 36, 64, 96, 406.

saccharifera, 406.
Argostema wallichii, 101, 102, 406.
Argiielles, A. S., see Brown and Argiielles.
Arizona, evaporation in, 355.
Aroma, 21, 23, 406.

Artocarpus cumingiana, ,23, 136, 188, 139
141, 406.
rubrovenia, 64, 406.
woodii, 64, 71, 72, 406.
Asclepiadaceae, 408, 409, 412.
Ash, 140.
Aspen, 139.

Asplenium nidus, 37, 42, 81, 392, 406.
Astronia lagunensis, 105, 107, 108, 406.

pulchra, 82, 161, 162, 163, 164, 170, 228,

242, 406.
rolfei, 84, 86, 90, 91, 93, 96, 406.
rolfei association, 83.
williamsii, 86, 90, 406.
epp., 84, 98, 107, 229, 242.
Atmometers, use of, 296.
Authorities of names mentioned in the text,

406.
Auymit, 45, 60, 54, 68, 59, 86, 90, 93, 409.

Bagtican lauan, 20, 26, 27, 44, 48, 53, 57, 59,
61, 62, 63, 67, 70, 72, 151, 152, 168,
154, 158, 870, 411.
Bailey, I. W., and Sinnott, E. W., work of,

390.
Bakke, A. L., see Fuller and Bakke.
Balanti, 25, 409.
Balinghasay, 64, 407.
Balobo, 29, 32, 45, 49, 64, 58, 62, $4, 68, 71„

72, 151, 169, 160, 408.
Bamboos, climbing, in dipterocarp forest, 84.
on Mount Banahao, 392.
View of, Plate VI.
Bambusa spinosa, 406. *

428

424

INDEX

Banato, 23, 137, 138, 410.

Bancal, 65, 411.

Barnes, C. R., work of, 358.

Barringtonia sp., 64, 406.

Basal region of tropical mountains, 113.

Batobato, 46, 61, 66, 411.

Bauhinia malabarica, 21, 23, 122, 123, 131,

132, 138, 139, 406.
Bayag-usa, 23, 66, 149, 150, 413.
Bayog, 412.
Beech, 139.

-maple forest, evaporation in, 351, 352.
Begoniaceae, 406.
Begonia, 102.

aequata, 102, 406, Plate XXXVII.
Bejuco, 407.
Bignoniaceae, 411, 412.
Binayuyu, 21, 23, 406.
Binucao, 45, 59, 409.
Binunga, 23, 135, 138, 139, 410.
Biophytum sensitivum, 22, 406.
Birch, paper, 139.

yellow, 139.
Bischofia javanica, 23, 24, 44, 48, 53, 56, 85,

88, 89, 93, 95, 406.
Bizarre plants in dipterocarp forest, 41.
Blue Mountains of Jamaica, 104.

evaporation in, 353.
Blumea balsamifera, 21, 407.
Bogna, 86, 90, 409.
Boho, 65, 412.
Bolong-eta, 64, 71, 72, 408.
Bombacaceae, 407.
Boraginaceae, 407.
Boyek, 65, 71, 72.
Bridelia minutiflora, 64, 407.
Briggs, L. J., and Shantz, H. L., work of,

261, 262, 263, 264.
Brown, W. H., work of, 41, 115, 170, 263, 353,
354, 394.

and Argiielles, A. S., work of, 171, 172,
260.

and Heise, G. W., work of, 229, 235.

and Matthews, D. M., work of, 18, 24, 25,
27, 29, 33, 40, 61, 62, 69, 75, 132, 143,
151, 155, 161, 170, 257, 327, 357, 375.

and Trelease, S. F. work of, 119.

and Yates, H. S., work of, 170, 230.
Buchanania arborescens, 64, 407.
Bulala, 32, 45, 50, 55, 58, 65, 71, 72, 411.
Bulbophyllum vagans, 392, 407.
Burgerstein, work of, 358.
Burseraceae, 407.

Buttresses in dipterocarp forest, 36, Plate
XII.

C

Cabalonga, 413.
Cabo negro, 64, 406.
Cabuyao, 66, 407.
Cahoy dalaga, 24, 149, 150, 410.
Calamus, 34, 60, 61, 74, 96, 97, 407.
Calanthe triplicata, 96, 407.
Calatumbago, 45, 50, 58, 410.
Caldwell, J. S., work of, 263, 264.

Calingag, 45, 49, 54, 58, 59, 85, 89, 407.
Callicarpa erioclona, 46, 51, 66, 407.
Calubcob, 86, 90, 93, 408.
Calumpit, 45, 50, 413.
Calyptrocalyx spicatus, 119, 407.
Camagon, 32, 45, 49, 54, 58, 408.
Canarium, 32.

ahernianum, 64, 407.
lucidum, 64, 407.

luzonicum, 31, 44, 48, 54, 57, 59, 63, 407.
villosum, 23, 44, 48, 137, 138, 139, 407.
sp., 44, 49, 54, 59, 63, 85, 89, 93, 95, 407.
Caprifoliaceae, 412.
Caricaceae, 407.

Carica papaya, 119, 122, 123, 124, 407.
Caryota cumingii, 36, 407.

sp., 64, 71, 407.
Casearia sp., 66, 74, 407.
Castanospermum, 119, 407.
Cataban, 65, 78, 85, 89, 92, 93, 95, 412.
Catalpa, 140.
Catang macsin, 407.

Catmon, 28, 32, 45, 49, 54, 58, 59, 64, 71, 72,
86, 90, 93, 151, 161, 408.
carabao, 86, 90, 93.
Cauayan, 406.

Caulifiory in dipterocarp forest, 36.
Cedar, 140.

Ceiba pentandra, 407.
Celastraceae, 408, 410, 412.
Celtis philippensis, 29, 31, 32, 44, 49, 54, 59,

63, 68, 70, 71, 72, 74, 88, 407.
Ceratostylis senilis, 407.
Cestrum nocturnum, 119.
Changes in girth of trees during the day,

119, 122, 123.
Chemical analysis of soils, 171, 172.
Chestnut, 140.
Chisocheton, 33.

cumingianus, 44, 49, 54, 85, 89, 407.
pentandrus, 44, 49, 407.
sp., 64, 71, 72, 407.
Chloranthaceae, 407.
Chloranthus officinalis, 60, 74, 96, 407.
Christisonia wightii, 82, 407.
Cinchona succirubra, 119, 407.
Cinnamomum mercadoi, 45, 49, 54, 58, 59,

85, 89, 407.
Cissus trifolia, 22, 407.
Citrus hystrix, 66, 407.
Classification of leaves, 378.
Clear length of first-story trees in diptero-
carp forest, 57.
of second-story trees in dipterocarp

forest, 57.
on plot in midmountain forest, 95.
Cleidion javanicum, 66, 407.
Clerodendron quadriloculare, 39, 46, 51, 59,

66, 407.
Clethraceae, 407.
Clethra, 107.

lancifolia, 102, 105, 108, 115, 393, 407.
Climbing bamboo, view of, Plate VI.
palms in dipterocarp forest, 34.
Cogon, 18, 19, 20, 21, 410.
Coleus multiflorus, 407.

INDEX

425

Columbia serratifolia, 23, 130, 131, 138, 139,

141, 143, 407.
Cornbretaceae, 413.
Commelinaceae, 407, 409.
Commelina nudiflora, 22, 407.
Comparison of epiphytes at different eleva-
tions on Mount Maquiling, 112.

erect woody plants more than 10 meters
in height on plots in dipterocarp, mid-
mountain, and mossy forests, 110.

small plants on plots in dipterocarp and
midmountain forests, 111.

vegetation at different altitudes, 107.
Compositae, 22, 407, 413.

Composition of different stories in culled
dipterocarp forest, 69.

on plot in virgin dipterocarp forest, 51.

on plot in midmountain forest, 91.

of small plot in culled dipterocarp forest,
74.

of small plot in dipterocarp forest, 59.

of small plot in midmountain forest, 96.
Connaraceae, 406, 412.
Convolvulaceae, 410, 411.
Cordia myxa, 23, 122, 123, 124, 137, 138,

139, 407.
Cornaceae, 406, 410.
Corysanthes merrillii, 407.
Cottonwood, 140, 141.
Cotylanthera tenuis, 82, 407.
Cox, A. J., see West and Cox.
Cratoxylon blancoi, 85, 87, 89, 93, 407.
Cratoxylon celebicum, 64, 78, 85, 89, 91, 92,

93, 95, 96, 407, Plate XVI.
Croton consanguineus, 66, 407.

leiophyllus, 85, 89, 93, 95, 407.
Cryptocarya lauriflora, 45, 49, 59, 407.

sp., 63, 70, 72.
Cucurbita, 118.
Cucurbitaceae, 413.
Culis, 45, 50, 86, 90, 410.
Cunoniaceae, 413.
Cupang, 24, 411.
Cyatheaceae, 407.
Cyathea, 80, 98, 100, 107, 407.
Cyathea-Astronia association, 98, 107.

caudata,. 84, 86, 90, 96, 105, 106, 107,
108, 382, 407.
Cyclostemon maquilingensis, 64, 74, 407.

sp., 45, 49, 64, 171.
Cypress, 140.
Cyrtandra incisa, 86, 90, 407.

I)

J'achnowski, A., work of, 316.

I>aemonorops, 34, 60, 61, 74, 96, 97, 407.

*>^guan, 72.

r)<iHngdingan, 44, 48, 409.

Dalunot, 23, 149, 150, 411.

])ho, 63, 408.

1 Wwin, Francis, work of, 118.

])<tes of measurements, 175.

1 itiscaceae, 411.

"caspermum paniculatum, 86, 90, 93, 407.

Dendroehilum glumaceum, 81, 99, 407, Plate
XXIII.
pumilum, 392, 408.
venustulum, 102, 393, 408.
Derry, R., work of, 120.

Description of plot in dipterocarp forest, 43.
Desmodium pulchellum, 408.
Diameters of trees in culled dipterocarp for-
est, 70.
in different stories in dipterocarp forest,

55.
in different stories on plot in midmoun-
tain forest, 94.
on plot in midmountain forest, 93.
on plot in virgin dipterocarp forest, 53.
Dichrotrichum, 102.

chorisepalum, 77, 100, 102, 408, Plate
XXI.
Dicotyledonous vines in dipterocarp forest, 34.
Dilleniaceae, 408, 412.

Dillenia philippinensis, 28, 32, 39, 45, 49, 53,
54, 58, 59, 64, 71, 72, 86, 88, 90, 93, 151,
161, 165, 166, 324, 408.
reifferscheidia, 45, 49, 54, 58, 86, 88, 90,
93, 161, 166, 337, 408.
Dimorphocalyx longipes, 64, 408.

luzoniensis, 59, 64, 408.
Diospyros ahernii, 32, 64, 408.

discolor, 32, 45, 49, 54, 58, 59, 408.
pilosanthera, 64, 71, 72, 408.
Diplodiscus paniculatus, 29, 32, 45, 49, 52, 54,
58, 59, 62, 64, 68, 70, 71, 72, 151, 157,
159, 160, 408.
Dipterocarpaceae, 409, 411, 412, 414.
Dipterocarp forest, area of, 27.
Bataan, view in, Plate X.
chemical analysis of soils in, 172.
classification of leaves in, 378, 380, 381.

383, 384, 386, 387, 389.
definition of, 19.
evaporation in, 324.
humidity in, 278.
light intensity in, 233.
mechanical analysis of soils in, 173.
Mount Maquiling, 27.
Mount Maquiling, view in, Plates V to

VIII.
Negros, view in, Plates IX and X.
rainfall in, 252.
rates of growth in, 151.
seasonal growth in, 375.
soil moisture in, 267.
successions in openings in, 75,
temperature in, 187.
Dipterocarp forest, culled, 61.

composition by volume of different stories

on plot, 73.
composition of different stories on plot,

69.
description of, 61.
diameters of trees on plot, 70.
heights of trees on plot, 63.
location of, 61.

426

INDEX

Dipterocarp forest, culled — Continued.

plants less than one meter high on plot,
74.

volume of trees on plot, 72.
Dipterocarp forest, virgin, 30.

bizarre plants, 41.

buttresses, 36.

cauliflory, 36.

clear lengths of first-story trees, 57.

clear lengths of second-story trees, 58.

composition of different stories on plot, 51.

composition of small plot, 59.

description of plot, 43.

diameters of different stories on plot, 55.

diameters of trees on plot, 53.

dicotyledonous vines, 34.

epiphytes, 37.

ferns, 36, 37.

first story, 31.

flowers, 38.

general description, 30.

general view, 40.

ground covering, 36.

ground covering of plot, 58.

height of trees on plot, 48.

hepatics, 37.

herbs, 36, 37.

humus-collecting plants, 37.

list of species on plot, 44.

monocotyledonous trees, 35.

monocotyledonous vines, 34.

mosses, 37.

myrmecophilous plants, 41.

orchids, 41.

palms, 34.

palms, climbing, 34.

palms, erect, 35.

parasites, 41.

pollenation, 39.

rattans, 34, 36.

saprophytes, 41.

seasonal changes, 40.

second story, 32.

stand of trees on plot, 44.

strangling figs, 35.

third story, 33.

vines, 34.

volume on plot, summary of, 46.

water-storing plants, 37.
Dischidia, 408, Plate XIII.

purpurea, 41, 408.
Dita, 23, 137, 138, 139, 406.
Dominant story of dipterocarp forest, 31.
Donax cannaeformis, 60, 74, 96, 408.
Dracontomelum dao, 63, 408.
Drimys piperita, 393, 408.
Drynaria quercifolia, 37, 42, 408.
Duguan, 65, 71, 410.
Duhat, 23, 408.
Dungao, 86, 90, 406.
Dysoxylum decandrum, 149, 150, 408.

pauciflorum, 64, 408.

rubrum, 64, 408.

turczaninowii, 85, 89, 408.

sp., 45, 50, 59, 74.

E

Ebenaceae, 408.

Elaeocarpaceae, 408.

Elaeocarpus argenteus, 105, 106, 108, 408.

calomala, 85, 89, 93, 95, 96, 408.
Elaphoglossum, 102.

sp., 408.
Elatostema, 37, 81, 83, 101, 361, Plate XVI.

carinoi, 81, 83, 96, 97, 408.

longifolium, 392, 408.

viridescens, 81, 83, 96, 97, 408.
*spp., 77.
Elfin-wood on tropical mountains, 113.
Enterolobium saman, 143, 144, 408.
Environmental conditions, Mount Maquiling,
16.

factors on Mount Banahao. 394.

the interrelation of, 368.
Epiphytes, comparison of, at different eleva-
tions on Mount Maquiling, 112.

dipterocarp forest, 37.

midmountain forest, 77, 81.

mossy forest, 98, Plates XXIII to XXXI.

Mount Banahao, 392, 403.

relation of evaporation to, in diptero-
carp forest, 328.

relation of evaporation to, in midmoun-
tain forest, 338.

relation of evaporation to, in mossy
forest, 344.
Epirixanthes cylindrica, 82, 408.
Eria sp., 408.
Ericaceae, 412.

Eriobotrya japonica, 119, 408.
Eriodendron anfractuosum, 119, 407.
Eugenia arcuatinervia, 85, 89, 96, 408.

astronioides, 86, 90, 408.

calubcob, 86, 90, 93, 408.

crassipes, 86, 90, 408.

cumini, 23, 408.

longifiora, 63, 408.

luzonensis, 44, 49, 54, 63, 85, 88, 89, 96,
408.

mananquil, 44, 49, 96, 408.

robertii, 105, 106, 408.

saligna, 408.

similis, 44, 49, 54, 57, 408.

spp., 31, 44, 49, 59, 63, 70, 72, 85, 89,
93, 95, 96, 105, 108, 408.
Eulophia exaltata, 21, 22, 408.
Euonymus javanica, 45, 50, 59, 64, 74, 408.

viburnifolia, 65, 408..
Euphorbiaceae, 406, 407, 408, 409, 410.
Euphoria cinerea, 45, 50, 65, 408.
Eurya acuminata, 105, 408.
Evaporation, 296.

at different elevations on Mount Ma-
quiling, 346.

comparison of lowest rate on Mount Ma-
quiling with high rates from the United
States, 355.

comparison of rates with heights of
trees, 359.

dipterocarp forest, 324.

Jamaica, 353.

INDEX

427

Evaporation— Continued.

lawn, 298, 310.

methods of measurement, 296.

midmountain forest, 335.

mossy forest, 339.

open, 318.

open in temperate countries, 353.

parang, 297.

relation to succession, 356.

relation to vegetation, 357.

second-growth forest, 298, 310, 311, 313,
320.

tall grass, 298, 312, 313, 323.

temperate-zone forests, 351, 356.
Everett, H. D., and Whitford, H. N., work

of, 52.
Evodia glabra, 65, 71, 72, 408.

semecarpifolia, 105, 108, 408.

villamilii, 65, 71, 72, 408.

sp., 45, 50, 54, 58, 409.
Exponential temperature indices for growth,
238.

F
Fagaceae, 412.
Families of species mentioned in the text,

406.
Ferns in dipterocarp forest, 36.

epiphytic, in dipterocarp forest, 37.

midmountain forest, 81.
Ficus, 31, 35.

ampelos, 65, 71, 72, 409.

banahaensis, 105, 108.

barnesii, 45, 50, 54, 58, 65, 71, 72, 409.

dementis, 409, Plate XI.

elastica, 119, 409.

garciae, 85, 89, 93, 95, 409.

hauili, 23, 122, 123, 144, 145, 146, 150,
409.

linearifolia, 65, 74, 86, 88, 90, 93, 409.

manilensis, 71, 72, 409.

minahassae, 45, 50, 65, 66, 71, 72, 409.

nervosa, 63, 70, 72, 409.

nota, 23, 86, 90, 137, 138, 139, 409,
Plate IV.

paucinervia, 85, 89, 93, 95, 409.

ribes, 45, 60, 54, 58, 59, 86, 88, 90, 93,
96, 409.

satterthwaitei, 65, 71, 72, 409.

ulmifolia, 23, 122, 123, 146, 147, 148,
150, 409.

validicaudata, 105, 409.

variegata, 45, 50, 54, 58, 85, 89, 93,
95, 409.

warburgii, 105, 108, 409.

sp., 22, 45, 50, 54, 58, 65, 71, 78, 86, 90,
93, 149, 150.
Filmy ferns in mossy forest, 99.
Wr, 140.

Fires in grass areas, 18.
First story of dipterocarp forest, 31.
1 lacourtiaceae, 406, 407, 409, 411.
placourtia sp., 45, 50, 409.
! ltfrida, evaporation in, 351.
« lowers in dipterocarp forest, 38.

mossy forest, 101.

Form of records, 176.
Forrestia philippinensis, 409.
Foxworthy, F. W., work of, 356.
Freycinetia, 34, 35, 100, 114, 115, 392.
robinsonii, 96, 409.

williamsii, 60, 96, 100, 409, Plate XXX.
spp., 77, 80, 83, 84, 409, Plates XVI,
XVIII, XXXII.
Fuller, G. D., work of, 350, 351, 352, 355,

357.
Fuller, G. D., and Bakke, A. L., work of,
378.

G

Galeola hydra, 41, 409.

Gano, L., and McNeill, J., work of, 351.

Garcinia binucao, 45, 59, 409.

rubra, 45, 50, 409.

venulosa, 45, 50, 54, 65, 409.

spp., 33, 409.
Gates, F. C., work of, 350, 352, 356.
Gedeh, 103, 230.

General view of dipterocarp forest, 40.
Gentianaceae, 82, 407.
Gesneriaceae, 407, 408, 413.
Gibbs, L. S., work of, 104.
Girth of trees, changes in, during the day,

119, 122, 123.
Glochidion album, 66, 86, 90, 409.

lancifolium, 45, 50, 86, 90, 409.

merrillii, 86, 90, 409.

philippicum, 66, 137, 138, 409.

reticulatum, 66, 409.

trichogynum, 86, 90, 409.

williamsii, 105, 106, 409.

sp., 45, 60, 66.
Goniothalamus amuyon, 409.

elmeri, 45, 50, 65, 71, 72, 409.
Gramineae, 406, 410, 412.
Grass areas, 18.

evaporation in, 298, 312, 313, 323.
Grassland, area of, 19.

Mount Maquiling, 19.
Graves, H. S., and Ziegler, E. A., work of,

129.
Grewia stylocarpa, 45, 50, 55, 66, 85, 89, 93,

95, 409.
Ground covering in dipterocarp forest, 36.
Ground covering of plot in dipterocarp

forest, 58.
Growth, 116.

Artocarpus cumingiana, 136.

Astronia pulchra, 162.

average annual diameter growth of sec-
ond-growth species, that do not reach
a diameter of 20 centimeters, 150.

Bauhinia malabarica, 131.

Columbia serratifolia, 130.

comparison of growth of Astronia pul-
chra and Parashorea malaanonan, 164.

diameters, changes in, during the day,
119, 122, 123.

Dillenia philippinensis, 161, 165.
reifferscheidia, 166.

Diplodiscus paniculatus, 160.

428

INDEX

Growth — Continued.

dipterocarp forest, 151.

Enterolobium saman, 143.

errors in measurements, 117.

fastest rates of growth of second-
growth species, 139.

Ficus hauili, 144.
ulmifolia, 147.

general discussion, 116.

Homalanthus* alpinus, 167.

Homalanthus, compared with second-
growth species at base of Mount Ma-
quiling, 168, 169.

Litsea glutinosa, 133.

Macaranga spp., 134.

Mallotus ricinoides, 128.

methods of measurements, 116.

midmountain forest, 161.

miscellaneous species, reaching a dia-
meter of 20 centimeters and over, 137.

mossy forest, 167.

parang trees, 125.

Parashorea malaanonan, 152, 158.

Premna cumingiana, 148.

Pterocarpus indicus, 143.

relation of evaporation to, 358.

relation of light to, 238.

seasonal rates of, 370.

dipterocarp forest, 375.
parang, 370.

temperature indices for, on Mount Ma-
quiling, 237, 404.

temperature-light indices for, 239.

Trema orientalis, 131.
Guava, 23, 149, 150, 411.
Guijo, 20, 27, 44, 53, 61, 63, 67, 70, 72, 412.
Gum, 140.
Gum, red, 141.
Guttiferae, 407, 409.
Guyong-guyong, 64, 85, 89, 91, 95, 407.
Gymnacranthera paniculata, 45, 50. 409.

H

Hagimit, 45, 50, 65, 71, 72, 409.
Hamamelidaeeae, 406.

Hamindang, 23, 46, 51, 55, 66, 71, 72, 410.
Hasselbring, H., work of, 358.
Hauili, 23, 145, 150, 409.
Hedyotis philippinensis, 409.
Heights of trees in culled dipterocarp forest,
63.

plot in midmountain forest, 85.

plot in mossy forest, 105.

plot in virgin dipterocarp forest, 48.
Heise, G. W., see Brown and Heise.
Hemigraphis strigosa, 60, 409.
Hemlock, 139.
Hemlock, western, 140.
Hepaticae, 412.

Hepatics in dipterocarp forest, 37.
Herbaceous plants, relation of evaporation

to, 361.
Herbs in dipterocarp forest, 36.

midmountain forest, 81.

Heterospathe elata, 36, 409.
Hevea brasiliensis, 120, 123, 373, 409.
Hickory, 140.

HinlfLumo, 23, 46, 50, 65, 71, 72, 410.
Histopteris incisa, 109, 409.
Homalanthus alpinus, 105, 108, 109, 167, 168,
169, 242, 243, 393, 409.

fastuosus. 86, 90, 409.

populneus, 25, 409.
Hopea acuminata, 44, 48, 409.
Hoya odorata, 37, 100, 409.
Humidity, 270.

at different elevations, 294.

dipterocarp forest, 278.

methods of measurements, 272.

midmountain forest, 285.

mossy forest, 291.

Mount Banahao, 400.

parang, 272.
Humus -collecting plants, 37.
Hydnophytum, 41, 82, 409.
Hymenophyllaceae, 81, 99, 101, 410, 413.
Hymenophyllum javanicum, 101.

Icacinaceae, 413.
Ilex crenata, 393, 410.

foxworthyi, 105, 108, 410.
Ilicineae, 410.
Illustrations, list of, 5.
Iloilo, 406.
Imperata exaltata, 18, 19, 20, 21, 22, 322,

410.
Indiana, evaporation in, 351, 352.
Interrelation of environmental conditions,

368.
Ipil ipil, 23, 149, 150, 410.
Ipomoea triloba, 22, 410.
Isangjuac, 85, 89, 93, 95, 407.
Isis, 23, 66, 71, 72, 146, 150, 409.
Itea maesaefolia, 105, 108, 410.
Ixora longistipula, 45, 50, 59, 66, 410.
macrophylla, 46, 50, 410.

J

Jamaica, evaporation in, 353.

forest on Blue Mountains, 104.
Jost, L., work of, 358.

It

Kapok, 119, 407.

Knema glomerata, 59, 65, 410.

heterophylla, 410.
Kniep, H., work of, 236.
Koorders, S. H., work of, 170, 230.
Koordersiodendron pinnatum, 28, 63, 410.
Kraus, G. von, work of, 119.
Kreusler, work of, 229.

L

Labayo, 23, 149, 150, 407, 410.
Lagasi, 46, 51, 86, 90, 410.
Lamog, 44, 49, 54, 57, 59, 63, 89, 93, 95.
Lanutan, 45, 50, 55, 66, 411.
Lapnit, 44, 49, 54, 57, 412.
Laportea subclausa, 33, 46, 50, 59, 86, 90,
410.

INDEX

429

Larch, 140.

Lauraceae, 407, 410, 411.

Leaves, 378.

classification of, in dipterocarp forest,

378, 380, 381, 383, 384, 386, 387, 389.

classification of, in midmountain forest,

378, 382, 385, 386, 387, 389.
classification of, in mossy forest, 378,

382, 386, 387, 389.
classified according to character of

margins, 390.
classified according to length and

breadth, 379.
classified according to Raunkiaer's leaf

sizes, 378.
classified according to whether simple or

compound, 388.
compound, 380, 381, 382, 383, 384, 385.
margins of, 380, 381, 382, 383, 384, 385.
simple, 380, 381, 382, 383, 384, 385.
Lecythidaceae, 406, 411.
Leea aculeata, 46, 50, 59, 86, 90, 410.

manillensis, 23, 24, 33, 46, 50, 59, 66,

86, 90, 149, 150, 410.
philippinensis, 46, 51, 66, 86, 90, 93, 410.
quadrifida, 86, 90, 410.
Leguminosae, 406, 407, 408, 410, 411, 412.
Lehenbauer, P. W., work of, 227, 228, 229,

231, 238, 241.
Leitch, I., work of, 228, 229, 241, 242, 404.
Lentibularieae, 413.
Lepisanthes schizolepis, 66, 74, 410.
Leucaena glauca, 23, 149, 150, 410.
Leucosyke capitellata, 46, 51, 66, 71, 72, 86,

90, 93, 410.
Ligas, 45, 50, 55, 58, 65, 412.
Light, 232.

intensity at different elevations, 232.
methods of measurement, 232.
relation to vegetation, 235.
Lipa, 33, 46, 50, 59, 86, 90.
List of species mentioned in the text, 406.
Litsea garciae, 45, 50, 54, 58, 85, 89, 410.
glutinosa, 23, 133, 134, 138, 139, 410.
luzonica, 66, 410.
perrottetii, 23, 122, 123, 124, 137, 138,

410.
sp., 96.
Livingston, B. E., work of, 229, 232, 238, 241,
242, 296, 350, 353, 355, 359, 404.
and Brown, W. H., work of, 118.
and Livingston, G. L., work of, 237.
Livistona sp., 30, 35, 39, 45, 50, 53, 54, 59,

381, 410, Plate VII.
Local names mentioned in the text, 406.
Logging on Mount Maquiling, 27.
Lophopetalum toxicum, 45, 50, 54, 58, 410.
Lygodium circinnatum, 60, 96, 410.

M

Macaranga, 25, Plate III.

bicolor, 23, 46, 51, 55, 66, 71, 72, 75,

134, 410.
grandifolia, 46, 51, 55, 66, 410.
tanarius, 28, 134, 410.
spp., 135. 138. 139. 141, 143, 410.

Machilus philippinensis, 105, 106, 108, 410.

Magna, 66, 86, 90, 409.

Magnoliaceae, 408.

Maguili, 23, 147, 411.

Malabago, 49, 413.

Malabayabas, 85, 89, 93, 95, 408.

Malacacao, 65, 412.

Malaicmo, 29, 31, 44, 49, 54, 59, 63, 68, 70,

407.
Malaisis, 65, 71, 409.
Malaruhat, 44, 49, 54, 57, 408.
Malaruhat puti, 44, 49, 54, 63, 85, 89, 408.
Malasaging, 44, 49, 58, 59, 64, 85, 89, 406.
Malatapai, 407, 411.
Malatopai, 71, 72.

Malatuba, 46, 55, 79, 86, 90, 92, 93.
Mallotus moluccanus, 23, 149, 150, 410.
philippensis, 23, 137, 138, 410.
ricinoides, 23, 46, 51, 65, 71, 72, 128, 129,
130, 138, 139, 141, 410.
Malugay, 63, 411.
Malvaceae, 412.

Mambog, 45, 50, 54, 58, 85, 89, 93, 410.
Mangifera indica, 119, 410.
Manicnic, 411.
Maple, 140.
Maple, sugar, 139.
Marang, 23, 137, 138, 408, 410.
Marantaceae, 411.
Marattiaceae, 406.

Mastixia philippinensis, 45, 50, 85, 89, 410.
Matthaei, G. L. C., work of, 229.
Matthews, D. M., see Brown and Matthews.
Mauili, 150.

McNeill, J., see Gano and McNeill.
Measurements, dates of, 175.

remarks on records of, 175.
Mechanical analysis of soils, 173.
Medinilla, 100, 115.

astronioides, 86, 90, 410.

multiflora, 100, 101, 410.

myrtiformis, 100, 410, Plate XXXI.

venosa, 86, 90, 100, 410, Plate XXXI.
Melastomataceae, 406, 410.
Melastoma, 102.

polyanthum, 101, 105, 108, 410, Plate
XXXVII.
Meliaceae, 406, 407, 408.
Meliosma macrophylla, 44, 49, 54, 410.

sylvatica, 63, 86, 90, 410.
Melochia umbellata, 23, 122, 123, 148, 149,

150, 410.
Memecylon paniculatum, 45, 50, 86, 88, 90,

96, 410.
Merremia hastata, 22, 410.

umbellata, 22, 410.
Methods of measurement of growth, 116.
Midmountain forest, 76, Plates XVI-XX.

Astronia-rolfei association, 83.

chemical analysis of soils in, 172.

classification of leaves in, 378, 382, 385,
386, 387, 389.

clear lengths of first-story trees, 95.

composition of different stories on plot,
91.

composition of small plot, 96.

430

INDEX

Midmountain forest — Continued.

definition of, 76.

description of, 76.

description of plot in, 84.

diameters of trees in different stories, 94.

diameters of trees on plot, 93.

epiphytes, 81.

evaporation in, 335.

ferns, 81.

first story, description of, 78.

heights of trees on plot, 85.

humidity in, 285.

light intensity, 232.

location of, 76.

mechanical analysis of soils in, 173.

orchids, 81.

palms, 80.

Quereus-Neolitsea association, 78.

rainfall in, 252.

rates of growth in, 161.

rattans, 80.

second story, description of, 79.

soil moisture in, 268.

stand of trees on plot, 89.

strangling figs, 82.

temperature in, 205.

tree ferns, 80.

undergrowth, 81.

vines, 80.
Mimosa pudica, 22, 410.
Moisture equivalents of soils, 260.
Moisture-holding capacity of soils, 260.
Monocotyledonous trees in dipterocarp forest,
35.

vines in dipterocarp forest, 34.
Montane region of tropical mountains, 113.
Moraceae, 406, 409.
Mosses in dipterocarp forest, 37.
Mossy forest, 98, Plates XXI-XXIII, XXIX,
XXXII-XXXVI.

chemical analysis of soils in, 172.

classification of leaves in, 378, 382, 386,
387, 389.

description of, 98, 102.

description of plots, 104.

epiphytes, 98.

evaporation in, 339. '

exterior view of, Plate XX.

flowers, 101.

ground covering, 101.

height of trees on plots, 105.

humidity in, 291.

light intensity in, 233.

list of species on plot, 105.

location of, 98.

mechanical analysis of soils in, 173.

Mount Banahao, Plate XL.

rainfall in, 252.

rates of growth in, 167.

shape of trees, 102.

soil moisture in, 269.

sucessions in, 109.

temperature in, 211.

tree ferns, 100.

vegetation in ravines, 101.

vines, 100.

Mount Banahao, 14, 125, 130.

description of, 391.

description of vegetation, 391.

environmental factors on, 394.

epiphytes on, 403.

forest views on, Plates XXXIX, XL.

humidity on, 400.

rainfall on, 398.

relation of environment to vegetation,
403.

temperature indices for growth for, 404.

temperature on, 395.
Mount Maquiling, climate of, 16.

description of, 15.

environmental conditions on, 16.

location of, 15.

map of, Plate XLI.

view of, Plate II.
Mount Mariveles, 14.
Mount Pauai, mossy forest on, 14.
Mud spring, view of, Plate XV.
Mussaenda philippica, 24, 149, 150, 410.
Myristicaceae, 409, 410.
Myristica philippensis, 65, 71, 72, 410.
Myrmecodia, 41, 82, 410.

Myrmecophilous plants in dipterocarp forest,
41.

view of, Plates XIII, XIV.
Myrsinaceae, 406, 412.
Myrtaceae, 407, 408, 410.

N

Narra, 143, 412.

Nauclea junghuhnii, 45, 50, 54, 58, 85, 89,
03, 410.

orientalis, 65, 411.

sp., 119.
Neolitsea villosa, 46, 51, 79, 86. 90, 91, 92,
93, 96, 105, 106, 108, 411.

sp., 59, 80.
Neonauclea calycina, 45, 50, 54, 58, 78, 85,
89, 93, 95, 96, 411.

media, 45, 50, 411.

sp., 44, 49, 54, 57.
Neotrewia cumingii, 46, 51, 66, 411.
Nepenthaceae, 411.

Nepenthes alata, 84, 100, 411, Plate XXX.
Nephelium mutabile, 32, 45, 50, 55, 58, 65,

71, 72, 411.
Nertera depressa, 393, 411.
Nevada, evaporation in, 355.
Nyctaginaceae, 411.

Oak, black, 140.

red, 140.

white, 140.
Oak-dune association, evaporation in, 352.
Oayan, 85, 89, 412.
Octomeles sumatrana, 63, 70, 72, 411.
Olacaceae, 412.

Oleandra colubrina, 100, 411.
Operculina turpethum, 22, 411.
Orchidaceae, 407, 408, 409, 411, 413.
Orchids in dipterocarp forest, 37, 38, 41.

mountain forest, 81.

INDEX

431

Oreocnide trinervis, 46, 51, 55, 79, 80, 86,

90, 92, 93, 96, 411.
Oreodoxa regia, 119, 411.
Orobanchaceae, 82, 407.
Oroxylum indicum, 65, 411.
Osmelia conferta, 65, 71, 72, 411.

philippinensis, 65, 71, 72, 411. .
Oxalidaceae, 406.

Pagsahing, 23, 44, 48, 54, 407.

Palac palac, 49, 54, 57, 63, 78, 85, 89, 93

95, 411.
Palaquium, 32.

merrillii, 63, 70, 72, 411.
philippense, 78, 85, 89, 93, 95, 411.
tenuipetiolatum, 44, 49, 54, 57, 63, 411.
sp., 44, 49, 59, 63, 74.
Palis, 66, 407.

Palladin, V. I., work of, 359.
Palmae, 406, 407, 409, 410, 411.
Palms, climbing, in dipterocarp forest, 34.
erect, in dipterocarp forest, 35.
in midmountain forest, 80.
Pandacaqui, 24, 46, 51, 59, 66, 413.
Pandanaceae, 80, 409, 411.
Pandanus gracilis, 36, 411.

luzonensis, 36, 411.
Pangaerango, 103.

Papualthia lanceolata, 45, 50, 55, 66, 74, 411.
Parang, chemical analysis of soils in, 172.
definition of, 18.
evaporation in, 297.
humidity in, 272.
light intensity in, 233.
mechanical analysis of soils in, 173.
Mount Maquiling, 19.
rainfall in, 246, 252.
soil moisture in, 266.
temperature* in, 179.
trees, growth of, 125.
vegetation, 18.
Parashorea-Diplodiscus association, 30, 34, 38,

39, 40, 48, 76, 79, 80, 82.
Parashorea malaanonan, 20, 26, 27, 28, 29,
30, 31, 32, 38, 44, 48, 52, 53, 57, 59,
61, 62, 63, 67, 68, 70, 71, 72, 74, 75,
88, 92, 121, 122, 123, 124, 151, 152,
153, 154, 155, 156, 157, 158, 159, 160,
161, 162, 164, 188, 228, 229, 240, 242,
324, 356, 361, 370, 373, 374, 375, 376,
411, Plates V, VI.
Parashorea plicata, see P. malaanonan.
Parasites in dipterocarp forest, 41.
Parkia javanica, 24, 411.

timoriana, 24, 411.
Peculiar plants in dipterocarp forest, 41.
Pentacme contorta 20, 27, 28, 61, 63, 67, 68,

70, 72, 74, 411.
Petch, T., work of, 120, 370.
Pfeffer, W., work of, 358.
Phaeelophrynium sp., 60, 411.
Phaius sp., 411.

Phalaenopsis amabilis, 38, 411.
Photosynthesis, 235.

temperature coefficients of, 229.
Phreatea, 392, 411.
Physiological temperature indices for growth,

238.
Pili, 31, 44, 48, 54, 57, 59, 63, 407.
Pinaceae, 411.

Pinanga barnesii, 80, 86, 90, 96, 115, 411.
insignis, 36, 411.
sp., 59.
Pincapincahan, 65, 411.
Pine forest, 115, Plate XXXVIII.
Pine, jack, 139.

loblolly, 140, 141.
lodgepole, 140.
longleaf, 140.
red, 139.
scrub, 140.
shortleaf, 140.
sugar, 140.
western yellow, 140.
white, 139.
Pinus insularis, 115, 411.
resinosa, 356.
strobus, 356.
Piperaceae, 411.
Piper longivaginans, 392, 411.

sp., 77.
Pipturus arborescens, 23, 149, 150, 411.
Pisonia umbellifera, 45, 50, 65, 71, 72, 411.
Pisum, 241, 243, 404.
sativum, 228, 241.

temperature-light indices for Mount Ma-
quiling, 241.
Pithecolobium subacutum, 66, 71,. 72, 74, 411.
Planchonia spectabilis, 38, 44, 49, 54, 57, 59,

63, 85, 88, 89, 93, 95, 411.
Plot in dipterocarp forest, 43.
midmountain forest, 84.
mossy forest, 104.
Plumeria acutifolia, 119, 411.
Podocarpus, 125, 170, 394.
costalis, 393, 411.

imbricatus, 102, 115, 125, 230, 393, 411.
view of, Plate XXXIX.
Pollenation in dipterocarp forest, 39.
Polyalthia cumingiana, 65, 411.
lanceolata, 4il.
sp., 65, 74, 85, 89, 93, 411.
Polygalaceae, 82, 408.
Polypodiaceae, 99, 100, 101, 406, 408, 409,

411, 412, 413.
Polypodium sinuatum, 41, 411.
Polyscias nodosa, 137, 138, 411.
Pometia pinnata, 63, 85, 89, 93, 95, 411.
Poplar, yellow, 140.
Pothos, 34, 60, 411, Plate VI.
Premna cumingiana, 23, 147, 148, 150, 411.

odorata, 137, 138, 411.
Presentation of results, 177.
Psidium guajava, 23, 122, . 123. 124, 149,

150, 411.
Psychotria sp., 66, 411.
Pteris quadriaurita, 60, 412.

432

INDEX

Pterocarpus indicus, 143, 144, 412.
Pterocymbium tinctorium, 44, 49, 59, 63, 70,

72, 412.
Pterospermum diversifolium, 65, 71, 72, 412.
Pugahan, 64, 71, 407.
Pulac pulac, 44.

Puso puso, 23, 133, 138, 139, 410.
Putian, 44, 49, 54, 58, 64.
Pygeum preslii, 65, 412.

Q

Quercus-Neolitsea association, 78, 79, 80, 82,
83, 84, 85, 86, 88, 89, 90, 91, 93, 94,
95, 382.
Quercus robinsonii, 85, 89, 412.

soleriana, 65, 78, 85, 89, 92, 93, 95, 114,

412.
spp., 65, 392.

II

Radermachera sp., 59, 412.
Rafflesiaceae, 412.

Rafflesia manillana, 41, 412, Plate XV.
Rainfall, 245.

at different elevations on Mount Ma-
quiling, 249.

in Parang-, 246.

on Mount Banahao, 398.

relation to vegetation, 257.

seasonal distribution of, 251.
Rain tree, 143.

Rapanea philippinensis, 105, 108, 412.
Raspberry, 109.
Rattans, 34, 96, Plates V, VII, X.

in dipterocarp forest, 34, 36.

on Mount Banahao, 392.
Raunkiaer, C, work of, 378.
Ravines in mossy forest, vegetation in, 101.
Records, form of, 176.

Records of measurement, remarks on, 175.
Redwood, 140, 141.

Relation of environment to vegetation on
Mount Banahao, 403.

soil moisture to vegetation, 270.
Remarks on records of measurement, 175.
Results, presentation of, 177.
Rhododendron kochii, 99, 393, 412.

quadrasianum, 99, 412, Plates XXIII,
XXIV.
Riccia, 21, 22, 349, 412.
Rosaceae, 408, 412.
Rourea volubilis, 96, 412.
Rubiaceae, 406, 407, 409, 410, 411, 412, 413.
Rubus fraxinifolius, 75, 109, 412.
Rungia sp., 60, 412.
Rutaceae, 407, 408, 409.

Sabiaceae, 410.

Saccharum spontaneum, 18, 19, 20, 22, 297,.

312, 322, 412.
Salaquing pula, 44, 49, 64, 71, 72, 406, 407.
Salaquin-puti, 44, 49, 54, 85, 89, 407.
Sambong, 21, 407.
Sambucus javanica, 46, 51, 412.

Sapindaceae, 406, 408, 410, 411, 412.
Sapindus saponaria, 137, 138, 139, 412.
Sapotaceae, 411, 412.
Saprophytes in dipterocarp forest, 41.
Sarcocephalus orientalis, 411.
Saurauia latebracteata, 46, 51, 55, 412.

luzoniensis, 79, 80,-86, 90, 92, 96, 412.

whitfordii, 85, 89, 93, 95, 412.

sp., 46, 51.
Saxifragaceae, 410.
Schefflera, 37, 81, 412.
Schimper, A. F. W., work of, 13, 14, 36,

113.
Schizaeaceae, 410.

Schizostachyum diffusum, 34, 60, 74, 96, 97.
412.

mucronatum, 412.

sp., 62, 65, 412,
Seasonal changes in dipterocarp forest, 40.

rates of growth, 370.
Second-growth forest, 18.

area of, 19.

evaporation in, 298, 310, 311, 313, 320,
323.

Mount Maquiling, 23.
Second story of dipterocarp forest, 32.
Selaginellaceae, 412.

Selaginella, 40, 77, 99, 101, 112, 349, 392,
Plate XXXIII.

belangeri, 21, 22, 412.

maquiliensis, 99, 412, Plate XXV.

pennula, 96, 412.
Semecarpus gigantifolia, 45, 50, 55, 58, 412.

philippinensis, 65, 412.

sp., 59.
Shantz, H. L., see Briggs and Shantz.
Sherrf, E. E., work of, 316.
Shive, J. W., and Livingston, B. E., work

of, 263, 264.
Shorea guiso, 20, 27, 28, 32, 44, 48, 53, 61,
63, 67, 70, 72, 412.

polysperma, 412, Plate X.
Shreve, F., work of, 99, 104, 349, 353, 354,

355, 359.
Sida javensis, 22, 412.
Sideroxylon sp., 65, 71, 72, 412.
Sinnott, E. W., see Bailey and Sinnott.
Siphonodon celastrineus, 66, 412.
Soil moisture, 260.

dipterocarp forest, 267.

midmountain forest, 268.

mossy forest, 269.

parang, 266.

relation to vegetation, 270.
Soils, chemical and physical composition of,
171.

depth of, on Mount Maquiling, 171.

mechanical analysis of, 173.

moisture equivalents, 260.

relation to plant growth, 173.

water-holding capacity, 260.

wilting coefficient, definition of, 262.

wilting coefficient of soil on Mount Ma-
quiling, 264.
Species mentioned in the text, 406.
Spruce, red, 139.

INDEX

433

Stand of trees in virgin dipterocarp forest,
44.

on plot in midmountain forest, 89.
Staphyleaceae, 413.
Stations, location of, 175.
Sterculiaceae, 410, 412.
Sterculia crassiramea, 63, 74, 412.

cuneata, 66, 412.

foetida, 412.

oblongata, 65, 412.

sp., 44, 49, 54, 57, 412.
Storied arrangement of dipterocarp forest, 31.

midmountain forest, 76.

tropical forests, 33.
Strangling figs, description of, 35.

midmountain forest, 82.

number of, 31.

view of, Plates X, XII, XIII.
Streptocaulon baumii, 22, 412.
Strobilanthes pluriformis, 77, 81, 84, 86, 90,

96, 97, 101, 392, 393, 412.
Strombosia philippinensis, 28, 33, 45, 50, 66,

68, 71, 72, 74, 412.
Strongylodon macrobotrys, 39, 412.
Styraceae, 412.
Successions on cleared areas, 24.

grassland, 25.

openings in dipterocarp forest, 75.

openings in mossy forest, 109.

relation of evaporation to, 355.
Sugar palm, 36.
Summary, 414.
Susumbic, 45, 50, 55, 59, 66, 85, 89, 93, 95,

409.
Symphorema luzonicum, 35, 39, 412.
Symplocaceae, 412.
Symplocos ahernii, 85, 89, 96, 412.

floridissima, 105, 106, 108, 412.

luzoniensis, 412.

merrilliana, 105, 106, 108, 412.

villarii, 66, 412.

whitfordii, 393, 412.

sp., 45, 50, 66.
Synedrella nodiflora, 22, 413.

Tabernaemontana pandacaqui, 24, 46, 51, 59,

62, 66, 74, 413.
Taeniophyllum philippinense, 41, 413.
Tagpo, 44, 54, 58, 59, 64, 85, 89, 93, 406.
Talahib, 18, 19, 20, 412.
Talisay-gubat, 85, 90, 93, 95, 413.
Taluto, 49, 59, 63, 70, 72, 412.
Tamarack, 139.

Tamayuan, 28, 33, 45, 50, 66, 68, 71, 72, 412.
Tambalao, 65.

Tambulao, 50, 59, 65, 409, 410.
Tangili, 412.
Tangisang biauac, 45, 50, 54, 58, 85, 89, 93,

95, 409.
Tapulao, 45, 50, 63, 85, 89, 410, 413.
Taquip asin, 46, 51, 55, 66, 410.
Taxaceae, 411.
Tectaria sp. 60, 413.
159549 28

Temperature, 178.

calculations of mean, 222.

coefficient of photosynthesis, 229.

comparison at different elevations, 216.

dipterocarp forest, 187.

form of records, 178.

indices for growth on Mount Banahao,
404.

indices for growth on Mount Maquiling,
237.

methods of measurements, 178.

midmountain forest, 205.

mossy forest, 211.

on Mount Banahao, 395.

parang, 178, 179.

relation to vegetation, 222.
Terminalia edulis, 63, 413.

nitens, 63, 74, 413.

pellucida, 45, 50, 85, 90, 93, 95, 413.

sp., 96.
Terrestrial plants as epiphytes in mossy

forest, 100.
Text figures, list of, 10.
Theaceae, 408, 413.
Thea montana, 33, 86, 90, 93, 413.
Third story, dipterocarp forest, 33.
Thoday, D., work of, 118.
Thuja, 351.
Thuja forest, evaporation in, 351.

occidentalis, 356.
Thymelaeaceae, 413.
Tibig, 23, 86, 90, 137, 138, 139, 409.
Tiliaceae, 407, 408, 409.
Tinaan pantai, 64, 407.
Transeau, E. N., work of, 350, 351.
Transition between dipterocarp and mid-
mountain forests, 82.
Transpiration, 359.
Tree ferns in midmountain forest, 80.

mossy forest, 100, Plate I.
Tree stories in dipterocarp forest, 47.
Trelease, S. F., see Brown and Trelease.
Trema orientalis, 23, 24, 25, 75, 81, 99, 101,
122, 123, 124, 132, 134, 138, 139, 413,
Plate IV.
Trichomanes apiifolium, 101, 413, Plate
XXVI.

pluma, 101, 413.

proliferum, 99, 101, 413, Plate XXV.
Trichosanthes quinquangulata, 75, 413.
Trichosporum philippinense, 77, 100, 413.
Tuai, 23, 24, 44, 48, 85, 89, 93, 95.
Tuff, 171, Plate III.
Turpinia pomifera, 44, 49, 54, 96, 413.

u

Uisac, 78, 85, 89, 9&, 95, 411.

Ulmaceae, 407, 413.

Undergrowth in midmountain forest, 77, 81.

Urandra luzoniensis, 63, 413.

Urophyllum banahaense, 86, 90, 96, 413.

Urticaceae, 408, 410, 411.

Uto-uto, 65, 412.

Utricularia rosulata, 100, 413, Plate XXXI.

434

INDEX

Verbenaeeae, 407, 411, 412.
Vernonia lancifolia, 86, 90, 93, 413.
Vines in dipterocarp forest, 38.

midmountain forest, 80.

mossy forest, 100.
Virgin dipterocarp forest of Mount Maqui-

iitig, iO. *

Vitaceae, 407, 410.

Voacanga globosa, 23, 66, 149, 150, 413.
Volcanic tuff, 171, Plate III.
Volume of different stories in culled diptero-
carp forest, 73.

trees in culled dipterocarp forest, 72.

trees on plot in midmountain forest, 89.

summary of, in virgin dipterocarp forest,
46.
Von Faber, D. C, work of, 230.

W

Wallace, A, R., work of, 33, 36, 38.

Walnut, 140.

Warming, E., work of, 13, 103.

Water-storing plants in dipterocarp forest,
37.

Weaver, J. E., work of, 350, 351, 356, 357.

Weinmannia luzoniensis, 78, 86, 90, 93, 95,
96, 413.

West, A. P., and Cox, A. J., work of, 171.

White lauan, 20, 27, 61> 63, 67, 70, 72, 411.

White nato, 65, 71, 72, 412.

Whitford, H. N„ work of, 14, 19, 25, 27, 30,
36, 68, 115.

Whitford, H. N., see also Everett and Whit-
ford.

Wickstroemia meyeniana 46, 51, 413.

Wilting coefficient, definition of, 262, 264.

Wind velocity, 363.

relation to vegetation, 367.

Yapp, R. H., work of, 315, 316.
Yates, H. S„ see Brown and Yates.

Ziegler, E. A., see Graves and Ziegler.
Zingiberaceae, 406.

O

.##!

;m^<.::?:

,. ;-f|p^:.. Ill

Fin. 1. Mount Maciuiiing as seen from the Collegu of Agriculture

ipteti

ri0, 2. The southwestern part of Mount Mac
PLATE li.

f*Y$ w

■ :C"rV:k *>'

^H^***^'^ ?#^J£#^ ''j^'Vlffc-^ ?l' '**" wife ' ■■"■■»'- ^:

;fe:f''::v;v#

::^^#^i/=-^

■Bfl-^i,'-.-'"

■j/:;;

ytMMH

rig. 2, Ficus nota.

\j: ■'■--■ ..J^^f- ■■;■■■■ '■**£<< £jM&i'vy&? ' *

%*. "... -■ •&&*' '^f.-^£:«&^>*^\.-\ ;*

, ..,.^,,^tm

;^

'pa:

<my^*

$'" £%'£&&■

. V^Vv^f :¥i^J"'

LATE IX. A GROUP 01

. ..J.-^"^!-^ '-;[!' Si' fe". i:'' ■'■ *" V"-?:-.,: ' "■'.;'" '■■!': T^ ■"■ :..i -i' ■ '' A- '

If :.1i,

- !g«rf Si?.

\M& i :-5:-

,f, -.^ ■

p

, ...... . .... - :w:,V.^;; .., . _

,/^- , .......

^ \*:M

"<;£'■■,-■*. . 'v^^

*;•'.. "''if:'' x'."; '

i**%J.--

g^^^v^SlHHS^'' ^'^

■:::ryS:#;;:;.

:'^:$:i-

%.

:%;r-'

*%*.,,.:'■

;Vfe

.?.

:;',vK

W

m

■ ,:..;;, ^i:;;, ^

:^m

■■:n- ■:■...■ : ... ■ ■■■■Ui::-:..: ■ ■■.. .■ ■ . .;, * ^.*> -■ : ■ , - ■.- ■ ■- . . ■ ,

::■:: V ■ .' -
::-:- ■::.■,. ■

.:aifc

^%:

rs'

:«, K:

■ ?:rr- ,''■*:<:•' .?■.!*' ?.*

■ ■■■:- .. .■■-.■■■ . " :-.:,.; ■■ ■ .::■-:.

..■..::,;: ■ ,,.... . .:, .:■ -_ r . ;;:■■ / . *,V , " , /^.-. ■ .<- -.

fcllfl

-:««y|ii

wmrngMm

■: , >■. V ■ . ;':'-'\::,, ■■■■■- r :■■:■; :fv--:

;-*£

4--v :-::

Jr" ,,<i.'::':-

?>r> .;,:■■;.

«illti

hM*?'" <:£*)* : : :i ■ - ■■:">-
■ .>;,:>' .ri: v ^/' .. -- ■ ' ■■ *"y J :' J' ■'■

. ^^m± -/- : -■ j! :;:,M,;i!

■■ t '::.^:.::::■::::■s^|a|ifi;;^i;iS■

mmmmmm

'■:.,'■. ■ :■■:■'■"■" V ' '\&^-.*;Wri-+ t'-^\- ■,■'•:.',■' -v.3}\ '.'■' '

■ : ■ ■ ■■........ , ■ - - : ;,: .;■ J^ :■■ J-^j . . ■ ; .,:: : : . . A ," .. ,- /...- ;*■ .* -J. ■*

:m^amj mm,: ■ . . v -a

T^kF. ''^:IP%:^^ft

5i-

..,%:■ ::

:%P»r-

■^r ■.-'.':r"'::lr>V#-

.■;■,■■ ;,.:::::;■!:;■

i*i

J'

^,11!

*&r; :

;ir

#^.:

■ $&i ■ ■ ,-.-,■ - ■■.?■■: m

:--:;: :;:;"h:-:

■:■■:■■■ & :::-- hO:--1

..:■'?.. :~^

^■V"W%

':>W:!-^,

'■■^■^^

^lL::&r:Y .^S&

EISS

|S«^

\ ■ \

.**;

■■^■t

V*-

.>-,'» •*;•
\*-'?~-</"<\
(•'•

/"

rs.'K

:/NA

##— !

«m-V

l-y>yyy&

■;.:-■. *-*?>?(-a...'^.;:3»f.

■*>■

?/;■

yT3

■ .V,:* ■

'M'--;-M^'^; '-"-"h

:;:•:;:■

It

^

■V F

-yst

- -"v. ■ ■ ■ :: \

,;■ rh

>'.y

NP FOREST IN BENGUET MOUNTAINS.

MgfL_.

■■flS

*"*&«•

»
'#

■,4<Z., •'>• ." ••.. *>>";;\:

- "^ys^gyrf wye

--«f^r:

f i> *

wX^k

titudt. 1,800 i

xy ♦ Nc.-; ar.cLri x.te

OCT LH 1S2B

a

UNIVERSITY OF MICHIGAN

3 9015 02327 5764

*. /

■•Htsl

^?j>: *;\

^•v ,^

■M^MM