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THE OXFORD GEOGRAPHIES
Epirep sy A. J. HERBERTSON

AN INTRODUCTION TO
PLANT GEOGRAPHY

BY.

M: E. HARDY, D.Sc.

OXFORD
AT THE CLARENDON PRESS
1913

HUMPHREY MILFORD M.A.
PUBLISHER TO THE UNIVERSITY OF OXFORD
LONDON, EDINBURGH, NEW YORK, TORONTO
MELBOURNE AND BOMBAY :

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PREFACE

THE importance of vegetation for the student of geo-
graphy, and in the teaching of geography, is gradually
being recognized. As an indication of the quality of a
region it must be taken into account. For instance, the
differences between the denser forests of the low-lying
swampy lands round equatorial rivers and the opener
woods of the better drained higher ground between them
are of great importance. In practical affairs the distri-
bution of this or that plant association may often be
taken as a guide to the profitable extension of cultivation
of this or that crop.

For teaching purposes the study of vegetation is
equally important. From descriptions of the different
kinds of vegetation it is natural on the one hand to
pass to a study of climatic conditions which are asso-
ciated with them, and on the other to the way in
which they have influenced the occupations and mode
of life of the peoples who dwell on them. The con-
trast between the vegetation and climate of the hot
wet jungles of the equator and the hot dry scrub lands
which border the desert are very striking, and their
influence on the life of the people quite as remarkable. In
fact vegetation is the link between physical geography
and human geography.

So important is this study of vegetation that special

wall maps for the world and for each continent have been
A 2

4 ' PREFACE

prepared on the same projections and scales as those
showing physical features and rainfall. (Oxford Wall
Maps.') These are so coloured that they can be used
either in lower or upper forms, the different colours alone
being regarded in the former, the varying shades of those
colours in the latter. For the upper forms this introduc-
tion to plant geography has been written by Dr. Marcel
Hardy, the compiler of the wall maps. It will be fol-
lowed by a more advanced book.

The author wishes to thank those whose names are
given below for the photographs they have been good
enough to lend; and Mr. Trevor Haddon for his sketches:
Mr. H. M. Lomas, Col. Couchman, Mr. A. W. W. Brown,
Mr. J. Lagarde, Mr. C. W. Mathers, Mr. Donaldson
Smith, and Miss H. F. M. King. Fig. la is reproduced
from Tansley’s Types of British Vegetation by permis-
sion of Mr. Tansley and the Syndics of the Cambridge
University Press.

A. J. HERBERTSON.

1 Prices (net): unmounted, 7s. (Asia, 10s. 6d.), or £2. 10s. for the set of
7 maps; mounted on cloth to fold, 8s. 6d. (Asia, 12s. 6d.), or £3 for the
set; mounted on cloth and rollers, varnished or unvarnished, 10s. 6d.
(Asia, 15s.), or £3, 15s. for the set.

CONTENTS

INTRODUCTION
CHAPTER
I. DIFFERENT VEGETATIONS IN DIFFERENT SUR-
ROUNDINGS
Il. VEGETATIONS AND OCCUPATIONS
PART I
MAIN VEGETATIONS OF THE GLOBE
ITI, SELVAS, OR EQUATORIAL RAIN-FORESTS . °
IV. Manecroves.. . | os fan,
V. Monsoon FORESTS, OR SUMMER RAIN-FORESTS
OF THE HoT BELT ¥
VI. Tropica, THORNWOOD oR CAATINGA
VII. THE SAVANA ; : :
VIII. Tropican Scrvuss oR SEMI-DESERTS .
IX. DESERTS t : : :
X. SUB-TROPICAL OR WARM TEMPERATE RAIN-
FoREST
XI. MErpITERRANEAN WOODLANDS
XII. Orner EVERGREEN FORESTS
- XIII. TEMPERATE SCRUBS
XIV. SaGce BrusH.
XV. STEPPE, PRAIRIE, PAMPA, VELD
XVI. TEMPERATE DECIDUOUS FORESTS
XVII. THE Taicga 2 ; :
XVIII. Tunpra—CoLp DESERTS OR BARREN GROUNDS
XIX. MOouUNTAINS .
XX. ALPS
XXI. PuNnas AND PAMIRS

PAGE

9
16

CHAPTER
\ XXII.

XXIII.
XXIV.
XXV.

XXVI.
XXVII.

XXVIII.
XXIX.

XXX.

XXXI.

x“

XXII.
XXIII.

4

XXXIV.
XXXYV.

INDEX

CONTENTS

Patt
CONDITIONS OF PLANT LIFE

FAcTORS OF PLANT LIFE

HEAT

WATER .

LIGHT

WIND

SorL F oe

Tue HABITAT OR HOME OF PLANTS
MIGRATIONS OF PLANTS

PAR® <i
SURVEY OF THE CONTINENTS

NortH AMERICA .

SoutH AMERICA .

AFRICA . ; :
AUSTRALIA AND PactFic ISLANDS
Asta

EUROPE

PAGE.
136

. 188

140
144
145
147
148
150

. isa
. ,160

165
170
174
184

189

LIST OF ILLUSTRATIONS

. An Oak Forest

. A Beech Forest

. A View on Dartmoor
. An Irish Bog

Exterior Aspect of SaivaG or ee Farcaks, North Borneo,
West Coast

Canopy of Selva

Interior of Tropical Rain- Forest

Ground Vegetation of Rain-Forest . ‘

Plank Buttresses of Large Trees in Tropical Rain- Beret

Mangrove at Low Tide

Monsoon Forest. Kaing Grass. pers ae

Monsoon Forest. Teak in Java

Light Tropical Forest in Central Africa

Tropical Thornwood or Caatinga in Brazil

Tropical Thornwood in Brazil

Orchard Savana in West Africa

Llano in Venezuela ; : :

Umbrella Trees in Savana. East Sudan

Tropical Semi-Desert in North Mexico .

Mexican Semi-Desert

Mexican Semi-Desert ;

The Reg Desert, Sinai Peninsula .

Desert in Arizona ;

Desert in South-west Africa

An Oasis in the Sahara

Forest near the Iguassu Falls, Mcinges apentina

Aspect of Sub-tropical Forest. Florida .

Undergrowth of Hill-Forest in East Australia

Roof of Exhausted Forest or Capoeira in South Brazil .

Undergrowth of Sub-tropical Rain-Forest

Cypress, Pine, and Evergreen Oak Woodland in South
of France ‘ : é 3 : ; ;

Rock Pine in Spain ;

Maquis in South of France

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LIST OF ILLUSTRATIONS

Big Trees Forest in Sierra Nevada, California

Silver Tree, Evergreen Shrubs and Bulbs. Cape of Good
Hope ; i é

Dense Eucalyptus Poweah in East fees

Araucaria Forest in Misiones, Argentina

Park Landscape or Savana Woods in Australia

Scrub or Chaparral in California

Mallee-scrub, Australia .

Sage brush, Semi-Desert

Sage brush. North Colorado .

Canadian Prairie

North American Prairie (cs

Manchurian Steppe and its Dwellers

Summer-Green Forest. South Appalachians, North
Carolina

. Sweet Chestnut Forest in Carebnes renee :

Summer Forest and Park Landscape in Sakhalin .
Portage in North Canadian Spruce Forest

Near the Limits of Russian Taiga .

Tree Limit in Northern Russia

Tundra in Northern Russia +
Cotton-Grass Tundra in Northern Riae
Bloom-Mat in Northern Russian Tundra ;
Mountain Vegetation . i : 7 Ge
Upper Engadine. Trees, Alps and Snow

Tree Limit in Alps. Arve ; ’

Vertical Zones or Girdles of Vegetation

Spruce and Aspen Mountain-Forest in Colorado

Pine Forests in South Canadian Rockies

An Alp

Crawling Juniper urs Tree Pickits in ‘ines Himalanee .

Alpine Rock and Cushion Plants
Vegetation of North America .
Vegetation of South America .
Vegetation of Africa
Vegetation of Australia .
Vegetation of Asia .

PAGE

77

79
80
81
82
85
86
89
91
93
95
97

101
103
104
107

. 109

LIE
115
116
117
120
121
125
125
126
127
130
131
132
154
161
167
Lay
175

INTRODUCTION

CHAPTER I

DIFFERENT VEGETATIONS IN DIFFERENT
SURROUNDINGS

Most of us have some favourite landscape. We like to
look at it at all seasonsof the year. We are accustomed
to its changes from the green leaves of summer to the
bare boughs of winter and explain them by the changes
of the seasons. But we do not usually ask ourselves the
question how it happens that the different woods and
meadows come to be where they are. If we have
travelled we know that landscapes differ. Let us begin
by looking at the vegetation of some of the different
kinds of landscape which are found in our own islands.

Exmoor. Let us picture to ourselves Exmoor with its
rolling hills and its deep rift-like dales. The rounded
tops are brown or black from heather moors and peat
bogs, swept by the damp moaning winds. No tree is
visible; only an occasional strip of hedgerow along
asunken path. The gentle upper slopes have a fresh
green sward studded with low prickly gorse or whin,
and chequered with fences of broom. Lower down, the
oak trees which formed strips of wood along the brooks
in the upper part spread all over the steeper slopes,
forming a continuous covering. There, old holly trees
thrive on damp carpets of woodruff, wild hyacinth, ferns,
and mosses. <A ‘hoe’ with a cottage and a green stands
out here and there on the wooded slopes. Thence,

10 INTRODUCTION

the cliffs sink precipitously to the sea, with a gorgeous
covering of flowering sloes and gorse, interspersed with
patches of russet and pale green bracken.

This is essentially a sheep, cattle, and pony farming
district, where agriculture plays a less important part.
It has a scanty population. Winter and summer are
fairly mild except on the heights. Rain is abundant
all the year round; the sky is often cloudy and the wind
strong, especially in winter; the soil is remarkable for
its red hue, and the rock below consists of a shaly red
sandstone.

Hampshire. (uite a different landscape is seen in
Hampshire, south of the North Downs (near Winch-
field). It is a gently rolling plain, apparently covered
with continuous forest. Tree growth is luxuriant and
abundant; the oak is conspicuous everywhere. Roads
are overhung and fields are encircled by hedges of oak,
hawthorn, maple, guelder-rose, and euonymus, draped in
wild bryony and hops, honeysuckle and anemone. The
commons are shaded with many stately old oaks, under
which pigs roam freely. Fields, greens, commons, and
orchards seem but clearings in the woodland. Villages
are buried in verdure. From a slight eminence the whole
district appears a continuous canopy of oak. This is a
drier district, with a fresher and deeper yellow chalk
clay soil.

The Fens. Another characteristic region is the fen-
land round the Wash. This is a vast marshy flat, often
flooded by its broad and sluggish rivers, chequered by
narrow dykes and broader drains, as the drainage canals
are called. It is a land of soft and far horizons, edged
with poplars and windmills. The broad acres of rich
wheat fields, juicy meadows, and marshy pastures are
crossed by lines of poplars, willows, ashes, elms, elders,

Fic. la. An Oak Forest. “(Photo : S. Maugham.)

Fie. 1b. A Beech Forest.

Notice the contrast between the undergrowth in the oak forest and
the absence of undergrowth in the beech forest.

12 INTRODUCTION

and hawthorns. Along the ditches and dykes run waving
fringes of reeds, rushes, and sedges, and waterlilies float
on the calm waters. Every night mists hang over the
damp surface. The winters are cold, and icy north-east
gales render them more severe, but there are hot days in
summer. This region is very like Flanders on the
opposite side of the North Sea.

Scottish Highlands. As a contrast let us pass over
the grassy dales of Yorkshire and the dreary Southern
Uplands and take one of the few wooded glens of the
eastern Scottish Highlands. There, as we climb the bold
slopes of lofty hills, we find a well-marked succession
of vegetations. Along the side of the stream is a belt of
dark beech forest, its floor carpeted with wood anemone,
sorrel, primrose, and wood hyacinth. Farther up are oak
forests, butof a poorer type than in the southern lowlands.
Scots pines and larches form a higher girdle of stately
woods, interrupted here and there by grassy pastures and
heather moors. The steeper slopes above form verdant
swards of short alpine pasture with bushes of bilberry,
cranberry, and other berry-bearing shrubs, while the
terraces and flats are covered with peat bogs. The
broad open plateaus on the top are barren grounds
with soft mats of bushy lichens and decaying rock
boulders coated with crust lichens.

Central Ireland. In the central plain of Ireland,
again, we find a totally different scenery. Much of it is
covered with a rough sheet of barren and impervious clay
dotted with hundreds of tiny lakes; the climate is cool
and rainy. The result is a vast peat bog, a black, spongy,
shaky, water-swollen cake of sodden plant-remains, where
sphagnum and other mosses, cotton grass, and heath grow
profusely. Heather makes a low bush on the drier moss
and knolls, Moor-grass and molinia grass cover the

Fie, 2a. A View on Dartmoor. (Photochrom Co.)

Fic. 2b. An Irish Bog. (Photo: R. Welch.)

14 INTRODUCTION

banks. Sedges, cotton grasses, and rushes form the coarse
wet meadows. Tufts of grass grow all along the stream-
lets. Sweet-gale hides the marshy slopes. Such morasses
cover a large portion of Ireland. They are also found
in broad tracts in Scotland, more particularly in the
barrens of Caithness.

Different Environments — Different Vegetations.
Thus we find within our own islands different kinds of
forests and woodlands, of pastures and meadows, of
marshes and swamps. These are formed of different sorts
of plants, arranged in different ways, growing differently,
and having different aspects and modes of life. Ap-
parently plants do not grow indifferently anywhere.
Different sets of plants are found in different landscapes,
and indeed they often form the distinguishing feature of
the landscape.

Let us use the word vegetations for such groups of
plants as are usually found together in different districts.
We can then say that the vegetation differs as we climb
from the base to the top of a mountain, as we descend
the hills to the plains, as we pass from the east to the
west of England, from the chalk downs to the fens, or
from these to the central plain of Ireland.

But these districts differ in more than vegetation.
We noted hills and plains, undulating and flat districts ;
red sandstone soils, black earth, whitish chalk clays,
stiff boulder clays, and even bare rock. The climate also
varied in each case, in one place more cloudy and rainy, in
another clearer and drier; in one district always mild, in
another, with cold winters and hot summers. These and
other features differed in each instance. The sculpture
of the district, the climate, the nature of the soil, and the
other circumstances, all of which we may call physical
conditions, varied as well as the vegetation. We are

ad

DIFFERENT VEGETATIONS 15

thus led to gonclude that differences of vegetation may be
associated with differences of physical conditions. This
will help us in our further studies.

Like vegetations in like surroundings. We shall
now look around for landscapes similar to those which
have just been described. For instance, the physical
conditions and the vegetation of Exmoor are reproduced
more or less exactly on Dartmoor, in Cornwall, on the
hills of south-western Wales and of southern Ireland.
The landscape of central Hampshire may be compared
with certain parts of Normandy in France. Similar physi-
cal conditions and vegetation are found on the downs of
southern England and on the chalk heights of the north
of France. The Fens are but a replica of the lowlands
across the North Sea. The moors of Yorkshire resemble
in many ways those of the Southern Uplands. The east-
ern Scottish Highlands are very much like parts of the
Central Plateau of France or the Fjelds of Scandinavia.
In each case we find that the circumstances of climate
and soil and the nature of the country are very much
alike. So we are led to expect like vegetations in like
surroundings.

Plant Geography. Clearly plants are not distributed
indifferently everywhere. Their distribution is con-
trolled by many circumstances which we term physical
conditions. Had we observed the plants themselves
more closely we should have noticed how the same
plant assumes a somewhat different aspect in different
surroundings. We should have been led to think that
the nature of the physical and other conditioris, which we
call the environment, imparts a special appearance to a
plant or a group of plants. In other words, only those
plants will live and reproduce themselves which assume
certain modes of living and growing in response to the

*

16 INTRODUCTION

conditions by which they are surrounded. This is what
is meant when we say the plants are adjusted to their
environment.

If we are justified in drawing such conclusions from
the few instances already given, we must next seek to

verify them on a larger scale and in greater detail. The ~
study of the distribution of different types of vegetation

and the way in which these types and their distribution
are related to the other geographical conditions is called
Plant Geography.

CHAPTER II
VEGETATIONS AND OCCUPATIONS

Different Vegetations—Different Occupations. Re-
turning to the various landscapes we have examined, we
may learn a further lesson.

Exmoor has good pastures. Agriculture hardly finds
any place on ‘those hills. The pastures support a fair
number of cattle, ponies, and sheep. Therefore a large
proportion of the population is occupied in looking after
these and with dairy-work. Some of the inhabitants of
the lower parts of the valleys where the climate is mild
grow early vegetables and flowers.

Passing towards Hampshire, we find on our way the
vales of Devonshire covered with richer pastures which
feed thousands of prosperous-looking cattle and sheep.
As we pass through the wooded commons of Hampshire
we notice the acorns under the old oaks. This is cheap
food for the pigs which roam about everywhere, and are

aa

VEGETATIONS AND OCCUPATIONS: — 17

an important part of the farmer’s stock. We are re-
minded of a time when England was largely covered
with oak forests and the Saxons were mostly swine-
herds. Of these forests little remains to-day, and the
crab apples that grew scantily among them have been
replaced by apple orchards for cider making. Devon-
shire has long been known for its cider, equal to that of
Normandy, another oak and apple country. Farther
east the humble hops that once hung on the hedgerows
have been trained on poles, and form the graceful per-
golas of the rich Kentish hop-fields, which supply the
hops for beer. The picking of these affords temporary
employment, every autumn, for a floating population
drawn from London and other towns.

The marshy tracts of the Fens formerly produced only
tall reeds, but since the rich and heavy black mud and
peat soils have been drained and dried we find here
heavy crops of wheat and much market-garden produce.

The uplands of northern England and southern Scot-
land are crowned with moors and poor pastures; and the
slopes are excellent for sheep, which wear a thick coat
of wool. The wool was formerly washed, spun, and
woven in the little villages and towns round the margin ©
of the uplands, and some of these have grown into great
industrial cities.

The eastern parts of the Scottish Highlands long
supplied good pinetimber. As the forests were gradually
destroyed and replaced by moorland, cattle, sheep, and
deer succeeded each other. Spinning and weaving
followed as occupations of the people who inhabited the
towns which sprang into existence round the base
of the Highlands. The Grampians, however, may once
more become an important timber region in the future,
if they are properly replanted.

1159 B

18 INTRODUCTION

Turning to the desolate central plain of Ireland, we
find little of economic importance. Peat fuel is the
chief product, the value of which for smelting purposes
has increased of late. When the peat is drained and
manured it can be cultivated. Where this is not
possible, as in the bogs of the far west, a scanty popula-
tion can-hardly eke out a bare living by rearing a few
cattle and sheep. Many people go every year to Scotland
and England at harvest time to earn a little money
as labourers. Others seek a living in industrial centres
-or migrate and settle in far distant and more fertile
lands.

From these examples we notice how the nature of the
vegetation may determine the occupations and develop-
ment of the people. Bearing in mind the influence of
the environment on the vegetation, we may conclude
that the environment influences the population mainly
through vegetation.

Like Vegetation—Like Occupation. This is yet more
clearly illustrated when we compare the development
and occupations of the people in regions with similar
vegetations. The rich vales of Devonshire, with their
cattle, their dairy industries, and their cider, vie with
Normandy in these respects. On both sides of the
North Sea, the fenlands of the Wash and those of the
Scheldt are prosperous granaries where the gaunt arms
of the windmills mark a similarity of occupation. The
hop-fields of Kent and Sussex and those of northern
France appear as parts of similar regions. The bleak
Scottish Highlands and the Scandinavian fjelds are
strikingly alike in many respects. The Irish bogs
find a replica in the German and Danish heather and
moors. We might enlarge our fields of observation and
find such similarities all over the world.

VEGETATIONS AND OCCUPATIONS 19

Causes and Effects. Our conclusion is that there
exists a chain of causes and effects. The physical en-
vironment has conditioned the vegetation, and the
vegetation has largely determined man’s occupations and
development, while man has altered the vegetation and
even modified slightly the physical environment to his
profit or detriment. The study of all these would be
the full scope of Plant Geography. Our attention,
however, may best be limited here to the first two
points, and more particularly to the first.

We shall first make a general survey of the main
plant landscapes of the world. This we may do con-
veniently by starting with the hot and wet regions of
the equator, and working our way gradually through
colder and poorer countries to the bleak circumpolar
deserts.

PARES

MAIN VEGETATIONS OF THE
GLOBE

CHAPTER III
SELVAS, OR EQUATORIAL RAIN-FORESTS

THE selva may be described as a roof garden on pil-
lars. Above, in the dazzling sunshine, is a sea of
verdure aglow with islands of gaudy colours, on and in
which gorgeous insects, birds, tree frogs, and numerous
small mammals are extremely busy. Below, lies a stu-
pendous gloomy vault, crowded with pillars, encumbered
with ropes and cables, hung everywhere with baskets of
foliage and laid with a soft and elastic brown mat, hidden
here and there by a mass of broad variegated leaves,

Such is the first impression of the equatorial rain-
forest, the product of the ever-moist, ever-hot equatorial
belt. It is found chiefly along the Amazon and its main
tributaries, in the heart of Africa, in Burma, Assam,
Bengal, and Malaysia. The sort of country for such
a vegetation is either flat or rolling plains, or the lower
slopes of mountains up to 3,000 feet. In these regions
it may rain every afternoon and night in the year, or
there may be one or two dry seasons, each not more
than two or three months, when the drought is broken
only by thunderstorms. During the rest of the year it
may pour for days or weeks; everything is soaked in
a thick grey mist. The temperature is uniform, varying
from 70° to 85° F. (20° to 80° C.), with an average of

Fic. 3. Exterior Aspect of Selva or Rain-Forest. North
Borneo, West Coast. (Photo: H. M. Lomas.)

22 MAIN VEGETATIONS OF THE GLOBE

about 77° F. (25° C.). Some notion of what such
a climate is like may be obtained in the tropical palm
houses of our botanical gardens.

The light is dazzling when the sun shines, for at noon
it is always high in the sky. It often becomes too
strong even for the green matter of the leaves which
are exposed toit. This light, however, is stopped by the
canopy: beneath, the forest is uniformly hot, moist,
stuffy, and gloomy.

The outline of the canopy is irregular. The crowns
of the trees, generally rounded or egg-shaped, jut out
at various heights and are connected with each other
by interlacing foliage. One must not, however, think
of this canopy as being composed of bunches of huge,
thin leaves like those seen in palm houses, The leaves
are of moderate size, similar to those of magnolias or
the usual rubber plant (ftcus) of our drawing-rooms,
or pinnate, not unlike those of the ash, but much larger,
or again fingered, like, those of the horse chestnut.
They are very mobile, and follow the sun in its daily
course, drooping, expanding, or rising in a surprising
manner, according to the strength of the light. They are
frequently fleshy and glossy. The tree crowns do not form
compact masses, but are divided into separate bunches.

It is difficult to realize the variety of trees in the
selva. The same tree only occurs two or three times in
an acre, hence the irregularity of the upper surface.
The intermediate vegetation which forms the pits,
hammocks, or sheets between the crowns consists of
lianas or huge climbers, several hundred feet long, and
of the heads of the taller palms and minor trees.

At any time of the year we may find some plants
bursting into leaf and others shedding their leaves, some
gay with flowers, others bearing their fruits, for it is

EQUATORIAL RAI N-FORESTS 23

always hot and moist, and there is no regular seasonal

change affecting the whole of the vegetation.

Fic. 4. Canopy of Selva.

great forest 1s bustling with
om below. ‘There
wts, lizards,

This upper tier of the
life, though nothing of it is seen fr
are innumerable insects, tree frogs and ne
tree-snakes, birds, squirrels, apes, and many other tree-

24 MAIN VEGETATIONS OF THE GLOBE

dwelling mammals, most of which never touch the
soil in their lives. The majority are brightly robed,

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Fic. 5. Interior of Tropical Rain-Forest. Lianas, climbers,
epiphytes, carpet.

plumed, or furred. Below the canopy is a sombre,

damp, stuffy, silent vault, supported by long, slender,

: EQUATORIAL RAIN-FORESTS 25

unbranched tree-trunks, with a thin, smooth bark. Huge
vines or lianas, varying in thickness from a man’s thigh
to his thumb, hang and twine in the most capricious
manner from the roof, making a network of cables and

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Fic. 6. Ground Vegetation of Rain-Forest. Large and
tender-leaf plants on mould.

ropes, some smooth, some prickly; all bare and un-
branched. They are frequently gorged with water and
milky sap. These lianas have climbed up the tree-
trunks and afterwards freed themselves from their
supports; some hang direct from the canopy, coiling
and twisting on the ground, and forming a tangle in

26 MAIN VEGETATIONS OF THE GLOBE

which progress is difficult; others, such as palms and
arums, cling to their supports and develop bunches of
huge thin leaves.

F rom every available nook and corner on the stems
of trees or lianas grow hanging baskets of plants called
epiphytes, i.e. plants living on other plants. Among
them are many orchid plants, but the commonest are
shaped like those of arums and pine-apples. An abun-
dance of moisture in the air and the mould which falls
from the roof enable these aerial gardens to attain
a great luxuriance.

Scattered here and there, a lower tier of the forest may
be found. It is made up of straight palms which often
reach the roof and become entangled in it.

The undergrowth is formed by a brush of thin, weakly,
unbranched, drawn-out saplings, generally fleshy and
Juicy, resembling overgrown herbs. In places one may
find carpets of arums, dwarf palms, and other herbs;
or again rosettes of variegated or brightly coloured
leaves. A soft brown felt mat, in which stumps, trunks,
and lianas are left half buried and decaying, often
covered with orchids and other epiphytes and sapro-
phytes (= plants living on decaying a matter)
completes the picture.

Two other features of the selva must be noted here.
In many tropical forests certain kinds of trees are sup-
ported at their base by roots growing out of the trunks
and resembling wings or props. These supports may
reach 8 to 10 feet in height and as many in breadth,
and are called plank buttresses. Another characteristic
is that some of the larger and many of the smaller trees
develop flowers and fruits directly on the branches and
sometimes on the trunks as well as on the smaller twigs.”
This is well seen in the cacao tree.

EQUATORIAL RAIN-FORESTS 27

This great gloomy forest hall appears to be deserted
by animals. An awe-inspiring silence prevails, except
for an occasional reminder of the life above. Animals
ean hardly be perceived owing to the subdued colours
of their skins. The buzz of mosquitoes is heard, an

Fic. 7. Plank Buttresses of Large Trees in Tropical
Rain-Forest. Lianas,

occasional newt, lizard, or snake is seen, but no other
sign of life is apparent.

That such conditions are unfavourable to human
development is shown by the inhabitants of the great
forest. It may teem with undeveloped wealth, but this
is almost invariably out of reach. Itis mostly by destroy-
ing the forest that man has discovered how to use the
ground. Only in clearings can he cultivate the necessary

28 MAIN VEGETATIONS OF THE GLOBE

plants; and to do ‘this he has to fight the forest,
which grows so quickly that it constantly threatens

to overwhelm him and his fields) Communication

through the forest is dangerous and difficult. Hunting,
fishing, and collecting the natural products are the chief
occupations of the people. and these involve a wander-
ing life. The real inhabitants of the selva are nomad
hunting tribes of the most primitive kind, scattered over
immense areas.

The large permanent clearings and the margins are
peopled by settled races. leading a more complicated life.
When the forest is dealt with by modern implements and
methods it can be transformed. and this has been done in
parts of South America and Malaya, where gardens of
extreme fertility have been formed. One by one the
natural products of the forest are being cultivated.
From the selva have come the banana. cacao, manioc,
yam, mamey, mango, papaw, sapotas, aguacate, bread-
fruit, cabbage-palm, vanilla, sugar-cane, sugar-palm,
betel-palm, spices, and many other food products, as
well as many industrial products such as caoutchoue
rubber, gutta-percha, palm-oil, and countless others. Rice
does well under the equatorial climate, of which it is
one of the most important features.

All equatorial rain-forests are not so dark as the type
which has just been described. More open varieties
are found in which the undergrowth is more luxuriant
and the distinction between the canopy and the interior
is consequently less marked. Such forests are even
more impassable than the dark columnar type. Palms
play a more important part. The flood-forest of the
Amazon, with a dense, continuous, flowerless, cheerless
canopy of uniform verdure, and a marshy floor, resem-
bles a close crop of giant tree-weeds.

aS
a

ss EQUATORIAL RAIN-FORESTS a

Among other varieties of the hot rain-forest may be
mentioned the bamboo forests of Assam and Burma,
partly due to cultivation, and the swamp-forests of
Burma, Sumatra, and Borneo, completely bare in the
rainy season.

In such hot and moist climates, forest growth can only
be checked with difficulty. The land which is not under
permanent cultivation is soon conquered again by a
dense jungle, the first step towards the reconstruction
of the selva. This is known in South America as
Capoeira or Capuera.

CHAPTER IV

MANGROVES

THE imagination of seamen and other travellers in
tropical seas was early struck by one form of the
wooded coastal swamps which sometimes rises to the
wank of low forest. The impressive aspect and deadly -
properties of it have gained for it a personality—
a name: the Mangrove.

—— are found along zamy a
but with within aaah of the tide, a the Si is some-
what quiet. They extend inland in the brackish
lagoons and swamps. They may form a fairly con-
tinuous fringe or be split up imto a labyrinth of islets

__ between which the sluggish tidal streams run.

“4 At high tide the mangrove appears like a mass of
. grey, or dull blue foliage sitting on the water—
a flooded forest. As the tide recedes it gradually reveals

30 MAIN VEGETATIONS OF THE GLOBE

ao

a low forest of ungainly tree-weeds. Their short and
shapeless trunks, covered with mud, are supported by
a tangle of crooked bow- or knee-shaped stilts emerging
out of soft blue-black slime. A stinking gas bubbles to
the surface of the rotten mire, which teems with
a crawling population of crabs and fishes.

A uniformly hot and wet climate, salt or brackish
water, a soft ground deprived of air, and the rhythmic
tidal flood are the conditions under which mangrove
plants develop. Their life is one of steady, monotonous
growth and decay, without interruption, with no other
rhythm than that of the tides and of the alternations
of equatorial downpours and scorching sun, They are
evergreen, and, as plants do not readily absorb salt
water, their foliage is protected against excessive
transpiration, being now thick and leathery, now fleshy,
now provided with a glossy impervious skin, now
with a woolly down. The trunks and branches are soft
and juicy, capable of storing water. The roots are
specially adapted for fixing the trees in the soft ground
by a spreading scaffolding of stilts or buttresses.
Sometimes additional roots grow down from the foliage
and striking in the mud support the expanding crowns.
On account of the difficulty of breathing under water
or slime the roots bend, arched or knee-shaped, above
the low water level. Or, covered with breathing mouths,
they crawl, jointed or in coils, over the mud laid bare
at ebb tide. Or again they send up out of the ground
special breathing stumps of various shapes. In some
species of mangrove bushes the seeds sprout on the very
boughs and, like arrows, drop vertically in the mud
where they strike roots. Mangroves are more frequently
found as shrubs than as low forests. They are useless
to man, extremely unhealthy, and uninhabited.

3]

‘
Ls

S

‘
4

M ANGROVE

Mangrove at Low Tide.

Fic. 8.

32

CHAPTER V

MONSOON FORESTS, OR SUMMER RAIN-
FORESTS OF THE HOT BELT

BEsIDES the lofty evergreen rain-forest there exists in
the tropics a large variety of forests and woodlands
which experience one well-marked period of drought
every year. These forests, which differ greatly in aspect
and composition, and range from the lofty type to that
of the high bush, may conveniently be termed Monsoon
Forests.

Their distribution coincides with that of the true
monsoon rains (India, Burma, Indo-China, and northern
Australia), or with the lands which receive rains during
summer, i.e. on the tropical margins of the equatorial
rain-belt in Africa, round the shores of the Gulf of Mexico
and the Caribbean Sea, and the north and eastern por-
tions of South America.

A hot climate, abundant summer rains, and a pro-
longed drought lasting from four to six months, are the
conditions which determine the appearance of the Mon-
soon Forests. The total amount of rainfall is smaller
than in the equatorial rain-belt, and the difference of
temperature between day and night and between cold
and hot seasons is more strongly marked. To these
conditions may be added the occurrence of strong dry
winds.

Monsoon vegetations vary in appearance from an im-
poverished type of rain-forest to that of the lower mixed
type of Burma, which is only 30 feet to 40 feet in height
and in some respects not unlike our oak woods,

MONSOON FORESTS 33

In comparison with the rain-forest, monsoon forests
are more open. There is no such scramble of all plants
for light, as the trees are farther apart. In the dry
season most trees shed their leaves, and the landscape

Fic. 9. Monsoon Forest. Kaing Grass. Upper Burma.
(Photo: Col. Couchman.)

has a wintry appearance. Even in the period of vegeta-
tion, some light pervades the forest and plays in the
undergrowth. The trees are from 40 feet.to 100 feet

high, and massive. The crown assumes great impor-
1159 é C

34. MAIN VEGETATIONS OF THE GLOBE

tance. Trunk and branches are stout, sometimes knotted
and gnarled, with a thick, fissured, scaly bark, and the
branching is abundant and starts at no great height.
In most cases the crowns are round and large.

In this forest there are three tiers, or layers: the
canopy, which is very much interrupted, the undergrowth,
and the ground carpet. The leaves in some cases, as
in the teak, are larger than those of the big trees in
equatorial selvas, but they are thin and simple. The
lianas and the climbers are fewer and smaller, the
latter being mostly herbaceous. Epiphytes are found
only in the canopy. As a consequence the undergrowth
consists of thickets of woody shrubs. Often, however,
it is replaced by a tall tufty grass.

The chief feature of this monsoon vegetation is its well-
marked periodicity. In the dry season which precedes
the rain the numerous bulbs flower. At the onset of the
wet monsoon all shrubs blossom before the leaves appear.
Teak is found in flower and leaf at the same time.
Herbs follow suit in the course of the rainy season. As
in the selvas, the variety of tree species is quite remark-
able. Some forests contain from forty to fifty kinds of
trees. The teak forests, however, are more uniform.

Types which most closely resemble the rain-forest are
found in Central America and the West Indies, in Upper
Guinea, and on the northern margin of the evergreen
Central African selvas.

In India and Burma varieties described as higher
mined forests (120 feet high) and lower mixed forests
(70 feet to 80 feet high) have a longer dry and con-
sequently leafless period.

The most typical instance of the monsoon forest is
the teak forest called ‘Jati-Forest’ in Java, where
the alternations of the dry bare stage and the rainy

MONSOON FORESTS 35

luxuriant stage, an adjustment to periodical droughts, are
beautifully exemplified.
Lighter and lower than the teak forest are the so-called
‘low forest’ and the Eng-forests, which grow in. Burma
‘on poor soil.

Se ol 4.
Ket

S

Fic. 10. Monsoon Forest. Teak in Java.

The common feature of these otherwise somewhat
dissimilar forests is the regular falling of the leaves,
which corresponds to the recurrence of the dry season.
Though there be enough water on the whole to support
tall trees, those trees will flourish best which provide

G2

36 MAIN VEGETATIONS OF THE GLOBE

against an excessive loss of water in the dry season by
shedding their leaves. , The foliage, which exists only
through the rainy period, needs no particular protec-
tion.

Since the conditions to which plants must adapt -

themselves in these monsoon lands are more numerous
than in the regions of hot rain-forests, the plants
which succeed in doing so are fewer in number but

wee
ZF, A
/ Zi ga.
Wy ffi
st VA te
Ea HAS ¢ ie 4
FOE Aa Be YoZe
4 i a aes REO
a ND gn 8, SAL a
Wes fA i
Z, fey | wt ;

Wes i
SUITS Ne,
PSA eS ont

a

Fie. 11. Light Tropical Forest in Central Africa.

display more variety. With less moisture in the air
and in the ground a smaller quantity of vegetable
life can subsist on each acre. Hence trees are both
lower and more scattered. But having more space,
they develop stronger, if lower, crowns. Receiving
more light, they grow stout trunks and branches; and
the undergrowth is dense and woody, but with small and
hard leaves. The huge lianas of the equatorial rain-
forest do not find enough water here and are replaced by
humbler climbers.

MONSOON FORESTS 37

The monsoon forest areas are perhaps less rich in natural
resources than the hot rain-forest, but they are healthier
and more easily cultivated. Less awe-inspiring and over-
whelming, they are more favourable to human settlement. «
Teak, a strong hard timber, is the most widely known
and useful product of these forests. From early times
use has been made by man of the monsoon regions,
where a prosperous tropical agriculture has developed
in many places. Maize and millet can always be grown.
Oil palms, coffee, kapok trees, shi-butter trees, and many
others flourish. Irrigation, which is in most cases easy,
allows the cultivation of rice, sugar, banana, and
most equatorial produce. It is not unlikely that a part
of India where there is now a dense population was once
~ covered with this lighter kind of forest.

CHAPTER VI

T

TROPICAL THORNWOOD OR CAATINGA

0D |

AN African traveller describes the landscape of the
thornwood as follows :—

‘An endless, impenetrable jungle of leafless and flower-
less bushes and trees. ... Grey is the tone of the land-
scape, grey the stony ground, grey to silver-white are the
bark and twigs of the trees and bushes closing in on both
sides of the track and forming an impenetrable wall.
Countless thorns resist any intrusion except that of
one single enemy—the axe of man. Large grey lizards

i

88 MAIN VEGETATIONS OF THE GLOBE

sun themselves on the boulders along the path. Lively
grey monkeys now and then appear on the tree branches,
the only sign of life in these deadly calm surroundings.
Here and there stately crowns of umbrella-shaped
acacias rise above the grey scrub, and the grotesque dull
green limbs of the candelabra euphorbias break through
the thornbush and stretch to heaven as if in dread.’

This lower type of tropical woodland, also subject to
long droughts, is chiefly displayed in north-eastern
Brazil on the eastern tableland, in Mexico and Central
America, in the Lesser Antilles, Venezuela, and the
-Guianas. In Africa it is to be found in western and
eastern Sudan and East Africa. It exists in some parts
of the Deccan, and forms a belt in the hinterland of
northern Australia.

A high temperature prevails all the year round,
ranging from 59° to 95° F. (15° to 35° C.). The dry
season lasts from six to eight months. In the compara-
tively short wet season there is a moderate to scanty
amount of rain, much of which falls in storms. The
annual rainfall may vary from 16 to 40 inches, and shows
ereat irregularities from year to year.

The typical tropical thornwood is a close jungle, 10 to 15
feet high, bare of leaves for six to seven months; a tangle
of leafless, loose, brittle, and dead-looking thorny bushes,
‘in which acacias play an important part. The high
scrub is studded with low, flat-crowned, umbrella-
shaped trees, often bristling with thorns or prickles;
with a few evergreen trees or shrubs whose hard leathery
leaves are covered underneath with a brown prickly
wool; also with tall, thick, prickly cacti or cactus-like
euphorbias in the shape of chandeliers; with barrel-
shaped trees like huge water bags bearing a crown of
a few short, stout branches; and with rosettes or tufts

TROPICAL THORN WOOD 39

of long strap-like, prickly leaves of pineapple-plants
and others resembling the dragon-tree or the aloe.
These act like barbed wires, and increase the difficulty
of passing through the scrub. Ragged patches of

Fig. 12. Tropical Thornwood or Caatinga in Brazil.

epiphytes, resembling lichens and mosses, hang from
trees and bushes. The prickly wires of a few dry vines
are found creeping or climbing. Grass is rare, and only
occurs in scattered tufts of dead, brittle straw. Such is
the appearance of this thornwood during the greater
part of the year.

40 MAIN VEGETATIONS OF THE GLOBE

When the rain sets in there is a sudden change. The
dead-looking scrub covers itself with gorgeous flowers,
and the air is laden with perfume. In a week’s time
the buds have swollen and burst. A shimmering pale
green clothes the landscape. A few days more and
there is a'sea of fresh verdure dotted over with flowers.
Innumerable herbs spring from the soil. The dry straw-
like tufts open, and the face of Nature is entirely
rejuvenated.

The types of thornwoods are varied. Instead of
a close jungle there may be (1) a thinner, more open
brush ; (2) a sort of park-like formation, made of more
or less extensive thickets, with bare open spaces; (3)
a very scattered formation where some trees stand alone
or are fringed round with a hedge of thorns, and a few
thickets dotted over the bare, or sometimes sparsely
grassy, ground; (4) a close, treeless brush, studded over
with evergreen shrubs; (5) a still more barren form of
rocky, broken ground, with patches of bush and a
prevalence of cacti and similar plants, tall ones like
chandeliers or organ pipes, or low globular ones like
prickly melons. In Brazil this kind of scenery is known
as the sertao.

To explain this vegetation we must remember the
physical conditions. They are: an active, continuous
evaporation; a long dry season and a short rainy one;
strong light, and no winter. The soil is generally poor or
permeable, consisting of sand, granite gravel, or fissured
limestone, which absorbs water readily. There are very
few permanent streams of any size at the bottom of
the canyons.

The prevailing drought, which is broken only by a
short rainy season, necessarily places severe limits on
the number of plants which are able to maintain life

-

TROPICAL THORNWOOD

_ = << =
“ye 2 Qe
eo Se :
BE FFARR
>> hg a Stes
SON, — FAB S s:,
Soe SED oe 4 SS
a", 22 ee = oe ;
ONS VAAZa\ Gee eee
>) Tf; MeTt> AY \
yh Yi; 4; Gy 5 aw Mas
Yo _ \
+: See oN \ re

WANDA

MEAN iN

Si

iN)

Fie. 18. Tropical Thornwood in Brazil.
(After Martius.)

barrel trees,

Cacti, prickly pears,

42 MAIN VEGETATIONS OF THE GLOBE

under such conditions. Plants are compelled to lead
a dormant life most of the time and then make sudden
use of what scanty rains they get. During the dry season
the sun scorches the leaves in a short time. Leaves are
the organs through which moisture is pumped out of the
plant. Those plants which can dispense with leaves
altogether during the dry season are therefore more
capable of surviving; next in order of adjustment are
shrubs or herbs whose thick leaves are encased in a
leathery impervious sheath, often coated over with
wax, resin, or gum, which protects them against the
excessive light and prevents undue loss of water.
Hence in many of these plants gum, wax, oil, resin, &e.,
are exuded. In some plants which have no leaves to
speak of, the work of the leaves is carried out by their
stems and branches, where green matter is found more
or less deeply seated under the skin. This implies a
continuous and slower growth. Such plants store water
in their spongy, fleshy tissues, e.g. cacti, candle-trees,
euphorbias, pineapple plants, and aloes. The shape of
some of these strange plants suggests huge water-barrels.
But even in the wet season the rain is irregular and
scanty. Water is quickly evaporated, and the leaves have
to be protected against excessive perspiration. This is
effected in many cases by movements of the leaves, which
either droop or so turn their edges as to present the least
surface to light and heat, and follow the sun in its

course. Leaves divided into leaflets respond most readily, —

because these are lighter and are easily spread or con-
tracted, as in the mimosas and acacias with which we
are familiar.

The closeness of the plants is regulated by the
nature of the soil and the amount of water in it.
Plants drain the soil, and too many of them will dry

as

TROPICAL THORNWOOD 43

it up, so that only the hardiest survive. Where there-
fore the ground is rocky and offers but few places
where roots can be inserted, or again where the soil is too
pervious and dry, plants naturally stand wider apart.
Grasses with shallow roots have little chance of surviving
in such conditions. The plants of the caatinga have
strong roots, branching and penetrating far down into
the ground. It is difficult to extirpate them and _ so
clean the soil for agricultural purposes. The function of
the prickles, thorns, and similar outgrowths is not
precisely known.

The scarcity of water causes the whole vegetation to be
reduced in height. Growth is necessarily slow. More-
over, tallness means more exposure to wind and greater
evaporation. Hence, while trees are the rule in the
monsoon forest, they are the exception in the caatinga.
They are lower and less exposed, and their needs are
very moderate; there is more space available for
shrubs.

The rhythm of life in thornwoods is even more strongly
marked than in the monsoon forests. Indeed the
caatinga may be described as a much impoverished
monsoon forest. As mentioned above, in the dry
season the plants look lifeless, but as most of them
have water and food reserves, they burst into bloom at
the first onset of the rains. This is probably a necessity
of their existence. If it were otherwise, and plants did
not flower until later on, they might not have enough
water left for the completion of the seeding process, and so
would disappear entirely. After flowering comes leafing,
ripening of the fruit, and building of the leaf-bud. This
is followed by leaf-shedding and the spreading of seeds.
Then comes the period of sleep.

The thornwood or caatinga areas are generally

44 MAIN VEGETATIONS OF THE GLOBE

barren and useless. They are generally avoided by
man. In some parts of Brazil and East Africa they
have been cut down, burnt, and replaced by coffee plan-
tations. Where irrigation is possible, maize and cotton
can be cultivated. In Mexico, parts of the caatinga
yield fibre-producing agaves.

CHAPTER VII

THE SAVANA

- WE have traced a gradual change from the rain-forest
to the deciduous bush or caatinga, and now we have to
examine another and poorer form of vegetation in the
grass formations of the Savana (or Savanna), Campo, or
Llano.

The savana covers a vast area in South America,
north and south of the Amazon forests, also in Africa, in
the Sudan, and the East African Highlands. It is found
round the Kalahari as far south as Natal. In Australia
it stretches in a circular belt round the central desert. .

The climate is hot, with a moderate range of tempera-
ture. The extremes vary from 32° F.(0° C.) in the cold-
est nights on the subtropical outskirts to 97°-104° F.
(36°-40° C.) in the warmest days. The average yearly
rainfall is from 40° to 70 inches spread over 120 to
190 days; and there is a prolonged period of drought
lasting from four to seven months. The moisture in
the air is greater than in caatinga. Considerable irregu-

-

THE SAVANA 45

larities in the amount of rain oecur from year to year,
The wind is strong at times.

The savana presents mostly a park-like appearance ;
a landseape of tall grass and scattered trees. In hollows
the trees frequently form woods; on ridges they are sparse
or wholly absent. But, though primarily a grass land,

Fie. 14. Orchard Savana in West Africa. _

the savana does not resemble our meadows. The grass
is commonly from 6 to 10 feet high, with a dry appear-
ance. It makes a dusty yellow straw and is clustered
in dense, stiff, tall tufts, crowned with waving silvery
spikes similar to those of the pampa grass, and showing
in the intervals patches of bare, parched soil, coloured
light-red, orange, or dull yellow. The savana becomes in
places a perfect tangle of giant elephant-grass, 12 to 15

46 MAIN VEGETATIONS OF THE GLOBE

feet high and quite impenetrable. Other places have
a thinner sprinkling of lower and softer species.

Interspersed among these grasses are dry-looking
shrubs and small trees. Some of them are low bushes
with hard, leathery, evergreen leaves; others are bare
and prickly, like thorny acacias or gooseberry bushes in
winter ; others still have smooth, swollen, fleshy stems
and twigs bearing bunches of small leaves. The grass- .
land may also be crowded with leathery, prickly, stiff
herbs resembling pineapple-plants. There are many
varieties of trees.

Among the several aspects of the savana may be
distinguished : (1) rolling downs, the troughs of which
are occupied by clear, dry-looking, loose woods of
small trees, from a few yards to a mile or more in
extent. These have been called oases by some
travellers. Along the rivers or streams are fringes of
more luxuriant forests. (2) Flat, mgnotonous tracts of
tall grass studded with isolated palms or with extensive
palm groves. (8) Grassy bush-lands dotted over with
mushroom- or umbrella-shaped trees, with flat crowns.
(4) Impassable tangles, 12 to 20 feet high, with low trees
giving them the appearance of orchards of crab-apple
trees overgrown with giant grasses. The trees are simi-
lar in aspect to our stunted, gnarled, and knotty coppice
oak, with thick, corky, fissured bark. (5) Open lands,
covered with grass 3 feet high, the home of the giant of
the savana, the baobab tree or monkey-bread, and other
similar bombax and ceiba trees. The monkey-bread
tree recalls an old giant oak, less knotty and twisted,
but more fleshy and swollen. The crown is not dense,
but spreading and patchy; the colossal trunk is not
high, but stout, some 12 to 30 feet in diameter, with a
smoother bark than that of the oak tree. The baobab

THE SAVANA 47

requires free space all round ; it cannot live in a crowded
place. There are also (6) treeless tracts of comparatively
short grass, with occasional candelabra euphorbias. The

Fie. 15. Llano in Venezuela. (After Sachs.)

savana may pass gradually into the tall bush called the
caatinga.

The climate of the savana differs from that of the mon-
soon tracts in having a longer period of drought and a

48 MAIN VEGETATIONS OF THE GLOBE

greater irregularity of rainfall,and from that of the thorn-
woodland in having more frequent rains. The soil is less
permeable and more moist than in the porous and dry
caatinga lands, where there is no grass. The climatic
conditions cannot favour the development of such heavy
masses of vegetation as the deciduous forests of the mon-
soon type. Humbler forms are alone tolerated here.
Tree-growth is restricted to places where the ground
water les at no great distance from the surface.
Only trees with roots long enough to tap this ground
water will thrive in the savana. Most of the savana
woods or oases are found in the hollows which are
nearest the ground-water level or where surface water
tends to accumulate. The remarkable capacity of some
trees for storing water in large quantities renders them
more independent as regards the soil; such are the
baobab, bombax, ceiba, and others. But palm-groves
are confined to places with sufficient ground water.
Indeed the presence of certain trees like the ceiba,
mitragyne, borassus- and dum-palms, is a sure indi-
cation of water at no great depth below the surface.

Most savana trees except palms are bare during the
dry season. A few others are evergreen, but their leaves
are sheathed in a leathery impervious skin, and their
bark is thick and corky. The crowns of these trees are
low and compact. A noteworthy feature is the umbrella-
shape of the majority of these, due to the blighting of
all outstanding buds by the wind. The form thus given
to the crown of the tree enables it to act as a sort of
wedge upon the strong winds that blow frequently over
the grass-lands,

That the characteristic growth-form of the savana,
namely grass, is able to withstand prolonged droughts
may be partly accounted for by its peculiar structure.

THE SAVANA 49

Savana grass grows in compact tufts with strong roots.
The straw of previous years accumulates and forms
a sponge, well covered and protected against evaporation,
and this sponge is continued below in the bulky and
close felt-work of the roots. These masses store a cer-
tain amount of water and help the plant to live a dormant
life through the dry season. The isolated tufts leave
the bare soil visible between them.

In many savanas the grass is mixed with a number of
hardy perennials and small shrubs, evergreen or deciduous

aw ae en > 4 =e
cn Wier t
-. = SIN AD < =
NN ne
yi { Wa Pex] = — ig es ae oe aS =F
Sa amipies \ , ‘eC \ N \ tat D —

“A 4 2 Ts E

Fie. 16. Umbrella Trees in Savana. East Sudan.

and thorny. Tubers and bulbs are also important ele-
ments of the vegetation. These water-storing devices
allow a vast number of plants to lead a slow life under-
ground until the recurrence of the rainy season, when
they burst forth into leaves and flowers. They are
common to all dry countries.

There is no doubt that the savanas have been artifi-
cially extended and that many kinds of plants in them
have disappeared, thanks to the custom of yearly grass-
burning. In Africa, for instance, the grass-land has en-
croached upon the monsoon forest, and even upon the

high rain-forest itself. In the natural savana, tree-growth
1159 D

50 MAIN VEGETATIONS OF THE GLOBE

has been either prevented or greatly reduced by such
fires, which are started with extreme facility.

The park landséapes of the savana all over the world
are eminently suited to animal life. Innumerable herds
of antelopes, buffaloes, zebras, and giraffes, together with
elephants, rhinoceroses, and many others, feed on the grass
and trees, and are themselves the prey of carnivorous
animals.

With a sufficient rainfall and a fair soil, great natural
resources, an undulating surface and easy communica-
tions, the savanas offered man the possibilities of
hunting, cattle-breeding, agriculture, and trading. By
means of irrigation he can grow there all the products
of the tropical and equatorial belts. Peoples engaged in
these various pursuits have occupied the savanas together
and fought against each other. Some of them have at
one time developed a high state of civilization. Thus, in
the grass-belt of the Sudan, south of the Sahara, the
prosperity of the settled agricultural communities has
been more than once destroyed by invasions from the
nomadic pastoral tribes. At present the savana lands
offer to man one of the most promising fields for activity.

CHAPTER VIII
TROPICAL SCRUBS OR SEMI-DESERTS

The Acacia Semi-Deserts are usually included among
and described as deserts. They form a transition between
deserts proper and the savanas, or between deserts and
thornbrush-woods, and possess some of the characteristics
of both. Acacia scrubs are often found on stony moun-

TROPICAL SCRUBS 51

tain sides, in rocky, rolling country, and on gravelly,
pebbly, or sandy grounds exposed to the full glare of the
tropical sun. They occur in some parts of Texas, Arizona,
New Mexico, and Lower California; in the northern
Sudan bordering on the Sahara, in Somaliland, in Arabia
and other parts of the northern shore of the Indian
Ocean, and in Australia. The climate and other charac-

4
, 2
a

Wf fe s-

Fie. 17. Tropical Semi-Desert in North Mexico.

teristics can best be described as intermediate between
the absolute desert of the tropical Sahara and the thorn-
brush-wood. Occasional rainfalls are the only indications
of a rainy season. The temperature at all seasons of
the year is very high. The abrupt and great variations
of heat and cold are sufficient to split the rocks.

The acacia scrub is the humblest form of savana or
of thornbrush. The grass is reduced both in size and

D2

52 MAIN VEGETATIONS OF THE GLOBE

quantity, and only meagre, thirsty, dwarfed, stiff bunches
occur, scattered and isolated, or in ragged patches.
The umbrella-acagia has dwindled to mere shrub size,
and stands bare for the greater part of the year. An
occasional undergrowth of a heathery or sage-like and
withered appearance, and a few fleshy, thick, or leathery

Fic. 18. Mexican Semi-Desert.

herbs may be seen now and then. The proportion of
tubers and other underground plant reservoirs and food
stores, resembling huge turnips or carrots, is much
greater here than in either the savana or the thorn-
brush. The bushes and low trees are set widely apart
or else loosely grouped, but they seldom obstruct the
view to the distant horizon. Looked at from above, the

* TROPICAL SCRUBS 53

eround appears as if it had been irregularly sprinkled
over with a stiff and dwarf vegetation. In Arizona
the abundance of thorns and prickles on fleshy, leafless
cacti is very striking. In some parts of Africa the
thorny and bushy acacias and euphorbias predominate,
along with a sprinkling of stiff, wiry grass.

\ NOAZINE i)
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Fie. 19. Mexican Semi-Desert.

All tropical deserts are bordered by belts of arid acacia
wastes, and these differ but little in aspect. Among the
varieties of these barren lands may be mentioned, in East
Africa, the semi-desert with succulents and occasional
acacia bushes; in Mexico and Arizona, the cactus and
creosote-bush wastes; in Texas, the yucca, opuntia, and

-

54 MAIN VEGETATIONS OF THE GLOBE

agave sotol ones; in Australia, parts of the mulga-scrub ;
in Sokotra, the adenium and euphorbia barrens; and in
South Africa some parts of the Kalahari and Karroo.
Such countries are unfit for human settlement. Only
swift and hardy animals, such as the camel and the
ostrich, can live inthem. For all practical purposes they
are hardly better than actual deserts.

Sub-tropical lands which are warm and dry throughout
the greater part of the year have a large variety of scrubs
and woodlands, intermediate in appearance and mode of
life between the mediterranean scrubs and the tropical
thornwoods. Such is the espinal, which covers a broad
strip of land along the foot of the Andes in western
Argentina and reappears in Chile. It ranges from low
woods to bare stony flats dotted with spreading bushes not
unlike cushions of long thorns and with candelabra-cacti.
The most forbidding form of the espinal is the chataral,
so called from its chief component, the acacia-like
chaiar bush, remarkable for its huge thorns and tiny,
divided leaves.

CHAPTER IX
DESERTS

ONE easily imagines vast, bare expanses of flat or
rolling plains, sunbaked or windswept, sparingly dotted
with low, dry, strange-looking plants, or destitute of
any vegetation. But it is difficult to realize the beauty
of the weird scenery of the desert with its merciless,
overwhelming light, and the awe-inspiring silence of
its boundless wastes. Vast areas of yellow sand-dunes,
broken and rugged rocky floors, ruined scarps of naked
hills sharply silhouetted against a deep-blue sky, are
a few of the manifold aspects of the hot deserts.

Broadly speaking, the equatorial belt is hemmed in
between two belts of tropical and sub-tropical deserts.
We can follow the northern belt from California, Arizona,
and Mexico across the Sahara and Arabia to the deserts
of Iran, Turan, and the Shamo or great sea of sand of
Mongolia. The broken links of the southern belt are
found in the Atacama, Kalahari, and Australian deserts.

Deserts are caused by an absence of rain; but the
cause of rainlessness may vary in the different regions.
A single shower in many years; an excessively dry
and clear atmosphere ; cloudless skies; considerable and
sudden changes of temperature, are the normal conditions
of hot deserts. But the coastal deserts of the austral
regions—in Peru and South-West Africa—are occasion-
ally wrapped in mists.

_ The ground may be rocky, stony and gravelly, sandy

56 MAIN VEGETATIONS OF THE GLOBE

or clayey. When rocky or clayey, it is covered with
cracks and fissures produced by the abrupt alternations
of temperature.

Several varieties of desert climates have been dis-
tinguished. There are (1) the coastal deserts of Peru
and Chile and of South Africa, which have alternations

Fia. 20. The Reg Desert. Sinai Peninsula.

of burning days and cool nights, when mists and dew
may spread over the coasts; (2) the typical tropical
deserts, of which the Sahara, Arabia, and central
Australia are the best examples; and (3) the deserts of
high latitudes with extreme winter cold, found in Central
Asia. The nature of the ground introduces further
varieties of desert. For instance, we find in the western
Sahara the Hrg, consisting of sand-dunes dotted over

DESERTS 57

-

with heath-like bushes and grass tussocks ; the Reg, or
pebbly-clayey desert, with half-buried cushions of prickly
‘desert cauliflowers’; the Hamada, or stony, rocky
desert, the most desolate of all, consisting of a floor of

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Fic. 21. Desert in Arizona.

split and broken rocks and boulders, with an occasional
plant-tuft anchored in the fissures. Then there are
saline depressions, which are either entirely plantless or
tolerate a few loose colonies of dwarf salt-bushes.
Passing over different types of the Egyptian and

58 MAIN VEGETATIONS OF THE GLOBE

Arabian deserts and the wormwood wastes of the
Caspian, we find in the Asiatic deserts all transitions
from the absolutely bare, moving sand-dunes and the
low, scattered brushes of dead, wiry tufts of grass, to
dense sandy heaths of tamarisk and small, leafless trees
like the saxaoul. The American deserts are known for

Fie. 22. Desert in South-west Africa. Welwitschia.

the forbidding aspect of their giant cacti, their strange
varnished creosote bushes, and other curious forms.
Desert plants have to depend on occasional showers at
long intervals, or on the subterranean water coming
from surrounding areas and from the residue of the
scanty rain-water which has sunk into the ground below
reach of evaporation. If the water-level is so low as to
be out of reach, the plant becomes dormant, and lives
(often for years) in the shape of dust-like seeds. Those
seeds which have survived the long sleep will, on the
first showers of any consequence, burst into an intensely
active life of very short duration. They sprout, grow,

DESERTS 59

flower, fruit, and seed, all within two or three weeks.
The desert will then be covered for a few days with
a thin, bright carpet of flowers, which will disappear
almost as quickly as it came. Some plants will live or
sleep through a similar life, buried in the ground, by
means of water-storing bulbs or tubers, resembling huge
potatoes protected by a leathery, impervious, rough sort

Fic. 28. An Oasis in the Sahara.

of coat. They send out their temporary shoots under
the stimulus of rain. Others again, more like dead and
buried stumps, develop with extraordinary slowness
trailing, strap-shaped leaves that seem to be without
beginning and without end, dying at one extremity and
growing at the other. In other instances the plants
possess such impervious coats that they hardly lose
any water, and their roots are quick to take advantage
of the slightest moisture that may come within reach.
These plants grow above the ground in the shape of
cushions, pillars, or even chandeliers, like the cerei and
other cacti of the American deserts.

60 MAIN VEGETATIONS OF THE GLOBE

In less arid conditions, where water may be had within
thirty to fifty feet of the surface, some plants seem to
send their rope-like roots down to those depths. In
fact, so enormous may be the length of some roots that
in the excavation of the Suez Canal roots were found in
its bed belonging to trees growing on its banks. Such
plants can then develop into bushes or low trees. Of
course, they are clad all over with a leathery, impervious
armour against desiccation. The sheath in most cases
is reinforced by a coat of wax, resin, or varnish, exuded
by the plants. The leaves are tiny, inconspicuous, hard
scales like those of our heaths and tamarisks. The
whole plant presents the appearance of a dense, prickly,
besom-like bush, or of a low, gnarled, brittle, thorny tree
(acacias). |

In places where the ground water rises near the
surface, e.g. in depressions, where a well can give a
permanent supply of water, or along the banks of a river,
such as the Nile, the Amu-Darya, or the Euphrates, the
vegetation shows at once the natural fertility of the
desert soil. Palms, especially date-palms, now find con-
genial conditions, and, under their protection, are
cultivated other food plants enough to support a small
community. Gardens of this sort may be found dotted
over the deserts, and often mark the course of trading
routes. It is in the oases that the difference between
the tropical and extra-tropical deserts is best observed.
Those of the Sahara and Arabia consist of groves of
date-palms, under which all tropical and sub-tropical
produce are grown—rice, cotton, olive, vine, sugar-
cane, millet, coffee, tobacco, oranges, and lemons. The
aspect changes but little from summer to winter.
The oases of the Gobi; on the other hand, are characterized
by rows of tall poplars and willows. Here we find

es

s DESERTS 61

a temperate vegetation with temperate products — wheat
and barley, peach and plum trees. Egypt, Mesopotamia,
the Amu- and Syr-Daryas, are so many oases due to
large rivers.

In some deserts surrounded by lofty ranges the
snow-fed torrents from the mountains lose themselves in
the sand at no great distance from the foot of the slopes.
The fans, deltas, or marshes, thus created form round the
deserts a broken belt of fertile islands, along which run
the trade routes. Deserts usually have wide, semi-arid
margins, characterized by poor acacia-scrubs on the
equatorial side, and by poor steppes on the polar side.

Except for the oases, such barren lands cannot be
places of permanent habitation, but are tracts to be
avoided, or crossed only when it cannot be helped.
Desert animals must be swift and need little to eat and
drink. Rapidity of motion is a vital condition of desert
life, whether for animals or men. Only nomads can live
there. Their routes are marked by the lines of wells
and oases; straying far from these lines may mean
death.

Deserts were not always so extensive as they now are,
or else they have gradually changed their positions. The
areas of many oases have also varied. The sands
now yield to the patient researches of explorers the
secrets of dead worlds, all trace of which seemed to
have been wiped out for ever. It is clear that flourish-
ing civilizations once developed where now nothing
exists but barren wastes, and that the extension or
shifting of deserts, by pushing back whole nations and
setting them in motion, has determined a succession
of wars and migrations which has largely shaped the
history of European countries.

62

CHAPTER X

SUB-TROPICAL OR WARM TEMPERATE
RAIN-FOREST

A FIRST impression of the warm, temperate, evergreen
rain-forest may be gained by imagining an intermediate
stage between the equatorial rain-forest and the most
luxuriant forests that can be seen in our northern
climates. The conditions favourable to their develop-
ment are a warm temperate climate, with a moderate to
abundant rainfall all the year round (60 to 120 inches).
There may, however, be one or two relatively dry seasons.
From 25 to 50 per cent. of the days of the year are rainy.
The temperature remains mild throughout, with yearly
averages from 50° to 70° F. Occasional frosts may occur ;
they are quite short and slight. With lower tempera-
tures, less water vapour suffices to give a fairly high
relative humidity, especially in winter. Prolonged dry
winds, whether hot or cold, are quite exceptional.

As we go farther from the equator the importance of
the nature of the soil increases. In hot moist regions
the luxuriant vegetation would in course of time enrich
even originally poor soils and gradually fit them for
heavier crops of foliage. The soil of the sub-tropical
rain-forest is fairly deep, fresh, and rich.

The combinations of circumstances required for the
growth of such forests are found both in lowlands and in
highlands. The map shows that they occur in low-
lands in the southern states of North America from Cape
Hatteras to eastern Texas, in southern Brazil and in the

WARM TEMPERATE RAIN-FOREST 63

higher valleys of the Parané, Paraguay and Uruguay, in
central and southern China and north-east India and
Burma, alone the eastern coast of Australia, in Tasmania

'

5

;

f

E xe
}*
f
.

Fic. 24. Forest near the Iguassu Falls, Misiones, Argentina.
Large-leayed Epiphyte high up in centre. (Photo: A. W. W.
Brown. )

and New Zealand, but in no part of Africa except the
southernmost extremity. In highlands similar con-
ditions are found on the slopes of equatorial mountain-
ranges above 3,000 feet, in eastern Mexico and Central
America,on the eastern slopes of the Andes from Columbia

64 MAIN VEGETATIONS OF THE GLOBE

to Tucuman, in Chile, in the higher mountains of equa-
torial Africa, in Assam, Burma, Indo-China and China,
Formosa, Malayia, and southern Japan.

We may best describe this vegetation by comparing it
with the typical equatorial rain-forest. In the temperate
moist forests the trees are generally lower (except the
eucalyptus), more spread out in the crown, stouter and
more complicated in their structure, and branch lower
down; they alsostand farther apart. Many of them are
evergreen. There is, however, asharper distinction be-
tween the summer and winter aspects than in equatorial
regions, and even an admixture of deciduous trees. The.
leaves are smaller, simple, oval or oblong, but somewhat
thick and leathery, with a glazed upper surface and
a fresher green than between the tropics; or again, finely
divided like those of some acacias. Tree-ferns and
small palms, bamboos, and countless shrubs and lower
trees form a second tier. The enormous extent of
delicate foliage of the plants indicates great atmospheric
moisture. The huge leaves that were so characteristic
between the tropics are not found here so abundantly,
but there may be a better show of bright blossoms, e.g. in
China and Japan. In New Zealand, on the other hand,
the flowers are mostly inconspicuous. The spaces between
the tall trees are packed with a dense undergrowth.
Lianas are comparatively rare. The climbers are mostly
herbaceous and in enormous profusion, ‘covering the
soil with a natural netting, coiling round every stem,
running up every limb and gliding from head to head,
entwining the topmost branches of a dozen trees in
Gordian knots.’ Epiphytes are abundant, though small
in size and leaf, Mosses, liverworts, lichens, ferns,
grasses, and orchids, cover all and pad the trunks with
a soft cushion a few inches thick. Many trees bear a

WARM TEMPERATE RAIN-FOREST 65

strong resemblance to our northern species—camphor
trees, laurels, sassafras, magnolias, camellias, beeches, and
oaks. Conifers are also a feature of the landscape.
These forests are perhaps more impassable than those
of the dark equatorial type on account of the tangle of

Fig. 25. Aspect of Sub-tropical Forest. Evergreen oak and
festoons of Tillandsia. Florida.

shrubs and climbers above a litter of decaying vegetation.
They differ from our own forests by the immensely
larger size and variety of trees, the gorgeous flowers,
the greater luxuriance, beauty, and variety of the foliage,
and the much greater wealth of epiphytes and climbers.

In both the equatorial and the warm temperate rain-
1159 E :

66 MAIN VEGETATIONS OF THE GLOBE

forests, there is a regular and sufficient rainfall throughout
the year and an absence of extreme cold and drought.
But the yearly average amount of heat is smaller in the
temperate regions. Hence growth is not so luxuriant.
There is a diminution in the intensity of life. Owing to
the uniformity of climatic conditions throughout the
year, and to the absence of well-marked seasons and
extremes of cold and drought, it is not especially neces-
sary or advantageous for plants to shed their leaves at the
same time, to flower or fruit at special periods.. In other
words, the lack of a strong seasonal climatic rhythm
results in the lack of a definite seasonal rhythm in plant
life. Hence, at all times of the year plants may be found
in their green and their bare stages, in flower and in fruit.
The temperate rain-forest includes many varieties rang-
ing from sub-tropical to mild temperate types. From
the hill forests of the equatorial belt to the coast forests
of Carolina, or to those of New Zealand, Japan, or Chile,
the main characteristics are the same, but there are im-
portant variations in the intensity of seasonal changes.

The limitation in the intensity of life and rapidity of
growth is shown first of all in the reduction of the
number and size of the trees. Broadly speaking, every-
thing is reduced in scale: the leaves are smaller and less
active and mobile. Species are fewer, and one begins to
experience something of the feeling of sameness which
is given by northern forests. The poorest types of
temperate rain-forests may even consist of a compara-
tively limited number of species uniformly repeated over
large areas. Such trees are then termed soczal.

The temperate rain-forests contain many plants of
great economic and commercial importance. They yield
valuable timber, especially in New Zealand and Chile.
Among shrubs, tea is the most important. Numberless

67

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68 MAIN VEGETATIONS OF THE GLOBE

ornamental plants have been obtained fromthem. Kauri
gum, camphor, chinchona, some kinds of rubber and
gutta-percha, coca, yerba maté (or Paraguay tea) are other

Fic. 27. Roof of Exhausted Forest or Capoeira in South Brazil.
Dense tangle of the undergrowth.

valuable products. By clearing these forests, man has
found an extremely rich field for sub-tropical agriculture,
cultivating rice, tea, cotton, mulberries, tobacco, &e.

WARM TEMPERATE RAIN-FOREST 69

The warm temperate rain-forests are to a large extent
free from the drawbacks of the hot rain-forests. They
have been supremely favourable to human settlement, and
have furnished a home for some of the most prosperous

~ “4A

Fig. 28. Undergrowth of Sub-tropical Rain-Forest.

and civilized agricultural nations of the world. China,
Japan, and some parts of India are the best instances
in the past; New Zealand, New South Wales, Chile, and
the southern states of North America are instances of
more modern development.

Reoad LEAVED «EVERGREEN
CHAPTER XI

MEDITERRANEAN WOODLANDS

UnpDER this name may be included the vegetation
typically represented in the Mediterranean region by
dry, evergreen, hard-leaf forests, woods, and shrubs.
The traveller who comes from our northern moist
forests receives the impression that the Mediterranean
is a poor, arid country, with scattered open forests,
low woods, and dense, thorny scrubs. He misses the
fresh green foliage and the rich, grassy swards. The
strong colour contrasts are apt to offend his eye. If,
however, his visit be in early spring he will find the land
robed in fresh verdure and bright flowers. For the
native, the exhilarating beauty of spring, the serene and
balmy autumn, and the mild winter redeem the dry and
scorching summer. ‘

The ETS and vegetation of the shores of the Medi-
terranean are represented, north of the desert belt, in
California. South of the austral arid belt they find
equivalents in the south-west of South Africa, in south-
western Australia, and in the valley of central Chile.

The climate may be generally described as warm
temperate, with a mild, rainy winter and a hot, dry
summer. The average temperature of the year differs
little from that of the temperate rain-forest lands, 50° to
70° F., but it has a much greater range, both daily and
seasonal. Snow and ice are not infrequent in mid-

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72 MAIN VEGETATIONS OF THE GLOBE

winter. The rainfall is smaller than that of the temperate
rain-forests; it is irregular, and varies from 20 to 40 inches.
The bulk of the rain falls during the short winter in
heavy showers, and the dry summer is broken only by
occasional storms. The quantity of moisture in the
atmosphere also fluctuates greatly.

The nature of the mediterranean lands is varied.
Broad, sandy flats, rich alluvial plains, marshes, downs,
rocky scarps, hill-lands and mountainsafford many dissim1-
lar conditions for vegetation; so there is much diversity in
the plant landscapes. The most important of these are:
(1) seattered and open woodlands of evergreen oaks—
stout trees with low, rounded, heavy and sombre crowns.
Among such woods are found a large variety of ever-
green, hard- and small-leaf, dull bluish shrubs and trees
of which laurustinus, oleander, myrtle, and rosemary may
be taken as examples, in addition to laurel, olive, carob,
orange, terebinth, and fig-trees. (2) Higher and more
regular but similar forests are formed of the valuable cork-
oak. (3) Groves of olive and fig-trees, although mostly
cultivated, occur also in the wild state, with a very
mixed hard-leaf vegetation. (4) Varied forests of conifers
—pines, firs, cedars, cypresses, and junipers— occur. Some
have bare floors or heath or dry, stiff grass brushes ; some
have dense undergrowths of evergreen, hard- and small-
leaf, often prickly and sticky shrubs. They are
especially common in hill- and inountain-lands, and are
most abundant in the Pacific mountains of North America.
(5) Areas with sufficient moisture in the ground are often
covered with light forests of deciduous oaks and other
trees, resembling, but not identical with, our northern
oak forests. (6) Where the forest has been destroyed
and the land left uncultivated a dense scrub springs up,

6 to 10 feet high, of mixed deciduous and evergreen —

od te

MEDITERRANEAN WOODLANDS 73

bushes, called maquis or macchia, of which there are
several types. It is made up of small trees, shrubs and
undershrubs, creepers and vines, similar to those of the
undergrowth of the destroyed woods. (7) Limestone
hills, scarps, and tables, with scattered thickets of
stunted, bushy, prickly evergreens, showing the naked
rock between them, are called in France ‘ garigues

SOT Hing “ph Apel wh Aste ye ve pe “Uh oD
ee | “typo 4 yO S

Fic. 30. Rock Pine in Spain.

(8) Extensive wastes, more especially on the southern
side of the Mediterranean, are covered by dwarf palm
bushes, which in'spreading ‘seem to crush out all other
vegetation. The rosettes of fan-shaped leaves, only a
few feet high, appear to rise out of the ground itself.’

It will help to emphasize the contrast between the
mediterranean plant life and that of the equally warm
temperate rain-forest, if we term the former a dry
evergreen type, and the latter a wet evergreen type, of

74 MAIN VEGETATIONS OF THE GLOBE

the warm-temperate vegetation. The wet evergreen
form is due to active growth throughout the year, which
is made possible by an abundance of warmth and water at
all seasons. The dry evergreen form is due to a con-
tinuous but slow growth throughout the year. This
may seem in contradiction to the marked seasonal
rhythm of the climate. In the Mediterranean, however,
no season is sufficiently unfavourable to render plant
life entirely dormant. Winter is mild; summer is dry
but not absolutely rainless. On the other hand, except
during the two short spells of early spring and late
autumn, no season is sufficiently favourable to encourage
intensely active growth. When the rainfall is satis-
factory, the temperature is rather low; but when
warmth is sufficient, water is scarce. The hard, ever-
green leaf is adapted to such a life. Its compact
structure, though not suited for intense activity, permits
it to survive short spells of extreme cold or drought. To
prevent excessive loss of water through the leaves during
the dry season, the total surface of foliage is reduced by
the leaves being fewer and smaller. The proportion of
wood to leaf seems great. For this and other reasons,
the whole appearance of the mediterranean vegetation is
compact and woody. The wood is protected by a thick,
rough bark of which cork is the type. There are many
other protective devices against excessive perspiration.

Conifers, most of which are evergreen and provided
with needles or scaly leaves, are well represented. in
mediterranean floras. They are the chief trees of the
regions of western North America with a mediterranean
climate. The similar regions of South Atfrica, south-
western Australia, New Zealand, and Chile have small-
leaf trees, but only few conifers.

The same steady, thrifty life characterizes the shrubs,

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76 MAIN VEGETATIONS OF THE GLOBE

undershrubs, and herbs of the lower layers of the
vegetation. In all of them protective, woody, and fibrous
tissues, and small and hard persistent leaves are
developed. Most herbs have the form of shrub-like
perennials,

As in all lands where water is scarce, a wealth
of underground bulbs and tubers is one of the
features of the Mediterranean; indeed, it is one of its
glories. Asphodels, irises, orchids, anemones, tulips,
arums, muscaris, narcissi, onions, gladioli, and leucotums
are some of the most familiar. Other forms store water
above ground, such as aloes, agaves, and even cacti, which”
though not indigenous, do remarkably well. Palms,
which flourish best in warmer lands, reach their pole-
ward limit and smallest size here.

In such regions the quantity and distribution of
ground water becomes of paramount importance. Con-
sequently the nature of the soil and subsoil deter-
mines the appearance of the vegetation, as well as
its economic value. Irrigation is often necessary.
Where it is practised the agricultural resources are very
varied owing to the great differences between the
seasons. The cultivation of northern cereals is possible
in the mild season. On the other hand, the cultivation of
sub-tropical and even tropical produce, e.g. rice, cotton,
maize, and hard varieties of wheat, is possible in the
hot summer. Fruits in amazing variety flourish in ad-
dition to those with which we are familiar in northern
countries. Olive, orange, fig, almond, peach, plum, grape,
and pomegranate are a few which may be mentioned.
Karly flowers, fruits,and vegetables are produced for the
northern markets. Indeed, the mediterranean region
has an extraordinary number of food-, industrial, and
ornamental plants. Among these are the carob or locust-

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78 MAIN VEGETATIONS OF THE GLOBE

bean, grape-vine, tobacco, cork-oak, water-melon, roses,
and other aromatic plants, bulbs, ornamental shrubs and
perennials, fodder, winter-grazing, and even timber.
From earliest times the Mediterranean has been the
mother of great civilizations. Whilst the heart of Asia
was acting as a pole of repulsion, the Mediterranean
acted as a pole of attraction. Through the conflicts of
races and civilizations its shores were repeatedly laid
waste, and its natural wealth temporarily somewhat
exhausted. But no other vegetation has exercised a
greater influence in the history of mankind.

CHAPTER XII

OTHER EVERGREEN FORESTS

THERE are other important types of evergreen forests,
the conditions of which are intermediate between those
of the Mediterranean and those of sub-tropical dry
lands :

The Eucalyptus Forests of southern and eastern
Australia form a sort of park landscape in which the con-
tinuity of the forest is frequently broken by grassy
glades, The gigantic eucalyptus, with light and patchy
crowns and a bark hanging in ragged strips, grow scattered
on a floor of dry grass. Their drooping, sabre-shaped
leaves, always turning edgewise towards the sun, do not
afford any shade. When acacias are absent, the under-

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MAIN VEGETATIONS OF THE GLOBE

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OTHER EVERGREEN FORESTS 81

wood is usually very meagre; the interior of the forest
remains quite sunny and open.

Araucaria Forests on tle table-lands of southern
Brazil, though very different in appearance from the
eucalyptus forests, agree with them in many of their
characteristics and have a similar type of life. In

AE IR as | Ee

Fie. 35. Araucaria Forest in Misiones, Argentina.

these, the straight and slender trunks of the monkey-
puzzle trees bear on their tops flat crowns of horizontal
branches. Their leaves are scarcely more than short,
hard, thick, needle-pointed scales. The araucarias grow
in loose clumps, often intersected by grassy glades or
campos. Their undergrowth is varied, consisting here

of a short grass sward, there of thickets of the ever-
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green Yerba Maté or Paraguayan tea, and other
shrubs.

In the South American Chaco extensive Quebracho
Forests make a transition from the swamps of the
Paraguay River to a more arid region in the rear. These
forests are also evergreen. The Quebracho trees have a
gnarly, bushy growth, and very light crowns. The leaves
are so tiny and inconspicuous that the trees look as
if they were bare. The heavy undergrowth is an im-
passable thicket of tall, hard-leaved, evergreen shrubs.
Here again the woods alternate with tracts of grass-
land, forming a park-like landscape graced by palm
groves.

These various types of evergreen forests in sub-tropical
lands have sometimes been called savana-forests, because
they are intimately associated with grass-lands. The
excellent quality of their timber, gum, and other pro-
ducts has made them very useful.

CHAPTER XIII

TEMPERATE SCRUBS

THE foregoing brief account of the evergreen vegeta-
tion of the mediterranean countries will make it easier
to understand how an even greater dryness of climate
leads to the disappearance of trees and the _pre-
dominance of shrubs. Such conditions are found in
the Australian scrub and the Californian chaparral.
It is difficult to say how far the absence of trees is due

F 2

84 MAIN VEGETATIONS OF THE GLOBE ~

to man in a great many cases, especially in California.
We have seen how, in the Mediterranean, the sheep, the
axe and torch of man, have extended the maquis.
There, however, if left alone for a sufficient time, the
forest will be regenerated. The maquis is, in fact, often
a preparation for the forest. But when the climate and
the soil are drier or have been permanently injured and
impoverished by the destruction of the timber, it is quite
possible that it takes hundreds of years to form anew a
fit soil, and that in the meantime the scrub remains the
exclusive master of the ground. Such seems to be the
case in many parts of California.

The relative permanence of the scrub thus adjusted to
its environment, its unique, well-defined appearance, the
probability of its spontaneous origin in most places, and
its wide distribution, all make it desirable to recognize it
as an independent and characteristic formation. In Aus-
tralia it is one of the dreariest and most dreaded land-
scapes. A traveller says: ‘The monotonous and dismal
look of an extensive scrub is depressing, especially
when viewed from an eminence; the equal height of the
vegetation, the dull glaucous colour of the foliage, look
in the distance like a rolling sea reaching the horizon—
at least the first sight of the Murray scrub, extending
hundreds of miles, produced this impression on my mind.’
Every one avoids the serub as much as possible; many
have lost their way there and perished for want of water.
All the different scrubs produce a similar impression, but
the plants comprising them are not of the same genera
and species. Locality and soil affect the character of
the flora.

Shrubs of one kind or another are found in flower, in
the serub, throughout the year. The majority, however,
blossom in early spring, but the rainy season alters the

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86 MAIN VEGETATIONS OF THE GLOBE

appearance of the vegetation very little, though it calls
into life numerous terrestrial orchids and other bulbs.
The scrub is a closely packed, prickly, sticky, scented
tangle of dull shrubs, without trees or grass, and destitute
of water, under a fierce sun, and a singularly clear atmo-
sphere. It is evergreen, and is composed chiefly of bushy
plants, with stiff, dry, simple, entire leaves, which are

Fig. 38. Mallee-scrub.

arranged obliquely to, or even parallel with, the light,
and possess a dull bluish surface, often due to a coating
of wax or resin.

Several kinds of scrub are found in Australia. There
is the Mallee-scrub, an impassable tangle of bushy
eucalyptus, in dense shrubs, 6 to 10 feet high, which
send directly from the soil bundles of long, thin shoots
ending in bunches of hard foliage. The shrubs are all

TEMPERATE SCRUBS 87

uniform in height and colour. Few other forms are
admitted, and these possess mostly heath-like or vertical
leaves. Grass is entirely lacking.

In the Brigalow-scrub two or three kinds of acacias
are predominant, with sickle-like leaves and a shimmer-
ing silver-grey colour. Round these the other humbler
plants are gathered in impenetrable thickets.

The Mulga-scrub, also composed of thorny acacias, is
generally more open and possesses a ragged carpet of
dry grass.

The Californian chaparral is very like the Medi-
terranean maquis. It is stocked with evergreen and
deciduous shrubs forming a continuous cover. Dwarf
oaks, mezquites, composites, rosaceous and leguminous
plants are common.

In many cases it is difficult to bring these scrubs under
cultivation and even to utilize them in any way. Climate
and soil, alike, are unfavourable to pastures or to agri-
culture. They are avoided, for they offer great obstacles
to communication.

CHAPTER XIV

SAGE BRUSH

PASSING now to a still more extreme case of dry
extra-tropical climate where there are only occasional
showers, we find a type of vegetation which in western
North America has received the name of sage brush. It

88 MAIN VEGETATIONS OF THE GLOBE

resembles an arid heath or a semi-desert, and is frequently
so described by travellers. The climate is dry and warm,
but has sudden and sharp contrasts of heat and cold.
The mean average temperature for the year ranges from
50° to 65° F. There isa brief vegetative season of two to
three months, with short, heavy showers or fine, drizzly,
irregular rains.

Sage brush soils are extremely varied, but are seldom
rocky. Thanks to the dry climate they often become
impregnated with alkali salts, as in true deserts.

Such general conditions occur on the high plateaus of
Asia Minor, in belts round the deserts of Central Asia and
Australia, in the Great Basin of North America, and as
far south as central Mexico; south of the Pampa,
in Patagonia, in South-west Africa (Kalahari and
Karroo), in North Africa, north of the Sahara, and north
of Arabia. Thus the sage brush is much more widely
distributed than the scrub and chaparral in extra-
tropical countries.

The sage brush region is generally a vast, undulating
or flat expanse. The bare soil is covered with hoary or
dull-grey, sticky, scented, sage- or heath-like shrubs,
3 to 6 feet high. These may grow densely in a grey
sea of woolly bushes, or be scattered over otherwise
naked tracts. In some countries the pale, blue-green
pillar of some solitary cactus plant may rise out of the
dull brush. No leafy trees, no green grassy swards
break the monotony of the landscape. Some variety is
afforded by the networks of waterless stream-beds,
marked by a taller and fresher growth ; by salt lagoons,
dry most of the year, but at times forming vast, shallow
sheets of water (such hollows are surrounded with belts
of dwarf, fleshy, pale green shrubs called succulents or
salt-bushes); or by bare tracts of soil powdered over

SAGE BRUSH 89

with whitish flakes of alkaline salts. Sometimes the
dwarf shrubs are replaced by stiff bunches of wiry,
fibrous grass, such as esparto; at other places the land-
scape is formed of a scattered, but regular, heath with
taller, lanky bushes.

The shrubby perennials, which compose the sage brush,
are besom-like in appearance. They rest on thick, woody

Fie. 39. Sage brush, Semi-Desert. Rio Mancos Valley,
north side looking west. (Photo: A. W. W. Brown.)

stumps, sending down a number of cord-like, fibrous tap-
roots to great depths. The leaves are usually less than
one inch long, narrow, leathery, stiff, and rolled inwards.
They are covered with a dense down of glandular hairs
which give them a whitish-grey tint, or coated over with
resin, gum, or wax. They stand mostly erect, seldom
flat or spread, but compressed against the stems or
at an angle with them. Few of these plants display large

90 MAIN VEGETATIONS OF THE GLOBE

and bright flowers. Many have large bunches or heads of
small flowerets, while others possess whitish, woolly, in-
conspicuous inflorescences. There is no sharp contrast
between the appearance of the vegetation in the rainy
and dry seasons, because the distinction between these
periods is not well marked. In addition to the shrubby
perennials a multitude of seeds lie in the soil and burst
into small, short-lived plants when rains are prolonged
enough. By reason of their relatively low position, in
vast hollows and on the margin of deserts, a certain
amount of ground-water is within reach of the plants,
but the supply is scanty. The evergreen, shrubby
perennials depend on it entirely ; hence a slow but con-
tinuous, almost dormant kind of life, throughout the
year. The subsidiary and ephemeral vegetation depends
on rain, which is generally under 15 inches per annum.
On the whole, this is a combination of conditions not en-
tirely unfavourable to hardy plants, but leaving them
constantly on the verge of drought.

Another class of plants adjusted to such an environment
is that of the cacti, aloes, agaves, and similar forms,
which contain large stores of water. Usually they have
no leaves, or when leaves are present they are so thick
that they form reservoirs.

If the climatic circumstances of the sage brush regions
are unfavourable to plant life, their soil is not. Indeed,
it is often very fertile. When reclaimed by irrigation
many such regions are transformed into rich farmlands.
Oases have been created in the barrens east and west of
the Rocky Mountains and in Arizona. In the last century
the sage barrens were the scene of an admirable instance
of dauntless courage and pertinacity, when those in-
dustrious colonists transformed the sage tracts of Utah
into a flourishing oasis, capable of supporting a dense

SAGE BRUSH 91

population. A special method of agriculture based on
the preservation and economical use of the surface
moisture has been devised and applied with success in
those regions. Thanks to this dry-farming, what looked
like waste sands have been made to yield paying crops
of maize and lucerne.

Fie. 40. Sage brush. North Colorado.
(Photo: A. W. W. Brown.)

Nor is the sage brush wholly devoid of natural re-
sources. In Mexico, for instance, the sage-like guayule
has yielded enough rubber to call into existence a small
industry in the desert. But these are only recent and
solitary developments. Except for oases which may be
found in Africa, Asia Minor, and Central Asia, most of
the sage brush lands are areas which have hitherto
not only received no attention but have been avoided.

92

CHAPTER AV
STEPPE, PRAIRIE, PAMPA, VELD

THE steppe is the dry grass-land of the temperate
countries. This form of vegetation covers vast areas,
chiefly in the heart of the continents, outside the tropical
belt. Thus it occupies the central part of the North
American lowlands and a large part of Argentina. It ex-
tends over the South African plateau as far north as the
tropic of Capricorn. In Eurasia it stretches between the
northern Siberian forest on the north and the central
deserts on the south, from Manchuria and Korea to
southern Russia and even covers parts of Bulgaria and
Romania, while outliers of decreasing importance are to
be found in the Hungarian Puszta, in Italy and in
Spain.

The Asiatic steppe extends like a ‘ vast floor, all green,
with a dash of yellow flowers here and there, while beds
of wormwood in silvery white glisten like a silken tapes-
try ora delicate gauze. ... The scenery is uniform : a sea
of grass, swelling undulations, to paint the ridges of
which Nature has exhausted all the greens of her
palette. The troughs are lined with bright yellow
masses of buttereups. In the height of summer the
steppe is carpeted with straw. It is then a dreary and
lifeless immensity, no longer relieved by brilliantly
coloured flowers.’

The steppe climate is characterized by a severe and
dry winter, a mild and moist early summer, with

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94 MAIN VEGETATIONS OF THE GLOBE

frequent showers, and a hot and dry late summer and
autumn. The rainfall is scanty, ranging from 14 to
24 inches with an average rarely exceeding 20 inches.
Each year has about 100 rainy days. The atmosphere
is dry, especially in winter when strong, icy winds sweep
across the plains.

Steppe regions, the soil of which commonly consists of
very fine loam, loess, clay, or sandy clay, as a rule, have
a flat or slightly rolling aspect, always very uniform.
On the American prairie, ‘One may ride for many miles
without seeing any distinguishable eminence to interrupt
the uniformity of the plain, which extends to the horizon
in all directions. There are no trees, no shrubs... , no
tall herbs.’

The vegetation, though varying in detail, is also ex-
ceedingly uniform. It consists of a low, close, continuous,
treeless sward. Compared with our meadows and pas-
tures the steppe grass is dry, bluish-green in the grow-
ing season, straw-yellow later on, brown, grey, or dark
for the rest of the year. Among the different aspects
which this steppe assumes may be mentioned (1) the
continuous, short, dusty-green turf entirely formed by
buffalo-grass; (2) the wavy,subdued silver-white, feather-
grass carpet of the Black Sea region, resembling rippling
water; (3) a brighter and more varied mixture of plants
in the hollows of the same region; (4) the sea of grass
may be sprinkled with short, woody undershrubs and
herbs of varied species, or again invaded by creeping
prickly-pears and cacti. (5) In the Argentine Pampa
the grass grows in separate big tufts, between which the
bare soil may be seen.

The appearance of the vegetation varies with the
season. In early spring, numerous bulbs and _ short
annuals diversify the carpet of tender green. In late

STEPPE, PRAIRIE, PAMPA, VELD 95

spring and early summer most grasses and taller annuals
come into flower ; this is the season of greatest luxuriance.
Later on, nothing is left but dried stalks and parched
tufts. In autumn, however,another grey, woolly, higher
and drier vegetation may spring up, which makes the
steppe look for the time being like a short, dense sage
brush.

The steppe grass is of a drier, hardier nature than
our meadow grass. This is seen in the narrower, stiffer

Fic. 42. North American Prairie Grass.

leaves, which are more fibrous, less juicy, and tougher
for grazing purposes, They point upwards and roll
up lengthwise or curl inwards. The tufts are dense,
compact cushions made up of bundles of dried-up sheaths,
the remnants of the previous years’ growth out of which
the new shoots arise. These tufts are seated on stools
of short, superficial, highly ramified roots. When the
_ plants are closely packed their roots become entangled
and form a dense, elastic felt, which acts as a sort of
sponge.

96 MAIN VEGETATIONS OF THE GLOBE

Other steppe plants are perennials and undershrubs,
bulbs and tubers. All these are comparatively small,
seldom more than 2 feet in height. This is partly due
to the shortness of their vegetative period. Evergreen
perennial shrubs and undershrubs have small, leathery
leaves, with protective coatings and air-containing
hairs.

The variety and abundance of bulbs is one of the
chief features of the steppe, as of all dry countries.
They are able to survive the extreme winters and
summers by means of their underground store of water
and food. They burst into a very intense, if tem-
porary, growth during the mild and rainy spring, when
they replenish their reservoirs. During the remainder
of the year the parts above ground die and those under-
ground elaborate the food materials and utilize them in
propagating.

The growth of trees and shrubs is prevented in the
steppe regions by several hostile circumstances, the
most important being the scarcity of water. A yearly
average rainfall of 20 inches seems to be neces-
sary for tree growth in the cool temperate regions,
and steppes generally have less than this. Neither
deciduous nor evergreen trees can stand extreme winters,
when strong and dry winds blow over a frost-bound
soil, as is the case with most steppe lands. In some
places, in addition to these unfavourable climatic con-
ditions, the soil is too fine and compact and therefore
dry and airless. The growth of a close mat of tiny and
tangled rootlets, covering the soil with a sort of im-
pervious felt and further depriving it of air and water,
is another factor inimical to the development of trees
and shrubs with their deeper-seated roots. Along the
margins of the steppe there is a struggle between grass

STEPPE, PRAIRIE, PAMPA, VELD 97

and trees, each taking advantage of the slightest variation
of the soil in its favour.

The grass-land of the steppes supports large herds
of wild and domesticated horses, cattle, and sheep. On

Fie. 43. Manchurian Steppe and its Dwellers.
(Photo : Donaldson Smith.)

the other hand the scarcity and irregularity of rain-
fall renders agriculture very precarious. Hence the
development of pastoral industries and modes of life.
Since the grass dries up periodically, and cattle have

1159 G

98 MAIN VEGETATIONS OF THE GLOBE

to move to other pastures, steppe dwellers must lead
a nomadic existence. The horse and camel are indis-
pensable means of conveyance and transport. Under
such conditions the population of these grass-lands
remains scarce and primitive. Steppe soils, however,
are not necessarily poor; indeed they are mostly rich,
and with the help of irrigation such crops as wheat,
barley, maize, and beetroot can be grown to perfection.
In recent years agriculture and industries have developed
on the Russian steppes, favoured by an exceedingly rich
soil, the black earth or chernoziom. Similarly in
Canada, the United States, and Argentina, large tracts
of prairie ground have been turned into prosperous
granaries, and bid fair to become the wealthiest wheat
districts of the world.

CHAPTER XVI

TEMPERATE DECIDUOUS FORESTS

THE cool temperate deciduous forest is the predominant -
feature of our northern countries, except on the higher
hills.

Though we now see only patches of it around us,
this forest once covered the greater part of central
and western Europe, north of the Alps and Pyrenees.
It extends eastward across Russia in a belt which is
wedged in between the northern resinous forests and
the southern steppe, and gradually dies out towards

TEMPERATE DECIDUOUS FORESTS 99

the Urals. In eastern Asia it reappears under a similar
climate in the Amur region and in Japan. In North
America it has its greatest development on both sides
of the Appalachians, westward beyond the Mississippi
and northward to the lake region. In the southern
hemisphere this type of forest occurs in small stretches
in Patagonia, southern Chile, and Tierra del Fuego. It
is nearly absent from Africa and Australia.

The temperate, summer-green forest is composed of
those oaks, beeches, ashes, maples, birches, rowans,
aspens, elms, lime-trees, and others with which we are so
familiar. There are, however, various types, the most
important of which may be noted.

(1) The tall, sombre beech forests form a uniform
and close canopy of heavy, globular crowns, intercepting
the light almost completely, and forming underneath
a dark vault supported by tall, slender trunks. Few
competitors are admitted among the beeches. The trees
are crowded together, shutting out smaller and lighter
species.

In the interior of the forest few shrubs and herbs
can withstand the semi-darkness, and these are all
lank and weak-looking, with few drawn-out twigs.
A brown mat of leaves and mould covers the ground.
It is only during the short early spring before the
_ leaves appear on the beech-trees that a number of
plants find an opportunity of putting forth bright
flowers. At that season primroses, wood hyacinths,
wood sorrels, white anemones, and others make a most
beautiful carpet under the bare branches. Such forests
are found in England, as well as in many parts of
western and central Europe. They are even more beauti-
ful among the Alps and on the higher slopes of the south
European mountains. The highlands of eastern Europe

. G 2

100 MAIN VEGETATIONS OF THE GLOBE

still shelter some luxuriant forests of beech and mixed
conifers, which, though varying in detail from our own
beech vegetation, display a similar appearance and mode
of life.

(2) The oak forest is more open, lighter, and smaller,
more varied and irregular, for oak trees require more
light and space for their crowns and roots, and the
sunshine can penetrate through the intervening spaces.
Along with oak we may find ash, birch, maple, aspen,
rowan, poplar, elm, and pine, according to the nature of
the ground. Smaller trees and shrubs, such as holly,
juniper, alder, hazel, hawthorn, wild cherry, logwood,
&c., flourish in the comparatively slight shade. A large
number of undershrubs, herbs, and grasses, such as
foxglove, willow-herb, ferns, &c., are found in a still
lower layer. Small creepers, mosses, and lichens grow
on the trees.

The plains of the Danube basin possess a species
of oaks and other summer-green trees unknown in
western Europe, but in spite of such differences, these
forests are most nearly related to the West-European
oak forests.

(3) A third variety of deciduous vegetation occurs
on marshy grounds liable to inundation. Here a closer
and more tangled mass of such trees as willows, poplars,
aspens, alders, birches, is interspersed with saplings
of the same kinds, and other shrubs clad with creepers,
clematis, honeysuckle, mosses, and ferns; while tufts of
tall grass, ferns, and other herbs flourish on the moist
ground. }

(4) The mixed summer-green forest is still more
varied and luxuriant in North America, as well as on
the southern shore of the Caspian and Black Seas,
on the eastern slopes of the Tibetan plateau, and in

101

ICIDUOUS FORESTS

TEMPERATE DI

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102 MAIN VEGETATIONS OF THE GLOBE

Japan. Numerous kinds of oaks, beeches, walnuts,
hickories, maples, aspens, poplars, tulip trees, magnolias,
and other trees are mixed with equally numerous and
varied kinds of pines, cedars, spruces, and allied conifers.
The undergrowth is luxuriant, and contains rhododen-
drons, azaleas, magnolias, fuchsias, kalmias, and others
with gorgeous flowers. Creepers with beautiful foliage
and herbs are abundant. This last formation is a link
between the northern summer-green forests of our
countries and the temperate rain-forests.

(5) The sweet-chestnut forests which grow on granite
and other siliceous soils on the southern slopes of the
Central Plateau of France and of the mountains of
southern and eastern Europe form another type. They
consist of stately trees with short and stout trunks, heavy
crowns, and broad, long leaves. The undergrowth, though
variable according to soil and position, is of the ordinary
northern mountain type in which ferns and grasses
predominate.

(6) A drier, lower, and thinner kind of woodland, in
which hornbeam, elm, lime, hazel, blackthorn, roses,
brambles, and juniper play a conspicuous part, with dry
grasses, characterizes the hilly limestone districts of
central Europe. This landscape might be appropriately
termed a temperate park-like woodland.

In spite of their minor differences all these forests
have a cool-temperate, moist climate, with rain all the
year round, and a fairly severe winter. The com-
paratively low temperature averages 46° to 54° F., with
extremes in winter and summer. The yearly rainfall
varies from 28 to 60 inches. The winds are moderate.
There is a sufficient amount of atmospheric moisture and
ground-water throughout the year. ‘This is very suitable
for the growth of trees and also of grasses. The struggle

TEMPERATE DECIDUOUS FORESTS — 103

between the two is controlled by the humidity and the
nature of the soil, the altitude above sea-level, and, last
but not least, by man’s intervention.

Compared with evergreen tropical or even with
temperate rain-forests, our northern forests show the

Fie. 45. Sweet Chestnut Forest in Cevennes, France.

effect of the much shorter vegetative period and the less
favourable temperature conditions. They have a slower
life and growth, resulting in a shorter stature and
diminished luxuriance, a foliage reduced both in variety
and in size, fewer and smaller creepers and epiphytes,

104 MAIN VEGETATIONS OF THE GLOBE

and a poorer undergrowth. The trees form a great
quantity of wood, for wood is one of the reservoirs of
plant food and water during the cold season.

A strong seasonal rhythm is the chief feature of these
northern climates, the most conspicuous result of which
is the alternation of the winter and summer aspects of
the vegetation. Plants generally have their resting

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Fie. 46. Summer Forest and Park Landscape in Sakhalin.
or sleeping period in winter, but they do not all show

it in the same way. Many of them, the so-called
annuals, take their rest in the seed stage; all the

other parts of the plants die at the close of the season .,

of growth each year. In the case of the perennials,’
certain parts, and at least the underground organs,
persist during the resting season; they do not grow, but
lead a dormant life. Recurring frosts and a heavy
evaporation due to the strong winds which occur in
our latitudes in winter, often coupled with ice-bound
and, therefore, dry soils, soon kill the broad and thin
leaves of the taller trees and shrubs. Trees that shed

TEMPERATE DECIDUOUS FORESTS — 105

their foliage before winter are therefore suited to our
climate. This produces in its turn a marked periodicity
in the lower layers of the forest. Most forest plants
produce their leaves and flowers before the leaves of
the trees above them cut off much light. Hence the
flowering and most active period of forest life begins on
the ground and gradually spreads upwards to the trees.
Outside and inside the forests the rhythm of the seasons
is marked by a succession of plants, displaying a
regular pageant throughout the year and forming
a climatic calendar.

Owing to the scanty variety of trees and shrubs our
summer-green woods consist essentially of social trees.
Hard-wood and soft-wood timbers are the chief economic
products. With the exception of a few fruit-bearing
bushes, food plants of any importance are absent. The
forest dwellers, however, manage to find in them an
incredible variety of resources, for their houses, furniture,
clothing, food, and even medicine, though only on a small
scale.

It should be remembered that the climate and soil which
encourage the growth of such forests also favoured the
development of the most prosperous agriculture and
grazing, and of the highest stages of civilization yet
reached by mankind.

106

CHAPTER XVII
THE TAIGA

THE taiga, or northern coniferous forest (also called
the sub-arctic forest), is one of the most widespread
vegetations on the globe. It covers almost uninter-
ruptedly the north of the great continents of America
and Eurasia. In Asia, its southern limit oscillates about
55° N.; in north-western Europe, this limit is about 60° ;
in North America, it is found farther south, and reaches
to 45° in the east. The taiga is bounded to the north —
by the tundra.

The taiga is composed of pines, firs, spruces, larches,
and allied species, intermingled here and there with
various kinds of birches, aspen, and a few other leafy
trees. In most cases, it forms a lighter kind of vegetation
than the forest of broad-leaf, summer-green trees. Its
cover, except for the spruce, is fairly light, there being
only small differences between the winter and the summer
aspects of the tree crowns.

A similar coniferous forest is found in nearly all
mountain districts below the upper timber limit and
above the belt of broad-leaf forests. This is generally
called the sub-alpine forest, from its development among
the Alps.

The climate of the taiga is decidedly cold and moist.
The yearly average temperature is 39° to 46° F., with
possible extremes from —58° to +122° F.; so there may
be extreme cold in winter and very great heat in
summer. The rainfall is moderate, generally more so

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108 MAIN VEGETATIONS OF THE GLOBE

than further south, and fairly regular throughout the
year. Winds are not so strong as either in the arctic
zone or over the steppe belt. The soil is generally poor
and of glacial origin, sandy, clayey, or pebbly.

Some aspects of the taiga may be briefly mentioned
here: there are light pine forests on drier, sandier soils
and rocks; dark and heavy spruce forests on moister
and marshy grounds; fir forests; larch forests on deep,
well-aerated soils; mixed forests of these species, in
addition to birch and aspen; scattered forests as in
northern Canada, formerly another sort of park-lke
landscape; the swampy taiga, intersected by marshes
which are overgrown with rushes and reeds or by
mossy bogs. The ground vegetation consists of a few
ferns, crawling undershrubs, and stunted bushes, such
as bilberry, heather, bearberry, cranberry, winter-greens,
crowberries, and of dwarf birch, dwarf rose, grasses,
lichens, mosses, &e. This undergrowth seldom constitutes
a close sward, and is often extremely scattered, especially
under the heavier trees like spruce and fir.

As one advances northward the forest grows more
stunted and scattered. Trees of great age remain thin,
low and gnarled, more and more branched and bushy in
aspect. The proportion of wood increases and the-bark
has a rougher and thicker structure. There is more and
more dead wood, and trees and branches are often covered
with moss and lichen.

A fairly sharp line can be drawn at the northern limit
where the forest is replaced by moors and pastures, and
only clumps of trees are found standing like islands
in the middle of the tundra. These outposts, exposed to
the fury of the winds, look very desolate. Their trees
remain scattered, stunted and gnarled, and sometimes
crawl. Halfof them are dead, and the ground is encum-

We

hall’

aA

Near the Limits of Russian Taiga.

Fia. 48.

110 MAIN VEGETATIONS OF THE GLOBE

bered with dead wood. In Canada and Alaska the most
northern part of the taiga is a plain with thinly scattered
trees. Only the banks of streams have a continuous
belt. A narrow fringe of stunted, bushy birch, beyond
the coniferous taiga, forms the polar limit of trees.

To withstand the severe climate trees must be well
protected against wind and cold, be very frugal in their
demands on both soil and climate, lead a slow life, and
store in their tissues an abundance of food materials.
The hardy northern conifers fulfil these requirements.
Their most active and delicate parts are reduced to
a minimum in the short, needle-shaped leaves, which
are generally rolled lengthwise, and have a thick,
leathery skin and a compact, fibrous structure, affording
but little grip tothe wind. Notwithstanding the number
of these needles, the total green surface is limited. In
short, the foliage is effectually protected against drought.

The whole structure of the conifers is interesting as an
adjustment to the prevailing conditions. The conical
shape of the trunks, with broad bases and tapering tops,
makes the trees stable even in strong winds. This
stability is increased by the remarkably short develop-
ment of branches; only when the top shoot has been
destroyed do the side branches approach the size of
those of our broad-leaved trees. The great proportion of —
wood to leaves is striking, and this wood stores an abun-
dance of reserve food in the form of starch in its tissues.
Indeed these conifers may be regarded as large stores
of food with growing tops which are not very active.
They spend little, earn little, and hoard much; they lead
a slow, thrifty kind of life, well adjusted to the cireum-
stances in which they are generally placed: a spell of bad
weather in the growing season would mean disaster to a
more luxuriant type of vegetation.

THE TAIGA 111

With such unfavourable conditions of climate and soil
the poverty of the undergrowth is not surprising. In
the forest the strength of the winds is broken, and this fact
favours the smaller plants but it is outweighed by the
freezing of the soil to a depth of from 3 to 5 feet. The
bushes, however, are protected by the deep snow-mantle
of winter. In spite of this, the frost makes root-life

Fie. 49. Tree Limit in Northern Russia,

impossible, and it is not until the frozen layers have
thawed that plants are able to revive. The changes of
volume of the ground-water with freezing and thawing
are another hostile factor, for the rootlets may become
torn or injured. The small shrubs and herbs depending
entirely on the surface layers of the soil are thus placed
in a precarious position for the greater part of the year.
Again, the resin-impregnated needle-leaf mould is gener-
ally understood to be detrimental to plants, acting as a

112 MAIN VEGETATIONS OF THE GLOBE

sort of poison; and the continuously dim light due to the
persistence of the coniferous leaves (except in the case of
the larch) also acts unfavourably on most plants, and
excludes bright-flowered species, which need plenty of
light for blossoming. Only a few plants can survive all
these disadvantages; hence the monotonous nature of
the undergrowth and its poverty both in individuals and
species. A certain number of evergreen or deciduous,
very woody shrublets and creeping perennials are adapted
to this mode of life, viz. those which, provided with
sufficient reserve material, are able to start growing as
soon as conditions improve, and to take advantage of all
the very irregular spells of good weather which mark
the opening of the season.

Few annuals resist such climates, for the frequent re-
currence of frost and high winds in early spring usually
kills them in the seedling stage. Tiny plants, whose
cycle of life requires but a very few months, or even
weeks, are among the features of the north.

The taiga is extremely useful for its soft timber,
which it supplies to the whole world. Lumbering is the
chief occupation in it at the present day, and has given
rise to several important industries. The logs are mostly
floated down the rivers to large saw-mills erected on the
banks, and often driven by water-power. The wood is
used for carpentry, joinery, and match-making. It also
yields tar, wood-alcohol, and other chemical products,
obtained in numerous distilleries. Mills have been built
to reduce the wood into paper-pulp, and to feed these the
lumberers have cut their way into the heart of the
American taiga. The old-world forests in the Russian
Empire have been less injured.

The chief occupation of the forest dwellers, however,
has been fishing and hunting for fur and feathers. The

THE TAIGA 113

taiga is the home of a large animal population, the pur-
suit of which has supported a nomad army of hunters
and traders. The backwoodsmen, whether Indians or
half-breeds, Samoyeds, Buriats, or Yakuts, have remained
at a crude and primitive stage of civilization. Trading
posts where the skins and furs are bartered are the only
settlements of the northern portions.

The southern belt of the taiga is a more favourable
field for agriculture. Barley, oats, and rye can be grown
where the soil is fairly rich. Under the spur of necessity
northern farming has even made bold strides in recent
years; and on the southern margin of the taiga the
plough is more and more following the axe.

CHAPTER XVIII

TUNDRA—COLD DESERTS OR BARREN
GROUNDS

A pWARF, treeless, shrubless vegetation extends over
the vast plains and islands beyond the limits of con-
tinuous forests or taigas around the polar cap. Its
southern limit corresponds to the northern limit of
tree growth, and roughly coincides with the Arctic
Circle.

The tundra is a bleak expanse of waste land, with
a scatteredystunted vegetation. The landscape consists
of monotonous, flat or rolling plains, broken in places

1159 H

114 MAIN VEGETATIONS OF THE GLOBE

by rugged dykes, rising here into low, rounded, bare,
rocky mounds, and bestrewn there with stony or pebbly
tracts, varied by gentle slopes, intersected by numerous
rivers or streamlets, and dotted over with lakes and
swamps.

Continuous night and also continuous light may last
for some weeks each year. Frost prevails during eight
months of the year, but during the brief summer the
temperature rises and falls irregularly according to the

situation. On islands, particularly on those on the west
of the continents, such as Spitsbergen and Novaya
Zemlya, there may be very broken weather, interrupted
by blizzards, hailstorms, and persistent fogs. In more
continental situations, such as the northern coasts of
Asia and America where there are large land masses to
the south, the summer appears to be more steadily
sunny, broken only by gales of icy winds. Wind is
indeed one of the terrible features of the Arctic climate.
~ During the long winter night it may howl for days —
on end, icy-cold and extremely dry—so dry, in faet,
that the breath does not condense as it leaves the
nostrils, and tobacco crumbles to dust. Water is pre-
cipitated mostly in the form of snow, hail, and fog.
Vast regions lie buried under snow for over two-thirds
of the year. In others, the winter wind is so dry and
strong that it carries away the thin layers of powdered
snow as they are deposited, and leaves the ground quite
bare. The soil is also unfavourable, for in the dry
tundra the frost-bound ground, deprived of the snow-
mantle, is exposed to the full fury of the icy gales;
and in moister regions the ground may always remain
frozen except for a thin superficial crust.

This seemingly uninteresting tundra has many diverse
aspects. (1) The most desolate is the stony tundra. The

a

TUNDRA 115

bare ground of stones and pebbles, gravel, or clay, is
thinly bestrewn with a few dwarf plants, patches of
lichens and mosses, or tussocks of flowering plants, mostly
evergreens with tiny, leathery leaves and strong, woody,
perennial roots. Here and there a dwarf juniper or

birch may be seen.

(2) The moss-heath, or moss tundra, has a less for-
bidding appearance. It is composed of dense mats, two
to four inches thick, of the larger, straight-stemmed
mosses. It may be quite continuous, or ragged and full
of bare patches. It rests on a thick, damp pad of brown
felt and raw, acid turf, known as raw humus, always
more or less swampy and peaty. Here and there tussocks
and dwarf bushes of crowberry, birch and willow, bil-
berry, &c., rise above the broken ground.

H 2

116 MAIN VEGETATIONS OF THE GLOBE

(3) The lichen tundra is a drier type, found in the
shelter of the shallow, stony depressions in rolling or
hilly parts, where the atmosphere is relatively moist and
still. As lichens simply lie on the ground without any
roots they depend entirely on the moisture in the air.
Exposed situations, open to the dry winter gales, are
unfavourable to them. On the other hand they flourish

Fic. 51. Cotton-Grass Tundra in Northern Russia.

where they can lie under a thick blanket of snow for six
or eight months and in summer are sprayed over with
frequent drizzles, rains, fogs, and hail. They are queer-
looking, leafless, crooked, miniature soft bushes, one or
two inches high, spreading and intertwined so as to
form a sort of yellowish-grey mat, often powdered over
with blood-red or yellow fruits, on a thin layer of raw
mould.

TUNDRA 117

(4) The mossy tundra, under favourable conditions,
may become so overgrown with dwarf undershrubs and
shrubby perennials as to deserve the name of dwarf-
shrub tundra, or dwarf-shrub heath. In Arctic regions

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heather plays but an inconspicuous part. More common
are other tiny-leaved evergreens—crowberry, different
sorts of bilberry and bearberry, stunted rhododendrons
and azaleas, &c. The ground underneath is carpeted
with mosses and lichens spread over a more or less thick
layer of raw humus. ©

118 MAIN VEGETATIONS OF THE GLOBE

(5) On badly drained ground are morasses, with pools
of stagnant water or overgrown with cotton-grass and
sedges, on which peat-moss tundra develops. This is
a damper variety of the moss-tundra, where raw humus
has accumulated to the extent of building peat.

(6) Along the streams are tracts where the remains of
dead plants carried away and deposited in the mud make
a more fertile, sheltered soil, on which fresh green grasses
mixed with flowers grow in profusion grassy tundra.

(7) The most luxuriant type of vegetation in the tun-
dra is found on slopes sufficiently steep for good drainage
yet retaining enough moisture. When these slopes are
sheltered from the dry winds and almost perpendicular
to the sun’s rays they are quickly warmed in summer,
and on them thrive the most delicate and brilliantly
coloured flowers of the tundra; these bright spots are
called flowery twndra or ‘bloom-mats’. They contain
only herbs. Among the flowers may be enumerated
monkshood, aconite, angelica, geranium, willowherbs,
achillea, geum, parnassia, sibbaldia, artemisia, yarrow,
polemonium, forget-me-not, saxifrages, &e.

The absence of trees and the extreme stunting of all
vegetation are the most noticeable features of the
tundras. It is not the cold alone that excludes trees,
for trees grow in Siberia where the temperature ranges
from —58° to+122°F. The probable causes are the dry
winter winds, producing an enormous evaporation at
a time when the ground is frozen, so that no water is
available.

The greatest cause of the reduction in size of the
vegetation is, of course, the shortness of the period of
active plant life, which lasts only two months every year ;
and in some places even this is interrupted. No doubt
the sun shines almost all day for some weeks or months

TUNDRA 119

and growth is continuous (except during blizzards). It is
possible, however, that a continuous illumination retards
the growth of plants in length. About the middle of
July all plants burst into active life at the same time, as
if by magic. They develop rapidly, and reach their best
in a very few days. They live very actively for six
weeks or two months, accumulating quantities of food
materials which pass into the protected underground
parts, root-stocks, and roots. In this respect they
resemble the desert vegetation after rain. The close of
the season is as abrupt as the beginning. According to
the arctic observer, Kjellman, ‘an arctic landscape at the
approach of winter most resembles a southern country
that has been ravaged by a severe night frost before
winter was expected. Many plants are put to rest while
still in full development. There they stand with
frozen but living leaves, with swollen flower-buds
in the inflorescences, with half-open and fully expanded
flowers, with half-ripe or quite ripe fruits. Whilst the
‘plants were in full activity they were paralysed by the
benumbing cold.’

Contrary to expectation, in these bleak countries
flowers assume an extraordinary brilliancy, and in many
places the bright colours even of the foliage have aroused
the enthusiasm of travellers. It is said to be partly due
to the long, continuous daylight. The fruits and seeds
of certain plants have time to ripen, but in many other
cases they are frozen before maturity.

Animals are abundant on the tundra, and many of
them provide valuable furs and feathers. Hence, as in
the taiga, hunting and fishing are important occupations.
Some of the miserable tundra-dwellers of Eurasia,
such as the Lapps and Samoyeds and others, depend for
their food, clothing, and much else almost wholly on

120 MAIN VEGETATIONS OF THE GLOBE

their herds of reindeer; the only additional supplies
afforded by the vegetation around them are a few berries
gathered during the short summer. It follows that they
are nomadic peoples, living amidst the greatest hardships,

Fig, 53. Mountain Vegetation.

CHAPTER XIX

MOUNTAINS

Diversity of vegetation is most strikingly seen in
mountain regions owing to rapid changes in the con-
ditions of climate, soil, exposure, drainage, &c. As

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122 MAIN VEGETATIONS OF THE GLOBE

mountains deflect the winds upwards much moisture is
condensed. Hence they are wetter than the adjacent
lowlands. Their vegetation is usually more luxuriant
than that of the neighbouring plains. Even in desert
regions, forests and rich pastures may be found among the
mountains.

The various vegetations are arranged in bands
or belts lying one above the other. Such bands may
be appropriately termed girdles or zones, and their
margins, limits. In some cases a girdle may encircle
a mountain at a fairly uniform level and with a fairly
uniform breadth. Much more frequently the girdle is
tilted ; it may be narrower on one side, or discontinuous,
or it may even appear on one side only. Three types of
vegetation succeed each other from the base to the summit
of a mountain: woodlands, grass-lands, and cold desert-
lands. The details, composition, and limits of these vary
from equator to poles, from region to region, and even
from slope to slope.

The Swiss Alps have three main girdles—the basal or
lower girdle, the middle or montane girdle, and the
upper or alpine girdle. The lowlands of Switzerland
consist of a park-land of beech forests and luxuriant
meadows, much altered by agriculture. The basal girdle
is similar, but more heavily clad with beech forests,
alternating with other broad-leaf, deciduous woodlands.
In the montane girdle the forests consist mainly of coni-
fers. At the lower levels they are mixed with deciduous
trees, e.g. chestnut and beech, and clumps of such trees as
rowan and maple. Higher up are more uniform belts
of spruce, which still farther up alternate with patches of
larch and pine. These become more and more important
until they spread out in a fringe above the spruce. A belt
where the pines occur only isolated or in small clumps

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124 MAIN VEGETATIONS OF THE GLOBE

succeeds and marks the lower limit of the alpine or
upper girdle. The latter consists first of a strip of ‘elfin
woods ’—made up of dwarf, bushy pines, alternating with
shrubberies of short green alders or rhododendrons.
The shrubs are surrounded by pastures gaudy with
bright flowers, here rich meadows, there carpets of drier
grass bestrewn with crawling junipers. This pleasant
landscape gives way farther up to rocks and _ screes,
presenting a more and more arid appearance, and
studded with low, broad cushions of densely packed
plants, extending up to the snowfields.

In the Scottish Highlands the sequence of girdles is
slightly different. The beech forest is the lowest and is
followed by a belt of oak which extends to 800 feet
above sea-level. The pine forests, which also occupy large
tracts of light and poor soil in the lowlands, are found
above the oak, and are much interrupted by pastures,
heather-moors, and peat-bogs. The tree-line in a few
cases stands as high as 1,800 feet. The alpine girdle
consists of varied landscapes of pastures, morasses, and
short brushes, and of screes with their dwarf cushion-
plants.

Mountain vegetation has no uniform pattern all over
the World. It is very varied from range to range,
although preserving a similar vertical order everywhere.
Tropical mountains have a great diversity of vegetation,
owing partly to great differences in rainfall and winds,
partly to the nature of the flora in the adjacent lowlands.
On the eastern slopes of the equatorial Andes, where the
climate is extremely moist, the heavy rain-forests rise to
a great elevation. But on the western slopes of the Peru-
vian Andes, which are dry and barren, there are only
broken strips of dry scrub and thornbush between the
coastal desert and the high, arid plateaus.

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MOUNTAINS 125

The sequence of vegetation from equator to pole may
be compared with that from the base to the top of a
tropical mountain. If a sinuous line be imagined
running from south to north through far eastern Asia
it will cross the tropical rain-forest, the warm ever-
green rain-forest, the cool broad-leaf forest, green only
in summer, the coniferous forest, the northern moors and
pastures, and the polar ice. Now this is in the main
the order of succession which is seen in an ascent of the

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Ea. 10° 20° 30° 40° 50° 60° 70° 80° PoLs

. Fre.56. Vertical Zones or Girdles of Vegetation. This is a generalized
diagram. The conditions along the western coasts are shown in capital
letters.

eastern Himalayas. Similarly, the zones of vegetation
which follow one another on a mountain such as the peak
of Orizaba, correspond broadly with the various belts
which one would encounter from the West Indies to
Labrador. There are, of course, obvious differences and
endless varieties, but the comparison is, on the whole,
correct.

The altitudes at which corresponding zones of vegeta-
tion are found on different mountains depend on many
circumstances—such as temperature, rainfall, winds,
steepness. Thus, round the World on the parallel of

126 MAIN VEGETATIONS OF THE GLOBE

40° N., the upper coniferous forest is found reaching to
altitudes as varied as 5,550 feet in Japan, 7,600 feet
on the Tian Shan, 6,600 feet on the Caucasus, 5,600 feet
in Macedonia, 6,000 feet in Italy, 6,500 feet in Spain,
5,500 feet on the Appalachians, 11,000 feet on the Rocky
Mountains, and 9,000 feet on the Sierra Nevada. From

Fic. 57. Spruce and Aspen Mountain-Forest in Colorado.
(Photo: A. W. W. Brown.)

south to north the same girdle decreases rapidly in
elevation until it hardly rises above sea-level within the
polar circle. This decrease in altitude towards the poles
is noticeable for all vegetation zones, though it is strongly
influenced by local circumstances. !

The causes of the variation in plant life from the base
to the summit of a mountain are primarily climatic.

MOUNTAINS 127

There is a regular decrease of temperature as we ascend.
The rainfall increases up to a certain height, and then it
diminishes rapidly. The density of the air also de-
creases regularly, so that the variations in temperature
from day to night and from sunlight to shade are very
great. This favours strong and frequent winds. At
great elevations winds and the rarefaction of the air

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Fic. 58. Pine Forests in South Canadian Rockies.

cause an excessive evaporation of water. For these
reasons, while the mild or cool but rainy girdles are
heavily forested, those lying above the line of greatest
rainfall, which receive a limited supply of moisture in
the shape of mist, drizzle, and snow, are more favourable
to grass-land. The moisture goes on diminishing until
it is insufficient for grass, and there follows an arid
climate which supports only a carpet of desert plant
forms.

128 MAIN VEGETATIONS OF THE GLOBE

The forested mountain girdles have long supplied the
world with timber, and the upper grass girdles \afford
good summer pasture for cattle and sheep. The steep-
ness of the sides confines cultivation to the bottoms and
lower slopes of the valleys. The forests were the abode
of woodman and hunter, while the grass-lands during
summer were the home of a pastoral population. In
course of time the mountain-forests, attacked at their
lower margins by the ploughman, at their upper margins
by the herdsman, and at their heart by the lumber-
man, have been greatly reduced, and in many cases
destroyed, and pastures have replaced them where the
climate was not too dry. Mountain-forests act lke
sponges, retaining part of the rain that falls on the
slopes, and delivering it gradually to the adjoining low-
lands; their destruction has therefore been attended by
results disastrous to the inhabitants of both highland
and plains.

CHAPTER XX
ALPS

ABovE the timber limit is the alpine zone proper.
On the whole, its vegetation is analogous to that of the
tundra. Its climate possesses, however, well-marked
peculiarities.

The vegetative period is very short, ranging from one
to three months, according to altitude. Beyond a certain
elevation there is practically no period of active growth,
the temperature remaining constantly at or below the
freezing-point. This elevation varies greatly according to
latitude and the general climate, and even from one side
to another of the same mountain, since a more rainy or
snowy side has the snow-line lower than a drier slope.

The regular alternation of day and night in the alpine
girdle of middle and low latitudes, as opposed to the long
summer day and winter night of the Arctic regions, con-
stitutes an important difference between the climates of
the polar and the alpine regions. Its effect is to halve
the time during which alpine plants can take in and ac-
cumulate food materials. On the other hand, sunlight is
~ very much stronger on high mountains than in the low-
lands, and may, indeed, be too strong. As in the Arctic,
the ground is frozen part of the year, and covered with
snow for five to eight months or even more (according
to position and elevation) where the wind is not strong
enough to keep it free.

3159 L

130 MAIN VEGETATIONS OF THE GLOBE

Three smaller belts are usually recognized in the alpine
girdle :

(1) There is a fringe of shrubs above the timber-line. It
may be continuous, or scattered in patches surrounded by
crass, or again restricted to the slopes of valleys. Peculiar
dwarf and gnarled trees, no taller than bushes, strangely
erooked and crawling, often covered with lichens, form

Fie. 59. An Alp. (Photo: Miss H. F. M. King.)

what the Germans call ‘Krummbholz’, or Elfin-wood. It
is composed of various trees in different countries ; in the
Alps it is represented by the dwarf pine and a green
alder. Rhododendrons, azaleas, bilberries, heather, ferns,
and other under-shrubs diversify the landscape of this
fringe.

(2) The grass-belt, which begins in strips on the margin
of the woods and breaks through the belt of shrubs,
now stretches uninterruptedly above the latter. It may

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consist of meadows of juicy grass, brightened with showy
flowers, or of rougher and drier pastures, studded with
the crawling juniper, or again of broken tracts of grass
tussocks, showing the bare soil between them.

(3) Above the meadow limit, at which the grass is
poorest and most scattered, spreads the cold scree-desert,
on stony wastes and rocks, where isolated, cushion-like
plants predominate. Tiny, leathery leaves, coverings of
white hairs, crowding of leaves and short woody stems
packed in tussocks or cushions, strong roots and root-
stocks, large and bright flowers, and crawling rosettes of
leaves, characterize the plant-life of the last belt. Baskets
of dwarf, compact shrubs hang frequently from the
ledges and fissures of the rocks.

The alpine meadows provide grazing grounds for the
pastoral populations, who migrate thither from the hot
lowlands every summer with their flocks and herds, and
erect temporary shelters or summer camps. A similar
custom prevailed in the Scottish Highlands when their
inhabitants were still a pastoral people.

CHAPTER XXI

PUNAS AND PAMIRS

Puna is the name given in South America to high
plateaus of considerable area lying in the cold, arid zone,
some 12,000 to 16,000 feet above sea-level, on the top of
the Andes. These elevated deserts are bounded on each
side by the jagged rims of the cordilleras, and extend
like immense troughs from Peru to middle Chile. The

184 MAIN VEGETATIONS OF THE GLOBE

high plateaus of Tibet and the Pamirs lying at an altitude
-: 15,000 feet possess similar features of climate sa
vegetation.

The punas lie above the line of maximum rainfall,
and receive but little precipitation. Most, if not the
whole, of this precipitation falls as snow during the
winter in daily storms. The air is extremely dry.
Owing to the peculiarly clear and rarefied atmosphere,
with practically no moisture to regulate the effects
of the sun, very great extremes of temperature, both
annual and daily, occur. A severe frost at night,
followed by a fierce heat at noon, is the normal con-
dition, especially on the sub-equatorial punas. Again,
the difference between sun- and shade-temperatures
may amount to as much as 54 F. Hence the rocks
and soil are being constantly split and broken up by the
abrupt changes in volume. Strong, icy winds prevail
the whole year round, sweeping over the broad plateaus
and carrying away the thin mantle of snow as soon
as it falls.

As a result of these conditions salt or alkaline tracts
abound, either as temporary lagoons or as drier patches.
This feature, intimately connected with a bad drainage
and a desert climate, is detrimental to plant life. The soil
is generally very poor, stony, pebbly, or sandy; often
permeated with salt, seldom fertilized by atmospheric or
river deposits, and nearly always parched.

The vegetation that can withstand such conditions
consists of a sparse dotting of grass-tufts and other
low plants. Grass is the chief constituent, and occurs in
bunches, 12 to 18 inches in diameter, mostly circular,
‘stiff, hard, brush-like, and almost always covered with
sand on the side of the prevailing wind, so that only
a segment of the circle vegetates, and even this for the

Lu “~«y

PUNAS AND PAMIRS 135

greater part of the year appears yellowish, grey, ‘or
blackish, as if charred.’ Rocky tracts support a curious
vegetation of cushion-plants of the alpine type. The
short stems, topped with rosettes and densely crowded
together, offer as little grip as possible to the wind.
They build low mounds or cushions, which strong, woody
roots anchor deeply among the rocks. Leaves are
reduced to short, thick scales, pressed against the stems
and protected by a strong, leathery skin. The tubers
and deep thick roots which characterize the low-lying
deserts are also present here.

Such is the high puna, puna brava, the most formid-
able one. There are, however, lower punas, in which life
for both plants and man is just barely possible, and
where in some protected parts even thin, low crops of
northern cereals can be grown. These have more the
character of poor, dry, high steppes.

A somewhat similar vegetation exists in the flat
valleys of the Tibetan plateau.

The punas and pamirs can only be regions of transit,
and are almost uninhabited. They support in Tibet
herds of yaks, wild asses, and sheep, and in South
America, llamas and alpacas, which are used as pack-
animals,

PART II

CONDITIONS OF PLANT LIFE
CHAPTER XXII
FACTORS OF PLANT LIFE

THE preceding descriptions of different vegetations
have shown that there is some relation between plants
and their environments. These environments vary in
character, and among the changing elements are heat,
water, light, wind, soil, and others which we may term
the factors of plant life. It will be useful to consider
each factor in detail and summarize briefly its effect on
vegetation. This we can do only for a few of the more
important factors. In all cases it is very difficult to
separate the action of one factor from that of the others.

A plant is a living organism which is growing con- _

stantly, for it is ever changing and ever increasing its
volume. We can see but a small part of these changes
in the outward appearance of the plant, just as we see in
the external appearance of animals only a minute portion
of all the changes that are continually taking place in
their bodies. In order to grow, a plant requires materials
from outside wherewith to build up new substance and
replace that which is expended. As in the case of

animals, only a limited number of materials serve as

plant-food. ‘These enter into its living, active substance
in very varying quantities.

FACTORS OF PLANT LIFE 137:

Water forms a large part of every plant, and is the
first requisite of living vegetation. Other bodies can
pass into the plant only when dissolved in water, for
plants take their food in a fluid state. Water is thus
of the utmost importance, not only as a food itself, but
as the medium which conveys other food-materials into
the body of the plant. This means that there is a
surplus of water which must be got rid of to make room
for new water laden with more food, so that a constant
stream through the plant is necessary.

Air, or a portion of it, goes to the making of the
living matter, and is therefore another plant-food.

The plant-food, when introduced into it, is inert and
useless. It has to be transformed by the living substance,
or protoplasm, which gradually changes it into living
matter like itself. This can only take place under cer-
tain conditions, the first of which is the presence of an
adequate amount of heat and light. 7

Though these and other requisites exist everywhere,
they do not occur in the same proportions in all places.
Plants differ in organization, each possessing charac-
teristics of its own, and requiring more or less of this
or the other food or condition than another plant.
Every environment has some plants which can live in
it. Each part of a plant has its own partialities. An
amount of water, light, air, &c., which may favour the
growth of the roots may not suit the production of
leaves, the formation of the flower, or the ripening
of fruit and seed.

Plants are not mechanically built, but are plastic and
will alter the number, size, shape, colour, and structure of
theirparts according to circumstances. The whole science
of agriculture and gardening is based on this fact.

Plants require more than food. Many depend on

138. CONDITIONS OF PLANT LIFE

wind, water, animals, heat, and light for the dispersion
of their seeds or the fertilization of their flowers.
Others depend on the nature of the ground for the firm
anchoring of their roots. Others find enemies in certain
animals which may eat or otherwise damage them. Even
among plants themselves there is some sort of inter-
dependence. Certain weeds may crowd out the good
crops. Plants can kill, injure, or drive out each other.
Each plant needs a suitable environment. No plant can
thrive and spread in all environments so as to become
a feature of the vegetation.

CHAPTER XXIII
HEAT

HeAT is extremely important in plant life, From
equator to poles vegetation steadily decreases in size,
luxuriance, and variety, and from base to summit of
mountains a similar reduction takes place. But so many
different agencies are at work, complicating the in-
fluence of heat, that it is difficult to determine what is
due to heat alone. |

Other things being equal, the cooler the climate the
more slowly plants will grow and the smaller they will
be. From uniformly warm climates, if there is sufficient
water, plants of luxuriant growth may generally be
expected, while from uniformly cold climates only smaller
plants with spare, slow growth may be looked for.

Different plants behave quite differently in their
demand for heat. Each part of the same plant has _

aoe Ue A:

HEAT 139

different requirements in that respect. Every plant will
develop best with a certain sequence of temperatures ; it
breathes best at one temperature, sprouts best at another,
leafs best at a third, and flowers best at a fourth. In our
climate many plants require less heat for developing
their flowers than for leafing. Gardeners know this,
and in many cases obtain the growth of flowers or of
leaves at will. |

The extremes of cold and heat which plants can stand
are very important, and these vary greatly for different
plants. Temperatures well above the freezing-point
may kill some plants from hot countries, whereas tem-
peratures of —95° F.(—70° C.) may leave unharmed other
species from cold climates. On the other hand, leafy
plants have been known to thrive at temperatures of
about 160°F. (70°C.), while others, even from warm
countries, were killed or injured at temperatures of 95°
to 105° F. (35° to 40°C.), temperatures which may be
reached in the sun in our own country, or even farther
north, on a very hot summer day.

Sudden transitions of temperature are still more
dangerous than extremes. The fatal effect of a strong
morning sun on plants frozen during the night is well
known to gardeners, who dread the sudden thawing
more than the freezing.

Plants that store a large amount of water in their
tissues, and those which, owing to a very active life,
require a rapid and constant stream of water through
them, are particularly susceptible to extremes of heat
and cold and abrupt changes of temperature. Cacti,
aloes, euphorbias, and other fleshy plants (so-called
succulents) may live in tropical deserts, but all except
the smallest are absent from the colder, extra-tropical
deserts. On the contrary, plants with a spare, slow,

140 CONDITIONS OF PLANT LIFE

wiry, compact growth stand adverse conditions much
better, and are remarkable for their powers of endu-
rance. Such plants are crowded out of places which
favour those with a more active and luxuriant growth.
Through all these influences of heat, direct and indirect,
numerous species of plants are weeded out in any par-
ticular place.

There seem to be many protective devices against
cold or heat, but little is yet known with any certainty
about them. Apparently naked and unprotected plants
are found, even at the flowering stage, entirely frozen for
months at a time, which, when thawed, continue their
growth from the point at which they had been sur-
prised by the cold, to all appearance quite unharmed.
Advantage is taken of this trait by florists for providing
lily of the valley and other flowers out of their usual
season.

CHAPTER XXIV
WATER

WATER exists in the air and in the ground. Most of
the larger plants derive their water from the ground
through the roots, and lose it by transpiration, i.e. they
get rid of it as an invisible vapour through tiny mouths
(stomata) dotted over the skin of their leaves and stems.
An atmosphere containing a large amount of water vapour
is favourable to plant life. Where it exists temporarily
or permanently there is abundant vegetation, conspicuous
for its fresh green aspect. An excess of water in the

WATER 14]

air is only of exceptional and temporary occurrence,
and is apparently harmless. Atmospheric moisture may
be temporarily deficient, as in regions periodically dry
or swept by drying winds, or it may be permanently
deficient, as in the deserts.

Plants are protected in many ways against excessive
loss of water through the leaves and stems. Wind
increases transpiration. As the wind increases in
strength from the ground upwards, and as the taller
a plant is the further away it is from the source of
water supply, plants exposed to drought are generally
shorter, and therefore stouter. The delicate leaves,
through which most of the water is lost, are reduced in
number and size. Their skin is thicker, often protected
by a down of hairs, or glossy and coated with wax,
resin, or varnish. The whole leaf is more compact and
consequently heavier, often rolled inwards. Stems or
trunks are protected by a thicker, rougher bark or
coat of cork. Buds and young shoots become hard,
woody, and often thorny. Conversely, plants that need
not fear loss of water are taller, more slender, especially
trees, and have broad, thin, light leaves, with many
empty spaces inside and many little mouths in the thin
skins. The bark of their stems is thin and smooth, and
breathes freely. Many trees of the tropical rain-forests
guard against alternate excess of rain and drought by
having their leaves divided into leaflets, which move
freely, standing erect and offering only their edges to
the Sun (and turning with it), or drooping in time of
rain, like our common Robinia.

An unlimited supply of ground-water can in most
cases make up for any dryness of the air. An abundant
stream of water in a desert suffices for luxuriant
vegetation on its banks. Egypt is nothing but a narrow,

142 CONDITIONS OF PLANT LIFE

winding strip of country consisting of the well-watered
banks of the Nile,in the midst of a dreary and barren
desert. By conveying water in canals or ditches man
transforms the desert into productive oe This is
called zrrigation.

On the other hand, an excess of der in the ground
may be harmful, by preventing the roots from breathes
freely. In hot countries certain swamp-trees, whose
roots are permanently deprived of air in the stagnant
water, possess special organs which jut out or bend
upwards above the water-level for breathing purposes.
On low, marshy, tropical sea-shores the mangroves have
such breathing roots. Where ground-water is tem-
porarily or permanently scarce, the plants which thrive
best have long and strong roots to tap the water reserves
at great depths below the surface. Eucalyptus trees
are known for the magnificent display they make in
apparently waterless regions, owing to the length of
their roots. In some deserts plants have been found
with roots over forty feet deep.

All kinds of water are not necessarily good for vegeta-
tion. Water containing salts may not be able. to ooze
into the roots, but may even suck water from them.
This is the case in the so-called alkali or nitrate coun-
tries. In many marshes the water contains acids
derived from the rotting marsh plants. In such cases
the ground is worse than dry, and the plants look like
those found in waterless regions—stunted, with small
leaves or none.

Where water is extremely scarce, many plants survive
because they store it in their tissues, give off little or
none, and renew it occasionally. They may be described
as impervious water-bags. In most of them the leaves
are reduced to a minimum; they are greatly swollen

WATER 143

water stores. The baobab, or monkey-bread tree, is the
best-known instance of such water-storing or fleshy
plants. Others are the aloes, agaves, and cacti and
their kindred.

The amount of available water is the most potent,
factor in determining the shape of plants and their mode
of life. Those which have an unlimited supply of it in
the ground and in the atmosphere are tall, with large,
thin leaves. When the supply is limited, plants are
smaller, with smaller leaves protected in many ways,
with long roots pushed down in search of deep-seated
ground-water, which may be stored in their swollen
bodies. The growth and life of the water-loving plants
is continuously active and luxuriant, whereas those in
dry conditions live a slow and thrifty life, a kind of
dormant existence broken by short spells of intense
activity. This is done either by their remaining bare
and apparently lifeless fora long period, or by forming
bulbs, tubers, and succulents for the dry season. In
regions of permanent drought, most plants remain in a
state of almost imperceptible life, in the shape of invisible
seeds. Under the stimulus of an occasional shower,
those seeds which have not perished burst, as if by
magic, into ephemeral and humble herbs, only to die out
in a few weeks, after producing a quantity of fresh
seeds. The capacity of some seeds to remain alive for
many years is quite remarkable.

144

CHAPTER XXV
LIGHT

LIGHT is necessary to plant life, for it is only in the
presence of hight that the green matter (chlorophyll) of
plants can be elaborated. This green matter is essential
for changing the raw materials of the food into the
living substance of the plant. Where the light is too
weak, e.g. under the dense canopy of certain forests,
plants tend to grow long, lank, weak, and pale, with
few leaves and branches, for their wood cannot mature
properly. A moderate light favours the formation of
large, thin, dark green leaves rather than of beautiful
flowers. A strong light produces short plants, with
small, thick, grey leaves, but their flowers are generally
large and brightly coloured.

Excessive light destroys the green matter. In countries
bathed in sunlight the leaves of most plants, especially
trees, move with the Sun, erect or drooping, so as to offer
only their edges to its rays. This is particularly notice-
able where strong and abrupt alternations of excessive
sunlight and rain are of regular occurrence. The mobility
of the leaves in tropical forests is quite striking.

Continuous daylight, such as prevails for weeks and
months in the far north, induces a growth of plants so
intense and rapid that it equals that in more favourable
places. Owing to this it is possible to cultivate cereal
crops in high latitudes, in spite of the short and cool
summers.

CHAPTER XXVI
WIND

Tue drier the air, the more a plant gives up its water
through the whole of its exposed surface, but more par-
ticularly through its leaves and the little openings which
are found in them as well as on the stems and trunks.
If the vapour exhaled by plants is constantly carried
away, this transpiration will increase. This is the chief
effect of wind. When this removal of water is more
rapid than the supply coming through the roots, the
exposed parts are liable to dry up and wilt. In this
way leaves, buds, and shoots are killed by wind-induced
drought. The most unfavourable conditions are found
when a dry wind blows over plants that cannot replace
the lost water by pumping more from the ground, either
because the soil is entirely dry or because it is frozen
and liquid water is not available. Such is the case in
circumpolar lands, deserts, and the alpine girdles of
mountains,

Strong winds may exclude plants with a luxuriant
growth, tall trunks, broad and thin leaves, and may
limit tree growth, as they do round the poles and on
mountains. Even shrubs may be kept out of regions of
strong winds, as is the case in the Pacific Islands, where,
in spite of water, heat, and other conditions which are
eminently favourable to heavy forest growth, mountain
ridges and tops exposed to the winds are destitute of
trees and even tall shrubs. In fact the limit of shrubs,
both arctic and alpine, is in most cases determined by *:
wind. |

1159 K

146 CONDITIONS OF PLANT LIFE

Nearly all means of protection against drought may
be found in very windy tracts—shorter growth, smaller

leaves, thicker and more leathery, with their little

openings all crowded on the under-surface in deep
recesses and grooves. Shrubs and small trees are
dwarfed, bent, and kept close to the ground. Shoots
and buds that stand out alone are killed, with the
result that those which survive are short and crowded
together so as to offer the least resistance to the wind.
The plants are thus either crouching, expanding into
large, low patches, or crawling on the ground. Such
tracts are characterized by tussocks and cushion-shaped
types. In tropical savanas most trees are umbrella-
shaped and in this way present the edge of a wedge to
the wind.

Exceptionally violent gales may uproot whole forests.
Sea winds may carry some salt water which is dropped
on the coasts, where the excess of salt kills most of the
vegetation and reduces the rest to such hardy types of
fleshy plants or succulents as are common in salt
marshes. Winds may also be beneficent. The mon-
soons and many other winds carry rain to the lands.

CHAPTER XXVII
SOIL

Most of the water and the mineral food of plants is got .

from the soil. The amount of water in the soil is of
the utmost importance, too much being almost as fatal
to most plants as too little. The amount of water
held in the soil depends largely on the size of the

gaat’

SOIL 147

particles of which it is composed. Rain quickly
runs off rocky soils or sinks into crevices. On stony,
‘cravelly, and sandy soils, water sinks rapidly as far
as it can and the surface layers are quickly dried by
evaporation: such porous dry soils are often barren.
Loams and marls, which are made of finer particles, do
not allow water to pass so readily through them or to
evaporate so easily. They are generally more fertile.
Clays, black soils, slimes, and muds offer the greatest
resistance to the percolation of water. They are heavy
and retentive, and often become cold and clammy, with
but little airin them. Their surface often dries, becomes
caked, and forms an impervious cover injurious to plant
life.

Loams and marls are on the whole most favourable
soils for vegetation, but their value varies with climate
and other circumstances. The lighter soils do not allow
plants with strong roots to get a firm hold, and are not
suited to heavy growths like forests. Plants with
shallow roots, such as bush or grass, thrive best on
them.

‘In soils where vegetation has grown for some time,
the dead and decayed remains of plants (roots, leaves,
wood) and of animals (insects, worms, and others)
accumulate in the upper layers, making what is called
a vegetable soil. When decomposition goes on with
a sufficient supply of air, moisture, and warmth, gases,
water, and soluble salts are formed which enrich the
soil. This is known as mould. If there is not much
air, water, or heat, a bad, sour mould, or raw humus,
is formed, which is generally harmful to plants. In the
most unfavourable circumstances the rotten remains
accumulate as a dark coloured, spongy, acid mass, called

peat,on which few species can live. Where grass grows
| K 2

148 CONDITIONS OF PLANT LIFE

well the countless small rootlets are so interlaced as to
make a sort of mat, called turf, which becomes imper-
vious to water and air and harmful to higher plants.

Soils vary greatly in the proportion of mineral food
materials which they contain. As in the case of light,
heat, and water, each plant has its own particular
requirements with regard to food, and what may suit
one plant may be poison to another. On poor soils
vegetation grows slowly and remains stunted. Some
plants cannot grow on certain soils; for instance, chest-
nut forests cannot exist on soils containing lime.

The growth of grass on our lawns may be helped and
the growth of certain weeds prevented by watering with
certain solutions. Differences of vegetation are caused
by differences of soil as well as by other conditions.
One of the most remarkable instances of this is found in
salt regions. More than a small amount of salt in the
soil excludes most plants ; but a limited number of herbs
and bushes with small, thick, fleshy leaves and stems
thrive on it. As the proportion of salt increases the
number of these becomes less and less until we find
absolutely bare tracts covered with salt crystals. The
saline vegetations are very like each other all over the
world, whether along the sea-coasts or far in the interior.

CHAPTER XXVIII
THE HABITAT OR HOME OF PLANTS

WHEN we speak of the place where a plant lives we
ought to think of the water, light, heat, wind, soil, &e.,
which are essential to its growth, and not merely of the
space it covers. All these together form the plant's

THE HABITAT OR HOME OF PLANTS 149

habitat or home, where it is able to thrive, spread, and
produce descendants to replace itself when it dies.
When all these conditions are favourable the plant and its
environment are adjusted. The adjustment is seldom
perfect. Climate is often variable, as in our own country.
Plants may be induced to bud, sprout, and flower by
a spell of good weather and then be injured or killed
by a late frost. In many countries one year may differ
considerably from another, the one being dry and hot,
the next cold and wet, affecting some plants favourably
and others unfavourably, and giving a different ap-
pearance to the vegetation.

Plants of quite different characters may be found in
the same region. On the Russian steppes the mild,
rainy spring brings forth a beautiful display of tender,
bright-blossomed meadow herbs and bulbs; but in the
hot, scorching autumn there is only a sea of dry-looking,
grey, woolly vegetation, giving the steppe the appearance
of a semi-desert.

A plant has to reckon with its neighbours both
vegetable and animal. Some of these may not affect it
at all, but others may either help or injure its growth.
On our own hills bracken kills grass, and heather
crowds out bracken, sweet-gale drives heather away,
and in its turn is conquered by peat-moss, which has to
give way before cotton-grass, and so on. On the other
hand, the tender wood-anemone prefers the shelter of
the beech, and the lily of the valley needs the deep
forest mould of the same tree. Many orchids and other
plants live on the bark and in the shade of trees:
creepers require their support, and may eventually kill
them. Many plants feed on the living or dead substance
of others.

The same is true of animal neighbours. Worms and

150 CONDITIONS OF PLANT LIFE

insects may improve the soil and make it more suitable
for the primrose, wood-hyacinth, and other bulbs.
Insects and birds fertilize flowers and help plants to
spread their seed. Slugs, caterpillars, locusts, and others
ravage and lay bare whole tracts of land. Certain
insects spoil the flowers of certain kinds of plants so
that they die away gradually. Leaf-cutting ants may
damage a whole banana plantation. Many birds live
on insects and worms and help to rid our gardens of
these pests. By feeding on fruit, such as strawberries
and gooseberries, they help to spread their seeds.

We must then include animals and other plants among
things which influence the life and distribution of plants.

CHAPTER XXIX
MIGRATIONS OF PLANTS

WE are accustomed to think of plants as fixed and
immovable. Yet we know that they spread. If not
held in check, raspberry bushes overrun our gardens,
and the grass of the lawn encroaches on the paths. The
cacao planter of tropical countries has constantly to fight
back the forest.

Plants spread not only by the distribution of their
seeds, but also by means of their roots and underground
and crawling shoots. They spread by natural cuttings
and by their buds being carried away, and some even
move bodily, swept along by the wind. In these move-
ments they are helped by the rain, river, and sea, by ice
and wind, by worms, insects, birds, and mammals, and
most of all by man. We speak of the migrations of —

MIGRATIONS OF PLANTS 151

plants. We say that the beech and spruce have travelled —
westward. Knowing, that Scotland was once buried
under ice, we say that it has been invaded by the
plants,coming from neighbouring countries. In some cases
we can follow the routes of these migrations or invasions.

When we remember these migrations and the power
of plants to change gradually and adjust themselves to
new surroundings we can understand how, in course of
time, plants have arranged themselves in well-defined
groups. Plants requiring the same climate and soil
naturally grow side by side. In a meadow several sorts
of grasses and herbs grow together. In North Euro-
pean forests the Scots pine and ‘the larch are rivals.
In tropical forests many species, to all appearance equally
suitable, compete for the ground. At the same time,
other plants with different needs may grow between
these. Hazel-nut, holly, rose-bushes, brambles, and many
others thrive under the cover of an oak forest and form
an undergrowth which spreads over the ground between
the trees. Beneath this undergrowth willow-herbs, bulbs,
lesser celandine, and many others take advantage of the
shelter and the mould; while climbers like clematis, ivy,
honeysuckle, and bryony find moisture, soil, and support ;
and ferns, lichens, mosses, and algae colonize the bark
of the trees. In this way each plant uses its neighbours
for its own purposes, and is so used by them that all
render each other mutual services.

Different species of plants with different needs may live
side by side without affecting each other, because they
do not all produce their leaves and flowers at the same
time. Among our wild plants bulbs flower before they
are shaded by the leaves of the shrubs, and these
shrubs blossom before the dark, leafy canopy of the
larger trees diminishes the light. These plant groups

152 ‘CONDITIONS OF PLANT LIFE

or plant associations must be regarded as communities
composed of species with similar requirements and of
plants which have what may be called complementary
needs to theirs. Similar associations are found in widely
separated regions where the general conditions of
climate and soil are similar.

The individual plants may vary in different regions
without affecting the similarity of the association, <A
meadow in North America, in Amuria, or in Europe,
may be composed of entirely different species, yet it has
practically the same appearance, the same mode of life,
the same organization, and is found in similar situations.
The same associations of plants may be found side by side
over wide tracts, where the general conditions are the
same. Combinations of forests, meadows, and marshes
are well known in our country. On the sea-coast
dunes, links, salt-marshes, brakes, heather, clumps of
gorse and broom, alternate one with the other. They
form groups of plant associations or plant landscapes.
The North American prairies, the South African veld,
the Russian and Asiatic steppes, all make similar land-
scapes. The complex vegetation of the Mediterranean
is similar to that of California, the south-west of Cape
Colony, and the south-west of West Australia. These
regions can all borrow ,useful and ornamental plants
from each other, as vines, peach and orange trees,
mimosas, and acacias. |

PART III
SURVEY OF THE CONTINENTS

CHAPTER XXX
NORTH AMERICA

The Barren Grounds. The tundra, which alone can
exist in arctic and sub-arctic climates, covers a narrow
strip along the Bering Sea coast and the northern
lowlands. The Barren Grounds, as the tundra is called
in Canada, extend from the mouth of the Mackenzie to
that of the Nelson River and over the northern part of
Labrador. The wealth of flowers which converts the best
parts of the Alaskan tundra into gardens gives way
further east to extensive tracts of lichen-tundras, above
the level of which the dwarf, crawling shrubs hardly
rise. These boundless wastes are inhabited by a scattered
population of backwoodsmen—Indian and white hunters
and traders, who hunt the caribou and moose, the fox,
and other fur-bearing mammals, also the birds which
have their home there. Temporary settlements, often
mere wooden forts and trading posts, are scattered along
the rivers, which afford natural routes for traffic, while
their wooded banks provide the necessary timber.

The Scattered Forest. Further south, from the
Alaskan and British Columbian plateaus to the eastern
point of Labrador, the tundra becomes more luxuriant
and dotted over with trees and clumps of trees, mostly
birches and conifers; this may be termed the sparse
or poor forest, which supports the woodman to some
extent beside the hunter.

154 SURVEY OF THE CONTINENTS

The Cold Forests. A less forbidding climate is

necessary for the dense, continuous forests, chiefly of
resinous trees.

These cover a large tract of North

~

i was my

(EUR
Ue iN

feiils

“| (1) & Coniferous

= Pacific ‘Temperate

YA, »Aediterranean

= epebies Temperate

SS i, oe C-4 Ste ppe
Me Hot Wet 5 Park Steppe
TA*Mountain [_) Scrub

fi) Savana CJ Desert

Fig. 62. Vegetation of North America

America from ocean to ocean almost uninterruptedly,

and stretch southwards in long tongues over the elevated
eastern and western regions

The Northern Forest extends from the Rocky Moun-

NORTH AMERICA 155

tains to Newfoundland. It is narrow in the west, where
the drier climate of the prairie pushes it to the north,
but it gradually broadens to the east in the region of the
Great Lakes, where the rainfall is more abundant. It
consists of a variety of pines, firs, spruces, larches,
hemlock-spruce, cedars, and other conifers, mixed with
birches and aspens. The felling of large quantities of
timber for paper-making together with forest fires effect
vast clearings every year.

Nearer the Great Lakes, where the climate is milder,
the Canadian forest becomes more luxuriant. Numerous
species of broad-leaved trees, of well-known European
types, such as oak, maple, ash, and chestnut, but in much
greater variety, form both pure and mixed woods. The
landscape becomes increasingly varied. Fruit and dairy
farming become important.

The Eastern Forests. Along the Appalachians this
mixed vegetation is found as far south as North Carolina,
with increasing variety and profusion. Many kinds of
hard-woods, tulip trees, magnolias, elms, walnuts, chest-
nuts, beeches, oaks, birches, and maples, appear mixed
with a few stately conifers, while rhododendrons, kalmias,
and diverse evergreens beautify the undergrowth. The
upper girdle of the mountains is one of conifers.

The Appalachian region has a more generous climate
than the Lake region, though more extreme than that of
western Europe. It was very heavily forested with
deciduous trees, of greater luxuriance and variety and so
forming a richer vegetation.than our own forests. Their
equivalent is found on the rainy south-eastern shores of
the Black Sea. According to situation broad-leaved trees
are mixed with or alternate with conifers.

The Allegheny Plateau sloping to the Mississippi is
(or was) clad with a similar broad-leaved forest, inter-

156 SURVEY OF THE CONTINENTS

rupted by glades of grass and a broken belt of cypress— ,

the ‘Cedar Glades’. Towards the west, as the rainfall
diminishes the forest becomes lighter, drier, lower, and
more open with many grassy areas. It gradually passes
into a park landscape of the temperate type which
fringes the central prairie from north to south.

The Plains. In the south-east the Appalachian region
is bordered by a drier, sandy belt where pines grow.
The poorer parts are called the Pine-Barrens.

Beyond this is a narrow strip of sub-tropical evergreen,
broad-leaved forests, extending over the coastal flats.
This frequently passes into wooded coastal swamps
where cypresses, palms, and other sub-tropical trees
play an important part. This coastal belt gradually
broadens on the shores of the Gulf of Mexico, round the
Mississippi delta, and in Texas.

To the west of the park landscapes of the Mississippi
valley is a belt of brush-prairie or bush-steppe, where
open woods appear only as islands. Beyond is the
great treeless prairie or steppe, which extends far
into Canada and gradually rises to the foot of the
Rocky Mountains. In places the prairie is broken
by poorer sand-hills, and in Dakota by the barren,

broken region known as the ‘Bad Lands’. In the south- |

west the prairie becomes drier and gradually disappears.
There is an arid region with thorns, stiff grass, and
cacti in western Texas and New Mexico, beyond which
lies the semi-desert of North Mexico.

The Western Mountains. In the west, the three
parallel mountain ranges running from Alaska to Mexico,
in spite of varied climates from north to south and from

west to east, are essentially the domain of resinous

forests, whereas the plateaus and troughs separating
them have a more arid character. From west to east,

ey P
er
hai Oe te

NORTH AMERICA 157

the rainfall decreases rapidly and the climate becomes
more extreme; consequently the coniferous forests are
lower, drier, and more scattered, the poorest ones being
found in the Rocky Mountains.

The Coast Range is open to the moist winds of the
Pacific and enjoys an equable, temperate climate. The
heaviest and densest coniferous forests in the World are
found in thisarea. The resinous forests are of unequalled
luxuriance in the centre of the range, near Vancouver.
Farther north, as the cold increases, they get gradually
poorer; while farther south, as the rainfall diminishes,
the vegetation passes gradually to the almost desert
forms of Lower California. The much drier Cascade
Ranges show the same gradual impoverishment south
and north of the state of Washington. The eastern
slopes have clearer forests than the Pacific slopes. The
Sierra Nevada is remarkable for its giant trees (Sequoias
or Big Trees).

Still farther inland the third and driest type of
coniferous forests is found in the Rocky Mountains.
Again there is a centre of greatest luxuriance in Montana,
from which the richness diminishes through drought in
the south and through cold and wind in the north. In
these three chains the forests are similarly arranged in
altitude. The lower slopes are too dry, and the upper
ones too cold, windy, and dry for timber, but between
them there is an intermediate zone of greater rainfall
which supports dense forests. The wealth and variety
decrease upwards and downwards from this central level.

From Vancouver northwards the trough between the
Coastal Chain and the Cascade Ranges is under the sea.
Farther south the trough is known as the Californian
Valley. It possesses a dry, sunny climate, but snow-fed
streams from the southern Cascades and the Sierra

158 SURVEY OF THE CONTINENTS

Nevada provide sufficient water for irrigation. Originally
the valley was a park landscape with grass-land, scrub,
and clumps of hard and broad-leaved woods, similar to
the Mediterranean trees and shrubs. By a judicious
use of the water it is now almost entirely utilized for
agriculture, cattle-breeding, and fruit-farming.

The Cascades and Sierra Nevada are separated from
the Rocky Mountains by a series of high plateaus,
known as the Yukon Plateau, the British Columbian
Plateau, the Snake Basin, and the Great Basin, most
of which are arid or semi-arid tracts. The British
Columbian Plateau is covered by the scattered Northern
Forest, like the Yukon Plateau. The Snake Basin may
be described as a treeless plain, mostly of dry grass-land
and sage-brush. In places the climatic aridity is ac-
centuated by the porous nature of the lava which covers
vast expanses. The Great Basin, with its hundreds of
small rocky ranges, is a vast sage-brush tract cut off by
the Cascades and the Sierra Nevada from the moist
Pacific winds. The short, parallel ridges have rocky
slopes, dotted with low stunted trees such as junipers,
rock pines, evergreen oaks, and scrub, which can hardly
be said to constitute a forest.

Between the Wahsatch and the Rockies lies the
Colorado Plateau, a monotonous succession of broken,
slanting tablelands, deeply trenched by steep canyons
and crossed by a number of ranges. Though the climate
is on the whole semi-arid and extreme, the landscape has
a certain variety. There are meagre pastures of short
grass on the tops or mesas, brushes of sage-like bushes
or salt-marsh succulents in the valleys, especially in the
Rio Grande valley; clear, scattered, and interrupted
forests of pines on the slopes of some canyons and
ridges, with patches of them here and there on the

NORTH AMERICA 159

plateaus, and small, isolated tracts of wooded alps. The
Black Table, or Mogollon Mesa, has a last belt of
coniferous forest on the south-west before the plateau
sinks abruptly by a great escarpment down to the level
of the Mohave-Gila desert. This has an extremely arid
vegetation, with sparse dry, bald thornbushes, and
a wealth of prickly sueculents—cerei, cacti, prickly
pears, yuccas, agaves, and others.

Mexico. The Mexican Plateau slopes from the
Anahuae Plateau, over 7,000 feet in the south, down to
the Rio Grande in the north. It assumes an increasingly
desert-like appearance from south to north. The northern
and lower portion is little more than a desert with
extensive plains covered with a monotonous carpet of
low, woody, evergreen shrubs, conspicuous among which
is the ‘guayule’ rubber bush, and inland basins with
salt bushes. The southern and more elevated portion is
of a less forbidding type. It is more of the nature of
a high steppe, much transformed by cultivation. Vast
grassy expanses with agaves, marshy plains, thorny
scrubs on rocky wastes, and cornfields, betoken a more
favourable climate. The jagged rims of the plateau and
the steep slopes which sink down to the hot plains are
covered on their upper slopes with stately forests of
conifers, but lower down they display a more and
more tropical character. The western slopes and the
plains (except for the malarial coast swamps and
the valleys) are largely covered with scrub and light
woodland, but the moist hot eastern slopes display the
luxuriance of tropical forests. On the rich coastal plain
of the Gulf, savanas and sub-tropical woods alternate in
the north; but the south, except for the drier savana of
Yucatan, is heavily timbered, though much of it has
been cleared for cultivation.

160 SURVEY OF THE CONTINENTS

Central America. The same characteristics are
common throughout Central America. The wetter
eastern lowlands, open to the trade winds, are the home
of dense equatorial selvas, whereas the drier western
lowlands show more of the lighter monsoonal woodlands
and savanas. Above 3,000 feet the hill-sides carry
a belt of moist temperate evergreen forest, with bamboos
and tree-ferns. The higher slopes and summits are
covered with shrubs, passing to drier alpine steppes.

CHAPTER XXXI
SOUTH AMERICA

The Selvas. One of the most notable features of
South America is the Amazonian selva. A low plain,
extending over 2,000 miles inland, subject all the year
round to heavy and continuous equatorial rains, in a
damp, cloudy, sweltering atmosphere, flooded periodically
over vast areas by abundant streams and chiefly by the
greatest of rivers, the Amazon, is the home of the densest
and most extensive of equatorial rain-forests. What may
be described as fresh-water mangrove—the Igapi—forms
a belt, with giant weeds closing over an uninterrupted,
sombre vault, follows the course of the main river and
its countless tributaries, and covers the flood-plain for
miles on either side. Beyond the zone of these flood-
forests extends the more luxuriant and less forbidding
rain-forest, known for its rubber, Brazil-nuts, and other
products. The low ridges between the principal tribu-
taries are clad with lighter woods, interrupted by glades.

Savanas, Campos, and Llanos. These extend north and

161

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SOUTH AMI

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Fic. 63, Vegetation of South America,

L

162 SURVEY OF THE CONTINENTS

south of the selva on higher ground, with a long dry season.
The country has a gently rolling appearance, and forms a
park landscape of the tropical type, with tall grass on the
ridges and open, clear, dry woods standing like islands in
the valleys. These lands are rich in pastoral and agricul-
tural possibilities. They are known as campos in Brazil.

The Guiana tableland, rising in terraces to Roraima,
has savanas of an analogous type, also called campos,
with an increasing proportion of light woods in the
higher terraces. They descend in the west to the
grassy lowland plains, or llanos, of the Orinoco. Here
occasional groves or even isolated palms and river-woods
are also found. The Orinoco itself favours the growth
of heavy fringing forests on its banks.

Higher Eastern Tablelands. In the higher and

more broken eastern Brazilian Highlands the scenery
is more varied. Dry woods and scrubs are conspicuous.
Light open woods (campos serrados) occupy the depres-
sions of the savana. The tall and forbidding thorny
scrubs called caatingas are found in abundance, especi-
ally in the north. The rocky slopes of ridges above
these are covered with the lower, poorer, and more
open scrub of the carrascos, full of cacti and cactus-
like succulents. Still drier and poorer tracts, called
sertoes, display scattered shrubs, short, stunted, and
thorny, and tufts of stiff grass and perennial herbs.
On the west these forms of dry, woody vegetation give
place to the savana. ‘Towards the tropic of Capricorn
the campo gradually loses its tropical luxuriance and
becomes park-savana, where the ridges are grassy and the
valleys are covered with sub-tropical evergreen woods.
In Southern Brazil, from the sources of the Rio Grande
to the Serra Geral, on the broken tableland 1,500 to

3,000 feet high, grass-land alternates with open forests.

©

SOUTH AMERICA 163

of araucaria, in which the yerba maté, or Paraguayan
tea, is frequently found as underwood.

The Plate Basin. <A quite distinct region is formed
by the Parana-Paraguay-Pileomayo basin. The upper
valleys of the Parana and Paraguay, trenched in the
Brazilian plateau, as well as the broad basin of the
Alto Parana, are covered with a tall and dense forest
of the moist sub-tropical type. The wide flood-plains
lower down, which the mighty rivers cover every year
with muddy deposits, are practically one vast, shallow
swamp, crossed by natural dykes and strips of grassy
higher ground. The parts left dry by the retreating
waters are quickly overgrown with low herbs and grass,
which form excellent pasture. A broad strip of the
strange, light, small-leaved quebracho-forests, with a
heavy underwood of evergreen shrubs, fringes the swamp
region on the west of the Paraguay River, in the Chaco,
whilst, east of the same river, stretch vast and marshy
pastures in a framework of wooded rises.

The Pampa. On the south-west of the great Parana
swamps lies the boundless pampa, ‘ the space’, a rolling
sea of treeless grass, the home of innumerable herds of
cattle, deer, ostriches, and horses. As it approaches the
Andes it gradually changes to a semi-desert with scat-
tered thorny scrub which extends to the foot of the
mountains, and has received the names of espinal and
chafaral. The chajiar is a dry, thorny, acacia-like shrub.

Patagonia. ‘The espinal is also found south of the
Rio Negro in the vast Patagonian semi-desert—a desolate
tract of shingle and sand dotted with solitary tufts of
stiff grass and low, stunted, gnarled bushes, under a clear,
cool sky. Where the tapering tail of the continent ex-
tends farther into the belt of westerly gales, and the

range of the Andes becomes lower, a little more rain
L 2

164. SURVEY OF THE CONTINENTS

becomes available. The southern point of Patagonia and
the north-eastern part of Fuegia has a broken, tree-
less steppe of grass tussocks suitable for sheep pastures.

The Andes. Through 4,500 miles, with altitudes rising
to 23,000 feet, the stupendous chain of the Andes may
be said to summarize the vegetations of the whole World.

The eastern slopes, from Venezuela as far south as
the Chaco, receive enormous quantities of rain, and are
drained by many mighty rivers. The luxuriance of
their rain-forests is unsurpassed. They are hot in the
lower parts, temperate higher up, and pass into sub-
alpine shrubland and alpine pastures.

From the Chaco to Patagonia the eastern slopes become
semi-desert, rocky wastes with solitary clumps of low
trees in their gorges, and sprinkled with dry sage- and
acacia-like bushes and thorny leafless cacti. Towards
the river Chubut the eastern slopes begin to share in the
forests of southern Chile, with austral beeches. These
descend to the plain, where they stretch along the foot of
the range down to Fuegia.

The western slopes are more varied in their vegeta-
tion. In Columbia and Ecuador they are covered with
lighter tropical forests. Farther south the narrow
coastal strip and the western slopes, though exposed to
fog and dew, are rainless and desert. The aridity is most
marked in the broad strip called the Atacama desert.

South of 30° §. the conditions improve considerably.
The vegetation is of the hard-leaved mediterranean type.
The Chilean valley is used for mediterranean agriculture.
From 40° S. to the extreme point of Fuegia, the western
Andes and islands, exposed to westerly storms, are
covered with: valuable conifers and austral beech rain-
forests of the cool, temperate type.

The Columbian Andes form lofty parallel ridges, with

SOUTH AMERICA 165

deep and narrow valleys between. Dense hot forests
clothe most of the wet bottoms, followed by succes-
sive zones of temperate and cool forests. The bleak alpine
zone, called Paramos, is covered with a dry, dwarfed
grass and low bush.

The high plateaus, hemmed in between the higher
cordilleras, like those of Bogota and Quito, are temperate
in climate and vegetation. They have become centres
of population and development.

The Peruvian, Bolivian, and North-Chilean Andes
contain broad and extensive plateaus lying at great alti-
tudes, and suffering from a dry and extreme climate.
These arid Punas are thinly covered by a treeless
grass-land. Some of the lower and moister portions grow
meagre crops of northern cereals, but the higher and
bleaker Punas Bravas are hardly more than deserts.
The Punas, with their alkaline tracts, or salinas, descend
by terraces and cordilleras to the coastal Atacama desert.

CHAPTER XXXII
AFRICA

Tue Dark Continent has no vegetation familiar to us.
It isa hot land with extremes of drought and of moisture.
Only the higher slopes of the plateaus and mountain
ranges enjoy a cool, temperate climate.

Barbary. The north-west corner of Africa, separated
by the Atlas ranges from the rest of the continent, is
relatively well watered. In its valleys and on its long
slopes and plains are fertile lands of olive-yards and

166 SURVEY OF THE CONTINENTS

orange-groves, with hilly belts of evergreen oak and
cedar forests. This hardly seems a part of Africa. It
belongs to the South European or Mediterranean region,
with its hard-leaved, evergreen vegetation.

Sahara. The great tropical desert of the Sahara,
with its deadly seas of sand dunes, its vast bare floor of
clay and stone, its scattered rocky blocks of hills stand-
ing like gigantic ruins, its network of waterless river-beds,
its chains of oases and wells, is the most remarkable
feature of this continent. It is a land of thirst, where
the eye occasionally meets a tuft of grass, a half-buried
tussock of apparently dead sticks, or a low thorny
shrub. In shallow troughs and round springs the palm
groves called oases break the monotony of the desert.
Man with his train of camels wanders along from well
to well and from oasis to oasis.

Egypt. The most remarkable of these oases is the
long trough winding through the desert, only a very
few miles broad, watered by the Nile and known as
Egypt. But for the Nile, Egypt would be the same
desert that extends on both sides. Thanks to the water
it is able to grow nearly all crops, and its fertility is
proverbial. In the north the Sahara passes gradually
into very poor steppes of esparto grass and sage-brush.
Arabia, in point of vegetation, continues the Sahara
eastwards. The southern hilly margin of this plateau,
however (the ancient land of the myrrh and frank-
incense), constitutes a fertile belt between the desert
shoreland and the arid interior. It conceals in its
secluded valleys an unexpected wealth of woodlands,
gardens, and orchards of a sub-tropical character. The
heart of the desert is occupied by a large group of oases.

Sudan. The Sahara passes through a belt of semi-
desert, a thorny scrubland, into the vast grassy parkland —

AFRICA 167

known as savana. The Sudanese savana extends from
ocean to ocean across the whole breadth of Africa, on
a higher tableland than the Sahara. Its grass supports

Mediterranean Veg"
LJ Desert & Poor Serub
Scrub

Steppe

Mountain Forest & Grass
Park Land (Savana)
MB Hot Wet Forest

Fie. 64. Vegetation of Africa.

innumerable herds of cattle, both wild and domesticated.
Vast tracts suitable for cultivation, often naturally
indicated by groves of palms and other trees, offer
opportunities for prosperous agriculture. It has con-

168 SURVEY OF THE CONTINENTS

sequently developed at different times higher types of
civilization, and its possession has been disputed by
many races and nations, both pastoral and agricultural,
nomad and settled, while it has been plundered periodi-
cally by the less fortunate dwellers in the desert. The
savana stands as a favoured belt between the arid Sahara
and the formidable equatorial forests to the south.

The Equatorial Forest covers most of the slopes and
plains descending to the Atlantic along the shores of the
Gulf of Guinea and the greater part of the Congo basin,
which lies within the belt of heavy rains. So over-
powering is the luxuriance of nature under the hot, wet
equatorial climate that man is practically crushed out.
Only temporary human settlements are found, and these
of the humblest type, in constant struggle with the
forest which relentlessly closes in upon all attempts at
clearing. ‘The Congo basin is a circular, plain-like
tableland, 1,500 feet above the sea, surrounded on all
sides by the edges of higher plateaus.’ Its heavy forest,
interrupted by belts of lighter woods and vast glades of
savana, extends almost to the western rift.

Beyond the equatorial rain-forest of the Congo basin
the great African savana resumes its hold on the higher
South African plateau, which rises as it approaches
the scarped edge of the Drakensberg. The landscape
is a monotonous succession of tablelands at different
levels, here deeply trenched by rivers flowing to the
ocean, there hollowed into large shallow depressions,
without outlet, made marshy by sluggish streams which
die out in salt-pans. Gradually, with increasing latitude
and altitude, the Zambezian savana loses its tropical
character and assumes the type of sub-tropical park
landscape known as Bushveld. Farther south this is
succeeded by the treeless grassy veld.

AFRICA 169

Southern Deserts and Semi-Deserts. In the west, as
the distance from the south-east trade increases, the
rainfall becomes more scanty and uncertain; the grass-
land becomes poorer and poorer, and gradually passes
into a broad semi-desert, the Kalahari, with scanty patches
of grass and thorny bushes. Westward it assumes
a typical desert appearance, and joins the Namib desert
across the Damara-Nama plateau. Beyond the High
Veld in the south are two long mountain-bordered
terraces, the Karroos, which receive little rain and grow
thirsty scrubs and bulbous plants.

All these countries are pastoral rather than agricultural.
Until recently they were well stocked with game and
formed a paradise for the hunter. They suited nomadic
rather than settled life.

The South. The extreme south of Africa lies in the
belt of westerly winter storms, and has the benefit of
winter rains along its southern shores, which accordingly
possess a mediterranean type of vegetation.

The South-east. Thanks to the trade winds, the south-
eastern margin of South Africa enjoys summer rains
and a comparatively luxuriant vegetation. Natal rises
in successive terraces from the sea and has, at least in
the lower ones, a semi-tropical character; but, perhaps
on account of the wind, it is not forested to any large
extent. Like the coastal plains farther north, the
vegetation consists of tropical, deciduous, light woods
and scrubs. On the middle and upper terraces there is
a grass-land to the south, and a park savana to the
north—a spur of the Zambezian savana.

The Eastern Coast and Tableland. ‘Towards the
equator the vegetation is more varied. There are
(a) fringes of swampy mangrove along the sea and the
main rivers; (0) tracts of hot wet forest on the lower

170 SURVEY OF THE CONTINENTS

eastern slopes of the mountains and in other moist
situations ; (c) lighter tropical woodlands, savanas, and
drier tropical scrubs. North of the equator the climate
is drier and North-east Africa is an arid region of grass-
lands in the south-west and poor scattered acacia
scrubland towards the east and north. The high
equatorial plateau east of the western rift is mostly
covered by a high savana and thorn-woodland, except
for the marshy fringes of the Victoria and other lakes.

Abyssinia rises out of a drier land. It is a very
much dissected tableland, with heavy summer rains and
a cool climate on the top. It is covered mainly with
pastures and scrublands. The loftier mountains and
some of the valleys possess noble forests.

Madagascar, an outlying fragment of the African
tableland, falls by a steep escarpment to the Indian
Ocean on the east, while it sinks by a succession of
terraces to sea-level on the west. The uppermost
plateau is covered with savana, while the eastern slopes,
which receive very heavy rains, have dense forests of
the equatorial type. On the western terraces there
spreads a variety of lighter tropical woodlands, savanas,
scrubs, and the south-west, which receives the minimum
of rain, is even semi-desert.

CHAPTER XXXIII
AUSTRALIA AND PACIFIC ISLANDS

Australia may be regarded as a tropical desert sur-
rounded by a fertile margin. From all sides sea winds
blow in at one season or another towards the interior of
the continent. Their moisture is precipitated on the

AUSTRALIA AND PACIFIC ISLANDS 171

more or less interrupted belt of higher land which
encircles it. Accordingly we find a roughly concentric
arrangement of the vegetation: a belt of woodland,
a belt of savana, a belt of serub, and the desert succeed

MB Hot Wet Forest

BSE Summer Rain Forest Savana

Ze Winter . " Scrub

Steppe LJ] Desert
14

Fic. 65. Vegetation of Australia.

each other from the coast to the interior. There are,
however, many variations of this general plan.
Northern Australia. The northern coast receives the
benefit of a strong summer monsoon, which varies in
strength from year to year. In the absence of any high

172 SURVEY OF THE CONTINENTS

mountain range the precipitation over the coastal belt is
not so large as it might otherwise be. As this region
lies well within the tropics, the landscape is one of light
tropical woods of the drier monsoon type, frequently
broken by grassy glades. The vegetation is, on the
whole, deciduous. The hot wet equatorial type of forest
is found only in tracts with sufficient ground water.
Mangroves fringe the coast here and there.

The North-East. In the north-east, especially on the
eastern slopes of the Eastern Highlands, the amount and
continuity of rainfall are sufficient for a dense forest
resembling the great equatorial selva. This is found only
here and there in patches.

The Eastern Highlands. [From the tropic of Capri-
corn southwards the forests that clothe the seaward
slopes of the Eastern Highlands are of the luxuriant
moist type of warm temperate countries, with tall
eucalyptus as the dominant feature. On the western
slopes the climate is much drier, and the vegetation
is chiefly remarkable for its thin forests of shadeless,
bark-shedding eucalyptus, with a grassy undergrowth.
Farther inland, at lower elevations, these light woods are
broken by still drier scrubs studded with clumps of
acacias and other trees, and by grassy glades of savana,
stretching on to the grassy belt that encircles the arid
interior.

The South. Both southern extensions of Australia lie
within the belt of westerly storms in winter, more so
than the southern fringe of South Africa. They there-
fore have a mediterranean type of evergreen vegetation.
This is especially the case in the south-west, where all
mediterranean produce can be successfully grown, and
vine, orange, olive, and other fruits are now cultivated.
The northward incurving coast of the Great Australian

AUSTRALIA AND PACIFIC ISLANDS 173

Bight is less fortunate in this respect, on account of its
more northerly position. Its grassy savanas are now
cultivated, and hard varieties of wheat are doing well.
The belt of mediterranean vegetation which it interrupts
is continued in the east along the slopes of the Highlands
of Victoria.

The Scrublands. Apart from the park-like savana
with its fringes of tall eucalyptus along the rivers, one of
the most striking features of the vegetation of the interior
of Australia is the dreaded scrub—boundless solitudes of
evergreen, small and thick-leaved, sticky, dull green
bushes, waterless and trackless, which form a broken
belt round the grass-lands. Different varieties of it
are known as the Mallee, Brigalow, and Mulga scrubs
and heaths. The Mulga is the poorest and most open
type, consisting of scattered shrubs and tufts of wiry
grass and saltbushes, not unlike the alfa steppes of North
Africa. It is found around and mixed with the sandy
deserts, penetrating far into the interior of the continent,
especially along the eastern margin of the Western
Tableland.

The desert itself is principally found on the Western
Tableland, with smaller tracts in the Central Lowlands.
It is very similar to the Sahara, but without the charm
of its oases. The camel has been introduced as the only
means of crossing it.

New Guinea. The southern lowlands of New Guinea
have similar vegetation to that of north-east Australia,
but owing to the greater rainfall it is more luxuriant.
Here is found a mixture of every variety of forest of the
monsoon type, and in places, of the dense equatorial
selvas and swampy forests. The northern part, separated
from the southern by a lofty mountain barrier, and
much more rainy and hilly, is clad, as far as we know,

174 SURVEY OF THE CONTINENTS

with luxuriant and continuous equatorial rain-forests
and wooded bogs. The long mountain ranges which run
along the axis of the island have a succession of equa-
torial and moist temperate rain-forests.

New Zealand. The North Island, with an equable,
mild, and rainy climate, supports a heavy and valuable
rain-forest of the warm temperate type. The South
Island is more diversified. The western slopes of the
New Zealand Alps receive much rain from the westerly
winds, and are heavily clad with temperate rain-forests
of antarctic beech. The drier eastern slopes and plains
are covered with grass and woods, not unlike the medi-
terranean type.

Pacific Islands. The countless islands of Oceania
have this in common: that they lie in the inter-tropical
belt, enjoy a warm and wet equable oceanic climate
without drought or cold. They are spots of equatorial
selva, generally of a lighter type.

Austral Islands. The few islands of the Austral
Ocean are in a zone of constant rains and gales and of
cool equable climate. All of them treeless. They have
good grassy pastures.

CHAPTER XXXIV
ASIA

ComPARING Asia with North America, the same succes-
sion of vegetation from arctic tundra to equatorial rain-
forest is apparent, as well as a similar distribution of
inland deserts and moister coastal tracts.

The Tundra. ‘The southern limits of the arctic tundra
lie farther north in Asia than in America. The moister
mossy tundra seems to be more abundant than the lichen
type which prevails in the Barren Grounds of Canada.

ASIA 175

The Taiga. South of the tundra lies the most exten-
sive coniferous forest of the World, one of its undeveloped
assets. This, the Siberian taiga, stretches almost con-
tinuously from the North Sea across the Urals, the

re

=

Tundra &Lofty Mountain =, Taiga or Pine Forest M1, Steppe
Cool Deciduous F. =, Mediterranean ZZ, SummerRainE Bees
Monsoon & Equatorial F Mmmm Savana B22 ScrubE=] Desert CC _]

Fie. 66. Vegetation of Asia.

lowlands of Northern Asia to Kamchatka. Western
Siberia, however, is an exception, for it is very flat and

badly drained, and is covered with morasses and marshy
forests. The taiga is not yet inhabited, and has hardly
been opened up except on its southern margin.

176 SURVEY OF THE CONTINENTS

The Steppes. [ringing the taiga on the south, at
about 55° N.,is a belt of park steppe, mainly composed
of grass-lands with clumps of birch of various sizes. It
forms a transition to the Asiatic steppe, and is a valuable
belt both for prosperous farming and easy routes.

Deserts and Scrublands. Next comes the vast arid
belt that stretches across Asia from the Mediterranean
almost to Amuria, covering lowlands, terraces, and huge
mountain ranges alike. The great deserts of Asia differ
from the Sahara in having greater extremes of tempera-
ture, both daily and seasonal, while excessively hard
winters are added to the horrors of the hot summer desert.

Around the desert belt vegetation is, roughly speak-
ing, arranged in parallel bands. The steppe is the outer-
most one. Between it and the desert is a loose brush of
low, stunted, dry evergreen bushes and dead grass, which
passes gradually into a low, scattered heath of bare or
small-leaved and woody shrubs like tamarix, saxaul, and
calligonum, and on salt soils, a threadbare carpet of thick-
leaved saltbushes. Beyond this is the desert where even
these outposts of vegetation disappear before the shifting
sand dunes among which the snow-fed rivers vanish.

Turan andits Borders. The Karakum (Black Desert)
and Kysylkum (Red Desert) of Turan are the western-
most deserts. They are bordered on the north by the
great Kirghiz steppe which succeeds the birch-steppe,
and are prolonged westward to the Caspian across the
Usturt plateau. In the middle of Turan lies the Aral
Sea, into which the two mighty rivers, the Amu- (Oxus)
and Syr-(Jaxartes) Daryas, fed by the snows of the Pamirs
and the Tian Shan, empty themselves. Along the banks
of these streams the water makes the ground fertile and
spreads a chain of oases. Man will soon reclaim wider
belts along these rivers by irrigation, and transform them

ASIA 177

into new Egypts. Bordering the desert, along the north-
western foot of the high mountain wall and penetrating
far into its recesses by the valleys of the Chu, Syr,
Zerafshan, and Amu, a belt of foot-hills and terraces
is fertilized by the waters from the mountains. Tree
growth is here mostly confined to the riverside (though
orchards are not uncommon),and the vegetation resembles
that of the steppe. Irrigation makes cultivation possible.

The western part of the Tian Shan and Alai ranges, as
well as the chains of Khorassan, condense the moisture
of the northerly winds and are on the whole fairly well
provided with water, especially in winter and spring.
They have the same series of zones of vegetation: culti-
vation on the foot-hills, rich grassy pastures farther up,
then a belt of conifers, followed by alpine or summer
pastures below the bare ridges. Between the summer
pastures and the winter meadows the herds and herds-
men move up and down with the seasons.

Iran and its Borders. The high plateau of Ivan,
screened by the higher rims of Elburz and Khorassan
from the north winds, is swept by dry icy gales and
exposed to great extremes of temperature. There the
high treeless steppe of short grass surrounds arid
depressions or salt-pans with the usual carpet of low,
fleshy salt-bushes and heaths of tamarixes. This is
especially the case in Khorasan and Kuhistan. The
broad plain of Ispahan more closely resembles an alpine
pasture, and where it is watered it has rich meadows.
The oases have magnificent gardens sheltered by high
walls. The mountain ranges which cross the plateau,
like those of its margins, contain fertile valleys with
good pastures and are more thickly peopled than
the open plain. Eastern Iran resembles Turan in its
deserts and salt tracts surrounded by meagre steppes and

1159 M

178 SURVEY OF THE CONTINENTS

scattered brushes along the foot of the outspurs of the
Hindu Kush, with oases along the rivers. The valleys that
diverge west and south from the Hindu Kush are centres
of agriculture and population, and owe their relative fer-
tility entirely to the snow-fed rivers.

The southern wall of Iran extends continuously from
Armenia through the Zagros chain to India, and is formed
of a succession of cliffs and terraces. Amid the wilder-
ness of bare craggy ridges and precipices, however,
a number of terraces and moist valleys shelter secluded
little oases of gardens, fields, and orchards, and even low
evergreen forests of a mediterranean type. The southern
parapet of Iran rises above a narrow fringe of sun-baked
desert, studded with palm oases.

The Tarim Basin, Zungaria, and Mongolia and their
Mountain Borders. The plateaus extending from the
Pamirs to the Khingans are enclosed on all sides by high
mountain barriers and shut off from rain-bearing winds.
Their relatively high latitude and the absence of moisture
render them extremely hot in summer and extremely
cold in winter. The chief plantless centres are found in
the Tarim basin and in the Western Gobi. The Tarim
basin is mainly covered by the Takla Makan desert, a sea
of shifting dunes. The narrow margin between it and
the mountains is occupied by concentric girdles of heath-
like brushes, marshes, and coarse winter pastures, of oases
on alluvial fans, of gravel wastes, and cultivated terraces,
above which, on the mountain slopes, summer pastures
extend. A similar arrangement is found on a larger scale
in the Gobi or Shamo desert. North of the Shamo there is
a zone of meagre sage-brush and short scattered grass.
A line of marshes and lakes joins the points where the con-
verging mountain streams lose themselves’ in the desert ;
a belt of steppe skirts the base of the foot-hills, and
mountain pastures follow on the slopes. Between the

—— a T oS o_o

.
/

:

ASIA 179

Altyn Tag and the Kwenlun systems the higher terrace of
the Zaidam, with its great swamps and deserts, has a yet
bleaker, colder, and drier landscape. Tall poplars replace
palms in the oases of Central Asia.

Of the mountains that bound the vast Asiatic plateaus
on the north, west, and east, the outward slopes are gene-
rally wooded, but the inward slopes are less so or are
treele The portions of those ranges which, like the
Aid ostngats and Tian Shan, extend far into the
deserts, are devoid of forests, and their alpine pastures
are gradually restricted to higher and higher elevations.

The Pamirs. On the Pamir plateauthe mountain ranges
are compressed into a narrow belt of lofty ridges and
high flat valleys. This is the Karadagh, the roof of the Old
World. Buried in snow for several months of the year,
these valleys possess good summer pastures of an alpine
type which are utilized by the Kirghiz herdsmen.

Tibet. Farther east the ranges spread out, the high
valleys broaden, and the Pamir plateau expands into
Tibet, which is made up of wide, level, west-east valleys
between mighty parallel ridges. Lying at elevations of
from 12,000 to 16,000 feet, subject to excessive alterna-
tions of heat and cold, swept by icy gales at all seasons
and snow storms in winter, the high flats can support in
some places only a loose, short sward of alpine grasses
and perennials on which herds of sheep and yaks feed.
The eastern part of Southern Tibet enjoys a somewhat
milder climate, and agriculture and even orchards are
found in its broad valleys and plains. The population
is almost restricted to this region.

The eastern slopes of Tibet are carved into narrow and
deep gorges between steep parallel ridges. They receive
rain from the summer monsoons of China, which are

carried far into the plateau. The vegetation is luxuriant.
M 2

180 SURVEY OF THE CONTINENTS

On this side prosperous alpine pastures are found far
into Tibet. Below them, a belt of conifers reaches down
to dense deciduous broad-leaved forests, and these again
to warm temperate, rain-forests, the beauty, wealth, and
luxuriance of which have been the marvel of travellers,

Eastern Monsoon Lands. East of the great system
of Siberian, Mongolian, and Tibetan plateaus, the broad
marginal belt is entirely open to the summer monsoon
rains; but differences in temperature as well as in rain-
fall permit a great variety of vegetation.

Amuria. The hilly region of Amuria has a climate
similar to that of Central Europe, but with much
greater extremes of heat and cold. It possesses a rich
park-landscape of broad-leaved deciduous and of coni-
ferous forests and excellent meadow-land, not unlike
our own. It is capable of great development. South
of it, shut in on all sides by mountain ranges, lies
_ the rolling land of Manchuria, a dry, treeless steppe,
which is often called the eastern Gobi. Only the ranges
east of the Sungari and the narrow coastal belt have
heavy woods of our northern type.

China proper has been so long under the influence of
an intensive agriculture, which has encroached high up
on the mountain woodlands, that little of its spontaneous
vegetation is left. The west-east range of the Tsinling
Shan and the highlands north of the Yangtse seem to
mark a natural division between two types of climate,
vegetation, and agriculture. In the north the country
suffers from the marked seasonal changes of temperature
and the dry as well as severe winters. Both the vegeta-
tion and agriculture have a northern, summer-green
character, similar in many respects to those of the centre
of North America. The chief crops are barley, millet,
wheat, maize, cotton, tobacco, and hemp. ‘The soil is the

i =

ASIA 181

rich yellow earth, which is immensely fertile, favours
intensive cultivation, and supports a dense population.
The southern slopes of the Tsinling Shan are partly clad
with rich forests. They show a decided change from the
northern conditions and have an ever moist, warm
temperate climate, corresponding to that of the south-
eastern region of North America. The whole valley of
the Yangtse, as well as the lower zone of forests in the
Sechwan and Hupei highlands, have the same generous
climate. Rice, tea, and cotton flourish under the best
conditions. The immense variety of crops, and the
patient, thrifty, strenuous industry of the natives make
the Yangtse basin one of the richest agricultural
countries in the World, while the forests are exceed-
ingly valuable for their economic products.

Japan. These mountainous islands, in a mild and
moist climate with no long period of drought, may be
divided into zones of altitude, ranging from the sub-
tropical, evergreen rain-forest to the snow-line. Coni-
fers play an important part in the landscape; a belt of
low hills and woods of black and red pines lie behind
the fringe of coastal dunes. Cedar and _ eypress
characterize the next forest zone. Above 3,000 feet
larch and fir recall our northern coniferous forests, while
after a girdle of dwarf pines, alpine pastures extend
above 6,000 feet. In the northern half of Honshiu
(Hondo) and the chain of islands to the north the lower
zone is of the cool, temperate type. Formosa is tropical.

The Southern Monsoon Lands. In the belt com-
prising India, Indo-China, and the Malay Archipelago,
we find a repetition of the conditions of tropical America.

The Malay Archipelago is equatorial in character ;
but whereas the southern and eastern slopes and plains
exposed to constant downpours are mostly clad with the

182 SURVEY OF THE CONTINENTS

heavy, hot and wet, evergreen rain-forests or selvas,
the northern and western slopes have dry seasons,
and their vegetation varies accordingly from lighter
deciduous forests, of which teak is the most valuable
component, to wooded types of savanas. The higher
zones of the mountains display a temperate, evergreen
aspect in their rain-forests; but the wind reduces the
vegetation of the summits to mere shrub- and grass-land.

Indo-China is strongly influenced by monsoons. Most
of Siam and Cambodia is covered by a park landscape of
light tropical woods of the teak type, savanas and jungles.
The mountain land to the north and west is heavily
forested, teak predominating in the lower zone, while the
little known upper zones are covered with moist, warm,
temperate rain-forests. Heavy equatorial selvas charac-
terize the lowlands of Cochin China, but they have
largely disappeared with clearing and _ cultivation.
Much of the lowlands of Indo-China, formed by the
enormous deposits of the great rivers, were reclaimed
directly from swamps and transformed into rice-fields
before they were occupied by forests. The Malay
peninsula lying in the equatorial belt is still largely clad
with hot wet forests.

The Himalayas. On the northern mountain barrier
of India the lower zone of vegetation up to 5,000 feet
is tropical. The western portion is relatively dry, the
eastern quite wet. The north-eastern corner of India
and the lower parts of its amphitheatre of mountains, as
wellas western Burma, lie under conditions which favour
the heaviest type of equatorial selva, The well-
timbered temperate zone of the Himalayas, including
wet evergreens and, higher up, deciduous woods of
northern aspect, stops at about 11,000 feet, and is
followed by treeless alpine pastures rising to 18,000 feet. —

ASIA 183

The Indo-Gangetic Plain. ‘he alluvial Indo-Gangetic
lowland is of the hot and wet description in the east,
but it gradually passes westward through all stages to
extreme aridity in the Thar Desert.

The Indus plain properly belongs to the system of
subtropical deserts which includes Arabia and Mesopo-
tamia. It is an arid land with a low vegetation of dry
herbs, dotted with acacias and other leaf-shedding shrubs.
It depends entirely for its water on the snow-fed rivers
from the Himalayas, and its cultivated tracts are all in the
nature of oases.

On the other hand, the Gangetic valley, which receives
the monsoon rains and many large Himalayan rivers,
is by the help of an abundant irrigation transformed
into a rich agricultural land where rice, cotton, indigo,
and opium yield heavy crops.

The Deccan and Ceylon. ‘he Deccan plateau has wet
margins but a drier interior. It receives heavy monsoon
rains from the south-west on its western escarpment.
The narrow strip of Malabar, together with the south of
Ceylon, possess an almost impassable barrier of dense
selvas. The eastern lowlands of the Coromandel coast
and northern Ceylon receive much less rain and have
a jungle vegetation of dry evergreen scrubs on hot sands.
The plateau itself, according to the dryness of the climate
and nature of the soil, consists of arid centres, grassy
expanses, vast areas of dry deciduous shrublands, light
deciduous woodlands, and teak forests.

Burma. Eastern and Lower Burma are well known
for their deciduous teak forests. The mountainous high-
lands in the rear, little known as yet, are heavily clad
with warm temperate rain-forests of the tea-camellia-
camphor type.

184

CHAPTER XXXV
EUROPE

The Tundra. Both on account of the lower latitude
of the northern shore of Europe and of its moderate
temperature as compared with that of Northern Asia,
the tree line is carried almost to the very margin of the
Arctic Ocean and the tundra comprises but a narrow
fringe of the mainland and the. Arctic islands. The
arctic-alpine vegetation of pastures and marshes, how-
ever, is carried far south into Scandinavia on the fjelds of
the Scandinavian highlands. On these barrens a scattered
population of Finns and Lapps roams after its half-wild
herds of reindeer, on which it largely depends. These —
nomads fish and hunt, and in favourable years reap a poor
crop of oats or rye on the margins of the forest.

The Taiga. The Siberian taiga extends westwards
across the Urals and covers the northern half of Russia
and Scandinavia, north of 638° N. It is fringed on the
north as well as on the slopes of the highlands by a narrow
strip of birch woodland. The Scottish Highlands, and
a narrow coastal fringe in southern Iceland, might be con-
sidered as outliers of this belt. Timber felling and its.
attendant industries of carpentry, match and wood-pulp
making, tar and wood distilling, along with fur-hunting
and fishing, and a very little agriculture, are the chief
occupations amid these forests. With such limited possi-
bilities, due to unfavourable soil and climate, the northern
populations hardly find enough to live on in any one
place, and many resort to seasonal migrations. Northern

EUROPE 185

Russia lacks facilities of transport for the marketing
of its timber. Finland and Scandinavia carry on an
extensive timber trade, chiefly by water-floating, and in
the preservation of their natural resources they have
developed a high skill in forestry. These hardy races
have also succeeded in evolving a science of northern
agriculture which makes the most of very poor circum-
stances.
Cool Temperate Forests. The cool temperate belt
\ includes the southern half of Scandinavia, most of
Britain, northern and western Spain, and the rest of
Western and Central Europe. Towards the east this
belt narrows between the taiga on the north and the steppe
on the south to a point in the vicinity of the southern
Urals. Its characteristic vegetation is a park landscape
of deciduous, broad-leaved woods and meadowland : most
of it, however, has been deforested. Oak, beech, maple,
elm, ash, poplar, and thornbeam are the chief trees,
~~Within this belt great varieties of landscape are found,
owing to differences in topography, soil, and climate.
From west to east the climate gradually becomes more
extreme, with harder winters and drier, hotter summers.
The west coast belt, comprising the south-west of Ire-
land and England, a narrow fringe of France, and the
northern and western slopes of Spain, is always wet,
cloudy, and mild. The luxuriance of the vegetation is
greater than farther inland. These regions are mostly
transformed into rich pasture lands.
The Central European plain, starting from Flanders,
»’ consists of lowlands covered with heather moors, peat
bogs, pine and birch woodlands, and sandy pastures. It
passes in the east to a bleak region of forests and marshes
and ends in Russia in the vast Rokitno swamp, the
marshlands of the Minsk and the Pripet.

186 SURVEY OF THE CONTINENTS

The Central Highlands and Karpathians. More or
less isolated masses of highland, such as the central
plateau of France, the Vosges, the Schwarzwald, the Lower
Rhine highlands, the Thiiringer Wald, the Harz, and the
highlands bordering Bohemia, rise above the deciduous
forests into pine- and pasture-clad slopes, often with peat
moors on their tops. The Karpathians are well stocked
with stately forests of conifers and possess alpine pastures.
They are decidedly moister on the northern than on the
southern slopes, in the west than inthe east. The Kar-
pathians are separated only by a narrow lowland gate
from the Alps, which resemble them in point of vegetation.

The Alps. Three main zones may be distinguished in
the Alps, (a) the deciduous, broad-leaved forests of oak
and beech, (b) the coniferous forests of firs, pines, larches,
and arves, forming the sub-alpine zone, while above a
fringe of scattered woods and shrubland rise (c) the alpine
meadows and marshes, followed higher up by lichen-
covered tracts under the snow-line. On the western and
southern slopes of the Alps a lower belt of evergreen oak
woodland is usually found in addition.

The Steppes. In the south of Russia the steppe cli-
mate, with its corresponding vegetation, succeeds to the
deciduous forest belt. The transition is almost abrupt in
places, but generally is made by a gradual thinning of the
forest followed by a fringe of islands of hornbeam-trees.
The steppe stretches from Rumania and Bulgaria to the
lower Volga, and joins the Asiatic steppe. Under proper
irrigation the chernoziom or black earth of southern
Russia which extends to the foot of the Caucasus is
exceedingly fertile. The northern margins of the Black
Sea are poorer and pastoral, except for the isolated hilly
tract of Crimea, which is a western outlier of fertile
Georgia.

EUROPE 187

The Caspian Semi-Desert, In the south-east, towards
the Caspian, the dryness of the climate increases, and the
steppe becoming poorer and more ragged passes into
a semi-desert of wormwood.

The Western Islands of Steppe. ‘The steppe extends
westwards to the foot of the Karpathians. There is an
outlier in the Hungarian lowland, encircled by mountain
ranges. The climate of Hungary, dry and extreme in
temperature, is hostile to forest growth and favourable
to a pasture-land in the nature of a steppe, though more
luxuriant, called the Puszta, famous for its horses. By
means of irrigation, which is easily carried out, a large
portion of the plain is cultivated for wheat. The sunny
and warm slopes of the hills are extremely favourable to
the vine.

Farther west again, similar conditions in a somewhat
milder form are found in the lowlands of the Po. These
are carefully irrigated and intensively cultivated. The
plain of the Po owes its fertility to its rivers.

Spain also offers a few low rainless centres, but only
the Ebro steppe has the northern type—the others are
rather African in character.

The Mediterranean. ‘This region of dry hot summers
and mild, moist winters includes the north-western corner
of Africa and the coastland of Syria and Asia Minor. It
extends across the southern part of the Balkan peninsula.
Its vegetation is characterized by thick, leathery, small-
leaved evergreen trees and shrubs in woodlands, scrubs,
and jungles, with but little pasture-land. The zones in
the mountains are those of (a) evergreen oak, (b) deciduous
oak, (c) beech, (d) conifers, and (e) pastures or rock
barrens. Its natural resources are many: olives, ever-
green and cork oaks, vines, figs, and carobs are among
the most common and characteristic. The scrubs,

188 SURVEY OF THE CONTINENTS

whether the rocky, loose garrigue or the denser and taller _
maquis, have replaced the original woodlands.

The varied appearances of the landscapes of this region
cannot be dealt with here.

The south and eastern coasts of the Black Sea receive
an abundant rainfall, and enjoy a generous climate, which
is revealed in a luxuriant vegetation of dense forests,
similar to those of south-eastern North America. Tower-
ing above this rich coast is the chain of the Caucasus
which condenses a large amount of moisture, and has
stately forests and tall luscious pastures. Here lies the
rich and rainy forest-land of Transcaucasia, which leads
to the north-west corner of Persia, and is continued south
of the Caspian on the northern slopes of the Elburz
Mountains.

Mediterranean conditions are found round the southern
wall of the Anatolian plateau and extend along the
mountains to the intermontane valleys of south-west
Persia, rising above Mesopotamia. The Anatolian plateau
is a high, treeless, half-desert steppe, studded with salt
depressions, and thinly -peopled.

Mesopotamia, mostly composed of alluvial land, is a
vast oasis, owing its fertility to the water and the rich
alluvial deposits of the two rivers. It is hemmed in
between the wall of Iran and the Syrian plateau. The
latter, with a mediterranean vegetation, which passes
into desert as the plateau descends gradually to Mesopo-
tamia. In Syria, however, the desert has lost its
tropical climate, and its winters may be cold.

INDEX

Abyssinia, 170.

Acacias, 46, 50.

Africa, 165; Central, 34; East,
38, 44, 53, 170; Equatorial, 32,
64; North, 88, 91, 166; South,
63, 92, 169.

Air in plant life, 157.

Alai, 177.

Alaska, 110, 157.

Allegheny Plateau, 156.

Alps, 122, 129, 186; vegetation,
129.

Altai, 179.

Amazon, 20, 28, 160.

America (Central), 34, 38, 63,
160.

America (North), West, 87; De-
ciduous Forest, 99; Desert, 58;
Prairies, 92, 94, 95; Southern
States, 62; Western Mountains,
156.

America (South), 32,160; Savana,
44.

Amu, 60, 61, 176.

Amuria, 99, 180.

Anahuac Plateau, 159.

Anatolian Plateau, 188.

Andes, 63, 133, 165,

Antilles, 38.

Appalachians, 99, 126, 155.

Arabia, 51, 55, 56, 88.

Araucaria Forests, 81.

' Arctic, 114.

Argentina, 54, 92, 94, 98.

Arizona, 51, 53, 55, 90.

Asia, 88, 91, 106, 174.

Asia Minor, 88, 91, 187.

Assam, 20, 29, 64.

Atacama, 55, 164.

Austral Islands, 174.

Australia, 32, 38, 63, 67, 78, 80,
170, 171; Deserts, 55, 56, 88,
173; Highlands, 172; Semi-
deserts, 51, 54.

1159

Bad Lands, 156.

Balkan Peninsula, 187.

Bamboo Forests, 29.

Baobab, 46.

Barbary, 165.

Barren Grounds, 153.

Bengal Selva, 20.

Bering Sea, 153.

Black Desert, 176.

Black Earth, 98, 186.

Black Sea, 94, 100, 156, 186, 188.
Black Table, 159.

Bloom Mats, 117, 118.
Bohemian Highlands, 186.
Bolivian Andes, 165.

Borneo Selva, 21, 29.

Brazil, 38, 39, 62, 162.

Brazil Highlands, 162.

Brigalow Scrub, 87.

Britain, 185.

British Columbian Plateau, 153,
158.

Brush Prairie, 156.

Bulgaria, 92.

Buriats, 115.

Burma, 20, 29, 32, 33, 34, 35, 63,
64, 182, 183.

Bush Steppe, 156.

Bushveld, 168.

Caatinga, 37, 162.

| Caithness, 14.

California, 55, 70, 77, 83, 87.
California (Lower), 51, 157.
Californian Valley, 158.
Cambodia, 182.

Campo, 44, 162.

Canada, 98.

Canadian (North), Forest, 107,
108 ; features of, 110; Scattered
Forest, 155.

Candelabra Cacti, 54.

Capuera; Capoeira, 29.

Carolina, 101, 155.

190 INDEX

Caribbean Sea, 52. | Factors of plant life, 136,

Cascade Range, 158. Fens, 10, 17, 18.

Caspian Sea, 100. Finland, 185.

Caspian Semi-deserts, 187. Finns, 184.

Caucasus, 126, 188. Fjelds, 15, 18, 184.

Cedar Glades, 156. Flanders, 12, 185.

Cevennes, 103. Florida, 65.

Ceylon, 185. Formosa, 64.

Chaco, 164. France, 15, 18, 102, 185, 186.

Chaiaral, 54. Fuego, 99.

Chernoziom, 98, 186.

Chestnut Forest, 103. Garigues, 71.

Chile, 54, 64, 99, 133. Geography (plant), 15, 16, 19.

Chilean Andes, 165. German Lowlands, 18.

Chilean Valley, 164. Gila Desert, 159.

China, 63, 64, 180. Gobi, 60, 178.

Chu, 177. Grampians, 17.

Coast Range (North America), 157. | Great Britain, 185.

Cochin China, 182. Great Lakes, 155.

Cold Forests, 154. Guiana, 38, 164.

Colorado Plateau, 158. Guinea, 34, 168.

Columbia, 65. Gulf of Mexico, 156.

Columbian Andes, 165.

Congo Basin, 168. Habitat of plants, 148.

Coniferous Forests, 106. Hamada, 57.

Crimea, 186. Hampshire, 10, 15, 16.
Harz, 186.

Dakota, 156. Heat in plant life, 188.

Danish Moors, 18. Himalayas, 125, 131, 182.

Danube, 100. Hindu Kush, 177.

Dartmoor, 15. Hop-fields, 17, 18.

Deccan, 38, 183. ‘Hungary, 92, 187.

Deserts, 55. Hupei, 181.

Devonshire, 16, 18.

Downs, 14, 15. Igapu, 160.

Drakensberg, 168. India, 32, 34, 68, 182.

Dry Farming, 91. Indian Ocean, 51.
Indians, 113, 153.

Ebro Steppe, 187. Indies (West), 34.

Ecuador Andes, 164. Indo-China, 32, 64, 182.

Egypt, 61, 166. Indo-Gangetie Plain, 183.

Elburz, 188. Indus Plain, 183.

Elfin Woods, 124, 130. Iran, 55, 177.

Eng Forest, 55. Ireland, 12, 14, 15, 18, 185.

England, 185. Irrigation, 142.

Environment, 15. Italy, 92, 126.

Epiphytes, 26.

Erg, 56. Japan, 64, 99, 102, 126, 181.

Espinal, 54. Jati Forests, 54.

Eucalyptus Forests, 78. Java, 34, 35.

Europe, 98, 102, 106, 184, 185, 186.

Evergreen Forests, 78. Kalahari, 54, 55, 88, 169.

Exmoor, 9, 15, 16. Karadagh, 179.

INDEX

Karakum, 176,
Karpathians, 186, 187.
Karroos, 54, 88, 169.
Kent, 17, 18.
Khorasan, 177.
Kirghiz Steppe, 176.
Korea, 92.

Kuhistan, 177.
Kysylkum, 176.

Labrador, 125, 153.
Lapps, 184.

Lianas, 24.

Lichen Tundra, 116.
Light in plant life, 144.
Llanos, 44, 47, 162.

Low Forest (Burma), 35.

Macedonia, 126.

Madagascar, 170.

Malabar, 183.

Malaysia, 20, 64, 181.

Mallee Scrub, 86.

Manchuria, 92, 97, 180.

Mangroves, 29.

Maquis, 73, 75, 84.

Mediterranean, 70, 187.

Mediterranean woodlands, 70, 73,
74,

Mesopotamia, 61, 188.

Mexico, 38, 51, 53, 55, 63, 88, 91,
157, 159.

Minsk, 185.

Misiones, 63.

Mississippi, 99, 156.

Mixed Forests, 34.

Mogollen Mesa, 159.

Mohave-Gila Desert, 159.

Mongolia, 55, 178.

Monsoon Forests, 32.

Monsoon Lands, 180, 181.

Montana, 157.

Moss Heath, 115.

Mountains, 120.

Movements of plants, 151.

Mulga Scrub, 87.

Murray Scrub, 84.

Natal, 44, 169.

New Guinea, 173.

- New Mexico, 156.
New Zealand, 63, 174.
Newfoundland, 155.

191

Nile, 60, 166.

Normandy, 15, 17, 18.
Northern Forest, 155.
Novaya Zemlya, 114.

Oases, 59, 60, 90, 91, 166, 179.
Orinoco, 162.
Orizaba, 125.

Pacific Islands, 174.
Pamirs, 135, 134, 179.
Pampa, 88, 92, 163.
Paraguay, 63, 83, 165.
Parana, 63, 163.
Patagonia, 88, 99, 164.
Peat, 18.

Peru, 135.

Peruvian Andes, 165.
Physical conditions, 14, 15.
Pilcomayo, 165.
Pine-Barrens, 156.

Plant acquirements, 156.
Plant food, 137.

Plant geography, 15, 16, 19.
Plate Basin, 163.

Po Valley, 187.

Prairie, 92.

Pripet Marshes, 185.
Punas, 133, 165.

Puszta, 92, 187.

Quebracho Forests, 83.

Red Desert, 176.

Reg, 57.

Rhine Highlands, 186.
Rio Grande do Sul, 164.
Rio Grande Valley, 159.
Rocky Mountains, 90, 126, 155, 158.
Rokitno Swamp, 185.
Romania, 92.

Russia, 92, 111, 115, 184.
Russian Forest, 98.
Russian Steppe, 98, 186.

Sage Brush, 87, 91, 158, 159.
Sahara, 55, 56, 59, 88, 166.
Sakhalin, 104.

Saprophytes, 26.

Savanas, 44, 45, 50.

Savana Woods, 82, 83, 162, 168,169.
Scandinavia, 184, 185.

Scattered Forest, 153.

192 INDEX

Schwarzwald, 186. Thiiringer Wald, 186.
Scottish Highlands, 12, 15,17, i8, | Tian Shan, 126, 177, 179.

124, 184. | Tibet, 100, 1383, 135, 179.
Scrubs, 50, 83, 173. Timber line, 108, 110, 124.
Sechwan Highlands, 181. Transcaucasia, 188.

Selva, 20, 62. Tsinling Shan, 180, 181.

Semi-deserts, 50, 53.
Sertao, 40, 162.

Shamo, 55, 178.

Shrub Tundra, 117.
Siam, 182.

Sierra Nevada, 126, 158.
Snake Basin, 158.

Soil in plant life, 147.

Tucuman, 64.
Tundra, 115, 115, 154, 174, 184.
Turan, 55, 176.

United States, 98.
Urals, 99.

Uruguay, 63.
Usturt Plateau, 176.

Sokotra, 54. Utah, 90.
Somaliland, 51.
Southern Uplands, 12, 15. | Vancouver, 157.

Vegetation, 18.

Veld, 92, 169.
Venezuela: 38, 47, 164.
Vosges, 186.

Spain, 73, 92, 126, 185, 187.
Spitsbergen, 114.

Steppes, 92, 95, 176, 186.
Stony Tundra, 114.

Sudan, 38, 44, 51, 167.
Sub-tropical Rain-forest, 62.
Sub-tropical Semi-desert, 54.
Sumatra, 29.

Summer Rain-forests, 32.
Sussex, 18.

Swamp Forests, 29.

Swiss Alps, 122.

Syr-Darya, 61, 176.

Syria, 187, 188.

Wahsatch, 158.

Wales, 15.

Wash, 10.

Washington (State), 157.
Water in plant life, 137, 140.
West Indies, 34, 125.

Wind in plant life, 145.
Wormwood, 58.

Yakuts, 113.
Yangtse, 180.
Yellow earth, 181.
Yorkshire Dales, 12.
Yukon Plateau, 158.

Taiga, 106, 108, 175, 184.
Takla Makan, 178.
Tamarisk, 58.
Tarbagatai, 179.

Tarim Basin, 178.
Tasmania, 63.

Teak Forests, 34, 35, 37.
Temperate Deciduous Forests, 98. | Zambezia, 168.
Temperate Scrubs, 83. Zealand (New), 63, 174,
Texas, 51, 53, 62, 156. Zerafshan, 177.
Thornwood (Tropical), 37. Zungaria, 178.

Zagros, 178.
Zaidam, 179.

Oxford: Horace Hart M.A., Printer to the University

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QK Hardy, Marcel E.

101 An introduction to
H27 plant geography

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