Historic, archived document

Do not assume content reflects current
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The

~ Caribbean forester

VOLUME 14, NOS. 1 AND 2

U. S. DEPARTMENT OF AGRICULTURE
FOREST SERVICE |
TROPICAL FOREST EXPERIMENT STATION
RIO PIEDRAS, PUERTO RICO

JANUARY - APRIL 1955S

Caribbean Forester

El-“Caribbean Forester”, revista que el
~ Servicio Forestal del Departamento de Agri-
cultura de los Estados Unidos comenz6 a pu-
blicar trimestralmente en julio de 1938 es de
distribucion gratuita y esta dedicada a encau-
zar la mejor ordenacion de los recursos fores-
tales de la region del Caribe. Su propdsito es
estrechar las relaciones, que existen entre los

cientificos interesados en la Ciencia Forestal

y ciencias afines encarandoles con los proble-
mas confrontados, las politicas forestales vi-
gentes y el trabajo que se. viene haciendo pa-
ra lograr ese objetivo técnico.

Se solicita aportaciones de no mas de 20
paginas mecanografiadas. Deben ser someti-
das en el lenguaje vernaculo del autor, con el
titulo o posicién que este ocupa. Es impres-
cindible incluir un resumen conciso del estu-
dio efectuado. Los articulos deben ser dirigi-
dos al “Director, Tropical Forest Experiment
Station, Rio Piedras, Puerto Rico.”

Las opiniones expresadas por los autores
de los articulos que aparecen en esta revista
no coinciden necesariamente con las del Ser-
vicio Forestal. Se permite la reproduccion de
los articulos siempre que se indique su proce-
dencia.

®

The “Caribbean Forester’, published since
July 1938 by the Forest Service, U. 8. Depart-
ment of Agriculture, is a free quarterly jour-
nal devoted to the encouragement of im-
proved management of the forest resources
of the Caribbean region by keeping students
of forestry and allied sciences in touch with
the specific problems faced, the policies in
effect, and the work being done towards this
end through out the region.

Contributions of not more than 20: type-
written pages in length are solicited. They
should be submitted in the author’s native
tongue, and should include the author’s title
or position and a short summary. Papers
should be sent to the Director, Tropical Fo-
rest Experiment Station, Rio Piedras, Puerto
Rico.

Opinions expressed in this journal are not
necessarily those of the Forest Service. Any
article published may be reproduced provided
that reference is made to the original source.

Le “Caribbean Forester”, qui a été publié
depuis Julliet 1938 par le Service Forestier du
Département de l’Agriculture des Etats-Unis,
est une revue trimestrielle gratuite, dediée a
encourager l’aménagement rationnel des fo-
réts de la region caraibe. Son but est d’entre-
tenir des relations scientifiques entre ceux
qui s’interéssent aux Sciences Forestiéres, ses

problémes et ses méthodes les plus récentes,

ainsi qu’aux travaux effectués pour réaliser
cet objectif d’amelioration technique.

On accept voluntiers des contributions ne
dépassant pas 20 pages dactilographiées.
Elles doivent étre écrites dans la langue ma-
ternelle de l’auteur qui voudra bien préciser
son titre ou sa position professionnelle et en
les accompagnant d’un résumé de l'étude. Les
articles doivent étre addressés au Director,
Tropical Forest Experiment Station, Rio Pie-
dras, Puerto Rico.

La revue laisse aux auteurs la responsibi-
lité de leurs articles. La reproduction est
permise si l’on présice l’origine.

“The printing of this publication has been approved by the Director of the Bureau of the Budget (August

17, 1950)”.

VoL. 14 Nos. 1 AND 2 JANUARY - APRIL, 1953

Wive Caribbean Forester

Gonmtrenmts

SHUsAOMAI©

sishnueteenthmannualreporth. =o. = = 22 eo) if

Tropical Forest Experiment Station, Puerto Rico

Decimotercer informe anual de la Estacién de
Hxperimentacion Horestal Tropical _-- .-.---.-_--____ 34

(Traduccién del articulo anterioy

The significance to Puerto Rico of Companhia Paulista

ExpemlenceswiuMelledhyptIs: == = 2 = 7 fe 65
Frank H. Wadsworth and José Marrero, Puerto Rico

Experiencias de la Companhia Paulista con Eucalipto,

SummpoKvancianparayluertokico === _- 22-2 -__ = us

(Traduecion del articulo anterior }

JANUARY - APRIL, 1953

THIRTEENTH ANNUAL REPORT

Tropical Forest Experiment Station
Tropical Region
Forest Service

The year 1952 was marked by a more
wide-spread application of the findings of
research than ever before. For the first
time in about 10 years large scale planting
on the public forests was recommended. Prior
to that period, about 22,000 acres of public
forest lands were planted, but large scale
planting was then discontinued because of
numerous failures and high costs. This
period has been marked by observation of
past plantings and cautious testing of new
species, techniques, and sites. Even now
only a very limited number of practices can
be recommended safely. <A result of these
recommendations this year has been the
underplanting with West Indian mahogany
of more than 2,000 acres of dry forest on
the south coast and the underplanting of
broadleaf mahogany on 450 acres of
secondary rain forest. An additional several
thousand acres of similar sites are to be
underplanted as soon as funds permit.

Another significant development has been
the demand which has appeared for
eucalyptus for underground piling. The
Tirst 30 feet of 12” trees (14 years old) is
worth $4.50 on the stump. This development
and other prospects for use of this tree for
its cellulose have removed the last reason
to hesitate in large scale planting of
eucalyptus at elevations between 2,000 and
3,000 feet. Areas of natural secondary
forest among existing plantations are to be
converted to eucalyptus. The planting of
eucalyptus by the taungya system is to be
throughly investigated during the coming
year. If successful it may lead to consider-
ably increased interest in tree planting on
private lands.

REORIENTATION OF THE
RESEARCH PROGRAM

A highlight of the year’s activities was

the visit of Dr. V. L. Harper, Assistant
Chief of the Forest Service in charge of
forest research, and Dr. H. G. Wilm, in
charge of the Division of Forest Influences
Investigations, both from Washington. They
went throughly over the forest problems oi
the island and the present program of the
Station. They gave much valuable advice for
the orientation of future work. There is
some prospect that as a result of their visit
the program of the Station will be extended
formally into the fields of forest utilization
and forest influences research,

A study of forest utilization in Puerto Ri-
co was made at the request of the Station by
Mr. C. C. Bell, Chief of the Forest Utilization
Service of the Forest Products Laboratory.
Mr. Bell spent 4 weeks in Puerto Rico
studying the forests, their products, and
wood conversion and fabricating plants. Mr.
Bell’s report emphasizes three major forest
utilization needs of Puerto Rico: (1)
increased use of small, low quality and
poor-form material, (2) increased production
of timber in sawlog size and of high-value
form and species, and (3) acceleration of
factory tests and field experiments to add to
the little information now available on the
properties and uses of Puerto Rico’s woods.
Mr. Bell recommended a broad program of
utilization research in the major fields of
industrial investigations, pulp and paper,
silvicultural relations, timber physics and
wood preservation, to be carried out largely
at the Station but with cooperation from the
Laboratory.

Increased emphasis on research in tne
field of forest utilization actually took place
with the assignment by the Commonwealth
Forest Service of Puerto Rico of a full-time
professionally trained forester, Miguel Her-
nandez-Agosto, to the Station to assist in the
research program. Mr. Hernandez has
been provided an allotment for materials

2

and supplies by that Service. Because his
training is in the field of forest utilization
and because research in that field is much
needed and has not made up an important
part of the Station’s program in the past,
Mr. Hernandez has been assigned research
within that field. He has taken over all

going forest products investigations and
has laid out a comprehensive program
which will lead to more knowledge con-

cerning the quantity and quality of avail-
able forest products in Puerto Rico, new
uses for these products, and increased
durability during their service life. Mr.
Hernandez arranged for and prepared a
cooperative agreement signed duving this
year ketween the Forest Services and the
College of Agriculture of the University of
Puerto Rico for joint research in timber
testing and wood chemistry and products
pathology.

ACTIVITIES OF INTERNATIONAL
SCOPE

Three international trips were made by
members of the Station staff during the
year. The Division Chief served as a United
States representative on the Preparatory
Committee for a conference on timber trade
to be held under the auspices of the
Caribbean Commission. The Preparatory
Committee met in Port of Spain and
suggested an agenda, papers, and work to
be done by the Secretariat prior to the
conference, which is now scheduled for April
1953. The Director spent a week in the
Dominican Republic during which time he
discussed with the Minister of Agriculture
the forest problems of the country and the
forestry program in progress.

The Division Chief served as a United
States delegate to the Fourth Session of the
Latin-American Forestry Commission of
FAO at Buenos Aires. On the return trip he
spent a week at Sao Paulo, Brazil, seeing the
extensive eucalyptus plantings of the
Companhia Paulista de Estradas de Ferro.
Also seen were the forests of the Essequibo

‘resources

CARIBBEAN FORESTER

river in British Guiana and those of Grenada,
St. Lucia, and Dominica in the British Lesser
Antijles. These stopovers yielded a wealth
of information concerning eucalyptus, the

cology of rain forest, and exotic tree species
wortn testing in Puerto Rico.

The Station was visited by 14 foresters
from 15 different foreign countries during
the past year. In adition, five forestry
students received training at the Station.
For three of these, who were at the Station
for five months, it was possible to lay out
a well-balanced program of study involving
many phases of forestry. Two of these
students are graduate foresters from the
University of the Andes, Merida, Venezuela.

Publications of the Caribbean Fcrester
lagged behind schedule during the year, and
the October issue is still in press. Seven
articles were published this year and these
concern Argentina, Brazil, the Virgin
Islands, and Puerto Rico. More than half
of the pages were dedicated to reports on
the research at the Station. The mailing
list at the end of the year contained 746
names, mostly foreign to the United States
and Puerto Rico.

At the request of the Fourth Session of
the Latin American Forestry Commission
of FAO the Spanish-English glossary of
forestry terminology in preparation at the
Station during the past ten years is to be
submitted in its present incomplete form to
the Latin American Forestry Office of FAO
at Rio de Janeiro for distribution and
comment throughout Latin America and
return to the Station for revision. One-
hundred and nine new Spanish words were
defined during the year, bringing the total
to date to 802. This is approximately half
of the number of terms defined in English.

LOCAL ACTIVITIES

The staff was primarily responsible for
the preparation of a report on the forest land
of Puerto Rico and recom-
mendations for their development and use.
The study involved a determination of

JANUARY - APRIL, 1953

critical watershed areas from topographic
maps, a through analysis of existing con-
servation program, and consideration of
practical means of more forestry progress.
The report made specific recommendations
for more forestry education and technical
assistance, acceleration of public acquisition
of forest land, more forest research,
incentives for private owners commensurate
with those for other conservation practices,
and through consideration of regulatory
legislation for critical areas. The report,
almost without modification, has been
included as Chapter VI of ‘““A Comprehensive
Agricultural Program for Puerto Rico” to
be published shortly by the U. S. Department
of Agriculture.

Dr. Elsert L. Little Jr., of the Division
of Dendrology and Range and Forage Inves-
tigations of the Forest Service in Washington
spent about 3 months in Puerto Rico at
the request of the Station to continue work
on the manuscript for two popular descrip-
tive books on the trees of Puerto Rico. On
a previous trip Dr. Little had collected
adequate herbarium material for one volume
describing 250 species. During this year
about 475 specimens were mounted in the
herbarium and he virtually completed the
descriptive text. The major task remaining
is the drawing of some of the species.

Cooperation with the Soil Conservation
Service in encouraging forest planting within
the Virgin Islands was continued during the
year. Detailed plans were laid out for an
extension program, seed collection, ground
preparation, propagation, sowing, and
planting during the year. Forest lands in
four ownerships were mapped and specific
recommendations were prepared for the
landowners. In addition, a possible 4-H Club
tree project was outlined, including activities
for seven different months during the year.
Three small growth plots were established
in natural stands of West Indian mahogany.
This program is moving forward slowly in
spite of the interest of the Governor. A
program of tree planting proposed by the
Virgin Islands Corporation in cooperation

with the Soil Conservation Service and the
Station for next year may produce more
results.

An outstanding research event was the
Cambalache field day, held on May 22 in
the Cambalache Experimental Forest.
About 120 persons participated, including
representatives of the following agencies
dealing directly with landowners: the Soil
Conservation Service, the Agriculturai
Extension Service, Production & Marketing
Administration, the Puerto Rico Department
of Agriculture and Commerce, Soil Conser-
vation District Boards, the Puerto Rico Land
Authority, the Farmers Home Administra-
tion, and the Commonwealth and Federal!
Forest Services. Some 30 boys in the upper
erades of a nearby vocational schoo! were
also present, as were ten leading farmers
from the region. By demonstration and expla-
nations the forest problems of the north coast
of Puerto Rico were presented to the group
by representatives of the Extension Service,
the Soil Conservation Service, and the two
Forest Services. Numerous plantations of
different species, some clearly successful and
some still experimental, were shown to the
group, as was demonstration improvement
cutting.

ther educational activities during the
year included addresses on forest conser-
vation and research to the Farm Forestry
students at the College of Agriculture, to the
Naval Dependent’s School, to about 190
leaders at the Boy Scouts Camp, and to the
Garden Club. The staff organized and led
a one-week training course for about 25 field
personnel of the two Forest Services. Part
of the course concerned purely administrative
matters, but the biological basis for forestry,
the need for research, experiments in
progress, and the results found to date which
are of importance to them were all presented
in detail. Five major field experiments were
shown to the group.

Mr. Marrero continued to put the results
of research directly to use in laying out and

Caribbean National Forest. This has involved

4

the survey and designation of areas of
highest priority for planting, plantation care,
and stand improvement; the recommendation
of techniques; inspection; and the prepara-
tion of an annual report. During this year
2,040 acres were treated, including the
planting of 810 acres and the eare of 1,230
acres of plantations. Similar but less
detailed assistance has been given to the
larger program of the Commonwealth Forest
Service. In adition the staff has served on
a committee working toward improved tree
distribution to farmers. Recommendations
involve direct aplication of research findings
and concern propagation techniques, species
to propagate, and the sites to which they are
adapted.

New publications received in the library
during the year total 763. Indexing of an
accumulation of past library accessions has
been completed. The library now contains
about 6,850 titles on tropical forestry or
closely allied fields. A much larger general
agricultural library is also available to the
staff at the University Agricultural
Experiment Station, located within 500 feet
of the Station headquarters.

The staff of the Station is small, and
progress has depended heavily upon assist-
ance from numerous cooperators. Important
cooperation received during the year from
outside Puerto Rico includes guidance from
the two research chiefs from Washington,
the forest utilization study by the Forest
Products Laboratory, and the progress made
on the manuscript. “Trees of Puerto Rico”
by a member of the Washington Office of
the Forest Service. The British Caribbean
Territories made a direct financial contrib-
ution for the Caribbean Forester. Another
important result of outside cooperation has
been the receipt of seed of new tree species
from many parts of the world. In exchange
for instruction, the foreign forestry students
have been of material assistance in carrying
out field work.

Within Puerto Rico the
protection, and maintenance of experimental
installations, provision of suitable sites, and

establishment, :

CARIBBEAN FORESTER

the use of field stations is contributed by
the Caribbean National Forest and the Com-
monwealth Forest Service. The Common-
wealth Forest Service also propagates most
of the trees used in regeneration experi-

ments. The assignment of Mr. Hernandez
to the Station, already mentioned, is
another major cooperative benefit from

this Agency. The University of Puerto Rico
has been an important cooperator, making
available its library facilities and through
its Agricultural Experiment Station has
provided the Station the Rio Piedras
Woodlot and has assisted directly in the
experimental work, particularly in the fields
of entomology and experimental design. The
Agricultural Extension Service has pro-
vided photographic service which at
times required the use of their photogra-
pher in the field for a day or more. In
addition, this Service has arranged for
the publication of press releases and
the broadcasting of radio talks by the staff.
Jointly, the Extension Service, Soil Conser-
vation Service and the Soil Conservation
District Board of Supervisors made possible
the Cambalache Field Day, by bringing
together key people, raising funds, arranging
the meal, and presenting some of the infor-
mation to the group. Re-examination of the
Mona Island plantations was made vossible
by transportation and lodging furnished by
the U. S. Coast Guard.

RESEARCH RESULTS

The experimental work of the Station has
been conducted on different forest areas
throughout the Island of Puerto Rico. Most
of the studies are made within public forest
lands, either those of the Federal Govern-
ment or of the Commonwealth. (Fig. 1).
Not all of the findings made during the year
are considered sufficiently important to war-
rant description here. Some studies reported
a year ago have not progressed sufficiently
to warrant another report. For others, not
recently reported, progress during the past
two or three years is described.

JANUARY - APRIL, 1953 5

@& GUAJATACA @ CAMBALAGHE

ST. JUST ©
r

af R.P.WOODLOT
RIO ABAJO ym LLO

8

Is
. MARICAO tap? A* TORO NEGRO

» & \GUILARTE
SUSUA

” GUANICA AGUIRRE

Fig. 1—Public forest areas of Puerto Rico mentioned in this report. (Areas forestales publicas mencionadas cn este
informe).

Fig. 2.—Principal areas of forest land in Puerto Rico. (Areas de terrenos forestales en Puerto Rico).

The experimental forests have continued
to be centers for much of the silvicultural
research. The Cambalache and St. Just
Forests are also of considerable value to the
local community as a source of wood pro-
ducts. At Cambalache 25 timber sales were
made, involving about 2,500 cubic feet of
roundwood worth $275. From the same
forest 11,018 bundles of fuelwood were taken
free of charge by 90 families living nearby.
The volume of this fuelwood was about 110
cords. At the St. Just Experimental Area,
1,407 bundles of fuelwood were taken by 20
families. The volume of this material was
about 14 cords. From the Rio Piedras
Woodlot 850 fence posts were made available
to the Agricultural Experiment Station of
the University in accordance with the plan
for management of this forest.

The experiments are here classified in
accordance with their major objectives.
These include the determination of:

1. The extent and nature of the forests
of Puerto Rico.

2. The present and potential contribu-
tion of the forests of Puerto Rico.

3. Practical methods of increasing
forest land productivity.

4. Practical methods of increasing the
utility of wood.

Most of the silvicultural research
reported involves studies of tree growth in
relation to environment. The only satis-
factory method of conducting such studies
within natural forests or old plantations has
been the establishment of permanent plots
in stands representative of the condition
desired. Twenty-five of these plots were
remeasured during the year and 12 new plots
were established.

At the close of the year a critical review
of a large number of studies of the site
adaptability of different tree species has
resulted in the termination of more than 100
of these. Many had already shown most of

the information that could be expected from

them and others were obviously destined for
failure. This represents a material saving in

CARIBBEAN FORESTER

tie future re-cxamination jo» load and will
free staff members for a number of more
important new studies.

Mr. Hernandez Agosto of the Common-
wealth Forest Service prepared the reports
presented concerning the studies of forest
products and wood utilization which have
been under his direction during the last half
of the year,

Frequent reference is made to earlier
annual reports of the Station. Recent revorts
were published in The Caribbean Forester as
follows: 1949, 11:59-80; 1950, 12:1-17; and
1951, 13:1-21.

Forest Land area approximated

Knowledge as to the area, location, and
character of the lands best suited for forests
is basic to forest research. Inadequate
information of this nature has been available
in Puerto Rico in the past. Therefore, in
the preparation of a report on forest land
resources and recommendations for public
forest land acquisition, an attempt was
made to locate and ascertain the area of
those lands where trees would produce a
higher sustained yield in terms of economic
and/or social benefits than other crops.

Trees will grow in any part of Puerto
Rico, yet on most of the island they are less
productive than other crops. Insufficient
data are available to make possible a direct
comparison of economic returns from forest
and nonforest crops. However, one category
of land almost unanimously recognized as
best for trees: those areas which because of
excessive slope (50% or more); heavy
rainfall; or shallow, infertile or poorly
drained soil cannot be cultivated or pastured
continuosly without soil deterioration and/or
very low yields, yet which can produce trees
as a permanent crop.

All areas exceeding 50% slope were
outlined on the topographic maps of the
island. By planimetering it was found that
the total was approximately 600,000 acres,
about one quarter of the land surface of the
island. Of this area, about 427,000 acres lie

JANUARY - APRIL, 1953

within blocks of 10,000 acres or more each,
which are suitable for efficient forest
management. These blocks are located as
indicated in Table 1. (See also Fig. 2).

Table 1—The larger blocks of fsrests land
in Puerto Rico

Location Area of ferest land

Acres
Northern limestone region 90,000
South slope of the Cordillera 83.000
Sierra de Cayey 60,000
Sierra de Luquillo 47,000
Rio Manati Valley 33,000
Rio Arecibo Valley 29,000
Sierra de Atalaya 25,000
Rio La Plata Valley 23,000
Guanica 16,000
Tallaboa 11,000
Lajas 10,000
Total 427,000

The remainder of the forest land is in
smaller blocks but should provide important
local sources of forest products. These data
served as a basis for a public forest land
acquisition program.

Slow growth in virgin forests confirmed

Studies have been made within Puerto
Rico’s few remaining virgin forests to
determine the nature of these forests and
of trees species which compose them, as an
indication of what may ke expected from
different silvicultural treatments. In the
past three reports the first data have been
presented as to the site requirements,
tolerance, and comparative growth rates of
different species in the undisturbed forest.

Growth measurements on a large number
of trees in the tabonuco and colorado types
in the Luquillo Mountains (lower montane
rain forest and montane thicket!,) led a few
years ago to the belief that tree diameter
growth in virgin rain forest was very slow.

1/ As classified by Beard. Climax vegetation in Tropica]
America. Ecokcgy: 25(2):127-158.

The period of measurement at that time was
only 2 years and did not provide conclusive
second

evidence to this effect. so a

The results of this remeasurement appear
in Table 2. The data for the tabonuco type
represent 399 trees of 10 canopy species,
tazonuco (Dacryodes excelsa Vanl) ; aguacatillo
(Meliosma herberti Rolfe); ausubo (Maenilkare
duflicata (Sessé & Moc) Dubard); caraco-
lillo (Homalium racemosum Jaeq); granadillo
Buchenavia capitata (Vahl) Eichl); guajon
Beilschmedia pendula (Sw.) Nees); masa
Tetragastris (Swe) ern ze ie;
motillo (Sleanea berteriana Choisy) ; nuez mos-
cada (Occtea moschata (Pavon) Mez.); and
roble (Tabebuic pallida Miers). Separate
analysis showed that in the virgin forest the
growth rates of the various species were not

balsamifera

sufficiently to warrant separation. More
than half of the trees (222) were of the

common dominant, tabonuco.

In the colorado type a larger number ot
trees of each common large species were
measured and the data were curved
separately. There were 480 trees of caimi-
tillo (Microtholis chrysophylloides Pierre) ; 260
of nemoca (Ocotea spathulata Mez.); 832 of
caimitillo verde (Micropholis garcinofolia
Pierre) ; 828 of camasey jusillo (Calycogoniuni
squamulosum Cogn.); 171
(Magnolia stlendens Urban) ; and 171 of palo

of laurel sabino

colorado (Cyvilla racemiflora L).

The data on growth rates were curved
over tree diameter, and then the age of trees
of different diameters were estimated by
summing periods required to pass from one

diameter class to the next.

Table 2.—Estimated age of

CARIBBEAN FORESTER

trees in virgin stands, Luquillo Forest

Estimated Age
Diameter
at Tabonuco
breast Type Colorado type
height ss
Canopy Caimitillo Camasey Laurel Palo
species Caimitillo Nemoca verde jusillo | sabino | colorado
Inches Years Years Years” ears Years Years Years
4 80 90 200 170 80 100 80
g 1°0 160 400 260 200 180 170
12 180 230 570 320 240 250 280
ig 270 290 700 370 440 340 420
90 560 430 430 580
24 300 540 730
36 420 1200

The slow diameter growth of the more
important trees in these virgin forests is
shown in another way in Table 3, which is
Lascd on the analysis of 2,488 trees of species
which grow to large size. The data presented
are cor trees between 2 and 20 inches in
diameter and are based upon 5 years of
measured growth. Table 3 shows dominant
tress to ke growing slower than the
codeminants in the tabonuco type, apparently
a ccnsequence of their greater age.

Table 3.—Diameter growth in virgin stands,

Luguille Forest
| Tabonuco type | Celorado type
: |
Crown Mo, Ave. annual| No. Ave. annual
class | t ees Diam. growth) trees Dian. growth
ie | |
Inches Inchss
Dominant 27 0.10 123 0.05
Codominant 64 0.13 212 0.05
Intermediate 204 0.13 567 0.04
Suppressed 359 0.05 952 0.03
All tzees 63 0.09 1854 0 04
The average annual gross increment

(without subtracting mortality) of two
j-acre plots in virgin tabonuco type forest
was 60 cubic feet per acre and for eight
1-acre plots in the colorado type was 28 cubic
feet per acre.

The slow growth shown in these virgin

c—

forests indicates the magnitude of the task

required of the forester in making these
areas highly productive. Not only must
trees which are inferior as to species and
form be removed but the growth rate must
be augmented many times to make forestry
pay.

Relative growth rates of different

Luquillo species determined

Puerto Rico’s existing forests can gen-
erally ke improved materially purely by
partial cuttings which leave the best trees
already present. While the introduction of
new superior species by underplanting pro-
mises to ke a more productive approach to
forest improvement on some sites, it nas not
yet proven entirely successful. In the mean-
time, reliance must be placed upon the best
trees now growing in such stands. The
appraisal of these species must consider a
number of their characteristics, one of the
most important of which is growth rate.

During this year an analysis of all past
growth records of the major sawtimber ana
polewood species within the tabonuco and
colorado types of the Luquillo Mountains was
made to provide a comparison of their
relative growth rates. These data, presented
in Table 4, are for trecs in the codominant
and intermediate crown classes (equal weig”:t
to each class), those most common in well
managed forest. They are for trees ‘rom 4
to 20 inches in diameter.

JANUARY - APRIL, 1953

9

Table 4—Diameter growth of codominant and intermediate trees, Luquillo Forest

Trees Avg. annual
Species measured | diam. growth
No. Inches
Gallina, Alchorneopsis portoricensis Urban £5 OY
Negra lora, Matayba domingensis (DC) Radlk. 85 0.28
Mato, Ormosia krugii Urban 47 0.27
Granadillo, Buchenavia capitata (Vahl.) Eichl. 15 0.26
Roble, Tabebuia pallida Miers 36 0.25
Guama, Jnga laurina (Sw.) Willd. 14 0.23
Ausubo, Manilkara bidentata (A.DC.) Chev. 40 0.20
Achiotillo, Alchornea latifolia Sw. 21 0.20
Masa, Tetragastris balsamifera (Sw.) Urban 4 0.20
Hueso blanco, Linzociera domingensis (Lam.) Knobl. 2 0.20
Motillo, Sloanea berteriana Choisy 30 0.19
Tabonuco, Dacryodes excelsa Vahl. 179 0.14
Yagrumo macho, Didymopanax morototoni (Aubl.) Dene. 54 0.14
Nuez moscada, Ocotea moschata (Pavon) Mez. 17 0.10
Roble de sierra Tabeduia rigida Urban 60 0.07
Caimitillo, Micropholis chrysophylloides Pierre 144 0.06
Laureal sabino, Magnolia splendens Urban 46 0.06
Caimitillo verde, Wicropholis garcinifolia Pierre 514 0.05
Jusillo, Calycogonium squamulosum Cogn 292 0.04
Nemoca, Ocotea spathulata Mez. 72 0.04

Within each species the growth rate of
different trees varied considerably, as did
the character of the various stands sampled.
Included, however, were a number of
managed, well thinned areas. The trees in
the lower third of this list grew so slowly
that they must be considered of low produc-
tivity regardless of the value of their wood.
Among these are all of the most common
species of the colorado type. It is therefore
seen that any considerable increase in the
productivity of this area will require a major
change in composition, probably involving
artificial regeneration with exotic species.

Sierra palm growth related to
diameter and height

Sierra palm (Extcrfe globosa Gaertn) is
common in forests above 2,000 feet eleva-
tion. Over extensive areas (5,000 acres in
the Luquillo Forest alone) it occurs as nearly
pure stands. Its value is only protective,
and its replacement by other equally pro-
tective but more useful trees is desirable.
Initially the plan was assumed to be an

aggressive rapid-growing species which
invaded openings caused by hurricanes. A
series of studies of palm growth described in
past annual reports have shown this to be
untrue; its growth is everywhere slow,
ranging from 4 to 10 inches in height per
year.

The paucity of trees of otner species in
mixture with the palms has created som:
doubt as to whether they will grow well cn
palm sites. These sites are usually areas of
unstable soil, such as rocky slides or river
banks. It appears that other trees gcnerally
fall over before reaching maturity, for la~k
of anchorage. Studies of palm growth and
of methods to estimate it by the condition
of the palms or their environment have been
carried out because relative palm growth
rates may indicate where within the palm
forest the introduction of other better species
is most promising. Studies reported a year
ago showed the more rapid growth of inter-
mediate and suppressed palms as compared
with dominants and codominants, apparentl:
partly a matter of age. Also, a method we

10

described for estimating the age of palms
from the vertical distance between adjacent
leaf sears on the trunk.

During this year an analysis of 5 years
of growth of 357 palms in the Luquillo
Forest provided further information about
this species. The relationship between
diameter at breast height and average height
growth is seen in Table 5 which is based on
The change in
growtn is most pro-
nounced below the 6-inch point. It should
ke understood in interpreting this table that
the relationship between diameter and age
The young vigorous

curved 5-year growth data.

rate with diameter

tends to be inverse.
palms are usually larger in diameter than
the older trees. It can be concluded from
this study that the the average
diameter, other things being equal, the better
the site for palms (and possibly also for

larger

other trees).

Table 5.—Sierra palm growth related
to diameter

Average annual
| height growth

Diameter at
breast height

Inches Inches
3 ial
4 25
5 4.5
6 5.9
ff 6.7
8 hes}
9 7.8
10 8.1

The relationship between initial tree
height and average annual height growth
during the succeeding 5 years is shown in
Table 6. These data show a genzrally inverse
relationship between height and_ height
This further bears out the fact
that the younger trees are the most rapid

growth.

growing.

CARIBBEAN FORESTER

Table 6.—Sierra palm growth related
to height

Inicial height Avg. annual hgt. growth

Feet Inches
5 6.4
10 flea
20 ial
30 6.1
40 4.6
50 3.0

The Present and Potential Contribution
of the Forests

Casuarina reaches 16-inch diameter
in 20 years on coastal sands

Casuarina (C. equisetifolia Forst), a
native of Australia, has for many years been
Puerto Rico’s most popular tree for farm
plantings. It is adapted to poor soils, it
grows rapidly, its straight trunk is suited
for many uses on the farm, and it is
attractive in appearance. The species does
not produce a workable wood, nor does it, on
most sites, grow large enough in diameter
for lumber.

One of the first plantations of this species
in Puerto Rico was established in 1922 by
Central Fajardo at Hacienda Monserrate near
the town of Luquillo. This plantation, about,
4 acres in area, contained 2,700 trees
spaced 8 x 8 feet. The site was considered
worthless for other purposes. The soil was
a white, nearly sterile sand, the water table
was high, and because of crabs no other crop
would grow on it.

This plantation proved to be exceptionally
rapid growing and showed the adaptability
of this species to protected coastal sands. By
early 1932, after 10 years, the topsoil had
taken on a dark brown color and was covered
by a carpet of needles. Few crabs remained
and open herbaceous vegetation had devel-
oped beneath the trees. At that time the
stand contained a volume of 2,750 cubic feet
per acre, nearly all of which was suitable for

JANUARY - APRIL, 1953

posts and poles. Later that same year
a hurricane uprooted or broke off all-but 25
trees.

A second plantation was established on
the same site in 1933. At the end of the
tenth year a measurement of 559 trees
showed a diameter range from 4 to 18 inches,
with a mean of 9.5 inches. The canopy was
85 feet tall and one tree was 105 feet. In the
17th year the number of trees had declined
to 206 through gradual thinnings of the
weaker trees. The average diameter ot
those remaining was 14.4 inches.

The 20-year remeasurement of this
plantation was made this year. It was
found that although the stand is now quite
open, many of the trees are declined in vigor.
More trees has been cut, so only 171 now
remain. These, which undoubtedly are the
earlier dominant and codominant trees, now
range from 8 to 25 inches in diameter and
average 16.2 inches.

The full value of this rapid growth of
casuarina has not generally been utilized in
Puerto Rico. Although the wood is not high
quality for lumber, experiments have shown
that it can be successfully treated with pre-
servative which will prolong its useful life to
at least 10 years as a post or pole in the
ground. Untreated fence posts do not last
24 months, and larger poles generally do not
last more than 5 years.

Casucrina plantations on
Mona Island deteriorate

During 1927 to 1939 about 400 acres
were planted to trees on the coastal plain of
Mona Island, midway between Puerto Rico
and Hispaniola. This area received about
40 inches of precipitation annually and the
soils planted are chiefly beach sands from
6 to 30 inches in depth. The main species
planted were casuarina (C. equisetifolia Forst)
and West Indian mahagony ( Swietenia
mahagoni Jacq.). Although this area is no
longer a public forest reserve, the island is
almost uninhabited and the plantations have
not been disturbed. Because they indicate
what might be expected of planting on

jul

similar unplanted sites on Puerto Rico, their
development has been followed by periodic

reexamination and measurement.

Casuarina has proved to be the out-
standing species. Possibly because of the
drier climate it has not grown as rapidly as
at Hacienda Monserrate (described elsewhere
in this report) but the trees generally have
good form and have produced closed stands.
Their diameter after 15 years range from 4
to 12 inches and heights from 30 to 100 feet.

The development of this tree is closely
related to the degree of protection from the
wind and the quality of the soil. In a pro-
tected cove with relatively deep soil the trees
average 7.5 inches in diameter and from 80
to 100 feet in height. On a nearby exposed
sandy point the trees are only about half as
large, the canopy is more open, the foliage
is thin and some have dead tops which are
being replaced by epicormic branches on the
lower trunks. The unhealthy appearance of
these trees has developed only recently.
There seems to be little prospect for
additional growth. The cause appears to be
largely the combined effect of exposure to
the wind and the almost sterile sandy soil
with brackish water beneath.

Although the trees in these plantation
are gradually deteriorating, they will
probably continue to provide attractive shade
along the beach for many more years. How-
ever, greater economic return might result
from coverting the more exposed areas to a
coconut plantation, using the casuarinas as
a protective nurse crop for the young palms.

The mahogany has also failed on the
more exposed sands but is growing well
where protected. In the better areas
15-year-old dominant trees range from 5 to
7 inches in diameter and to 40 feet in height.
Where planted closely their form is good.
Natural regeneration is abundant in pro-
tected areas.

Increasing Forests Land Productivity
Studies in cutover forest guide management

Studies of virgin forest have produced
valuable results in that they have shown

12

silvical relationships in the relatively stable
climax environment. Similar studies in
forest which has been improved by the
reduction in stand density with the removal
of overmature and inferior trees show more
directly the best silvicultural practices.
Significant results of this character were
yielded in four half acre plots in the tabo-
nuco and colorado forest types of the
Luquillo Mountains, remeasured during the
past year, 5 years after establishment.

These plots were improved by a partial
cutting in 1947. The residual stands at that
time are described in Table 7. Nearly all of
the stands above 20 inches in diameter was
removed, and the basal area was reduced to
about 50 percent of that common in virgin
forest. The cutting either removed or
liberated at least half of the trees which
formerly had been suppressed, leaving a

Table 7.—Residual stand per acre in improved plots.

CARIBBEAN FORESTER

much smaller number of trees in this non-
productive class.

The 5-year growth in these plots is shown
in Table 8. A sharp contrast in the results
in the two types is quite evident. Whereas
diameter growth in the tabonuco type
accelerated 50 percent, there has been no
change in the colorado type. <A total of 204
trees in that type, more than half of those
in the plots, made no measurable diameter
growth during the 5 years. Even the
dominant, codominant, and _ intermediate
trees are not growing rapidly. Trees of the
most rapid growing species (roble de sierra,
Tabebuia rigida Urban) in these classes were
growing only at the rate of 7 inches in
diameter per century. This result confirms
that shown in Table 4. It is possible that
this is partly due to the great age of many
of these trees, as shown in Table 2.

Luquillo Forest, 1947

Colorado type | Tabonuco type

Index Plot 1 | Plot 2 | Plot 1 | Plot 2

Number of trees by diameter classes

2 - &” 726 938 746 682

Ul ara AM 58 42 60 68

13 - 20” 20 2 12 18

20”+ 2 2

Total 804 984 820 768
Total basal area, sq. feet 91 68 98 100
Percentage of trees suppressed 38 27 24 27
Total volume, cubic feet 1,708 1,186 1,368 1,456

Table 8.—Growth in improved Luquillo plots, 1947-52

Tabonuco type | Colorado type

acre, sq. ft.

Index Plot 1 Plot 2 | Plot 1 Plot 2
5-year ingrowth; new trees per acre. 298 220 —— 52
Mean annual diameter growth, all trees, inches 0.13 0.14 0.08 0.05
Mean annual diameter growth of dominant and 0.20 0.26 0.05 0.05
codominant trees, inches.

5-year basal area increment per 30 34 —5 5
5-year gross increment per acre, cu. ft. 600 595 98 115

85 15 68 60

5-year mortality, cu. ft.
Five-year net increment, cu. ft.

515 580 30 55

JANUARY - APRIL, 1953

Continued management, gradually
elminating the old trees, might eventually
create a more productive stand. However,
during the past 5 years there has been
almost no crown development, and mortality
has continued high, so that a second cutting,
if made soon, would excessively open the
stand. Moreover, there is almost no young
sapling growth so the replacement of the old
stand with a young one will apparently be a
very slow process. A more promising solu-
tion seems to lie in the introduction of other
species.

In the tabonuco type the cutting produced
a noticeable flush in the undergrowth. (See
Fig. 3). The stand density increased rapidly
toward its initial basal area. Crown develop-
ment was also rapid, and closed the canopy.
Therefore, in 1952 a second cutting was made
in Plot 1 reducing the number of trees per
acre from 1,072 to 848 and the basal area
from 120 to 105 square feet per acre. In Plot
2 the number of trees was reduced from
1,178to 978 per acre and the basal area from
102 to 89 square feet per acre.

There is some indication that the some-
what heavier cut made in Plot2 5 years
ago was more desirable than that in Plotl.
Diameter growth, and net increment were
higher in this plot. Conclusive evidence
will require a separate investigation. It
was shown, nevertheless, that the heavier
cutting in Plot 2 did not cause serious
invasion by vines.

Broadleaf mahogany reacts well to direct
seeding, underplanting, and thinning

The successful establishment of West
Indian mahogany (Swietenia mahagoni Jacq.)
by direct seeding on the limestone hills of
the Cambalache Experimental Forest (sea
level, precipitation 55 inches annually) and
the good growth of broadleaf manogany
(Swietenia macrophylla King) on this same
site led to tests of direct seeding with the

latter, more rapid growing species. The
advantage of this practices with West
Indian mahogany, as compared wit

9
oO

planting, were that potted stock (the only
alternative) was made unnecessary and that
therefore the planting was much cheaper.
Direct seeding also was easier because deep
pockets of soil did not have to be located
for sowing, as was necessary for planting
the potted trees. The early growth of
seedlings in the forest has been rapid. This
practice has been successsful only under
partial shade, however, and has failed
because of drought on the south coast (sea
level, precipitation 30 inches annually).

A sowing was made in late 1950 in the
Cambalache Forest, with four seeds per spot
under a thinned canopy about 20 feet high.
This proved to be a failure because of poor
germination. A resowing was made in 1951
and has produced nearly a complete catch.
At the end of 1952, after the seedlings had
passed through one dry season, nearly all of
the spots contain living seedlings which
range from 12 to 18 inches tall. The develop-
ment of a few remaining trees from the
earlier sowing shows that these are capable
of rapid height growth if provided con-
tinuous overhead light.

In the humid mountains the planting of
broadleaf mahogany nursery stock appears
to be more satisfactory than direct seeding
(although the latter has not been tested)
because vigorous nursery stock makes much
more rapid early growth and is thus better
able to compete with the dense native
vegetation under those conditions. As on
the coast, underplanting is proving to be a
safer practice than field planting with this
species.

About 40 acres of secondary rain forest
were underplanted with broadleaf mahogany
in late 1950 in the Luquillo Forest (elevation,
1,000 feet ; precipitation, 120 inches annually).
The canopy was thinned to provide only
about half shade and the trees were spaced
15 to 20 feet apart beneath openings. Because
of excessively wet weather survival was only
about 60 percent, and a replanting was made.
After 18 months the trees averaged 5 feet
in height and were very vigorous. There
was no sign of damage by the shoot borer

CARIBBEAN FORESTER

Fig. 3-—Young forest of the Tabonuco Type 2 years after improvement cut-

ting showing the dense flush of under growth. (Rodal joven del Tipo
Tabonuco 2 anos después de una corta parcial mostrando un marcado vigor
en el sotobosque).

Se:

Fig. 4.—Recently thinned 13-yecr-old flantation of broadleaf mahogany
(Swietenia macrophylla King) at Rio Abajo showing the density of the
stand left. (Plantacion de caoba hondurena de 13 anos de edad reciente-
mente aclarada en Rio Abajo mostrando la densidad del rodal remanente),

JANUARY - APRIL, 1953

(Hypsipyla grendella). It was clear, however,
that all plantation care may not be avoided
merely by planting under a canopy. The
need for cutting grass and herbs is virtually
eliminated, but vines must be removed at
least once or twice, and the maintenance of
an open canopy above the trees calls for
attention probably every 24 months for the
first few years. The result of this test and
evidence from older field plantings nearby
has served as basis for the underplanting of
about 800 acres of secondary rain forest on
the more protected sites of the Luquillo
Forest during the year.

Evidence of the potentialities of broad-
leaf mahogany in the rain forest zone, has
come largely from a small 1931 planting.
This plantation, about 4 acres in area, has
bteen allowed to develop without silvicultural
attention. After 20 years the basal area
was 140 square feet per acre, and the stand
was so dense and uniform that 85 percent of
the trees were in the intermediate crown
class. The crowns are opaque and a deeper
green color than is usual in younger planta-
tions. Diameters range from 4 to 15 inches,
the average being 9.6 inches. The mean
annual basal area increment per tree for the
first 17 years was 0.0238 square feet; for
the last 3 years it was 0.0342 square feet,
indicating continued rapid growth. Many of
the trees were forked, but a thinning made
this year has eliminated almost all of these.
This 20-year thinning yielded nearly 1,000
board feet of sawtimber per acre and has
paid the cost of the planting (without
interest). The health, size and growth rate
of these trees shows this species to be the
most promising prospect for similar pro-
tected sites within the rain forest zone.

A study of more timely thinnings in the
Rio Abajo Forest (elevation, 500 feet; pre-
cipitation, 80 inches annually) is serving as
a guide for practice on more than 500 acres
of young plantations of this species through-
out the island. In 1950 tests were made in
a 13-year-old plantation in a protected lime-
stone sinkhole. This plantation had attained
an average diameter (210 dominant and

15

codominant trees) of 6.2 inches, a canopy
height of about 50 feet, and a basal area
ranging from 80 to 110 square feet per acre.
Mean annual tasal area growth per tree for
the first 13 years was 0.0161 square foot.
Current annual basal area growth per tree
for the past 2 years in unthinned stands
was 0.0151 square foot, only a slight
decrease.

Two quarter-acre plots in this stand were
thinned in 1950, removing about 320 trees
per acre and leaving about 400. The residual
basal area ranged from 56 to 76 square feet
per acre. The thinning eliminated trees of
poor form regardless of size, nearly all of the
suppressed trees, and more than half of the
intermediates. The opening increased from
¥% to % the proportion of all trees in the
dominant and codominanit crown classes, and
even those trees previously in these classes
were given more growing space. (See Fig. 4).

Re-examination of these thinned plots
this year showed some of the early results.
The opening was not sufficient toe give rise
to a vine problem, although the few vines in
the more open areas indicate that this would
have been a result of heavier thinning.
Almost no trees were bent over by the wind
following release. Sprout growth from the

stumps of trees cut 2 years ago is
unimportant. The diameter growth has
keen accelerated by the thinning. The

average annual diameter growth per tree in
these classes for the 2 years since thin-
ning was 0.48 inch (basis, 42 trees), as
compared with 0.44 inch (basis, 42 trees) in
adjacent unthinned plots. The difference
is more marked if all of the remaining trees
(including the subordinates) are included in
this comparison: 0.26 inch vs. 0.17 inch. A
most significant result is the increased
dominance of the larger trees. They are
making very rapid height growth and at least
50 trees per acre stand out well above the
general canopy level. These are undoubt-
edly final crop trees. Another thinning will
not be needed for growth acceleration until
the crowns of these large trees grow toge-
ther, at least 5 years and possibly 10 years

16

after the 1950 thinning. At the end of 5
years, however, it may be desirable to thin
from below, harvesting merchantable
material available in declining subordinate
trees.

Twenty-year mangrove responds quickly
to thinning and seed cutting

Tidal forest dominated by white
Mangrove (Laguncularia racemosa (L.)
Gaertn.) covers an area of more than

15,000 acres on the banks of estuaries,
iagoons, and protected bays of Puerto Rico.
Because of its accessibility this forest has
been heavily used since early times. The
large trees are now gone but rezrowth is
rapid so these areas are still largely covered
with young forest. Invasion by most other
species is precluded by the adverse soil, and
white mangrove is nearly pure over most of
the area. (See Fig. 5).

In spite of what appear to be favorable
conditions, the growth of mangrove is not
generally satisfactory. Clear cutting, the
usual practice, has resulted in dense sapling
stands which stagnate. Studies have shown
that as many as 19,000 stems per acre may
devolop to a diameter of half an inch or
more. Then, as no trees quickly outgrow their
neighbors and become dominant, growth
must await the slow elimination of thousands
of trees, often accomplished by boring insects.
A study of 223 1-inch trees in this stage
showed their average diameter growth to be
only 0.6 inch over a period of 11 years. Since
the trees are too small for must uses and
their thinning is expensive, this stagnation
is an important obstacle to high productivity
of this type of forest.

Two methods which may reduce the
density of these young stands are being
tested, The first consists of partial cuttings,

CARIBBEAN FORESTER

with the objective of creating an all-aged
forest. The major problem which must be
faced are the apparent intolerance of
the species and the danger of windthrow.
The second method is clear cutting in narrow
strips perpendicular to the prevailing winds.
Here the plan is to gradually progress wind-
ward, cutting a new strip as soon as the
existing one is satisfactorily regenerated.
The dangers here are windthrow and the
prospect that a strip sufficiently wide to
assure regeneration may also produce an
overdense young stand.

The stand selected for these tests, located
within the Aguirre Forest, developed after
clearcutting in 1930. The average diameter
of the dominant and codominant trees is 8
inches and the basal area ranges from 110 to
140 square feet per acre. The canopy
is at about 60 feet. Four quarter-acre plots
were established in 1949 to determine the
growth rate within the stand prior to any
change. It was found during the past 5
years diameter growth. averaged only 0.11
inch per year (0.20 inch for dominant and
codominant trees alone), that an average of
95 trees died per acre per year; and that
there was no net change in basal area or
volume.

In two of the plots (excluded from the
above analysis) a windstorm in 1950 blew
over 82 trees, creating openings in the
canopy. Adjacent trees were remeasured and
reclassified as to crown position after the
storm. An analysis of the growth of 104 of
these trees appears in Table 9. The growth
comparison is based on the periods 1949-50
(cefore the storm) and 1950-52 (after the
storm). The last two lines in Table 9
indicate that marked immediate growth
acceleration of subordinate trees is possible
in this stand as a result of release, even
among those trees which have probably been
dominated for 20 years.

JANUARY - APRIL, 1953

al

Table 9.—Effect of release or mangrove growth-

|

|
Grown class Avg. annual diameter growth
| Number Saat

Before | After 0 Before After
release | release | trees release release
Inches Inches

Codominant Dominant 9 0.23 0.27
Intermediate Codominant 38 0.18 017
Intermediate Dominant 4 0.04 0.40
Suppressed Intermediate 53 0.06 0.17

The windstorm provided valuable infor-
mation concerning silviculture. As has just
been shown, the stand will react to release.
It was also found that it was generally the
largest trees which blew over. Thus a thin-
ning, which is desirable to increase incre-
ment, should harvest these large trees.
Accordingly, two of the plots were thinned
with this in mind, removing 208 trees per
acre from one plot and reducing the basal
area from 129 to 78 square feet per acre. In
the other plot 328 trees were removed per
acre, and the basal area was reduced from
108 to 63 square feet per acre. These plots
will be observed to determine future growth,
windthrow, and regeneration.

The strip cutting was started in 1951 in
the same stand. A strip 66 feet wide by
660 feet in length was cut through the forest
from north to south. The wood was converted
into charcoal. Examination at the end of
one year showed no wind damage along the
edges of the strip. The number of stumps
which had sprouted was insufficient to make

a stand. Moreover, their stems are crooked
and will not produce good trees. A fair crop
of new seedlings about 4 inches _ tall

appeared in the eastern half of the strip.
Most of these are beneath overhanging
branches of trees on the east side of the strip.
Elsewhere within the strip are a few lines
of seedlings located at what was evidently
the high water line when they matured. To
the windward of the strip, to about 30 feet
into the forest, the soil is covered with a
dense stand of seedlings, apparently suf-
ficiently tolerant to withstand overhead

shade with side light. Further observations
will be necessary to determine whether the
strip is the proper width and when a second

adjacent strip can be cut on the windward
side.

Eucalypus experience summarized

Eucalyptus, because of rapid growth in
South America and elsewhere, attracted
attention years ago and many species were
introduced into Puerto Rico. By 1940, a
few trees were growing on farm throughout
the island and there were a few small
plantings in the public forests. Since then
more than 2,000 acres have been planted
with E. robusta and E. kirtoniana on the public
forests. Seed of additional species has been
introduced from Brazil and Guatemala and
planted experimentally on different sites.
The progress of these plantings has been
described periodically in past annual
reports. Experience to date with the out-
standing species is briefly summarized here.

E. triantha Link. Planted on a
variety of sites from sea level to 3,500 feet
elevation. Not promising. Has failed on
laterite soils and growth has been erratic
elsewhere. On one of the best sites with a
deep loose red soil in the Luquillo Forest
(elevation, 500 feet; precipitation, 120 inches)
individual 8-year-old trees have attained a
diameter of 7 inches and a height of from
49 to 60 feet. Nevertheless, most of the
trees are much smaller, poorly formed, and
weak.

E. alba Reinwardt.—Planted on a variety

ie2)

CARIBBEAN FORESTER

* ~

Fig. 5.—Typical young mangrow: stand in the San Juan forest. This
stand, prior to thinning, kad become so dense that diameter growth was
negligible. (Rodal tipico de mangle en el bosque de San Juan. Este
vodal, antes del aclareo, era tan denso que el crecimiento diametral fué
lento).

Fig. 6.—

Fifteen-year-old plantation of Euca-
lyptus robusta Smith in the Toro Negro
Forest showing the good form of the
trees, and also the open character of the
stand. (Plantacion de Eucalyptus ro-
busta de 15 anos de edad en el Bosque
Toro Negro mostrando la buena forma
de los arboles y la naturaleza abierta del

redal Ne

JANUARY - APRIL, 1953

of sites from sea level to 3,500 feet elevation.
The best adapted species yet found for
elevation from sea level to 500 feet. Ona
shallow soil in the St. Just Experimentai
Area (elevation, 300 feet; precipitation, 70
inches annually) an 8-year-old plantation
is 40 to 60 feet tall, with trees 3 to 5 inches
in diameter. On a deep loose red soil in the
Luquillo Forest (elevation, 500 feet; preci-
pitation, 120 inches annually) 8-year-old
trees are 6 to 9 inches in diameter and 60
to 75 feet tall. On a poor heavy soil in the
Toro Negro Forest (elevation, 3,500 feet;
precipitation, 110 inches annually) 7-year-old
trees average 13 feet in height, with
a maximum of 25 feet. Excessive taper and
flat-topped crowns indicate that this species
is not as well adapted to this higher site as
some other species. On a very poor laterite
soil in the Maricao Forest (elevation, 2,000
feet; precipitation 100 inches annually) this
species failed to grow.

E. botryoides Smith. — Planted on a
variety of sites from sea level to 3,500 feet
elevation. Only fair on the best sites tested,
elsewhere a failure. In the Luquillo Forest
(elevation, 500 feet; precipitation, 120 inches
annually) 8-year-old trees are 60 feet tall
on a deep loose soil. The stand is not
uniform, however, and many trees are
stunted.

E. citriodora Hook. — Planted on a
variety of sites from sea level to 3,500 feet
elevation. Generally slow-growing and thin-
crowned irrespective of site. On a deep soil
in the Luquillo Forest (elevation, 500 feet;
precipitation 120 inches annually) gummosis
is common and most of the trees have died
during the first 8 years. In the Toro
Negro Forest (elevation, 3,500 feet; preci-
pitation, 110 inches annually) on a heavy
degraded soil 7-year-old trees average only
10 to 12 feet in height.

E. gummifera (Gaertn) Hookr. — Planted
only in the mountains. Survival good, trees
thrifty and growth slow. At Toro Negro
(elevation, 3,500 feet; precipitation, 110
inches annually) 6-year-old trees average
from 15 to 20 feet in height.

1

E. globulus Labill. — Planted only in the
mountains. Unadapted. A planting in the
Toro Negro. Forest (elevation, 3,800 feet;
precipitation, 120 inches annually) is not
growing well. After 8 years a few trees
are 25 feet tall, but the average is not more
than 12 feet. Experience elsewhere indicates
that this species requires a cooler climate.

E. kirtcniana F. v. M. — Planted on a
variety of sites, mostly above 2,000 feet ele-
vation. This species, previously reported as
E. resinifera Smith, was identified during the
past year. It is as well adapted to Puerto
Rico as any other species, and its height
growth is possible better than all others
Trees planted in the Toro Negro Forest (ele-
vation, 3,000 feet; precipitation, 110 inches
annually) in 13 years have grown to
diameters from 6 to 13 inches and to heights
trom 75 to 90 feet. This is on a deep loose
soil of fair to low productivity. Codominant
trees in this plantation are growing at the

rate of more than 1 inch in diameter
annually. Form excellent.
E. mcculata Hook. — So far has been

planted in four locations from 500 to 3,500
ft. elevation. On a deep loose red soil in the
Luquillo Forest (elevation, 500 feet; preci-
pitation, 120 inches annually) 8-year-old trees
are 35 to 45 feet tall and trees 3 to 5 inches
in diameter, one of the best species on this
site. Ona poor heavy soil in the Toro Negro
Forest (elevation, 3,500 feet; precipitation,
110 inches annually) 7-year-old trees average
22 feet, with a maximum of 25 feet, are
thrifty and very uniform and one of the best
in this poor soil. Ona very poor laterite soil
in the Maricao Forest (elevation, 2,000 feet;
precipitation, 100 inches annually) 5 year
old trees average 6 feet with a maximum of
12 feet. E. maculata is one of the best
adapted species particularly at the higher
elevation. It does not show gummosis and
early death anywhere to the same extent
than E. citriodora in the sites where both have
been planted.

E. pilularis Smith.— Planted only in the
mountains. Growth only fair. In the Toro

20

Negro Forest (elevation, 3,500 feet; preci-
pitation, 110 inches annually) survival was
high and the trees are healthy and well
formed, and average height is 25 feet after
8 years.

E. propingua Deane & Maiden.—Planted
on a variety of sites from sea level to 3,500
feet elevation. Requires better soils than
where tested. In the Luquillo Forest eleva-
tion, 500 feet; precipitation, 120 inches
annually) only a few trees developed well, in
the lower better areas of the plantation. Here
the maximum size is 7 inches in diameter
and 60 feet in height after 8 years. In
the Toro Negro Forest (elevation, 3,500 feet;
precipitation, 10 inches annually) a few trees
along the valley bottom attained 25 feet in
height after 7 years.

E. resinifera Smith. — Planted on a
variety of sites from sea level to 3,500 feet

elevation. One of the best adapted species
in the mountains. In the Toro Negro Forest
(elevation, 3,500 feet; precipitation, 110
inches annually) T-year-old trees are

thrifty, uniform and from 30 to 35 feet in
height. In the Maricao Forest (elevation,
2,000 feet; precipitation, 100 inches
annually) on a very poor laterite soil where
20 other species of eucalyptus have failed.
the trees average 20 feet in height after
8 years. In the Cambalache Experi-
mental Forest (sea level; precipitation, 55
inches annually) the trees have also attained
20 feet in height, and 4 inches in diameter
in 8 years. This is better development
at sea level than most other species of euca-
lyptus, but since growth has declined recently
it appears that the species is not well adapted
here.

E. robusta Smith.— Planted on a variety
of sites from sea level to 3,800 feet eleva-
tion. The most widely planted species in
Puerto Rico. Well adapted to poor soils,
particularly those which are wet, and even
laterite, above 1,500 feet elevation.
adapted at sea level. On wet deep soils at
elevations from 2,000 to 3,000 feet 13-year-
old trees range from 8 to 16 inches in

Not.

CARIBBEAN FORESTER

diameter and to 75 feet tall, and there is no
sign of a decline in growth. (See Fig. 6).

E. sideroxylon A, Cunn. — Planted only
in the mountains. Not outstanding, but
thrifty and of good form. In the Toro Ne-
gro Forest (elevation, 3,500 feet; precipi-
tation, 110 inches annually) 7-year-old trees
average 30 feet in height.

E. umbellata (Gaertn) Domin.—Planted on
a variety of sites from sea level to 3,500 feet
elevation. Like £. alba, and unlike all others
tested, this species has grown best at low
elevation. In the St. Just Experimental
Area (elevation, 300 feet; precipitation, 70
inches annually) on a well-drained shale soil
8-year-old trees are from 3 to 6 inches
in diameter and 50 to 60 feet tall. On the
other hand, in the Cambalache Experimental
Forest (sea level; precipitation, 55 inches
annually) trees of the same age on a heavy
soil are not thrifty. They average about
3 inches in diameter and form 35 to 59
feet in height and their crowns are thin.
In the Rio Abajo Forest (elevation, 500 feet;
precipitation 80 inches annually) 8-year-
old trees average only 8 to 25 feet in height,
This is largely due to a very infertile
degraded soil. At 3,500 feet elevation they
have made almost no growth and are
apparently destined to fail.

The recent appearance of a good market
for eucalyptus piling and the possibility that
it may also be used for wall board make
eucalyptus production one of the most pro-
mising prospects for thousands of acres of
idle private land which is deforested and
needs protection. In recognition of this
development further investigation will be
made of the site adaptability of different
species. Additional species are being
introduced, and those already growing here
will be tested on better sites. Investigations
will also be directed toward better utilization
of the wood.

Mexican cypress continues rapid growth

Mexican cypress (Cupressus lusitanica
Mill), a valuable conifer native to Central

JANUARY - APRIL, 1953

America and Mexico, was introduced 4
years ago and has been tested on a variety
of sites, mostly at upper elevations. It
appears to be one of the most outstanding
trees ever introduced.

A 4-year-old plantation in the Luquillo
Forest (elevation, 1,800 feet; precipitation,
140 inches annually) on a deep but
waterlogged soil has reached a height of 12
feet. In the Toro Negro Forest (elevation,
3,500 feet; precipitation, 120 inches
ennually) a 2-15-year-old plantation on an
exposed slope and a rocky shallow soil is
more vigorous than either eucalyptus or
roble (Tabebuia pallida Miers). The average
height of the cypress is 7 feet, with trees
to 12 feet. Trees underplanted beneath
abandoned coffee shade in the Toro Negro
Forest are growing well despite the shade.
On a very poor lateritie soil in the Maricao
Forest (elevation 2,000 feet; precipitation,
100 inches annually) the trees have kegun
height growth immediately after planting
and exhibit a bright green color not found
in any of the other trees tested on this site
nor in the native vegetation. At this
location even eucalyptus appears destined to
failure.

This species appears to be outstanding
in many respects. With a minimum of
weeding, young trees are able to compete
with aggressive vegetation such as tall
ferns and molasses grass (Melinus minutifolia).
It is growing well in an_ exceptionally
wide range of conditions, from near sea
level to 3,500 feet elevation and on
the poorest soils of the island. It
apparently will grow well both under shade
and in the open. Its early growth rate
exceeds that of most other trees planted.

Only one undesirable characteristic has
become apparent so far, and that may prove
to be of minor importance as the trees
develop. On some sites the trunks grow so
fast that they are very flexible and tend
to bend over in the wind. This is not every-
where a problem, since little wind damage
has taken place at Toro Negro.

Casuarina stands provide good
environment for under planting

Casuarina (C. equisetifolia Forst) is
planted widely in Puerto Rico to protect
soils degraded by cultivation. The tree is
adapted almost everywhere in the island
below 1,000 feet elevation, and it grows
rapidly. However, because ants destroy the
seed it does not reproduce itself. Thus if
casuarina is to be perpetuated it must be
replanted periodically at a considerable cost.
If other tree crops are to succeed it,
technique of conversion are needed which do
not expose the site.

A study of conversion from casuarina to
other forest crops was begun recently by
underplanting different trees beneath stands
of casuarina. It was thought that if these
species were established in advance of the
cutting that continuous soil protection could
be provided. The first underplanting was
made in 1949 on a shallow soil in the St.
Just Experimental Area (elevation, 300 feet;
precipitation, 70 inches annually) beneath a
4-year-old stand of casuarina which pro-
vided a continuous canopy. A second under-
planting was made in 1950 on a degraded
deep red soil under a similar plantation in
the Rio Abajo Forest (elevation, 509 feet;
precipitation, 80 inches annually). In this
latter case the casuarina itself was declined
due to what appears to be a root rot.

Results at St. Just are encouraging. Six
species are very thrifty after 3 years,
much more so than would have been expected
in the open on this site. These include
guaraguao (Guwarea trichilioides L.) and capa
prieto (Cordia allidora (R. & P.) Cham), two
valuable timber species common in natural
forests. The first is known to be tolerant,
and has grown slowly, as is typical shortly
after planting. The capa prieto, a less
tolerant tree, ranges from 4 to 8 feet tall.
Another species, capa blanco (Petitia domin-
gensis Jacq.), is generally considered very
intolerant, ranges from 3 to 7 feet in height

aA
and is only slightly spindly because of the
shade. Roble (Tabebuia pallida Miers),
another intolerant tree, is from 2 to 6 feet
tall, growing rapidly and showing no effects
of suppression. The common coffee snade,
tree guaba (Jnga vera Willd) average 5 feet
in height and is very vigorous. Broadleaf
mahogany (Swietenia macrophylla King) is
the most vigorous tree of all those tried. It
ranges from 5 to 8 feet in height, and the
new growth is succulent and deep green as
if fertilized with nitrogen. (See Fig. 7).
Casuarina seedlings underplanted in this
experiment are dying apparently for jack of
light.

Results to date indicate that the shade of
casuarina is insufficient to prevent rapid
devolopment of a number of other trees
species in the understory. The thrift and
good color of the underplanted trees do not
bear out the common belief that casuarina,
because it grows rapidly on poor sites,
exhausts the soil. The good development of
the coffee shade tree, guaba, makes desirable
further research on the conversion of casua-
vina stands to coffee plantations. Coffee
trees planted beneath casuarina at Rio Abajo
are also growing well.

Two pre-emergence herbicides prove effective

Weeding in the forest nurseries is one of
the largest costs of stock production. The
use of selective herbicides has in many places
reduced this cost, and a few experiments
have been undertaken in Puerto Rico to
determine the suitability of herbicides for
this purpose here. A year ago it was

sodium trichloro-acetate (TCA) at the rate
of 50 pounds per acre and 2,4-D (amine salt)
at the rate of 8 pounds per acre gave weed
eontrol in the Toa Nursery for 8 weeks,
and that transplanting of seedlings of
casuarina or sowing seeds of mahogany could
be done safely 2 weeks after treatment.
Pre-sowing treatment as described is both
effeetive and advantageous. However, in
the hope that similar control might be posi-

CARIBBEAN FORESTER

sible using herbicides which could be applied
after sowing (and thus saving the period of
time between pre-sowing treatment and
sowing) a number of tests of pre-emergence
treatment were made this year. Three
herbicides were used: TCA, sodium pen-
tachlorophenate (Santobrite) and ‘“Matona
30-2-2” (a dinitro weed killer in weak solu-
tion). TCA was used at the rate of 20, 50
and 100 pounds per acre. Sodium pentachlo-
rophenate was used at 15 and 30 pounds per
acre. Matona was applied at the rate of 6
gallons per acre. The species tested was
broadleaf mahogany (Swietenia macrophylla
King). To determine the tolerance of the
seedlings the herbicides were applied at one,
two, and three weeks after sowing
(Mahogany seedlings typically appear above
the surface about 3 weeks after sowing).

TCA at 20 pounds per acre was effective
as an herbicide, especially against grasses.
When applied more than one week after
sowing or with applications heavier than 50
pounds per acre it was injurious to the
seedlings. The 20-pound application kept the
beds sufficiently clean (not more than 35%
covered with weeds) for 8 weeks after
treatment.

Sodium pentachlorophenate at either rate
of application, was both safe and effective
when applied cne week after sowing. Later
applications did not damage the tree
seedlings but neither did they control the
weeds, which at that time had aiready
germinated. Application of 15 pounds per
acre 1 week after sowing kept the beds
sufficiently clean for 8 weeks. Matona did
not kill weeds at the rate applied.

The best pre-emergence treatments with
TCA and sodium pentachlorophenate found
this year are superior to the pre-sowing
treatments recommended last year because
they eliminate the period of waiting between
application and sowing. In addition, and for
his reason, they are effective to 8 weeks
instead of 6 weeks after sowing. Also,
with TCA it was found that application of
20 pounds per acre is as effective as 50
pounds (the lightest application last year).

JANUARY - APRIL, 1953

Additional tests with these and other
pre-emergence herbicides are warranted. Sub-
sequently post-emergence herbicides will be
tested. This type of treatment, which might
prove permissible at any time after the
seedlings come up, would be much more satis-
factory than any of those described here
(these do not eliminate the final weeding),
but the prospect of finding so selective a
material seems remote.

Cojfee shade research begins

Recent reports have pointed to the
desirability of perpetuating the presently
declining coffee industry. The coffee planta-
tions provide a protective cover on nearly
10 percent of the land surface of the island,
the steepest and most erodable areas. The
cutting of coffee plantations, which has
taken place on a large scale during the past
10 years, leads to a brief cycle of cultivated
crops which degrades the soil and terminates
in idle grasland or brush.

A year ago a survey of coffee yield was
conducted jointly with the Bureau of Plant
Industry to orient research in this field
which might assist coffee farmers. Several
important forestry phases deserve investiga-
tion. Study of a number of present and
potential shade trees was begun this year.
BPI has undertaken a formal study of
shadeless coffee production.

The common coffee shade tree species in
Puerto Rico are guaba (Jnga vera Willd.)
and guama (Inga leurina Sw.). The former
is apparently exotic; the latter native. Guaba
is generally superior to guama because of
its more spreading form. Both have insect
and disease problems which not only mate-
rially limit the development and life of the
shade trees themselves but also adversely
affect the coffee plants. In the belief that
some of the many Ingas native to other
countries might prove superior for coffee
shade, a number of species were introduced
from Venezuela by the Puerto Rico Depart-
ment of Agriculture and Labor in 1929 and
1930.

Most of the early plantings following the

23

introduction are now gone, and there is little
record as to their development. The most
outstanding species, however, guama venezo-
lano (Inga speciosissima Pittier) has inecome
popular as a coffee shade tree, and each year
hundreds of thousands of seedlings are being
propagated by the Forest Service and dis-
tributed to farmers. A few of the original
trees still remaining at Utuado (elevation.
400 feet; precipitation, 80 inches annually)
after 23 years are about 10 inches in
diameter, 30 feet tall and of spreading form
with denser shade than guaba and guama.
This species is easy to propagate, its survival
after planting is uniformly high, and it has
been free from significant insect attacks and
disease. In the coffee region (elevation, 1,500
to 2,000 feet; precipitation, 90 to 100 inches
annually) this species makes very fast
growth. Three-year-old trees average 2
inches in diameter and 10 to 15 feet in
height. Six-year-old trees average 3 to 5
inches in diameter and 15 to 18 feet in
height.

Other less well known species introduced
at the same time include J. fastuose (Jacq.)
Willd., 7. spuria Humb, & Bonpl. and an uni-
dentified species, probably J. punctata Willd.
The first two of these species have grown to
50 feet in height in 23 years and are of better
form for shade than J. sfeciosissima. Trees
of J. fastuosc 13 years old on a protected site
with deep soil at 1,500 feet elevation (pre-
cipitation, 90 inches annually) have grown
to 10 inches in diameter and 35 feet in
height and are very vigorous.

A collection of small plantings of these
different species has been established in the
arboretum at La Catalina in the Luquillo
Forest to provide seed for additional testing.
Seedlings of J. spuria Humb. & Bonpl.
apparently one of the best of the introduc-
tions (yet little used to date) were dis-
tributed to five farmer cooperators for
testing in the coffee region.

Preliminary tests, described elsewhere
in this report, were begun with casuarina
as a nurse crop for coffee shade trees. First
indications are that casuarina shade is

24

sufficiently open for rapid development of
guaba beneath these trees. A test is also
being made of broadleaf mahogany (Swietenia
macrophylla King) as a coffee shade. The
crown of mahogany is so dense that wide
spacing or frequent prunines and thinnings
will undoubtediy be required. This first
test, begun, on the St. Just Experimental
Area (elevation, 300 feet; precipitation 70
inches) will ke carried out also on a few
farms in the coffee region. Future studies
will also include eucalyptus as a _ coffee
shade.

Young limestone forest closes

rapidly after improvement cutting

The limestone hills of the north coasts of
Puerto Rico make up more than 10 percent
of the land surface of the island. They
are nearly completely covered with
secondary forest and have been cut over so
frequently that only small trees remain.
Although good tree species not native to
this site, such as West Indian mahogany,
will grow on it, the soil is so shallow that a
dense stand of sawtimber probably will
never develop. On many sites the impro-
vement of the existing forest by partial!
cuttings with the objective of maximum
post and pole production is the most pro-
mising silvicultural practice. Since nearly
all of this land is in private ownership this
improvement must be cheap and must yield
carly returns.

A typical young stand on the west slope
of a limestone hill in the Cambalache Experi-
mental Forest (sea level; precipitation, 55
inches annually) was selected in 1959 to
investigate this problem. The area was
opened to about 60 percent shade by eli-
minating trees unsuited for post or poles
because of poor form or inferior wood. Dense
clumps of better trees were also thinned
where necessary. This cutting yielded, per
acre, about a cord of fuelwood and 40 fence
posts, and cost about four man days.

The stand left contained 1,160 trees per
acre of 2 inches or more in diameter, with an

CARIBBEAN FORESTER

average diameter of 2.4 inches and a basal
area of 39 square feet per acre. About 57
percent of the basal area was in good post
species. Vines have not formed a problem,
and at the end of 1 year another light cut-
ting was made to reopen the canopy. Another
similar cutting was made at the end of the
second year. These each removed less. than
half as much volume as the first cutting
but provided fuelwood such as would be
needed by a farmer. The 235 dominant and

codominant trees per acre now average
3.6 inches in diameter and contain
good posts. They are growing in

diameter at the average rate of 0.21 inch
per year. Future cuttings should yield as
much or more polewood as fuelwood volume.

Continued study of this area is needed
before the economics of this practice are fully
known. In the first 2 years only a few
saplings have appeared beneath the stand.
Host of these are sprouts from stumps left
after the first cutting. The amount and
quality of the natural reproduction will in a
large measure determine the success of this
technique.

Bamboo continues rapid
erowth on better sites

Bamboo appears to have great poten-
tialities in Puerto Rico. Numerous species
adapted to the island are elsewhere of
value as raw material for a wide variety of
articles of commerce. The availability at
the Federal Experiment Station of pianting
stock of a number of useful species not here-
tofore throughly tested led to experimental
plantings on forest lands throughout the
island.

The earliest plantings were made on a
poor lateritic soil in the Toro Negro Forest
(elevation 3,000 feet; precipitation, 110
inches annually) in 1945. Three species,
Bambusa tulda Roxb; B. tuldoides Munro; and
B. longispiculata) Gamble ex Brandis were
planted on an area of about 20 acres. After
a slow start, the 7-year-old plants now
have more than half of their culms ready
for harvest. The diameter of these culms

JANUARY - APRIL, 1953

varies considerably with site and should
continue to increase with age. 8B. tulda is the
largest, with culm diameter from %,”’ to
1-14” in the ridges and from 2” to 3” in the
valley bottoms. This bamboo is suited for
furniture.

On a better site in the Luquillo Forest
(elevation, 800 feet; precipitation 120 inches
annually) on a deep red soil 4-vear-old
plants of B. tulda and longispiculata are up to
30 feet in height in 4 years. At a spacing
of 10 x 10 feet they have killed out all
competing vegetation.

On a limestone hill in the Camblache
Experimental Forest (sea level; precipita-
tion, 55 inches annually) a 5-vear-old
underplanting ranges from 15 to 30 feet tall.
The culms have reached the canopy level and
are developing rapidly in spite of a very
shallow soil. -

On a poorly drained site beneath montane
thicket in the Luguillo Forest (elevation.
2,500 feet; precipitation, 180 inches
annually) 5-year-old clumps of the four
species B. tuldoides, B. tulda, B. longispiculata,
and -Dendrocalamus strictus Nees are stunted
and chlorotic. The tallest clumps (B: tulda)
are only 10 to 15 feet in height and the
culms are only about 1 inch in diameter.
Dendrocalamus strictus is only 6 feet tall and
many plants are dying back.

The use of young sprouts as pianting
material has continued.~ About 100 rooted
sprouts removed from recently planted
offsets were planted in the Cambalache
Forest. The survival was above 90 percent.
Those piants which died were those with least
roots and rhizome attached.

Studies proposed for the future include
fertilizing in the montane thicket and
extending tests in the northern limestone
region.

Cedro macho survives planting well

Cedro macho (Hieronyma clusioides (Tul.)
Griseb), a tree of the limestone region of the
north coast, which produces a beautiful dark
red furniture wood, has not been widely

25

tested because of the irregularity of seed
crops and the difficulty of collecting, drying,
and storing the seed. Small-scale tests made
years ago in the Rio Abajo Forest (elevation,
500 feet; precipitation, 80 inches annually)
showed that the tree was only moderate in
growth rate but was tolerant and generally
of excellent form.

An exceptional seed crop in 1951 and
rapid drying of the seed made possible the
production of 100,000 seedlings for more
extensive testing. Of these, 86,000 were
underplanted in the Guilarte Forest (eleva-
tion, 3,000 feet; precipitation, 100 inches
annually) and in the Rio Abajo Forest where
this species is native. Underplanting of about
2,000 trees each were made on five other
sites, including two in the rain forest, on
sites similar to those in the Lesser Antilles
where the close relative H. caribaea Urb., is
a prominent tree. The stock used was 10 to
16 inches tall and bare-rooted, and the
weather was good. With the exception of
the planting in the Cambalache Experimental
Forest survival has everywhere exceeded 80
percent. At Cambalache an unseasonal dry
period immediately after planting killed
avout 50 percent of the trees. Most of the
surviving trees showed little sign of shock
due to planting and resumed growth shortly
thereafter.

Roble dominiceno survives planting well

Roble dominicano (Macrocatalpa longissima
(Jacq.) Britton) is one of the most important
trees species in Haiti, growing well on
adverse sites and producing a timber suited
for construction and general farm uses. It
is related to Puerto Rico’s roble blanco
(Tabebuia pallida Miers) but grows to a larger
size. In the belief that this might prove a
superior species for the reforestation of
degraded soils, test plantings of 6,000 trees
were made this year on _ several sites,
including the Luquillo Forest (elevaticn, 800
feet; precipitation 120 inches annually), the
Cambalache Experimental Forest (sea level,
precipitation, 55 inches annually), the Susua

26

Forest (elevation, 500 feet; precipitation 50
inches annually) and the Maricao Forest
(elevation, 2,000 feet; precipitation, 100
inches anually).

Survival has been more than 90 percent
on all sites, indicating that this species
stands transplanting exceptionally well. On
laterite soil at Susua and Maricao, however,
it appears destined to fail. The best develop-
ment is in the Luquillo Forest, where the
trees have reached a height of 4 to 5 feet on
the more protected areas. This is taller
than most other trees at this age. Although
this species appears to be more delicate than
the native roble its development will be
followed by further examinations.

Mago makes outstanding
growth on north coast

Mago (Hernandia sonora Li.) produces a
wood used for interior work in Trinidad and
the Lesser Antilles. It is native to Puerto
Rico but is relatively uncommon. It has been
tested for regenerating degraded farm lands.
A small 1944 planting in the St. Just
Experimental Area (elevation, 200 feet; pre-
cipitation, 70 inches annually) has shown
this species well adapted to a loose shallow
soil in this environment. In 1952, after 8
years, the average diameter is 3 inches and
the average height is 30 feet. The trees are
very thrifty and of excellent form. They
have shed side branches very satisfactorily.
More extensive tests on other sites are
warranted.

Mistletoe on mage less
virulent than predicted

The report for 1951 described a mistletoe
(Phthirusa sp.) which has attacked extensive
young plantations of maga (Montezuma
speciosissima (Sessé and Moc.) Dubard) in the
Guajataca Forest (elevation, 500 feet; preci-
pitation, 70 inches annually). It was found
in 1950 that in one area 80 percent of the
trees in a 13-year-old- plantation of this

valuable furniture species had become

infected from trees of capaé prieto Cordia
allidora (R. & P.) Cham.) in adjacent mixed

CARIBBEAN FORESTER

forest. A plantation in a 14-acre sinkhole
was thinned and pruned in 1950 to eliminate
all visible mistletoe. A year later
mistletoe reappeared on half of the trees,
and was so common that it was thought to
be largely reincidence. The only practical
solution appeared to be conversion of the
plantation to a tree species immune to attack,
possibly by underplanting.

Re-examination of this area in 1952, a
year later, shows the mistletoe to be still
common, but apparently not so vigorous as
it appeared a year ago. Close study of a
number of marked trees has shown that
aimost no new incidence has appeared in the
second year following treatment. This
indicates that most of what seemed to be an
alarming re-invasion of the parasite a year
ago was rather a regrowth of plants not
thoroughly removed from the trees. More-
over, because the plantation is growing in
height, the older lower limbs (which
supported the best developed parasites) are
weakening and dying, a process which kills
the mistletoe also. Even some of the clumps
of mistletoe found a year ago on the trunks
are now gone. Although these may be
merely dormant, the parasite is apparently
inactive. Possibly even more important is
the fact that the infected trees have not been
deformed and are growing as rapidly as their
uninfected neighbors. It may prove that
maga can grow satisfactorily despite the
mistletoe. Further examinations will be
made to determine whether this is true.

Avelluelo develops rapidly

in central mountains

Avelluelo (Colubrina arborescens (Mill)
Sarg.) is a favored polewood native to the
coastal plain, chiefly in the limestone section.
it was planted early in several forests at low
elevation and was rejected because of slow
erowth. What may be a larger form of this
tree was found in the interior of the island
and planted in the Guilarte Forest (elevation,
3,000 feet; precipitation, 100 inches
annually) in 1944. This plantation has made
outstanding growth and the trees are

JANUARY - APRIL, 1952

of excellent color and form. They have
outgrown all species planted except euca-
lyptus. In 4 years they averaged 8 feet
in height, and this year, after 8 years
they averaged 28 feet in height. They are
located on ridges with poor soil, indicating
that this is a promising species for the
regeneration of degraded sites. Additional
plantings are to be made.

Pomarrosa can be controlled
by partial cuttings

Pomarrosa (Eugenia jambos L.), a natura-
lized exotic, is an understory tree in
secondary forests in much of the humid
portion of Puerto Rico. It is bushy in form
and although under favorable conditions its
growth is very rapid, it generally produces
no straight stems and is used primarily for
fuel. It produces such a dense shade as to
preclude the development of trees of better
species beneath it. Whereas in scme places
it is valuable for reforesting abandoned farm
lands, in mixed forest it is generally inferior
to its associates and should be removed. Its
great vigor as a sprouter following clear cut-
ting indicated that it would aggressively
resists efforts to remote it, so study of this
problem was begun in1950.

A year ago it was reported that sprouting
vigor was affected considerably by the size
of the canopy opening above the stumps.
Re-examination of the same 50 stumps this
year, 2 years after cutting, showed that

almost no new sprouts were produced and the:

height growth of those produced during the
first year has since been negligible. These
findings apply both to solitary stumps and
those connected to a living clump.

The explanation lies in the fact that the
canopy openings above these clumps, which
initially ranged up to 10 feet in diameter,
averaging about 6 feet, have now almost all
closed as a result of crown development by
the adjacent trees. Although almost no
stumps have died, they may be no problem,
because growth of the sprouts can apparently
be prevented indefinitely by maintenance of
a dense canopy above. The elimination of

27

“pomarrosa from mixed forest does not appear

difficult, particularly where advanced repro-
duction of desired species is present. On
the other hand, the conversion of a pure
pomarrosa stand to another species will
require frequent cleanings until the desired
species dominates.

Teak silviculture tested in two sites

Past reports have shown that teak
(Tectona grandis L.) generally demands better
sites than Puerto Rico can spare from food
and forage production. Because of the great
value of teakwood, however, and the fact
that plantation growth on good sites is
spectacular, it has been planted and is being
studied on sites generally considered “too
good for trees.” Only through such studies
will it be possible to prove whether it can
compete economically with other crops.

In the Cambalache Experimental Forest
(sea level; precipitation 55 inches annually)
on the north coast there is a considerable
area of level land between small limestone
hills. Here the soil is deep and is a red
Jateritic clay. Previously some of this area
produced sugar cane. About 5 acres were
planted with teak in late 1950. Half of the
area was leased to farmers for intercultiva-
tion for two years. The other half was kept
weeded within 18 inches of each tree. At
the end of 2 years there is little apparent
difference in development due to the type
of weeding. The intercultivated teak is less
uniform than that elsewhere, possibly a
result of root damage caused by cultivation.
Both plantations average about 12 feet in
height. (See Fig. 8).

An older plantation, also on a good site,
is located within the Carite Forest (300 feet
elevation; precipitation, 89 inches annually)
on a stony alluvial soii. This plantation, 16
years old this year, has an average diameter
of 7.4 inches (100 dominant and codominant
trees). Mean annual basal area growth per
tree for dominant and codominant trees for
the first 13 years (to 1949) was 0.0219
square feet. In the past 3 years it has

iw

(> 4)

~

UARIBBEAN

Fig. 7.—Young broadleaf mahogany (Swietenia macrophylla King)
irees 1 year after underplanting beneath a stand of casuarina (Casua-
rina equisetifolia Forst). (Arboles juvenes de caoba houdurena un
ano después de subplantados bajo un rodal de casuarina).

Fig. 8—Two-year-old plantation of teak (Tectona grandis L.) established
with intercultivation on an excellent soil in the Cambalache Experimental
Forest. (Plantacion de teca de 2 anos de edad establecida con intercultiva-

cién en suelo fértil en el Bosque de Cambalache).

FORESTER

JANUARY - APRIL, 1953 29
been only 0.0059 square feet showing that mahogany (Swietenia macgoni Jacq.) are

the stand is too crowded. About 40 percent
ot the trees were intermediate or suppressed

provided in Table 10. This mahogany is
a 20-year old plantation growing in « com-

and growing less than half as rapidly as the parable valley within the same forest. The
dominants and codominants. A quarter- data shown are for dominant and
acre plot was thinned from 124 to 94 square codominant trees only. Both stands are
feet of basal area per acre, removing 204 closed and of a comparabie density. It is
trees per acre. All of the suppressed trees seen that the mesquite is growing more

and about half of the intermediates were
removed. Measurements will be made in the
future to show the effect of this thinnning.

Mesquite outgrown by West Indian
mahogany on south coast

Mesquite (Prosofis juliflore DC) became
naturalized in Puerto Rico years ago and has
invaded the forests of the dry limestone hills
along the Southwest Coast. It now dominates
the forest in a valley within the Gudanica
Forest (elevation, 100 feet; precipitation,
30 inches annually}. The facts that it has
invaded the natural forest and that it sprouts
vigorously led to the conclusion that it was
rapid growing and might ke a highly pro-
ductive source of posts and ties. Four years
ago measurements showed the growth of this
tree to be slower than had been expected.
It was concluded that the rapid initial growth
diminishes at an early age, before the trees
attain post size.

Remeasurement of 24 tagged dominant
and codominant trees within the Guanica
Forest during this year provided more
reliable data as to their growth. The
results of these measurements, and a com-
parison with those for West Indian

slowly than the mahogany. Since the latter
species produces by far the more valuable
products it should replace the mesquite, at
least cn the deeper soils where large trees
ean develop. No furtrer research on
me2squite is proposed as present.

Primavera fails to grow
in the limestone region

Primavera (Tabeduia donnell-smithii Rose)
is one of the most valuable timters of Centra:
America. There, on the west coast, it grows
rapidly on good sites, either underplanted or
in the open. An introduction 5 years ago
produced a few trees which when planted on
a well drained deep soil in the Luquillo
Forest (elevation, 809 feet; precipitation,
120 inches annually), grew very rapidly, so
additional seed was imported last vear.

Experimental plantings of 400 seedlings

each were established beneath an open
canopy in the Cambalache Experimental
Forest (sea level; precipitation, 55 inches
annualiy) and the Rio Abajo Forest (eleva-
tion, 500 feet; precipitation, 80 inches
annually). On both sites the soil, although

fertile, is shallow, ranging from 6 to 18

Table 10.—Mesquite and mahogany growth at Guanica

; Number | Avg. diam at breast height |
Species of — ———— Ave. annual diam. growth
trees 7 years ago Now
Inches Inches Inches
Mesquite 24 4.7 5.6 0.13
Mahogany 59 4.1 5.4 0.19

30

inches in depth. These trees have made no
growth during the first year. The new
leaves are small, thin, and chlorotic and
appear as though attacked by a mosaic
disease. With few exceptions this condition
is universal, and not related to the amount
of light received. The only apparent expla-
nation is the soil, which is less acid (pH 6)
and shallower than where the trees are
growing well. An attempt will be made to
determine the deficiency.

The older plantation in the Luquillo
Forest is now from 30 to 45 feet tall and very
thrifty. Trees in the open are 3 to 5 inches
in diameter. Trees in a new planting on this
site range from 10 to 15 feet in height at
the end of the first year.

Hat palm establishment proves slow

The Puerto Rican hat palm,
(Cook) Beccari) has been an
important basis for a local hat industry. The
source of palm leaves was greatly reduced
by the reservation of a large palm area for
military purposes. In an effort to increase
production the artificial regeneration of this
palm has been investigated. Production of
nursery stock required 24 months. Some of
this stock was planted in 1946 in the Camba-
lache Experimental Forest (sea level; preci-
pitation, 55 inches annually) on clav loam
soil similar to that where the trees are native.
Growth has been very slow, the palms
attaining from 2 to 5 feet in height in 6
years. For 3 years they were of poor color
and almost entirely inactive. The first usable
leaves were produced after 5 years. The
productivity of this species is low and does
not appear to warrant further research at
this time. A few palms are being propagated
by the Forest Service for small plantings
about rural homes.

(Sabéal

causiarum

Seed of 53 species imported

The need for new, more productive forest
crops has made desirable the testing of exotic

CARIBBEAN FORESTER

species to determine their adaptability and
productivity in Puerto Rico. About 120
exotic tree speces have been tested by the
Station in the past 13 years. During this
year seed of 53 species was imported from
tropical and subtropical regions throughout
the world. Twenty-seven of these species
are introductions new to Puerto Rico. Species
imported included 12 gymnosperms and 24
species of eucalyptus. Seed weights were
determined for 24 species.

Increasing the utility of wood

Insects and decay both important
in post cutting time study

There is a widespread deep--seated belief
in Puerto Rico (as in other tropical areas)
that wood varies in durability with the time
of cutting. Common explanations include

moon phases, tides, or seasons of the year.
Although studies elsewhere have mailed to
show that time of cutting, as such, has any
effect on the durability of wood, a study

taking into account these factors appeared
to be of value at least for demonstration
purposes. A year ago the Station under-
took a study of this nature in which the
following variables were included: site,
species, moon phases, season of the year,
tides weather, and whether the trees were
dormant or growing. A total of 1,800 posts
were included in this experiment and were
set in the Toro Negro and Cambalache
Forests.

At the end of the first 12 months a com-
plete inspection was made to determine the
presence, nature, and extent of deteriora-
tion. It was found that no post had
become unserviceable and it was not yet
possible to analyze the effect of different
treatments. Nevertheless agencies of destruc-
tion were active in nearly half of the posts.

Insect damage appeared to be more important

than decay. The most common insects were
powder post beetles and wood borers. Locally
there was also some termite damage.

JANUARY - APRIL, 1953

A total of 1.390 of the posts have been
re-examined aft<r 18 months (as will be
continued each 6 months thereafter). At
this time each post was subjected to a
moderate push to determine its serviceability.
In all, 575 posts broke off, but no marked
difference among the treatments is yet
apparent. Weakening of these posts,
whether caused by insects or decay, was
greatest at the ground line. Only a few of the
posts failed solely because of insect damage.
Most of the posts which failed primarily
because of decay had been attacked by
insects. Insect tunnels were undoubtedly an
important contributing factor to the progress
of the decay.

Further examinations will shed additional
light upon the causes of post deterioration
and will make possible comparison of the
different treatments.

Sfecific gravity and shrinkage
determined for several species

In the absence of strength data from

51

actual testing, knowledge of the specific
gravity of different woods is of value in
approximating several of their mechanical
properties and in tke estimation of shrinkage,
weight per cubic foot, void volume and
maximum moisture percent attainable, and
witndrawal resistance of nails and screws.
Shrinkage figures are used determining
changes in dimensions with changes in
moisture content, converting specific
grayities from green to oven dry volume and
conversely.

For several years the Station has been
computing the specific gravity of several
wood species. During this year the specific
gravity of eleven species and the volumetric
shrinkage of seven of these have been deter-
mined. The data appear in Table 11. As

found elsewhere, the volumetric shrinkage of
these tropical species is generally lower than
that of woods of comparable density from
temperate zones.

Table 11.—Speciific gravity and volumetric shrinkage of eleven woods

Volumetric
shrinkage from
green to oven

dry based on

Specific gravity, oven dry,
based on volume

Green Oven dry green dimen-
sions
Percent
Casuarina, C. equisetifolia Forst. — 0.93 ---
Balsa, Ochroma piramidale Sw.
Butt log
Heart — 0.29 --
Sap -- 0.24 a=
Upper branch — 0.18 ——
Capa prieto, Cordia alliodora (R & P.) Cham 0.49 0.58 15.9
Jacana, Lucuma multiflcra A. DC 0.76 0.88 14.2
Aguacatillo, Weliosma herberti Rolfe 0.44 0.51 14.0
Caimitillo, Micropholis chysophylloides Pierre 0.69 0.78 11.6
Laurel avispillo, Nectandra coriaceae (Sw.) Griseb — 0.59 =
Caimitillo verde, Micropholis garcinifolia Pierre = 0.81 =
Guaraguao, Guarea trichilioides L. 0.49 0.57 13.6
Capa blanco, Peticia domingensis Jacq. EDS) 0.61 10.2
Mamey, Wammea americana L. 0.66 0.76 ister

bo

Considerably more effort is to ke placed
on this project during the next few years.
A difficulty that has attended past work
has been the lack of good equipment for
volumetric measurement. This deficiency is
to be corrected during the coming year.

Untracted Eucalyptus fence
post serve for three vears

Eucalyptus (E£. robusta Smith and E.
kirtcniana F. v. M.) has proven so well adapted
to the central mountains of Puerto Rico that
various studies of its utilization have been
undertaken. One of the first studies of this
nature concerned the durability of these
species for fence posts, started in 1949.
Twenty posts were set in a well drain-d deep
soil in a fence within the Guilarte Forest
(elevation, 3,000 feet, precipitation, 110
inches annually). The posts were 4 to 5 inches
in diameter.

This year (3 years after installation)
11 posts broke off when subjected to moder-
ate push, and the others which resisted were
very weak.As these posts were slightly larger
than those normally used it is safe to con-
clude that the average life of untreated fence
posts of these species is not more than 3
years in this environment. The desirability
of developing preservative treatment is clear,
and studies described elsewhere in this report
are directed to that end.

Zinc chloride treated posts
attacked by insects

The introduction of wood preservation as
a practice in rural areas requires simple
techniques applicable with a minimum of
cost and on a small scale. A search for such
techniques led in 1951 to the testing of the
end diffusion process, which is applicable to
green unbarked wood. The _ preservative
tested was copperized chromated zinc
chloride, said to be relatively resistant to
leaching.

Three common post species of the moun-

tains were tested, eucalyptus (E. robusta Smith,
and E. kirtoniana F. v. M.) and guaba (Inga

CARIBBEAN FORESTER

vera Willd.) Sixteen posts of each species
were treated. The chemical was used in a
25 percent aqueous solution. The posts were
left in the solution until they had absorbed
1 pound of chemical per cubic foot of wood,
a period which varied from 7 to 21 days.
Shorter periods were necessary during dry
weather. To determine the depth of pene-
tration, several posts were split open and
sprayed with equal parts of a 1 percent
potassium ferricyanide solution, a 1 percent
potasium iodide solution, and a 5 percent
solution of soluble starch. The preservative
was found to be confined to the outer
sapwood and the Jower 24 inches of the posts.
The treated posts were inverted and dried
for 3 months before setting.

After 1 year, all treated eucalyptus
posts are severely attacked by termites
whereas all untreated posts are sound. No
insect damage appears on any of the treated
or untreated guaba posts but one treated post
shows incipient fungus development.

Although service records on zine chloride
treated material are numerous in the States
no such records were found on copperized
chromated zine chloride which is a relatively
new product. Evidence from this experiment
strongly points to more favorable termite
development in eucalyptus in the presence
of copperized chromated zine chloride. The
termite attack began in the bark and spread
into the wood. Further tests will be made
with this and other preservatives to
determine effectiveness without bark, and
how to obtain better penetration.

Carbolineum-treated posts of three species
sound after two years

The most successful test of preservation
of posts at the Station is one made in 1944
when several posts of casuarina (Casuarina
equisetifolia Forst) were treated with car-
bolineum by the hot-cold bath method. These
posts are still sound.

It was decided to test the same treatment
with three common species of posts.

JANUARY - APRIL, 1953

Eucalyptus robusta Smith, E. kirtoniana F. v. M..,
andWicrofholis chrysophylloides Pierre. The posts
were dried to a moisture content below 30
percent after which they were placed in hot
carbolineum (100°C) for 4 hours and allowed
to cool fer 16 hours. Preservative absorption
varied from nearly 6 to almost 8 pounds per
cucic foot of wood. Half of the posits were
set in the Toro Negro Forest (elevation
2,500 feet; precipitation, 110 inches
annually) and half in the Cambalache
Experimental Forest (sea level; precipita-
tion, 55 inches annually) Untreated E. robusta
controls were set on both sites.

All treated ones are still completely sound
2 years after setting. The preservative
appears to be leaching out of some of the
posts. Half of the untreated E. robusta posts
have faiied. Probably none of the untreated
posts will last longer than one more year.
On the other hand, the service life of the
treated posts will certainly be much longer.

Future experiments of this nature will
utilize coal-tar creosote (which is cheaper
than carbolineum) and will be directed
toward the economic aspects of such treat-
ment.

PLANS FOR 1953

Developments during the past year point
strongly to the need for greater emphasis on
investigations of forestry practices which
are practical for private forest lands. This
will involve not only the retesting on such
lands of species and techniques already found
satisfactory elsewhere, but also companion
experiment directed toward opening markets
to a degree that trees can be considered a
short-rotation cash crop.

Specitically, cooperative studies of the
pulping properties of eucalyptus, coffee
shade trees, and a few other common species
are proposed. Extensive testing of eucalyptus
establishment with intercultivated crops is
to be done on private lands. The use of more
productive shade trees for coffee should also
be tried on private lands. Efforts will also
be made to get a pressure-treatment plant
set up for the preservation of both imported
and domestic poles, piling, timbers. axd ties.
Closely related activities proposed include a
public exhibit of local forest products,
surveys of forest products consumption and
waste by local industries, seasoning practices,
the use of wood preservation, and service life.
To encourage forestry on private lands,
formal demonstration areas are to be set up
within public forest areas representative of
private lands. Plans for the development of
these areas are to be drawn up jointly with
the Extension Forester and the use of the
areas is to be primarily by the Extension
Service. In addition, the survey of
established plantations on private lands
begun 2 years ago is to be completed. The
results are to be incorporated into a bulletin
on tree planting.

The new work proposed will require a
reduction in emphasis on some past projects.
A large number of adaptability tests were
terminated at the close of this year, and
revision of the re-examination schedule has
resulted in an additional saving in time. A
manual standarization certain research pro-
cedures and techniques on the basis of ali
past experience should further increase
efficiency. A revision of the problem analysis
and working plans is to be completed early
in the year.

9
o

CARIBBEAN FORESTER

(Traduccion del articulo anterior)

Decimotercer Informe Anual de la Estacion
de Experimentacion Forestal Tropical

El ano de 1952 se sefial6 por un uso mas
intenso que nunca de los trabajos de inves-
tigacion. Por primera vez en 10 anos se re-
comendo la siembra en gran escala de los
montes publicos. Con anterioridad a esta
fecha se habian sembrado 22,000 acres de
bosques publicos, pero estas siembras en gran
escala se descontinuaron debido a los mu-
chos fracasos y al alto costo de las mismas.
La pauta a seguir luego ha sido observar las
siembras anteriores y hacer minuciosas prue-
bas de nuevas especies, tecnicas y ambientes
estacionales. Attn hoy solo podemos reco-
mendar con seguridad un numero limitado de
estas practicas. Un resultado de estas re-
comendaciones ha sido la subplantacion este
ano de mas de 2.000 acres de bosques secos
en la costa sur de caoba antillana (Indias
Occidentales) y 450 acres de bosques pluvia-
les en caoba hondurena. Varios miles de
acres de sitios similares a los anteriores se-
ran subplantados tan pronto lo permitan los
fondos.

Una consecuencia importante ha sido la
demanda por eucalipto para pilotaje. Los
primeros 30 pies de arboles de 12 pulgadas
(de 14 anos) valen $4.50 en pie. Estas y
otras perspectivas para la utilizacion de este
arbol por su celulosa han hecho desaparecer
las dudas en cuanto a la plantacién en gran
escala del eucalipto en elevaciones entre 2.000
y 3.000 pies. Los bosques secundarios na-
turales que se encuentran entre las planta-
ciones se dedicaran al eucalipto. La siembra
del eucalipto por el sistema taungya sera
cuidadosamente investigada el afio préximo.
Si los resultados son satisfactorios ésto po-
dria fomentar la siembra de Arboles en terre-
nos particulares.

LA REORIENTACION DEL PROGRAMA
DE INVESTIGACION

Un punto culminante entre los aconteci-

mientos del ano lo fué la visita del Dr. V. L.
Harper, Jefe Auxiliar del Servicio Forestal
a cargo de la investigacion de bosques y del
Dr. H. G. Wilm a cargo de la Division de la
Investigacion de las Influencias Forestales,
ambos de Washington. Estudiaron deteni-
damente los problemas forestales de la isla
y el programa actual de la Estacion. Hicie-
ron recomendaciones de gran valor para la
orientacion del trabajo. Es probable que co-
mo resultado de su visita se incluya formal-
mente en el programa de la Estacion la uti-
lizacion de bosques y la investigacion de in-
fluencias forestales.

Un estudio de la utilizacion de bosques en
Puerto Rico se hizo a solicitud de la Estacion
por el Sr. C. C. Bell, Jefe del Servicio de
Utilizaci6n de Bosques del Laboratorio de
Productos Forestales. Después de 4 sema-
nas de estudio en la isla, el Sr. Bell hizo en-
tre otras, tres recomendaciones basicas en
torno a la utilizacion de bosques, sus produc-
tos, conversion de madera y fabricas: (1)
mayor uso del material inferior en tamano,
calidad y forma, (2) aumento en la produc-
cion de madera de aserraje, de buena forma
y de especies valiosas y (3) aceleracién en
las pruebas de fabrica y experimeritos de
campo que han de aumentar los pocos conoci-
mientos que ahora tenemos sobre las propie-
dades y usos de las maderas de Puerto Rico.
KH] Sr. Bell recomendé un amplio programa
de investigaciones sobre utilizacién indus-
trial, pulpa y papel, relaciones selvicultura-
les, fisica de la madera de aserraje y con-
servacion de maderas, para ser llevado a cabo
en la Estacion pero con la cooperacion del
Laboratorio.

Con el nombramiento por el Servicio Fo-

_restal de Puerto Rico del Sr. Miguel Hernan-

dez Agosto, un selvicultor profesional, para
ayudar en el programa de investigacién de
la Estacion se le ha dado un verdadero

JANUARY - APRIL, 1953

empuje al estudio de la utilizacion de bosques.
Dicho Servicio también ha provisto al Sr.
Hernandez de un fondo para la compra de
material y equipo. Al Sr. Hernandez se le ha
designado para el trabajo de investigacion
en el campo de la utilizacion de bosques por
su pericia en ese ramo y por la necesidad de
estudio que hay en ese campo que hasta la
fecha ha tenido menor importancia en el pro-
grama de la Estacion. El se ha hecho cargo
de todas las investigaciones en progreso y
ha instrumentado un programa de largo al-
cance que resultara en mayores conocimien-
tos en cuanto a la calidad y cantidad de los
productos forestales a mano en Puerto Rico;
nuevos usos para estos productos y mayor
durabilidad de servicio. El Sr. Hernandez
hizo arreglos para un acuerdo de cooperacion,
firmado este ano, entre los Servicios Fores-
tales y el Colegio de Agricultura de la Uni-
versidad de Puerto Rico para investigacio-
nes conjuntas sobre madera de construccion,
quimica de la madera y patologia de los pro-
ductos.

ACTIVIDADES DE ALCANCE
INTERNACIONAL

Oficiales de la administraci6n de la Es-
tacion hicieron tres viajes a paises extran-
jeros. El Jefe de Divisi6n sirvid como re-
presentante de los Estados Unidos en el co-
mité organizador para una conferencia que
estudiaria el mercado maderero y que se lle-
varia a cabo bajo los auspicios de la Comi-
sion del Caribe. El comité organizador se
reunio en Puerto Espanfa y recomendé una
agenda, apuntes y otros trabajos para ser
hechos por la Secretaria con antelaci6n a la
conferencia que esta senalada para abril del
1953. El director pas6 una semana en la
Republica Dominicana donde discutié con el
Ministro de Agricultura los problemas fores-
tales de aquel pais y los programas foresta-
les en curso.

E] Jefe de Divisién asistid como delegado
de Estados Unidos a la cuarta sesion de la
Comision Forestal de la F.A.O. de la Amé-
rica Latina en Buenos Aires. A su regreso

(oN)
oO

se dituvo una semana en Sao Paulo, Brasil
visitando extensas plantaciones de eucalipto
de la Companhia Paulista de Estradas de
Ferro. También visit6 los bosques del rio
Essequibo en la Guayana Inglesa y los de
Grenada, Santa Lucia y Dominica en las An-
tillas Menores inglesas. Estas paradas pro-
porcionaron valiosa informacion sobre el eu-
calipto, la ecologia de los bosques pluviales
y arboles de especies exdticas con las que
valdria la pena ensayar en Puerto Rico.

El ano pasado la Estacion fué visitada por
14 selvicultores de 13 paises extranjeros.
Ademas cinco estudiantes de selvicultura re-
cibieron adiestramiento en la Estacion. Para
tres de éstos que permanecieron en la Esta-
cion 5 meses, fué posible prepararles un pro-
grama de estudios bien equilibrado que cu-
bria muchas fases de selvicultura. Dos dé
estos estudiantes eran graduados de ia Uni-
versidad de los Andes, Mérida, Venezuela.

Algunas ediciones del Caribbean Forester
se retrasaron de manera que el ntimero de
octubre esta aun en prensa. Este afio se pu-
blicaron siete articulos sobre la Argentina,
ei Brasil, las Islas Virgenes y Puerto Rico.
Mas de la mitad de las paginas se dedicaron
a informes sobre el trabajo de investigacion
de la Estacion. La lista de envios contiene
746 nombres, la mayor parte extranjeros.

Por solicitud de la cuarta sesién de la Co-
mision Forestal de la F.A.O. de la América
Latina, el glosario espanfiol-inglés de términos
de selvicultura que ha estado en preparacién
en esta Estacion durante los tiltimos 10 afios
sera sometido, aunque atin sin terminar, a
la oficina forestal de la F.A.O. de la América
Latina en Rio de Janeiro para su distribucién
y critica en los paises Sudamericanos de don-
de sera devuelto a la Estacion para su revi-
sion. Este afio se han afadido las defini-
ciones de 109 palabras del espafiol haciendo
un total de 802. Esto es aproximadamente
la mitad del numero de términos del inglés
ya definidos.

ACTIVIDADES LOCALES

Por iniciativa de la administraci6n se pre-
paro un informe sobre los recursos forestales

“
oO

de Puerto Rico y se hicieron las recomenda-
ciones pertinentes para su uso y desarrollo,
Por medio de mapas topograficos se deter-
minaron las areas eviticas de cuencas hidro-
eraficas, se hizo un analisis de los actuales
programas de conservacion y se consideraron
medios practicos para mayor adelanto fores-
tal. El informe recomienda especificamente
mayores conocimientos forestales y ayuda
técnica, la pronta adquisicion de bosques
para propiedad publica, mas investigaciones
forestales, incentivos para propietarios par-
ticulares proporcionados a los de otras prac-
ticas de conservacion y cuidadosa considera-
cidn de la legislacién reglamentaria para
Areas criticas. El informe apenas alterado
se ha incorporado como capitulo VI de “A
comprenhensive agricultural program for
Puerto Rico” que sera publicado dentro de
poco por el Departamento de Agricultura de
los Estados Unidos.

El Dr. Elbert L. Little Jr., de la Division
de Investigaciones sobre Dendrologia, Pasto
y Forraje del Servicio Forestal de
Washington paso 3 meses en Puerto Rico a
solicitud de la Estacion para continuar el
manuscrito en lenguaje corriente de dos li-
bros descriptivos sobre los arboles de Puerto
Rico. Durante una visita anterior el Dr.
Little habia recogido material herbario su-
ficiente para un volumen en el que se des-
criben 250 especies. Este ano él casi ter-
mino el texto descriptivo de 475 especimenes
que se montaron en el herbario. Solo resta
hacer los dibujos de algunas especies.

Este ano se continuo cooperando con el
Servicio de Conservacion de Suelos para es-
timular la plantacion de bosques en las Islas
Virgenes. Se formularon planes detallados
para un programa de extension, recoleccién
de semillas, preparacion de suelos, propaga-
cion, sementeras y plantaciones. Se deslin-
daron bosques en cuatro propiedades parti-
culares y se les hicieron recomendaciones ex-
plicitas a los propietarios.
paro un proyecto sobre la propagacion de ar-
boles con trabajo especifico para 7 meses
distintos de! alo que posiblemente podrian

Ademas se pre- .

CARIBBEAN FORESTER

Nevar a cato los Clubes 4-H. Tres pequevios
cuarteles de crecimiento se establecieron en
rodates naturales de caoba antillana: A pe-
sar del interés del Gobernador, este programa
adelanta poco. Puede que tenga mayor éxito
el programa propuesto pare el ano proximo
por la Corporacion de Islas Virgenes en coo-
peracicn con el Servicio de Conservacion de
Suelos y la Estacion.

La reunion de campo que se celebro el 22
de mayo en el Bosque Experimental de Cam-
balache, fué un evento sobresaliente. Alre-
dedor de 120 personas participaron, incluyen-
do representantes de las siguientes agencias
relacionadas con terratenientes: Servicio de
Conservacion de Suelos, Servicio de Exten-
sion Agricola, Administracion de Produccion
y Mercadeo, Departamento de Agricultura y
Comercio de Puerto Rico, Juntas de Distrito
de Conservacion de Suelos, Autoridad de Tie-
rras de Puerto Rico, Administracion de Ho-
gares Rurales y los Servicios Forestales Fe-
deral y de Puerto Rico. También asistieron
unos 30 ninos de grados superiores de una
escuela vocacional cercana y 10 prominentes
agricultores del distrito. Los problemas fo-
restales de la costa norte de Puerto Rico se
presentaron por medio de demostraciones y
explicaciones ofrecidas por representantes del
Servicio de Extension, del Servicio de Con-
servacion de Suelos y de los dos Servicios Fo-
restales. Se mostraron numerosos plantios
de diferentes especies, unos plenamente lo-
grados y otros aun en estudio, como también
una demostracion de corta de mejora

Otros ejercicios educativos del ano inclu-
yeron conferencias sobre investigaciones y
conservacion de bosques ofrecidas a estudian-
tes de dasonomia del Colegio de Agricultura
a ninos de la Escuela Naval, a unos 100 guias
en el Campamento de Ninos Escuchas y al
Club de Jardineria.

La administracion organiz6 un curso de
adiestramiento de una semana para 25 del
personal de los dos Servicios Forestales.
Parte del curso giré en torno a asuntos ad-
ministrativos solamente, pero se les explicé
detalladamente la base biolégica de la selvi-
cultura, la necesidad de_ investigaciones,

JANUARY - APRIL, 1953

experimentos en curso y los resultados cbteni-
dos hasta la fecha y que tienen alguna im-
portancia para ellos. También se les mos-
traron cinco experimentos de campo de ma-
yor importancia.

El Sr. Marrero ha seguido poniendo en
uso los resultados de investigaciones al de-
linear y dirigir el programa de regeneracion
del Bosque Nacional del Caribe. Esto en-
vuelve la exploraciOn y sefalamiento de areas
de mayor prioridad para plantios, cuido de
plantaciones, mejoramiento de rodales, reco-
mendacion de técnicas, inspecciones y la pre-
paracion de un informe anual. Durante este
ano se han tratado 2.040 acres que incluyen
la siembra de 810 acres y el cuido de 1.230
acres de plantaciones. Similar pero menos
detallada ayuda se le ha dado a los progra-
mas mas extensos del Servicio de Bosques de
Puerto Rico. La administracion ha servido
también en una comision encargada de me-
jorar la distribucion de Arboles a los agri-
cultores. Las recomendaciones comprenden
ja aplicacion directa de los hallazgos de inves-
tigaciones relacionadas con técnicas de pro-
pagacion, especies a propagar y el medio es-
tacional a que éstas se adaptan.

Este ano se ha recibido en la biblioteca un
total de 763 obras nuevas. Se ha terminado
de catalogar una acumulacion de adquisicio-
nes recibidas anteriormente. La biblioteca
contiene ahora 6.850 obras que tratan de sel-
vicultura tropical o de otros campos estre-
chamente relacionados a éste. La adminis-
tracion tiene también a su disposicion la bi-
blioteca de la Estacion Experimental Agri-
cola de la Universidad que es mucho mas
grande y queda a 500 pies de la oficina cen-
tral de la Estacion.

El personal de la administracion de la Es-
tacion es pequeno y el adelanto ha dependido
grandemente de la ayuda de numerosos co-
operadores. La cooperacién recibida del ex-
terior incluye la orientaci6n ofrecida por los
dos jefes de investigacién de Washington, el
estudio sobre la utilizacién de bosques por el
Laboratorio de Productos Forestales, y el

progreso hecho en el manuscrito de “Trees
of Puerto Rico” por un miembro de la oficina
del Servicio Yorestal en Washington. Los
territorios britanicos del Caribe hicieron una
contribucién en efectivo para el Caribbean
Forester. Otra contribucion de gran impor-
tancia ha sido la de semillas de nuevas espe-
cies de arboles recibidas de todas partes del
mundo. A cambio de instruccion, los estu-
diantes extranjeros de dasonomia han sido
de gran ayuda en trabajos de campo.

El Bosque Nacional del Caribe y el Ser-
vicio Forestal de Puerto Rico contribuyen al
establecimiento, proteccion y mantenimiento
de las instalaciones experimentales; propor-
cionan sitios convenientes y el uso de esta-
ciones de campo en Puerto Rico. El Servicio
Forestal de Puerto Rico también propaga la
mayor parte de los arboles que se usan en
experimentos de regeneracion. El nombra-
miento del Sr. Hernandez para la Estacion,
como se ha dicho, es otra gran contribucion
beneficiosa de parte de esta agencia. La Uni-
versidad de Puerto Rico ha sido otro impor-
tante cooperador, facilitando el uso de su
biblioteca y a través de la Estacion Experi-
mental Agricola ha cedido a la Estacion el
Bosquecillo de Rio Piedras y ha prestado ayu-
da directa en el trabajo de experimentacion,
particularmente en los campos de entomolo-
gia y diseno experimental. El Servicio de
Extension Agricola ha proporcionado servi-
cios fotograficos que a veces requirieron el
empleo de su fotografo por un dia o mas.
Ademas este Servicio ha hecho arreglos para
la publicacion en la prensa y por la radio de
charlas dictadas por miembros de la adminis-
tracion. Conjuntamente el Servicio de Ex-
tension, el Servicio de Conservacion de Sue-
los y la Junta de Supervisores de Distrito de
Conservacion de Suelos hicieron posible el dia
de campo en Cambalache, reuniendo perso-
nas clave, allegando fondos, ocupandose de la
comida y suministrando informacion al gru-
po alli reunido. El] reexamen de las planta-
ciones en La Mona pudo hacerse gracias a
la transportaciOn y hospedaje que ofreci6é el

de

Servicio de Guardacosta Federal.

38
RESULTADOS DE INVESTIGACIONES

Ki trabajo experimental de la Estacion
se ha llevado a cabo en distintas areas fo-
restales de la isla de Puerto Rico. La mayor
parte de los estudios se hacen en montes del
Estado, bien del Gobierno Federal o del In-
sular. (Véase ilus. 1). No todos los hallazgos
del ano se consideran suficientemente impor-
tantes para ser discutidos en este informe.
Algunos de los estudios informados hace un
ano no han progresado lo bastante para me-
recer otro informe. Solo se describira el
progreso alcanzado durante los dos o tres Ul-
timos anos en algunos estudios que no han
sido informados recientemente.

Los bosques de experimentacion conti-
nuan siendo centros para gran parte de las
investigaciones selviculturales. Los bosques
de Cambalache y St. Just son de gran utili-
dad a la comunidad como fuentes de produc-
tos madereros. En Cambalache se hicieron
25 ventas de madera de aserraje que inclu-
ian 2.500 pies cticicos de rollizos por $275.
Del mismo bosque 90 familias de los alrede-
dores sacaron gratis 11.018 haces de lena o
sea un volumen de 110 cuerdas de madera*
(14.080 pies cub.) Del area experimental de
St. Just 29 familias sacaron 1.407 haces de
lena equivalentes a 14 cuerdas de madera
(1.792 pics cubicos). Del bosquecillo de Rio
Piedras se le suministraron 850 postes para
cercas a la Estacion Experimental de Agri-
cultura de la Universidad de acuerdo con el
plan para la administracion de este bosque.

Los experimentos se clasifican aqui segtn
sus objetivos principales. Estos comprenden
la determinacion de:

1. Extension y naturaleza de los bos-

d

ques de Puerto Rico.

2. Contribucion actual y potencial de los
bosques de Puerto Rico.

3. Métodos practicos para aumentar la

productividad de los terrenos foresta-

les.

Medida de cubicacién ave se usa para medir lena y que
equivale a 128 pies cUbicos de madera,

CARIBBEAN FORESTER

4. Métodos practicos para aumentar el
aprovechamiento de la madera.

La mayor parte de la investigacion sel-
vicultural informada comprende estucios so-
bre el crecimiento de los arboles con relacion
a su situacion. El tnico método satisfactorio
para llevar a cabo estos estudios dentro de
los bosques naturales o antiguas plantacio-
nes ha sido el establecimiento de cuarteles
permanentes en rodales que satisfacen las
condiciones deseables. En el curso de este
ano pasado se midieron de nuevo 25 de estos
cuarteles y se establecieron 12 mas.

Al finalizar el ano una revision critica de
un gran numero de estudios sobre la adap-
tabilidad de diferentes especies de Arboles al
ambiente estacional, dio por resultado la eli-
minacion de mas de 100 de éstas. Muchas
va habian dado toda la informacion que po-
dia esperarse y otras era obvio que habrian
de fracasar. Esto constituye una economia
considerable en el volumen de reexamen y
observacion, dejando asi a los miembros de la
administracion mas libres para hacer estu-
dios ulteriores de mayor importancia.

El Sr. Hernandez Agosto adscrito al Ser-
vicio Forestal de Puerto Rico preparo los in-
formes relacionados con la produccién fores-
tal y la utilizacion de la madera que han es-
tado bajo su direccion durante los ultimos
6 meses. En éstos se alude frecuentemente
a informes previos de la Estacion.

Informes recientes se publicaron en The
Cariobean Forester en las fechas siguientes:
1949, 11:59-80; 1950, 12:1-17; y 1951, 13:1-
7)

Area apfroximada de terrenos forestales

En el trabajo de investigacion forestal los
conocimientos en cuanto al area, situacion y
naturaleza de los mejores terrenos apropia-
dos para el desarrollo de bosques son esen-
ciales. En el pasado ha habido en Puerto
Rico informes en este sentido, pero poco con-
fiables. Por consiguiente para la prepara-
cion de un informe sobre los recursos fores-

JANUARY - APRIL, 1953

tales y recomendaciones pertinentes para la
adquisicién de montes, se ha tratado de lo-
calizar y determinar el area de los terrenos
en los cuales los arboles habrian de dar ren-
dimiento continuo y mayor (desde el punto
de vista econdmico y/o social) que otras co-
sechas.

Los arvoles se dan en todo Puerto Rico,
aunque en la mayor parte de la isla econo-
micamente dan menos rendimiento que otras
cosechas. Datos insuficientes hacen imposi-
ble la comparacion clara entre los beneficios
economicos de productos forestales y no fo-
restales. Sin embargo hay una clase de te-
yreno casi unanimemente aceptada como la
mejor para arboles: aquellas areas que de-
bido a un declive extremo (50% o mas); a
fuertes lluvias; 0 a terreno bajo, estéril o de
drenaje insuficiente no sirven para cultivo o
pastoreo continuo sin deterioro de su suelo
y/o poco rendimiento, empero pueden pro-
ducir arboles como cosecha permanente.

Todas las areas con declive mayor de 50
por ciento, han sido indicadas en los mapas
topograficos de la isla. Por planimetria se
ha encontrado que éstas comprenden aproxi-
madamente 600.000 acres o sea la cuarta
parte de la superficie de los terrenos de la
isla. De esta drea como 427.000 acres se re-
parten en lotes de 10.000 0 mas acres cada
uno, que se prestan para una ordenacion fo-
restal efectiva. Estos lotes estin situados
cemo se ndica en la Ttabla 1. (Véase ilus. 2).

Tabla 1.—Las d4reas mayores de terrenos
forestales en Puerto Rico

Situacion Area forestal

Regicn caliza del norte 90.000
Pendiente sur de la Cordillera 83.000
Sierra de Cayey 60.000
Sierra de Luquillo 47.000
Valle del Rio Manati 33.000
Valle del Rio Arecibo 29.000
Sierra de Atalaya 25.000
Valle del Rio La Plata 23.000
Guanica 16.000
Tallaboa 11.000
Lajas 10.000

Total 427.0000

39

El remanente de los terrenos forestales
esta en predios menores pero debiera ofrecer
importantes fuentes locales de productos
madereros. Estos datos sirvieron de base
para un programa para la adquisiciOn de
montes para propiedad publica.

Se establece lentitud de crecimiento
en selvas virgenes

En Puerto Rico se han hecho estudios de
los pocos bosques virgenes que restan para
determinar la naturaleza de estas selvas y
la de los arboles que las integran y asi esta-
blecer lo que puede esperarse de los diferen-
les tratamientos selviculturales. En los ul-
timos tres informes se han ofrecido los pri-
meros datos relacionados con los requisitos
de estancia, tolerancia y crecimiento relativo
de las varias especies en los bosques no ex-
plotados.

Mediciones de crecimiento hechas en un
gran numero de Arboles en los tipos tabo-
nuco y colorado de las Montanas de Luquillo:
(bosque pluvial pedemontano y bosque mon-
tano) llevaron hace algunos afos a la creen-
cia de que el crecimiento diametral en los ar-
boles en los bosques pluviales virgenes era
muy lento. El periodo de medicién enton-
ces era solo de 2 anos y no se llego a conclu-
sion definitiva alguna. Por esta razon, 5 aflos
mas tarde, en 1952, se hizo una segunda me-
dicion.

Los resultados de esta segunda medicién
aparccen en la Tabla 2. Los datos sobre el
tipo tabonuco cubren 399 arboles de 10 espe-
cies de dosel: tabonuco (Dacryodes excelsa
Vahl), aguacatillo (Meliosma herberti Rolfe),
ausuco (Manilkara duplicata (Sessé & Moc)
Dubard), caracolillo (Homalium racemosum
Jacq.) granadillo (Buchenavia capitata (Vahl)
Hichl), guajon (Beilschmedia pendula (Sw.)
Nees.), masa (Tetragastris balsamifera (Sw.)
Kuntze), motillo (Sloanea berteriana Choisy),
nuez moscada (Ocotea moschcta (Pavon) Mez.)
y roble (Tabebuia pallida Miers). Analisis

1/ Segun clasificacién de Beard, Climax Vegetation in Tropica!
America. Ecology: 25 (2) : 127-158.

CARIBBEAN FORESTER

Tabla 2.—Computo de la edad de arboles en rodales virgenes
Bosque de Luquillo

Caleulo de edades

Diametro | Ti |
a la | 1po : :
altura tabonuco | Tipo colorado
del | | —
pecho : Leo 2
Especie fee “ P Caimitillo Camasey Laurel Palo
HGeel Caimitillo | Nemoca | verde jusillo sabino colorado
Pulgadas Anos Anos Anos Anos Anos Anos Anos
4 80 90 200 170 80 100 80
8 130 160 400 260 200 180 170
12 180 230 570 320 340 250 280
16 220 290 700 370 440 340 420
Z0 260 30 430 580
24 300 540 730
36 420 1200

por separado demostraron que en las selvas
virgenes la proporcién de crecimiento entre
las varias especies era muy poca para mere-
cer separaciOn entre ellas. Mas de la mitad
de los arboles (222) eran del tabonuco co-
mun prevaleciente.

Del tipo colorado se midiéd un numero ma-
yor de Arboles de las especies comunes gran-
des y se tiré una curva con los datos sobre
cada una. Habia 480 Arboles de caimitillo
(Micropholis chrysophylloides Pierre), 260 de
nemoca (Ocotea spathulata Mez), 832 de caimi-
tillo verde (Micropholis garcinifolia Pierre), 828
de camasey jusillo (Calycogonium squamulosum
Cogn.), 171 de laurel sabino (Magnolia
splendens Urban) y 171 de palo colorado
(Cyrilla racemiflora L.).

Se tiré la curva del grado proporcional de
crecimicnto sobre la del didémetro de los ar-
boles y entonces se calculé la edad de los 4r-
boles de distintos didmetros sumando los pe-
riodos necesarios para pasar de una clase
diametral a la siguiente.

En la Tabla 3 se indica de distinta mane-
ra el crecimiento diametral lento de los 4ar-

boles mas importantes de estas selvas vir-
genes y esta basado en el andlisis de 2.488
Arboles de especies que alcanzan gran tama-
no. Los datos presentados se refieren a Ar-
boles de 2 a 20 pulgadas de didmetro segtn
mediciones de hace 5 anos. La Tabla 3 in-
dica como los arboles dominantes crecen mas
lentamente que los codominantes del tipo ta-

bonuco, aparentemente debido a su mayor
edad.

Tabla 3.—Crecimiento diametral en rodales
virgenes, Bosque de Luquillo

Tipo Tabonuco Tipo Colorado

Clase segun Crecimiento Crecimientc

la copa Numero de| diametral | Namero de| diametral

arboles | promedio arboles promedio
anual anual

Pulgadas Pulgadas
Dominante 27 0,10 123 0,05
Codominan- 64 0,13 212 0,05
te

Intermedio 240 0,13 567 0,04
Dominado 339 0,05 952 0,03
Todos 634 0,09 1854 0,04

JANUARY - APRIL, 1953

El incremento anual bruto (sin excluir la
mortalidad) de dos cuarteles de un acre en
bosque virgen de tipo tabonuco fué de 60
pies clibicos por acre y el de ocho cuarteles
de un acre cada uno en bosque de tipo colo-
rado, fué de 28 pies cubicos por acre.

El] crecimiento lento dentro de los bosques
virgenes demuestra la magnitud de la tarea
del selvicultor para hacer de éstos areas de
alta produccion. No solo habra que eliminar
los arboles inferiores en especie y forma sino
que habra que multiplicar por mucho el cre-
cimiento para que la dasonomia rinda ingre-
Sos.

Se determina el ritmo de crecimiento

relativo de diferentes especies de Luquillo

Los bosques actuales en Puerto Rico se
pueden mejorar mucho sencillamente con
cortas parciales que dejen en pie los mejores
arboles. Aunque la subplantacién en nuevas

Al

especies superiores promete ser un ataque
mas beneficioso para el mejoramiento fores-
algunos sitios, todavia no se ha com-
Mien-

tal en
prebado que sea un éxito completo.
tras tento, tendremos que depender de los
mejores arboles que ahora crecen en estos
rodales, En ia evaluaciGn de estes especies se
debera tomar en consideracién un numero de
caracteristicas entre las cuales una de las
mas importantes es el ritmo de crecimiento.

Durante este ano se consultaron todos los
estudios sobre crecimiento, ya registrados, de
las principales especies de madera de cons-
truccién y postes dentro de los tipos tabo-
nuco y colorado de las montafnas de Luquillo
con el fin de hacer una comparacion de sus
ritmos relativos de crecimiento. Los datos
presentados en la Tabla 4 son de Arboles co-
dominantes e intermedios de clase segtn la
copa (igual peso para cada clase) que son los
mas comunes en bosques bien ordenados. Se
trata de arboles de 4 a 20 pulgadas de dia-
metro.

Tabla 4—Crecimiento diametral de Arboles codominantes e intermedios
Bosque de Luquillo

‘ « | Crecimiento
Especies Arboles | dijametral pro-
medio anual

No Pulgadas
Gallina, Alchorneoposis portoricensis Urban 15 0,32
Negra lora, Matayba domingensis (DC) Radlk 85 0,20
Mato, Ormosia krugii Urban 47 0,27
Granadillo, Buchenavia capitata (Vahl.) Eichl 15 0.26
Roble, Tabebuia pallida Miers = 36 0,25
Guama, Inga laurina (Sw.) Willd. 14 0,23
Ausubo, Manilkara bidentata {A..DC) Chev. 40 0,20
Achiotillo, Alchornea latifolia Sw. 21 0,20
Masa, Tetragastris falsamifera (Sw.) Urban. pee 14 0,20
Hueso blanco, Linociera domingensis (Lam.) Knobl. 12 0,20
Motillo, Sloanea berteriana Choisy 30 0,19
Tabonuco, Dacryodes excelsa Vahl. 179 0,14
Yagrumo macho, Didymopanax morctotoni (Aubl.) Decne. 54 0,14
Nuez moscada. Ocotea moschata (Pavoni) Mez. il7/ 0,10
Koble de sierra, Tabebuia rigida Urban 6 0,07
Caimitillo, Micropholis chrysophyiloides Pierre 144 0.06
Laurel sabino, Magnolia splendens Urban 46 0,06
Caimitillo verde, Micropholis garcinifolia Pierre 514 0,95
jusillo, Calycogonium squamulosum Cogn. Z92 0,04.

fie 0,04

Nemoca, Ocotea spathulata Mez. — --—

42

Dentro de cada especie el promedio de
crecimiento de distintos arboles variO consi-
derablemente como lo hizo también la estruc-
tura de los varios rodales examinados. Sin
embargo habia un numero de areas ordena-
das bien aclareadas. Los arboles en el Ul-
timo tercio de la lista crecieron tan lenta-
mente que hay que considerarlos como ar-
boles de baja produccion a pesar del valor de
su madera. Entre éstos estan las especies
mas comunes del tipo colorado. Como se
vera cualquier aumento considerable en la
productividad de esta area requeriria un cam-
bio mayor en la composicion, que probable-
mente envolveria la regeneracion artificial
con especies exdticas.

Crecimiento de paimas de sierra en
relacion al didmetro y altura

La palma de sierra (Euterpe globosa Gaertn)
es comun en los bosques a mas de 2.000 pies
de elevacion. En vastas extensiones (5,000
acres en el bosque de Luquillo solamente)
aparece en rodales casi puros. Su valor es
sélo de proteccion y su reemplazo por otros
arboles igualmente protectores, pero de ma-
yor utilidad es deseable. De primera inten-
cion se creyO que la palma era una especie
agresiva de crecimiento rapido que invadia
los claros causados por huracanes. Una se-
rie de estudios sobre el crecimiento de pal-
mas analizadas en informes anuales anterio-
res han demostrado que esto es falso; su cre-
cimiento en todas partes es lento, fluctuando
entre 4 y 10 pulgadas por ano.

La escasez de arboles de otras especies
entre las palmas ha creado alguna duda en
cuanto a que si éstos crecerian bien en pal-
mares. Estos palmares son de suelos ines-
tables tales como iberas o despenaderos. Pa-
rece que otros arboles se caen antes de ma-
durar por falta de agarre. Los estudios
sobre el crecimiento de palmas y los métodos
para computarlo a base de la condicion de és-

tas o su medio se ha llevado a cabo porque:

el promedio relativo de crecimiento de las
palmas pudiera indicar donde dentro del pal-

CARIBBEAN FORESTER

mar podria la introduccién de mejores espe-
cies ser mas prometedora. Los estudios in-
formados hace un ano indicaron el mas ra-
pido crecimiento de las palmas intermedias
y dominadas al compararseles con las domi-
nantes y codominantes, aparentemente cues-
tidn de edad. También se descubri6 un mé-
todo para calcular la edad de las palmas se-
gun la distancia vertical entre las sefales de-
jadas en el tronco por las hojas adyacentes.

Un estudio del crecimiento de 5 afos
de 357 palmas del Bosque de Luquillo propor-
cionaron este ano mas informacion sobre esta
especie. La relacién entre el diametro a la
altura del pecho y el promedio de altura
puede verse en la Tabla 5 que esta basada
en una curva sobre datos de crecimiento de
5 anos. El cambio en el ritmo de crecimiento
con diametro se pronuncia mas después del
intervalo de 6 pulgadas. Debera entenderse
al interpretar esta tabla que la relaciOn entre
diametro y edad tiende a ser inversa. Las
palmas jovenes y vigorosas tienen general-
mente un diametro mayor que el de las mas
viejas. Puede llegarse a la conclusién de
que mientras mayor el promedio de diadmetro,
en paridad de condiciones, tanto mejor el
ambiente estacional para palmas (posible-
mente para otros arboles también).

Tabla 5.—E! crecimiento de la palma de
sierra con relacion al diametro

Diametro a la Promedio anual

altura del pecho de altura
Puigadas Pulgadas
3 1,1
4 2,7
5 4,5
6 5,9
7 6,7
8 7,3
i] 7,8
10 8,9

JANUARY - APRIL, 1953

La relacion entre la altura inicial del arbol
y el promedio anual de crecimiento durante
los siguientes 5 afios queda senalada en la
Tabla 6. Estos datos muestran una rela-
cién generalmente inversa entre la altura y
el crecimiento. Esto comprueba el hecho de
que los arboles jOvenes crecen mas rapida-
mente.

Tabla 6.—Crecimiento de la palma de sierra
con relacion a la altura

Promedio anual de

Altura inicial altura
Pies Pulgadas

5 6,4
10 Heal
20 tial
30 6,1
40 4,6
50 3,0

Contribucion Actual y Potencial de
los Bosques

La casuarina alcanza 16 pulgadas de didmetro

cn 20 anos en los arenales costaneros

La casuarina (C. equisetifolia Forst), oriun-
da de Australia ha sido por muchos anos el
arbol favorito de Puerto Rico para siembras
en fincas. Se adapta a suelos pobres, crece
rapidamente, su tronco recto se presta para
muchos usos en la finca y es de aspecto atrac-
tivo. Su madera no es facil de trabajar, ni,
en la mayor parte de ambientes estacionales,
adquiere un didmetro suficientemente gran-
de para madera aserrada.

Una de las primeras plantaciones de esta
especie en Puerto Rico la establecié en 1922
la Central Fajardo en la Hacienda Monserra-
te cerca del pueblo de Luquillo. Esta plan-
tacion, de cerca de 4 acres, contenia 2.700
arboles espaciados de 8 x 8 pies. Este sitio
se consideraba sin valor para otros proposi-

43

tos. El suelo de arena blanca casi estéril, el
limite de saturacién de agua era alto y nin-
euna otra cosecha se daba alli debido a los
cangrejos.

Esta plantacién result6 ser de crecimien-
to extraordinario y demostro la adaptabili-
dad de esta especie a los arenales costaneros
abrigados. A principios de 1932, 10 anos
después, el suelo exterior habia tomado un
color pardo oscuro y estaba alfombrado de
agujas. Quedaban pocos cangrejos y una
vegetacion herbacea se habia desarrollado
bajo los arboles. En aquella época el rodal
contenia un volumen de 2.750 pies cutbicos
por acre, casi todo apropiado para postes y
espeques. Mas tarde ese mismo ano un hu-
racan arranco 0 partido todos menos 25 de los
arboles.

Una segunda plantacion se estabecio en
el mismo lugar en 1932. A los 10 anos una
medicion de 559 arboles arrojo una escala dia-
metral de 4 a 18 pulgadas, con un promedio
de 9,5 pulgadas. El dosel tenia 85 pies de
alto y uno de los arboles media 105 pies. A
los 17 anos el numero de arboles habia ba-
jado a 206 debido a la eliminacién gradual
de los arboles mas débiles. El diametro pro-
medio de los que quedaron era de 14,4 pul-
gadas.

La medicion de los 20 anos se hizo este
ano. Se encontr6 que aunque el rodal esta
ahora completamente abierto, muchos de los
arboles estan perdiendo vigor. Se han
cortado mas arboles y solo quedan 181. Es-
tos que indudablemente son de los primeros
arboles dominantes y codominantes tienen
ahora una escala diametral de 8 a 25 pulga-
das con un promedio de 16,2 pulgadas.

En Puerto Rico no se ha aprovechado el
beneficio de este crecimiento rapido de la ca-
suarina. Aunque la madera no es de alta
calidad para construcci6n, experimentos han
demostrado que se le pueda tratar con éxito,
con preservativos que prolongaran su utili-
dad a por lo menos 10 aflos como espeque o
poste en tierra. Los espeques que no han
sido tratados duran muy poco, los postes mas

dd

erandes pueden durar hasta 5 afos pero la
mayoria no dura 24 meses.

Plantacionces de casuarina en la
isla de La Mona se deterioran

Durante los afos de 1937 a 1939 se plan-
taron en arboles cerca de 400 acres en los
lianos costaneros de la isla de La Mona si-
tuada entre Puerto Rico y La Espanola. Es-
ta area recibe como 40 pulgadas de precipi-
tacion anualmente y los terrenos sembrados
son mayormente arenas de playa con una
profundidad de 6 a 30 pulgadas. Las prin-
cipales especies sembradas fueron casuarina
(C. equisetifolia Forst) y caoba antillana
(Swietenia mahagoni Jacq.). Aunque esta zona
ya no es reserva forestal publica, la isla esta
casi deshabitada y las plantaciones no han
sido tocadas. Porque estas plantaciones in-
dican lo que podria esperarse de plantaciones
en sitios similares en Puerto Rico, su desa-
rrollo ha sido seguido de examenes y medi-
clones periddicas.

La casuarina ha probado ser la especie
sobresaliente. Posiblemente debido al clima
mas sece no ha crecido tan rapidamente como
en la Hacienda Monserrate (ya descrita en
este informe) pero los arboles generalmente
tienen buena forma y han producido rodales
cerrados. Su diametro a los 15 anos flucttia
entre 4 y 12 pulgadas y la altura entre 30 y
100 pies.

El] desarrollo de este Arbol esta intima-
mente relacionado con el grado de proteccién
contra el viento y la calidad del suelo. En
una ensenada protegida, con suelo relativa-
mente profundo, los arboles tienen un prome-
dio de 7,5 pulgadas de didmetro y de 80 a
100 pies de altura. En una punta arenosa y
cescubierta de las cercanias, los arboles tie-
nen solamente la mitad de este tamafi, el
Cosel esta m4s abierio, el follaje escaso y al-
gunos tienen las copas muertas que estan
siendo reemplazadas por ramas desarrolladas
ce brotes en reposo en las partes bajas de los
troncos. La apariencia enfermiza de estos Ar-

CARIBBEAN FORESTER

boles se ha desarrollado ultimamente. Pa-
rece haber poca perspectiva de crecimiento
adicional. La causa parece ser el efecto com-
binado de exposicion al viento y del casi es-
téril suelo arenoso sobre aguas salobres.

Aunque los arboles de estas plantaciones
se estan deteriorando poco a poco, probable-
mente continuaran ofreciendo sombra hala-
gadora a lo largo de la playa por muchos
anos. Sin embargo, mayor rendimiento eco-
nomico podria resultar convirtiendo estas
areas expuestas en cocales, usando la casua-
rina como cosecha tutora para las palmas
jovenes.

La caoba tampoco ha tenido éxito en los
arenales mas descubiertos pero esta creciendo
bien donde esta protegida. En las areas me-
jores, arboles dominantes de 15 anos tienen
de 5 a 7 pulgadas de diametro y hasta 40
pies de altura. Donde estan estrechamente
sembrados su forma es buena. La regene-
racion natural abunda en areas abrigadas.

Para Aumentar la Productividad de Bosques

Estudios sobre mejora forestal
sirven de guic en ordenacién

Los estudios de bosques virgenes nan sido
de gran valor pues senalan las relaciones
selvosas en el relativamente estable medio
climatico. Estudios similares en bosques que
han sido mejorados con la reduccion de la
densidad del rodal al eliminar arboles extra-
maduros y de calidad inferior dejan ver mas
claramente cuales son las mejores practicas
selviculturales. Esto qued6o altamente de-
mostrado con los hallazgos en cuatro cuarte-
les de 14 acre cada uno de los tipos tabonuco
y colorado de las montanas de Luquillo que
se midieron el ano pasado después de 5 anos
de establecidos.

Estos cuarteles se mejoraron con una
corta parcial en 1947. Los rodales restantes

para esa fecha se describen en la Tabla 7. Se

removio casi todo el rodal de mas de 20 pul-
godas de diametro y el area basimétrica se

JANUARY - APRIL, 1953

redujo a casi el 50 por ciento de la que gene-
ralmente tienen los bosques virgenes. La cor-
ta extrajo o libero por lo menos la mitad de
los arboles que habian estado dominados, de-
jando en pie un numero mucho mas reducido
de arboles de esta clase no productiva.

El crecimiento de estos cuarteles queda
indicado en la Tabla 8. Se observa un mar-
cado contraste entre los dos tipos, el creci-
miento diametral del tipo tabonuco aumento
en un 50 por ciento, en la del colorado no
hubo cambio. Un total de 204 arboles de

45

ese tipo, mas de la mitad de los que habia
en los cuarteles, tuvieron un aumento diame-
tral insignificante durante los 5 anos. Aun
los arboles dominantes, codominantes e in-
termedios estan creciendo lentamente. Ar-
boles de especies de crecimiento rapido como
el roble de sierra (Tabebuia rigida Urban) en
estas clases crecian a razon de solo 7 pulga-
das por siglo. Estos resultados confirman
los indicados en la Tabla 4. Puede que ésto
se deba a la edad avanzada de muchos de
estos Arboles como se indica en la Tabla 2.

Tabla 7—Rodal remanente por acre en cuarteles mejorados
Bosque de Luquillo, 1947

Tipo tabonuco | Tipo colorado

Indice Cuartel Cuartel | Cuartel Cuartel
1 2 1 2
Numero de arboles segtn clase diamétrica

2 - 6” 726 938 746 682
gamle 5 42 60 68
13 - 20” 20 2 12 18

20” + 2 2
Om raw 804 984 820 768
Area basimétrica total, pie cuadrado 91 68 98 100
Por cientos de arboles dominados 38 27 24 27
Volumen total, pies cubicos 1708 1186 1368 1456

Tabla 8.—Crecimiento en cuarteles mejorados de Luquillo, 1947-52

Indice

Arboles nuevos, por acre

Crecimiento diametral anual medio — todos los
arboles, pulgadas

Crecimiento diametral anual medio, arboles
dominantes y codominantes, pulgadas

Incremento basimétrico por acre a los 5 anos,
pies cuadrados

Incremento bruto por acre a los 5 anos,
pies cubicos

Mortalidad a los 5 anos, pies ctbicos

Incremento neto a los 5 afios pies cubicos

Tipo tabonuco | Tipo colorado

Cuartel | Cuartel | Cuartel | Cuartel
il 2 1 2
298 220 52

0,103 0,14 0,03 0,05
0,20 0,26 0,05 0,05
30 34 —5 5
600 595 98 115
85 15 68 60
515 580 30 55

46

Ordenacion continuada, eliminando gra-
dualmente los Arboles viejos podria crear
eventualmente un rodal mas productivo. Sin
embargo, en los tltimos 5 afos se ha regis-
trado poco desarrollo de copa, la mortalidad
ha continuado alta y por consiguiente una
eorta secundaria, si hecha muy temprano
abriria demasiado el rodal. Ademas casi no
hay arbolitos jovenes de manera que el re-
emplazo del rodal viejo por uno nuevo seria
aparentemente un procedimiento muy lento.
Una solucién mas prometedora parece ser la
introduccién de otras especies.

En el tipo tabonuco la corta produjo un
marcado vigor en el sotobosque. (Véase ilus.
3). La densidad del rodal aumento rapida-
mente hacia su area basimétrica inicial. El
crecimiento de copa también fué rapido y
pronto cerré el dosel. En consecuencia se
hizo, en 1952 una nueva corta en el cuartel
No. 1 reduciendo el numero de arboles de
1.072 por care a 848 y el area basimétrica de
120 a 105 pies cuadrados por acre. En el
cuartel No. 2 se redujeron los arboles de
1.178 a 978 por acre y el area basimétrica
de 102 a 89 pies cuadrados por acre.

Perece haber indicaciones de que la corta
algo mayor que se hizo en el cuartel No. 2
el aflo pasado fuera mas beneficiosa que la
que se hizo en el cuartel No. 1. El creci-
miento diametral y el incremento neto fue-
ron mas altos en este cuartel. Para eviden-
cia concreta seria necesario una investiga-
cion por separado. Quedd demostrado que
la corta mayor que se hizo en el cuartel No. 2
no causO una seria invasion de trepadoras.

La cacha hondurena responde bien a la
siembra directa, subplantacion y corta

El exito obtenido con la caoba antillana
(Swietenia mahagoni Jacq.) en siembra di-
recta en los montes calizos de la Estacion
Experimental de Cambalache (al nivel del

mar; precipitacion de 55 pulgadas), y el buen '

crecimiento de la caoba hondurena (Swietenia
macrothyvlla, King) en el mismo sitio con-
dujo a pruebas de siembra directa con esta

CARIBBEAN FORESTER

ultima especie de crecimiento rapido. La
ventaja de esta practica en el caso de la caoba
antillana fué que el trasplante a macetas (la
unica alternativa) se hizo innecesario y por
consiguiente la siembra result6 mas barata.
La siembra directa fué también mas facil
porque no habia que localizar los bolsillos de
suelo profundo donde sembrar arbolitos. El
crecimiento temprano de semillones en el bos-
que ha sido rapido. Este método ha tenido
éxito solamente bajo sombra parcial, y ha
fracasado debido a sequias en la costa sur
(nivel del mar; precipitacion, 30 pulgadas).

A fines de 1950 se hizo un sembrado en
el bosque Cambalache, echando cuatro semi-
llas en cada punto bajo dosel abierto de 20
pies de altura; éste fracas6 debido a germi-
nacion escasa. Se volvid a sembrar en 1951
y esta vez fué un gran logro. Para fines
del 1952 después que los arbolitos habian su-
frido una estacion de seca, casi todos los pun-
tos contenian arbolitos vivos de 12 a 18 pul-
gadas de altura. El desarrollo de los pocos
arboles que quedaban de la siembra anterior
demuestra que estos pueden alcanzar altura
rapidamente si se les provee de luz de arriba.

En las montanas humedas, la siembra de
semillones de caoba hondurena parece mas
satisfactoria que la siembra directa (aunque
no se ha experimentado con esta ultima)
porque el producto de viveros crece mas ra-
pido y temprano y por eso puede competir
ventajosamente con la densa vegetacion na-
tural. Como en la costa, la subplantacion
parece ser un método mas seguro que la siem-
bra de campo con esta especie.

En 1950 unos 40 acres de bosques hidro-
fiticos secundarios del Bosque de Luquillo
(elevacion, 1.000 pies; precipitacion, 120 pul-
gadas) se subplantaron en caoba hondurena.
Se despejo el dosel para media sombra y los
Arboles se espaciaron de 15 a 20 pies bajo
los claros. Debido al tiempo sumamente llu-
vioso solamente sobrevivio el 60 por ciento y
fué necesario sembrar de nuevo. A los 18

meses los arboles tenian un promedio de 5

JANUARY - APRIL, 1953

pies de aitura y estaban bien vigorosos. No
habia sefales de dafmos causados por el in-
secto taladrador (Hypsipyla grandella). Es
evidente que no todo el cuido del plantio pue-
de abandonarse porque se siembra bajo do-
sel. La necesidad del desyerbo queda casi
eliminada pero hay que quitar las trepadoras
una o dos veces, y para mantener el dosel
abierto sobre los arboles, habra que atenderlo
cada 24 meses durante los primeros anos.El
resultado de esta prueba y la evidencia obte-
nida con siembras de campo anteriores, han
servido de base para la subplantacion de 800
acres de bosques hidrofiticos secundarios en
los sitios mAs abrigados del Bosque de Lu-
quillo.

Evidencia de las potencialidades de la
caoba hondurena en zonas de bosques hidro-
fiticos se ha obtenido mayormente de un
plantio pequeno hecho en 1931. Este plan-
tio, de unos 4 acres, se dej6é desarrollar sin
cuidos selviculturales. A los 20 afios el area
basimétrica era de 140 pies cuadrados por
acre, y el rodal era tan denso y uniforme que
el 80 por ciento de los arboles estaban en la
clase de copa intermedia. Las copas son
opacas y de un verde mas obscuro que lo re-
gular en plantios jovenes. Los diametros
fluctuan entre 4 y 15 pulgadas, siendo el pro-
medio 9,6 pulgadas. El] incremento medio
anual del area basimétrica por Arbol para los
primeros 17 anos fué 0,0238 pies cuadrados;
para los ultimos 3 anos fué 0,0342 pies cua-
drados, lo que indica un crecimiento continuo
y rapido. Muchos de los Arboles estaban
ahorquillados pero una corta este afio los eli-
mino totalmente. Esta corta a los 20 afios
rindid 1.000 pies cibicos de madera de ase-
rraje por acre con lo que se sufragaron los
gastos de siembra (sin réditos). La salud,
tamano y ritmo de crecimiento de estos 4r-
boles indican que esta especie es la mas pro-
metedora para sitios protegidos dentro de la
zona de bosques higrofiticos.

Un estudio de aclareos mas oportunos en
el Bosque Rio Abajo (elevacion, 500 pies;
precipitacion, 80 pulgadas) esta sirviendo de
guia para ensayar en mas de 500 acres de

AT

iza abrigada. Este plantio (210 4r-
dcminantes y codominantes) habia al-
canzado un diametro medio de 6,2 pulgadas,
un dosel de 50 pies y un area basimétrica de
8) a 110 pies cuadrados por acre. El creci-
miento basimétrico promedio anual para los
primeros 13 anos fué de 0,0161 pies cuadra-
dos. El crecimiento basimétrico anual co-
rriente por arbol para los dos ultimos afios en
rodales sin aclareos fué de 0,0151 pies cua-
drados, un pequeno descenso.

De dos cuarteles de 14 acre cada uno en
este rodal se cortaron 320 Arboles por acre
dejando unos 400. El area basimétrica res-
tante fluctuaba entre 56 y 76 pies cuadrados
por acre. El aclareo elimino los arboles de
forma indeseable sin tomar en consideracion
el tamano, los dominados y los intermedios.
El claro aumento de 1/3 a 2/3 la proporcion
de todos los arboles en las clases copa, domi-
nantes y codominantes, y aun a los Arboles
que ya estaban en estas clasificaciones se les
did mas espacio. (Véase ilus. 4).

Un reexamen de estos plantios aclareados
ofreci6 algunos de los resultados previos. El]
claro no era lo suficientemente grande para
ocasionar problemas con las trepadoras aun-
que las pocas que se encontraron en las areas
mas abiertas indican que ésto hubiera sido el
resultado de ser mayor el aclareo. Casi nin-
guno de los arboles se doblegé con el viento
al ser liberado. El crecimiento de retonos
en los troncos de los arboles cortados hace 2
aflios no tuvo mayor importancia. El creci-
miento diametral se aceleré con el clareo.
El! crecimiento diametral anual promedio por
arbol en estas clases para los 2 anos después
del clareo fué de 0,48 pulgadas (base, 42 ar-
boles), comparado con 0,44 pulgadas (base,
42 arboles) en los cuarteles adyacentes sin
clarear. La diferencia es mas notable si to-
dos los arboles restantes (incluso los subor-
dinados) se incluyen en esta comparacion;
0,26 pulgada vs. 0,17 pulgadas. Un resul-
tado muy significativo es la _ creciente

A8

preponderancia de los arcoles grandes. Estan
aleanzando altura rapidamente y por lo me-
nos 50 de ellos por acre sobresalen del dosel.
Estos son sin duda arboles de cosecha final.
Otro aclareo para acelerar el crecimiento no
sera necesario hasta que las copas de estos
Arboles grandes no se unan, ésto es, de 5 a
iS anos después del clareo de 1950. Al cabo
cde 5 anos puede que sea conveniente aclarar
ce abajo apara aprovechar el material comer-
ciable que proporcionen los arboles decaden-
tes.

El mangle de 20 anos responde prontamente

cl aclaveo y a la coria de diseminacion

Hay mas de 15,000 acres de bosques de es-
teruos dominados por el mangle (Laguncularia
vecemosa (L.) Gaertn) en las margenes de as-
tuarios, lagunas y bahias protegidas de Puer-
ta Rico.. Como estos bosques accesibles han
sido despojados constantemente desde tiem-
pos. remotos ya no quedan Arboles grandes,
pero como la regeneracion es rapida estas
Areas estan todavia cubiertas de bosques jo-
venes. Suelos poco propicios evitan la inva-
sién per otras especies quedando el mangle
casi puro. (Véase ilus. 5).

Pero a pesar de las aparentes condiciones
favorables el crecimiento del mangle no es
del todo satisfactorio. La corta total, el pro-
cedimiento regular, ha dado por resultado ro-
dales de arbolitos que se estancan. Estudios
han probado que hasta 19.000 renuevos por
acre pueden desarrollar un diametro de una
pulgada o mas. Entonces, como ningtin ar-

kol sobrepasa pronto a los que lo rodean, el
crecimiento tiene que esperar la lenta elimi-

nacién de miles de arboles a menudo llevada

a cabo por insectos taladradores. En un es-
tudio de 223 arboles de una pulgada se en-
ccntro que el crecimiento diametral medio
cra de 0,6 en 11 anos. Como los arboles son

demasiado pequenos para la utilizacion y su

aclareo es caro, este estancamiento es obs-
taculo para la alta productividad de este tipo
ce bosque.

CARIBBEAN FORESTER

Se esta experimentando con dos métodos
para reducir la densidad en estos rodales. El
primero, la corta parcial para crear un bos-
que de edades multiples. Pero habia que en-
carar la aparente intolerancia de la especie
y el peligro de derribo por el viento. El se-
gundo método, la corta total en fajas perpen-
diculares a los vientos prevalecientes, mo-
viéndose hacia barlovento y cortando otra
faja tan pronto se obtenga la regeneracion
de la anterior. Los peligros aqui son el de-
rribo por el viento y el temor de que una
faja, bastante ancha para asegurar la rege-
neracion, pueda también producir un rodal
joven demasiado denso.

EK] rodal seleccionado para estas pruebas
en el Bosque de Aguirre se desarrollo después
de una corta total en 1930. El diametro
promedio de los Arboles dominantes y codo-
minantes es de 8 pulgadas y el 4rea-bdasimé-
trica de 110 a 140 pies cuadrados por acre.
El dosel tiene unos 60 pies. Cuatro cuar-
teles de 14, de acre cada uno se establecieron
en 1949 para determinar el ritmo de creci-
miento en el rodal antes de hacer cambio al-
guno. Se encontro que durante los ultimos
3 anos el crecimiento diametral promedio
fué de 11,6 al ano (0,20 pulgadas para los do-
minantes y codominantes solamente), que
al ano se moria un promedio de 95 arboles
por acre y que no habia cambio en el area
basimétrica o volumen.

En dos de los cuarteles (excluidos del
analisis anterior) una tormenta tumbo 82 4ar-
boles en 1952, ocasionando claros en el dosel.
Después de la tormenta se volviéd a medir y
clasificar los arboles adyacentes al claro con
relacion a la posicion de las copas. El anali-
sis del crecimiento de 104 de estos Arboles
aparecen en la Tabla’ 9. Los crecimientos
para la comparacion son los de 1949-50, an-
tes de la tormenta, y 1950-52 después de ésta:
Las ultimas dos lineas de la Tabla 9 indican
que es posible la aceleracién inmediata del
crecimiento de arboles dominados en este ro-
dal al ser liberados, aunque hayan estado do-
minados por 20 anos.

JANUARY - APRIL, 1953

Tabla 9.—Efectcs de

Ag

liberacién sobre crecimiento de manglares

Promedio anual de crecimiento diametral

Clase segtn la copa Numero
Antes de la Después de la ue Antes de la Después de la
liberacion liberacion arboles liberacion liberacion
Pugadas Pugadas
Codominantes Dominantes 9 0,23 0,27
Intermedios Codominantes 38 0,18 0,17
Intermedios Dominantes 4 0,04 0,40
Intermedios 53 0,06 017

Dominados

La tormenta proporcioné conocimientos
valiosos sobre selvicultura. Qued6 demos-
trado que el rodal responde a la liberacion y
que son los arboles mas grandes los que caen;
por consiguiente éstos se deben cosechar, la
corta es deseable para el increments. En
efecto, se hicieron cortas en dos de los cuarte-
les; en uno se arrancaron 208 arboles ¥ se re-
dujo el area basimétrica de 129 a 78 pies
cuadrados por acre, del otro se sacaron 328
arboles por acre y se redujo el area basimé-
trica de 108 a 63 pies cuadrados por acre.
Estos cuarteles seguiran en observacién para
determinar futuro crecimiento, derribo por
vientos y regeneracion.

La corta por fajas se empezo en este ro-
dal en 1951. Una faja de 66 pies de ancho
por 660 pies de largo se extendié de norte a
sur. De esta madera se hizo carbon. <A fin
de ano se constat6 que los vientos no habian
perjudicado esta faja. El nimero de tocones
que, habian retofiado no podian constituir
rodal, ademas sus tallos torcidos no podian
dar: buenos-arboles. Semillones de 4 pulga-
das surgieron en abundancia bajo las ramas
colganteside-los arboles a lo largo de la orilla
este de la:faja. Otros semillones surgieron
dentro de la faja donde evidentemente era el
limite de la marea alta cuando maduraron.
Hacia barlovento, extendiéndose 30 pies den-
tro del bosque, el suelo esta cubierto de un
denso rodal de semillones que aparentemente
pueden soportar sombra de arriba y luz la-

teral. Sera rocesario continuar observando
hasta ver si la faja tiene el ancho adecuado
y cuando puede cortarse otra faja adyacente
hacia barlovento.

Resumzen de las experiencias
con el eucalipto

El eucalipto por su rapido crecimiento en
la América del Sur atrajo la atencion hace
anos y muchas especies se introdujeron en
Puerto Rico. Para 1940 habia algunos 4r-
boles en las fincas de la isla y algunos plan-
tios pequefios en los bosques publicos. Lue-
go se han sembrado mas de 2.000 acres de
bosques publicos en E. robusta Smith y E.
kirtcenianc. FE. V. M.- Con semillas de otras
especies traidas del Brasil y de Guatemala
se han preparado plantios de prueba en dis-
tintos medios estacionales. El progreso de
estos plantios se ha analizado periodicamente
en intormes anuales anteriores. Aqui se re-
sume brevemente la experiencia obtenida
hasta la fecha con Jas especies mas impor-
tantes. ;

E. ecmenioides Schauer.—Sembrado en dis-
tintos ambientes estacionales desde el nivel
del mar kasta 3.500 pies de elevacién. No
promete. Ha fracasado en suelos lateriticos
y el crecimiento ha sido erratico en otros si-
tios. En uno de los mejores sitios de suelo
suelto, rojo y profundo en el Bosque de Lu-
quillo (elevacion, 500 pies sobre el nivel del
mar; precipitacion 120 pulgadas) algunos ar-

boles de 8 anos han alcanzado un diametro de
7 pulgadas y una altura de 40 a 60 pies. Sin
embargo la mayor parte de los arboles son
mas pequenos y de forma pobre y débil.

E. alba Reimwardt.—Sembrados en una
variedad de -medios cstacionales desde el ni-
vel del mar hasta 3.500 pies de elevacion. Es
la mejor especie hasta la fecha para eleva-
ciones hasta de 590 pies. En suelos de poca
profundidad en el area experimental de St.
Just (elevacion, 300 pies; precipitacion, 70
pulgadas), un plantio de 8 anos ha alcanzado
entre 40 y 60 pies de altura con arboles de
3a5 pulgadas de diametro. En suelos rojos,
sueltos y profundos del Bosane 27> © -uillo
(elevacion, 500 pies; precipitacion, 120 pulga-
das), arvoles de 8 anos tienen diametros de
6 a9 pulgadas y altura de 60 a 75 pies. En
terrenos pobres y arcillosos en el Bosque
Toro Negro (elevacion, 3.500 pies; precipita-
cion, 110 pulgadas), Arboles de 7 anos tienen
una altura promedio de 15 pies con 25 pies
de altura maxima. Las copas conicas y
achatadas indican que esta especie no se
adapta tan bien a estas alturas como otras
especies. En suelos lateriticos pobres del
Bosque de Maricao (elevacion, 2.000 pies;
precipitacion, 100 pulgadas), esta especie
fracaso.

E. botryoides Smith.—Sembrado en distin-
tos ambientes estacionales hasta 3.590 pies
sobre el nivel del mar. Logro mediano en
algunos de los mejores sitios, fracaso en el
resto. En suelo suelto y profundo del Bosque
de Luquillo (elevacion, 500 pies; precipita-
cion, 120 pulgadas) arboles de 8 anos miden
60 pies. El rodal no es uniforme y muchos
de los arboles estan achaparrados.

E. citriodora Hook.—Sembrada en varie-
dad de ambientes estacionales desde el nivel
del mar hasta 3.500 pies de elevacion. Gene-
ralmente lenta en crecimiento y de copa es-
casa en todo sitio. En suelo profundo del
Bosque de Luquillo (elevacion, 500 pies; pre-
cipitacion, 120 pulgadas), la gomosis es co-
mun y la mayor parte de los arboles se mue-
ren durante los primeros 8 anos. En suelos
pesados degradados en el Bosque Toro Negro

CARIBBEAN FORESTER

(elevacion, 3.500 pies; precipitacion, 110 pul-
gadas) arboles de 7 ahos tienen una altura
media de 10 a 12 pies.

E. corymbosa Smith.—Sembrada en mon-
tanas solamente. Supervivencia buena. Ar-
boles lozanos, crecimiento lento. En el Bos-
que de Toro Negro (elevacion, 3.500 pies; pre-
cipitacion, 110 pulgadas), arboles de 6 anos
tienen altura media de 15 a 20 pies.

E. globulus Labill—Sembrado en monta-
nas — no se adapta. Un plantio en el Bos-
que Toro Negro (elevacion, 3.800; precipita-
cion, 120 pulgadas), no se esta desarrollando
bien. Al cabo de 8 anos algunos arboles mi-
den 25 pies. La experiencia ha demostado
que esta especie requiere un clima mas fres-
co.

E. kirtoniana F. v. M.—Sembrada en dis-
tintos ambientes estacionales, mayormente a
2.000 pies de elevacion. Esta especie, ante-
riormente informada como E. resinifera Smith
fué identificada el afo pasado. Esta entre
las que se adaptan mejor a Puerto Rico y su
rendimiento en altura es posiblemente ma-
yor que el de las otras. Arboles sembrados
en el Bosque Toro Negro (elevacion, 3.000
pies; precipitacion 110 pulgadas), en 13 anos
han aleanzado didmetros entre 6 y 13 pul-
gadas y alturas de 75 a 90 pies. Esto en te-
rrenos sueltos de mediana a baja producti-
vidad. Los Arboles codominantes en este
plantio estén creciendo a un ritmo de mas
de una pulgadas de diametro al ano. La
forma es excelente.

E. maculata Hook.—Hasta la fecha se ha
sembrado en cuatro medios desde 500 hasta
3.500 pies de elevacién. En suelos sueltos
del Bosque de Luquillo (elevacion, 500 pies;
precipitacion, 120 pulgadas) hay Arboles de
8 afios que miden de 35 a 40 pies de altura,
algunos con didmetro de 3 a 5 pulgadas, sien-
do este plantio uno de los mejores en este
medio. En suelos pobres y arcillosos del Bos-
que Toro Negro (elevacion, 3.500 pies; pre-
cipitacién, 110 pulgadas), Arboles de 7 anos
tienen un promedio de 22 con un maximo de
25 pies, estan lozanos, son uniformes y entre

JANUARY - APRIL, 1953

los mejores de estos suelos pobres. En un
suelo lateritico de pobre calidad en el Bos-
que de Maricao (elevacién, 2.000 pies; pre-
cipitacion, 100 pulgadas) Arboles de 5 afios
tenian altura media de 6 pies con un maximo
de 12 pies. E. maculata es una de las espe-
cies que mejor se adapta especialmente a
elevaciones mayores. No desarrolla gomosis
ni mortalidad temprana en el grado que los
desarrolla E. citriodora en los medios estacio-
nales donde se han sembrado ambos.

El pilularis Smith.—Sembrada s6lo en las
montanas. Crecimiento mediano. En el
Bosque Toro Negro (elevacién, 3.500 pies;
precipitacion, 110 pulgadas) la superviven-
cia fué alta, los Arboles estan saludables y
bien formados, con una altura promedio de
25 pies a los 8 anos.

E. propingua Deane & Mainden.— Se le
siembra en distintos ambientes estacionales
desde el nivel del mar hasta 3.500 pies de
elevacion. Requiere mejores suelos que los
que se usaron para las pruebas. En el Bos-
que de Luquillo (elevacion, 500 pies; precipi-
tacion, 120 pulgadas) sdlo algunos arboles se
desarrollaron bien en las areas mejores del
plantio. A los 8 anos el tamano maximo es
7 pulgadas de diametro y 60 pies de altura.
En el Bosque de Toro Negro (elevaci6n,
5.900 pies; precipitacién 110 pulgadas) po-
cos arboles en el fondo del valle alcanzaron
a 25 pies de altura después de los 7 afios.

E. resinifera Smith—Sembrado en distintos
medios estacionales desde el nivel del mar
hasta 3.500 pies de elevacién. Una de las
especies que mejor se adapta a las montanas.
En el Bosque Toro Negro (elevacién, 3.500
pies; precipitacion, 110 pulgadas) Arboles de
7 anos estan lozanos, uniformes y miden de
30 a 35 pies de altura. En el Bosque de Ma-
ricao (elevacion, 2.000 pies; precipitacién,
100 pulgadas) en suelos lateriticos pobres
donde 20 especies de eucalipto han fracasado,
los Arboles tienen una altura media de 20 pies
alos 8 anos. En la Estacion Experimental
de Cambalache (nivel del mar; precipita-
cién, 55 pulgadas) los arboles han alcanzado
también 20 pies de altura y 4 pulgadas de

d1

diametro en 8 afios. Este es un desarrollo
mejor que el que regularmente se ha obtenido
al nivel del mar con otras especies de eucalip-
to, pero el crecimiento ha declinado Ultima-
mente y parece ser que la especie no se adap-
ta bien aqui.

E. robusta Smith.—Sembrado en distintos
medios estacionales hasta 3.800 pies de ele-
vacion. Es la especie que mas se ha sembrado
en Puerto Rico y se adapta bien a suelos
pobres particularmente los himedos y alna
los lateriticos, a elevaciones mayores de 1.500
pies. No se adapta al nivel del mar. En
suelos profundos y himedos de 2.000 pies de
elevacion los arboles de 13 afios flucttian en-
tre 8 y 16 pulgadas de didmetro y miden has-
ta 75 pies de altura. No hay sefiales de de-
cadencia en el crecimiento. (Véase ilus. 6).

E. sideroxylon A. Cunn.—Sembrado solo
en las montanfas. No se destaca pero es
vigoroso y de buena forma. En el Bosque
Toro Negro (elevacion, 3.500 pies; precipita-
cidn, 110 pulgadas) arboles de 7 afios tienen
una altura media de 30 pies.

E. tereticornis Smith.—Se ha sembrado en
toda clase de ambiente estacional desde el
nivel del mar hasta 3.500 pies de elevacion.
Como el E. alba y distinto a otros probados
esta especie se ha dado mejor en elevaciones
bajas. En la Estacion Experimental de St.
Just (elevacion, 300 pies; precipitacion, 70
pulgadas) en un suelo bien drenado de arci-
lla esquitosa los arboles tienen de 3 a 6 pul-
gadas de diametro y de 50 a 60 pies de altura.
Por el contrario en el Bosque Experimental
de Cambalache (nivel del mar; precipitacion,
55 pulgadas) arboles de la misma edad en
suelos arcillosos no prosperan. Tienen un
promedio de 3 pulgadas de diametro y miden
de 35 a 50 pies de altura: sus copas son raras.
En el Bosque Rio Abajo (elevacion, 500 pies;
precipitacion, 80 pulgadas) los arboles de 8
afios fluctuan entre 8 y 25 pies de altura.
Esto se debe a un suelo poco fértil y degra-
dado. A elevaciones de 3.500 pies no han
tenido crecimiento perceptible y parecen des-
tinados a fracasar.

Ot
bo

El reciente mercado para postes de eu-
calipto y la posibilidad de que pueda utilizar-
se para la fabricacién de cart6n para divi-
siones hacen del eucalipto una produccién
prometedcra para los miles de acres de pro-
piedad particular baldios y falta de abrigo.
A base de este desarrollo se haran nuevas in-
vestigaciones sobre la adaptabilidad de dis-
tintas especies. Se estan introduciendo nue-
vas especies y se ensayara con las que ya se
tienen en mejores ambientes estacionales.
También se encaminaran experimentos a des-
cubrir mejor utilizacion de la madera.

El ciprés mejicano sigue

creciendo rapidamente

Hii ciprés mejicano (Cupressus lusitanica
Mill.), un conifero de valor nativo de la Amé-
rica Central y de Méjico, se trajo hace 4 anos
y se ha experimentado con él en varios am-
bientes estacionales especialmente a niveles
altos. Parece ser uno de los arboles mas
sotresalientes que se hayan introducido.

Un plantio de 4 anos en el Bosque de Lu-
quillo (elevacion, 1.800 pies; precipitacion,
140 pulgadas) en suelo profundo pero pan-
tanoso ha alcanzado una altura de 12 pies.
Kn el Bosque Toro Negro (elevacion, 3.500
p-e3; precicipitacién, 120 pulgadas) un plan-
tio de ciprés de 214 anos en una ladera descu-
bierta de suelo llano y rocoso esta mas vigo-
roso que el eucalipto o el roble (Tcbebuia pa-
‘lida Miers. La altura media del ciprés es
ce 7 pies con arboles, hasta de 12 pies. Ar-
boles subplantados bajo las sombras de ca-
fetales abandonados en el Bosque Toro Ne-
gro estan creciendo bien a pesar de la som-
cra. En un suelo lateritico pobre en el Bos-
que de Maricao (elevacion, 2.000 pies; preci-
pitacion, 100 pulgadas) los arboles empeza-
ron a ganar en altura tan pronto fueron sem-
brados y son de un color verde brillante que
no se ve en ningun otro arcol sembrado en el
raismo sitio ni «n la vegetacion nativa. En
este sitio aun el eucalipto parece destinado
al fracaso.

D

Rsta especie parece sobresalir en muchos
respectos. Con un minimo de desyerbo, ar-

CARIBBEAN FORESTER

boles jovenes pueden competir con la vege-
tacion agresiva como los helechos y la yerba
melado (Melinus minutifolia). Esta creciendo
bien bajo gran variedad de condiciones des-
de el nivel del mar hasta 3.500 pies de eleva-
cion en los peores suelos de la Isla. Parece
crecer bien tanto bajo sombra como en des-
cubierto. En ritmo de crecimiento tempra-
no supera al de la mayor parte de los arboles
sembrados.

Hasta la fecha solo se ha notado una ca-
racteristica indeseable que no guardaria ma-
yor importancia segun se desarrollen los ar-
boles. En algunos sitios los troncos crecen
tan ligero que son muy flexibles y ei viento
los doblega. Esto no ocurre en todas partes,
por ejemplo, en Toro Negro ha habido poco
dano causado por los vientos.

Los rodcles de casuarina ofrecen buen
ambiente para la subplantacion

La casuarina (C. equisetifolia Forst) se
siembra extensamente en Puerto Rico para
proteger suelos degradados por el cultivo. E!
arbol crece muy rapidamente en toda la Isla
y se adapta a todas las altitudes menores de
1.000 pies. Pero como las hormigas destru-
ven las semiilas no se propaga naturalmente.
Por consiguiente si ha de perpetuarse la ca-
suarina habra que sembrar de nuevo perio-
dicamente a un costo considerable. Si han
de seguirle otras cosechas se necesitaran <éc-
nicas de conversion que no dejen el sitio
expuesto.

Un estudio para‘la conversion de casua-
rina a otras cosechas forestales se empezd
recientemente por medio de la subplantacion
de distintos arboles bajo rodales de casua-
rina. Se penso que si estas especies se esta-
blecian antes de la corta podria prove:rse
proteccion continua. al suelo. La primera sub-
plantacion se hizo en 1949 en suelo llano en
el Area Experimental de St. Just (elevacién,
390 pies; precipitacion, 70 pulgadas) bajo un
rodal de casuarina de 4 anos que ofrecia un
dosel continuo. Una segunda subplantacion
se efectu6d en 1950 en suelo rojo, profunis y

JANUARY - APRIL, 1953

degradado, bajo un plantio similar del Bos-
que Rio Abajo (elevacion, 500 pies; precipi-
tacion, 80 pulgadas). En este caso la casua-
rina iba decayendo parece que debido a pudri-
cidn de raiz.

Los resultados obtenidos en St. Just son
halagadores. Seis especies estan muy loza-
nas al cabo de 3 anos, mucho mas de lo
que se hubiera podido esperar en descubierto
en este sitio. Estas incluyen guaraguao
(Guarea trichilioides Li.) y cap6 prieto (Cordia
allidora (R. & P.) Cham.), dos valiosas espe-
cies de aserraje comun en los bosques natu-
rales. El primero se sabe que es tolerante,
ha crecido lentamente como es regular pron-
to después de la siembra. El capa prieto, un
arbol menos tolerante fluctta entre 4 y 8
pies de altura. Otra especie, capa blanco
(Petitia domingensis Jacq.) se considera gene-
ralmente muy intolerante, fluctua entre 3 y 7
pies de altura y es algo delgado debido a la
sombra. El roble (Tabebuia pallida Miers),
otro arbol intolerante de 2 a 6 pies de alto, de

crecimiento rapido y no muestra efectos de
dominacion. El arbol de sombra mas comun

para el café, la guaba (/nga vera Willd.), tiene
un promedio de 5 pies de altura y es muy Vi
goroso. La caoba hondurena (Swietenia
macrophylla King), es el mas vigoroso de to-
dos los arboles con los cuales se ha ensayado.
Fluctia entre 5 y 8 pies de altura y la nueva
vegetacion es jugosa y verde oscura como si
se le hubiese fertilizado con nitrégeno.
(Véase ilus. 7). Los semillones de casuarina
subplantados para este experimento se estan
muriendo, parece que por falta de luz.

Los resultados hasta la fecha indican que
la sombra de la casuarina no es suficiente
para evitar el rapido desarrollo de otras es-
pecies en el estrato inferior. El vigor y buen
color de los arboles subplantados no comprue-
ban la creencia general de que la casuarina,
debido a que crece rapidamente en sitios po-
bres, agota el suelo. El buen desarrollo de
la sombra para el café, la guaba, hace nece-
saria la investigacion en relacion con la con-
version de rodales de casuarina en cafetales.
Arbustos de café sembrados a la sombra de

la casuarina en Rio Abajo estén
bien.

Dos herbicidas resultan efectivos
para antes de la emersion

El desyerbo en los viveros forestales cons-
tituye uno de los mayores gastos de produc-
cidn. El uso de herbicidas ha reducido estos
gastos en muchos sitios, y algunos experi-
mentos se han emprendido aqui en Puerto Ri-
co para determinar la conveniencia de herbi-
cidas a este proposito. Hace un ano se infor-
mo que la aplicacion de una mezcla de triclo-
ro-acetato de sodio a razon de 50 libras por
acre y 2,4-D (sales aminicas) 8 libras por
acre habia dominado las hierbas en el vivero
de Toa por 8 semanas y que el trasplante de
semillones de casuarina o la siembra de se-
millas de caoba podia hacerse sin peligro 2
semanas después del tratamiento.

El tratamiento antes de la siembra es
ventajoso y eficaz. Sin embargo en la es-
peranza de que se pudiera lograr el mismo
resultado usando Ices herbicidas después de
la siembra (y asi economizar el tiempo de es-
pera entre el tratamiento y la siembra) se
hicieron algunas pruebas con tratamientos
pre-emersion este ano. Se usaron tres her-
bicidas: TCA, pentaclorofenolato de sodio
(Santobrite) y “‘matona 30-2-2” (un dinitro
matayerba en solucioOn simple). Se uso tri-
cloro acetato de sodio a razon de 20, 50 y 100
libras por acre, y pentaclorofenolato de sodio
a razon de 15 y 30 libras por acre y Matona
a razon de 6 galones por acre. La especie
bajo tratamiento era la caoba hondurena
(Swietenia macrophylla King). Para determi-
nar la tolerancia de los semillones se les apli-
caron los herbicidas después de la primera,
segunda y tercera semana de sembrados.
(Los arbolitos de caoba brotan generalmente
como a las 3 semanas de sembrados).

Veinte libras de tricloro acetato de sodio
por acre result6 eficaz como herbicida, es-
pecialmente contra las gramineas. Cuando
se aplicd a mds de una semana después de la
siembra o en aplicaciones mayores de 50

54

libras por acre result6 perjudicial. La apli-
cacion a razon de 20 libras por acre conserv6
las eras lo suficientemente limpias por 8 se-
manas (no mas del 35 por ciento se cubrid
de hierbajos).

KH] pentaclorofenolato de sodio usado en
cualquiera de las dos formas result6 ser efec-
tivo y sin peligro cuando se usO una semana
después de la siembra; usado mas tarde no
hizo dano a los semilleros pero tampoco do-
mino los hierbajos que para entonces ya ha-
bian germinado. Usando 15 libras por acre
una semana después de la siembra se conser-
varon los lechos lo suficientemente limpios
por 8 semanas. Matona en la soluci6n usada
no mato las hierbas.

Los mejores tratamientos para antes del
brote con TCA y con pentaclorofenolato de
sodio aplicados este ano son superiores a los
recomendados el ano pasado para antes de la
siembra porque eliminan la espera entre la
aplicacion y la siembra. Ademas estos son
eficaces hasta 8 semanas en vez de 6 des-
pués de la siembra. También se encontr6é
que la aplicacién de TCA a razon de 20 libras
por acre es tan efectiva como la de 50 libras
(la mas floja del afio pasado).

Deben hacerse mas pruebas con éstos y
otros herbicidas para aplicarse antes del bro-
te. Luego se haradn pruebas con herbicidas
para aplicarse después del brote. Este tipo
de tratamiento que podria resultar conve-
niente en cualquier momento después de na-
cidos los arbolitos seria mucho mas satisfac-
torio que cualquiera de los ya descritos (estos
no eliminan el desyerbo final), pero la pers-
pectiva de encontrar tal herbicida parece es-
tar algo remota.

Empieza la investigacién sobre
la sombra para cafetales

Informes recientes senalan lo aconseja-
ble de perpetuar la decadente industria del
café. Los cafetales ofrecen abrigo a casi el

10 por ciento de la superficie de los terrenos ©

de la isla, las dreas mas escarpadas y mas
erosivas. La corta de cafetales, que se ha
producido en gran escala durante los tltimos

CARIBBEAN FORESTER

10 anos ha traido un breve ciclo de cosechas
de cultivos que degenera el suelo y termina

por convertirlo en yerbaje o brenal.

Hace un ano se hizo un examen del ren-
dimiento del café conjuntamente con el Nego-
ciado de Industria Vegetal para orientar in-
vestigaciones en este campo que pudieran
ayudar a los cafeteros. Varias fases impor-
tantes de la selvicultura merecen investiga-
cion. Este ano se empezo un estudio de los
actuales y potenciales arboles de sombra.
El Negociado de Industria Vegetal ha comen-
zado un estudio formal de produccion de ca-
fetales sin sombra.

Los arboles de sombra mas comunes en
los cafetales son la guaba (Jnga vera Willd)
y el guama (Jnga laurina Sw.). La primera
parece ser exotica; la ultima nativa. La gua-
ba es generalmente superior al guama porque
es mas frondosa. Los dos arboles sufren de
insectos y enfermedades que no solamente
minan su vida sino que afectan el cafeto ad-
versamente. En la creencia de que algunas
de las muchas /ngas oriundas de otros paises
pudieran resultar mejores para sombra de
cafetales el Departamento de Agricultura y
Trabajo de Puerto Rico introdujo un numero
de especies traidas de Venezuela en 1929
y 1930.

La mayor parte de los plantios hechos
con ellas han desaparecido y hay poca infor-
macion en cuanto a su desarrollo. La espe-
cie mas sobresaliente, el guama venezolano
(Inga speciosissima Pittier) se ha hecho popu-
lar como sombra para café y cada ano cien-
tos de miles de semillas son diseminadas por
el Servicio Forestal y distribuidas a los agri-
cultores. Algunos de los arboles originales
que aun quedan en Utuado (elevacion, 400
pies; precipitacion, 80 pulgadas) al cabo de
23 anos tienen un didmetro de 10 pulgadas
y 30 pies de altura, es frondosa y de sombra
mas densa que la guaba y el guama. Esta
especie es facil de propagar, de supervivencia
alta después de sembrada y casi libre de in-
sectos y enfermedades. En la region cafe-
tera (elevacion, 1.500 a 2.000 pies; precipita-
cién, 90 a 100 pulgadas) esta espeeie crece

JANUARY - APRIL, 1953

muy rapidamente. Los arboles de 3 afios
tienen un promedio de 2 pulgadas de diame-
tro y de 10 a 15 pies de altura. Los de 6
anos tienen un promedio de 3 a 5 pulgadas
de diametro y de 15 a 18 pies de altura.

Otras especies menos conocidas introdu-
cidas para la misma fecha incluyen J. fastuosa
(Jaeq.) Willd., J. spuric Humb. & Bonpl., y
una no identificada pero probablemente es
I. punctata Willd. Las primeras dos de estas
especies han alcanzado 50 pies de altura en
23 anos y tienen mejor forma para sombra
que J. speciosissima. Arboles de I. fastuosa de
13 afios en sitio abrigado de suelo profundo
(elevacion, 1.500 pies; precipitacion, 90 pul-
gadas) han alcanzado 10 pulgadas de diame-
tro, 35 pies de altura y estan muy vigorosos.

Una coleccién de pequefios plantios de es-
tas especies diferentes se ha organizado en el
criadero de La Catalina en el Bosque de Lu-
quillo para obtener semilla para pruebas adi-
cionales. Los semillones de /. spuria aparen-
temente una de las mejores de las introdu-
cidas, (se ha usado poco) se distribuyeron a
cinco agricultores cooperadores para pruebas
en la region cafetera.

Las pruebas preliminares, descritas en
otro sitio de este informe, se iniciaron con
la casuarina como planta tutora para los 4r-
boles de sombra para cafetales. Hay indi-
caciones de que la sombra de la casuarina es
bastante abierta para el rapido desarrollo de
la guaba sembrada bajo ella. También se
estan haciendo pruebas con la caoba hondu-
rena (Swietenia macrophylla King) para som-
bra de café. La copa de la caoba es tan
densa que la siembra espaciada o la poda
frecuente y el clareo seran sin duda necesa-
rios. Esta primera prueba iniciada en el
Area Experimental de St. Just (elevacion,
300 pies; precipitacion, 70 pulgadas) se hara
también en otras fincas de la region cafetera.
Estudios futuros incluiran también el euca-
lipto como arbol de sombra para cafetales.

Bosque joven en terrenos calizos cierra
fronio después de la corta de mejora

Los montes calizos del norte de la isla

55

comprenden mas del 10 por ciento de la su-
perficie de la isla. Estdn casi completa-
mente cubiertos de bosques secundarios que
se han cortado tantas veces que ya no quedan
mas que arboles pequenos. Aunque especies
buenas no nativas como la caoba antillana
crecen alli, el suelo es tan Ilano que un rodal
denso de madera aserrable nunca se desarro-
aria. En muchas estancias el mejoramiento
del bosque por medio de cortas parciales con
el objetivo de una produccién maxima de pos-
tes y espeques es la practica selvicultural
mas prometedora. Como casi todos estos
terrenos son propiedad privada esta mejora

tendra que ser barata y de rendimiento tem-
prano.

Un rodal joven, tipico en la ladera occi-
dental de un monte calizo del Bosque Expe-
rimental de Cambalache (nivel del mar; pre-
cipitacién, 55 pulgadas) fué seleccionado en
1950 para la investigacién de este problema.
Esta area se abrié hasta dejar un 60 por
ciento de sombra por medio de la elimina-
cién de los arboles que no servian para pos-
tes 0 espeques por su forma y maderas in-
feriores. Tupidos grupos de los mejores 4r-
boles se clarearon donde fué necesario. La
corta rindi6o un haz (128 pies ctibicos) de lefia,
40 espeques para cerca por acre y costo cerca
de 4 jornales.

E] rodal que quedo contenia 1.160 arboles
por acre de 2 0 mas pulgadas de diametro,
con diametro promedio de 2,4 pulgadas y un
area basal de 39 pies cuadrados por acre.
Como el 57 por ciento del Area basimétrica
contenia especies buenas para postes. Las
trepadoras no han sido problema. Al cabo
de un ano se hizo otra corta ligera para abrir
el dosel. Otra corta similar se hizo al final
del segundo ano. Cada una de éstas did me-
nos de la mitad del volumen que dio la pri-
mera pero produjo lena del tipo que necesita
el agricultor. Los 235 arboles dominantes
y codominantes por acre tienen ahora un
promedio diametral de 3,6 pulgadas y contie-
nen buenos postes. Estan aumentando en dia-
metro a un ritmo de 0,21 pulgadas por ano.
Futuras cortas debieran rendir tanto 0 mas

56

volumen de postes como de lefia. Para cono-
cer a cabalidad el rendimiento econdmico de
esta area se necesitara hacer un estudio con-
tinuo de la misma. En log primeros 2 afos
sdlo unos arbolitos han aparecido bajo el ro-
dal. Muchos son retofios de tocones que que-
daron después de la primera corta. La can-
tidad de la reproduccion natural determinara
en gran medida el éxito de esta téenieca.

El bambu continiia crecimiento rapido

en mejores ambientes estacionales

El bambu parece tener grandes potencia-
lidades en Puerto Rico. Numerosas especies
que se han adaptado en la isla son de va-
lor en otros sitios como materia prima para
una extensa variedad de articulos de mer-
cadeo. La provisién en la Estacién de Ex-
perimentacién Federal de un numero de es-
pecies utiles hasta ahora sin probar condujo
a plantaciones de experimentacion en montes
por toda la isla.

Los primeros plantios se hicieron en sue-
lo lateritico de mala calidad en el Bosque
Toro Negro (elevacién, 3.000 pies; precipita-
cion, 110 pulgadas) en 1945. Tres especies,
Bambusa tuldc, Roxb., B. tuldoides Munro, y B.
lougispiculata Gamble ex Brandis se sembra-
ron en un area de 20 acres. Después de un
lento comienzo, las plantas de 7 anos tienen
ahora mas de la mitad de sus cafias listas
para cosechar. El didmetro de estas cafas
varia considerablemente con el ambiente es-
tacional y debiera seguir aumentando con la
edad. El B. tulda es el mas grande, con ca-
nas que miden de 34, a 1-14 pulgadas en las
crestas y de 2 a 3 pulgadas en el fondo de los
valles. Este bambu es bueno para muebles.

Kn una estancia mejor en el Bosque de
Luquillo (elevacion, 800 pies; precipitacién,
120 pulgadas) en un suelo rojo y profundo,
plantas de 4 anos de B. tulda y longispiculata
tienen 30 pies de altura. Espaciadas de 10 x
10 pies han matado toda otra vegetacion.

En un monte calizo del Bosque Experi-
mental de Cambalache (nivel del mar; pre-
cipitacién, 55 pulgadas) una subplantacion de

CARIBBEAN FORESTER

¥y anos fluctua entre 15 y 30 pies de altura.
Las canas han llegado al nivel de dosel y se
estan desarrollando rapidamente a pesar de
lo Nano del suelo.

En sitio mal drenado bajo bosque mon-
tano en Luquillo (elevacion, 2.500 pies; pre-
cipitacion, 180 pulgadas) grupos de arboles
de 5 anos de las cuatro especies B. tuldoides, B.
iuldc, B. longispiculata y Dendrocalamus strictus
Nees estan raquiticas y clordticas. Los
grupos mas altos de B. tuldc solo tienen de
10 a 15 pies de altura y las canas solo miden
1 pulgada de didmetro. Dendrocalamus strictus
solo mide 6 pies y muchas de las plantas se
estan muriendo.

El uso de retonos tiernos como material
de siembra se ha continuado. Unos 100 re-
nuevos sacados de pimvollos sembrados re-
cientemete se plantaron en el Bosque Cam-:
balache. La supervivencia fué de 90 por
ciento. Murieron las plantas que tenian
menos raices y rizomas adheridas.

Los estudios propuestos para el futuro
incluyen la fertilizacion de plantaciones en
los montes y la extension de pruebas en la
region caliza del norte.

El cedro macho sobrevive bien al tras plante

El cedro macho (Hieronyma _ clusioides
(Tul.) Griseb) un arbol de la region caliza
de la costa norte, que produce ua hermosa
madera rojo oscuro propia para ebanisteria
no se ha probado extensamente debido a la
irregularidad de la cosecha de semillas y a
la dificultad en recolectar, secar y almace-
narlas. Ensayos en pequena escala hechos
hace anos en el Bosque Rio Abajo (elevacion,
500 pies; precipitacion, 80 pulgadas) demos-
traron que el ritmo de crecimiento del arboi
es moderado pero éste es tolerante y general-
mente de forma excelente.

En 1951 hubo una cosecha excepcional y
la semilla se sec6 pronto haciendo posible la
produccion de 100.000 semillones para ma-
yores ensayos. De éstos se subplantaron
86.000 en el Bosque Guilarte (elevacion,
3.000 pies; precipitacion, 100 pulgadas) y en

JANUARY.- APRIL, 1953

el Bosque Rio Abajo donde es nativa esta es-
pecie. Subplantaciones de wnos 2.000 arbo-
les cada una se hicieron en cinco sitios dis-
tintos, incluyendo dos en bosques _ hidrofi-
ticos en sitios similares a los de las Antillas
Menores donde la H. caribaea Urd., de la mis-
ma familia, es arbol prominente. Se utili-
zaron pimpollos de 10 a 16 pulgadas de al-
tura y raiz limpia. Hacia buen tiemps. Con
excepcién del plantio del Bosque Experimen-
tal de Cambalache la supervivencia ha so-
brepasado el 80 por ciento en todas partes.
En Cambalache una sequia intempestiva in-
mediatamente después de la siembra destruy6
el 50 por ciento de los arboles. La mayor
parte de los arbolitos que sobrevivieron no
parecian afectados por el trasplante y reasu-
mieron el crecimiento prontamente.

El roble dominicano soporta bien el trasplante

El] roble dominicano (Macrocaialpa longissima
(Jacq.) Britton) es una de las especies mas
importantes de Haiti, crece bien en sitios
adversos y produce madera buena para cons-
trucciOn y para usos corrientes en las fincas.
Es de la familia del roble blanco (Tabebuia
jallida Miers) de Puerto Rico pero alcanza
mayor tamano. En la creencia de que esta
especie pudiera resultar superior para la re-
forestacion de suelos degradados, plantios de
ensayo de 6.000 arboles se hicieron este ano
en varios ambientes estacionales: en el Bos-
que de Luquillo (elevacion, 800-pies; preci-
pitacién, 120 pulgadas) ; en el. Bosque Exne-
rimental de Cambalache (nivel del mar; pre-
cipitacién, 55 pulgadas), en el Bosque Sustia
(elevacién, 500 pies; precipitacion, 50 pul-
gadas) y en el Bosque de Maricao (elevacion
2.000 pies; precipitacion, 100 pulgadas).

La supervivencia ha sido mas del 90 por
ciento en todas las estancias lo que indica
que esta especie soporta e! trasplante excep-
cionalmente bien. En los suelos lateriticos
de Susua y de Maricao no prospera. Su
mejor desarrollo se produjo en el Bosque de
Luquillo donde los arvoles ya miden de 4 a
5 pies de altura en las areas mas abrigadas.
Esta es una altura mayor que la de otros

57

arboles a la misma edad. Aunque esta es-
pecie parece ser mas delicada que el! roble
nativo su desarrollo sera objeto de mas es-
tudio.

El mago sobresale en crecimiento
cn la cesta norte

El mago (Hernandia sonora L. produce una
madera que se usa para maderaje interior en
Trinidad y las Antillas Menores. Es nativo
de Puerto Rico pero relativamente escaso. Se
le ha probado para regeneracién de tierras
degradadas. Un pequeno plantio del 1944
en el Area Experimental de St. Just. (eleva-
cién, 290 pies; precipitacion, 70 pulgadas)
ha demostrado que esta especie se adapta
bien a suelos sueltos llanos en este medio.
En 1952, a los 8 afios, el didmetro promedio
es de 3 pulgadas y la altura un promedio de
30 pies. Los Arboles se ven lozanos y en ex-
celente forma. Han limpiado el tronco sa-
tisfactoriamente. Se justifican pruebas mAs
extensas en otros ambientes estacionales.

El muérdaga menos daiino
fare la maga que lo previsto

En el informe de 1951 se descubrié un
muérdago (Phthirusa sp.) que ha atacado nu-
merosas plantaciones jévenes de maga (Mon-
tezuma Speciosissima (Sessé y Moc.) Dubard)
en el Bosque de Guajataca (elevacion, 500
pies; precipitacién, 70 pulgadas). En 1950
se descubri6 que en un 4rea el 80 por ciento
de los arboles de un plantio de 13 afios de
esta valiosa especie de ebanisteria se habian
contagiado con arboles de capa prieto (Cordia
allicdora (R. & P.) Cham) de un bosque mixto
adyacente. Un plantio en un abra de 14
acres se aclaré y se podé en 1959 para elimi-
nar el muérdago. Al afio el muérdago rea-
parecio en la mitad de los Arboles y era tan
comun que se consideré reincidencia. La
unica solucion practica parecia ser la conver-
sidn del plantio a una especie inmune, posi-
blemente por subplantaci6n.

La investigacion de esta Area en 1952,
un ano mas tarde, descubri6 que el muérdago
todavia abunda pero no tan vigoroso como

58

el ano anterior. Una observacion minucio-
sa de arboles marcados demostr6 que apenas
hubo nueva incidencia e] segundo ano des-
pués del tratamiento. Lo que indica que lo
que parecia ser otra invasion alarmante del
parasito, fué sdlo el crecimiento de plantas
que no se habian exterminado completamen-
te. Es mas, como la plantacién esta aumen-
tando altura, las ramas inferiores (que sos-
tenian el pardasito mejor desarrollado) se es-
tan debilitando y muriendo, lo que también
matara el pardsito. Aun los manojos de
muérdago encontrados en los troncos hace un
ano han desaparecido. Esto pudiera ser un
mero reposo, pero el parasito esta aparente-
mente inactivo. Posiblemente el hecho mas
importante es que los Arboles infectados no
han sido deformados y estan creciendo tan
rapidamente como sus vecinos sanos. Esto
puede indicar que la Maga puede crecer sa-
tisfactoriamente a pesar del muérdago. Se

haran exdmenes para verificar esta conje-
tura.

Fl avelluelo se desarrolla rd pidamente
en la Cordillera Central

El avelluelo (Colubrina arborescens (Mill)
Sarg.) es madera favorita de postes, nativa
de los llanos costaneros mayormente en la
seccion caliza. Se sembr6é temprano en va-
rios kosques a elevaciones bajas pero se des-
carto debido a su crecimiento lento. Lo que
pudiera ser una variedad mas grande de este
arbol se encontré en el interior de la isla y
Se sembr6 en el Bosque Guilarte (elevacion,
3.000 pies; precipitacién, 100 pulgadas) en
1944. Este plantio ha tenido un crecimiento
extraordinario y los Arboles son de color y
forma excelente. Han sobrepasado a todas
las especies sembradas menos al eucalipto.
Kn 4 anos tenian un promedio de 8 pies de
altura y este afio, 8 afos mas tarde, tienen
un promedio de 28 pies de altura. Estdn
sembrados en crestas de suelo pobre, lo que

indica que esta especie es prometedora para

la ‘regeneraciOn de sitios degradados. Se
haran mas siembras.

CARIBBEAN FORESTER

La pomarrosa puede controlarse
con cortes parciales

La pomarrosa (Eugenia jambos L.) wna
exotica naturalizada es un arbol del estrato
inferior en los bosques secundarios en la ma-
yor parte de la region himeda de Puerto Ri-
co. Es espesa y aunque crece rapidamente
bajo condiciones favorables generalmente no
produce tallos derechos y se usa principal-
mente para lena. Da una sombra tan densa
que no deja desarrollar los arboles de espe-
cies mejores que crecen bajo ella Aunque a
veces es de valor para la reforestacién de
terrenos yermos, en bosques mixtos, es re-
gularmente inferior a los otros arboles y de-
biera removerse. Responde al aclareo con
gran cosecha de retonos lo que indica que re-
sistira agresivamente los esfuerzos para re-
moverla. Se empezo a estudiar este proble-
ma en 1950.

Hace un afo se informo que el tamano del
claro del dosel sobre los tocones afectaba el
vigor de los mismos para retonar. Otro exa-
men de los mismos 50 tocones, este ano, 2
anos después de la corta, demostr6 que ape-
nas se habian producido renuevos y que el
crecimiento en altura de los que se produje-
ron el primer ano no ha tenido importancia
desde entonces. Estos halazgos se refieren
a tocones solitarios y a los que estan entre
grupos activos.

La explicacion reside en el hecho de que los
claros del dosel sobre estos grupos que Ori-
ginalmente median hasta 10 pies en diametro,
con un promedio de 6 pies, se han casi ce-
rrado como consecuencia del desarrollo de las
copas de los arboles adyacentes. Aunque po-
cos tocones han muerto, no serian problema
porque el crecimiento de retonos puede apa-
rentemente arrestarse indefinidamente man-
teniendo un dosel denso. No parece dificil
eliminar la pomarrosa en los bosques mixtos,
especialmente si hay reproduccion avanzada
de especies deseables. Por el contrario la
conversion de un rodal puro de pomarrosa
requirira frecuentes cortas hasta que la es-
pecie deseada domine.

JANUARY - APRIL, 1953

Selvicultura de la teca ensaycda
en dos ambientes estacionales

Informes anteriores han indicado que la
teea (Tectona grandis L) generalmente nece-
sita mejores sitios de los que Puerto Rico
puede distraer de la produccién de alimento
y forraje. Pero en vista del gran valor de
la madera de teca, y el hecho de que el pro-
greso de las plantaciones en medios estacio-
nales favorables es espectacular, se le ha
sembrado y se esta estudiando en sitios que
se consideran “demasiado buenos para arbo-
Sélo por medio de estudios podra pro-
barse si la teca puede competir desde el punto
de vista econdmico con otras cosechas.

les.”

En el Bosque Experimental de Cambala-
che (nivel del mar; precipitaciOn, 55 pulga-
das) en la costa norte hay extensas vegas en-
tre montes calizos. El suelo profundo de
arcilla roja lateritica. En otros tiempos esta
area produjo cana de azucar. En 1950 se
sembraron de teca 5 acres. La mitad de esta
area se le cedié a los agricultores para inter-
cultivo por 2 anos. La otra mitad se man-
tuvo desyerbada hasta 18 pulgadas alrededor
de cada arbol. Al cabo de los 2 afios no hay
diferencia perceptiva en el desarrollo debido
al tipo de cultivo. La teca intercultivada es
menos uniformes que la otra, posiblemente
a causa de dafios a la raiz durante e! cultivo.
Ambos plantios tienen un promedio de 12
pies de altura. (Véase ilus. 8).

Una plantacion mas antigua, también en
buen sitio, se encuentra en el Bosque Carite
(elevacion, 300 pies; precipitacién, 80 pulga-
das) en suelo aluvial pedregoso. Esta plan-
tacién que tiene ahora 16 afios tiene un dia-
metro promedio de 7,4 pulgadas (100 Arboles
dominantes y codominantes). El crecimien-
to basal medio por arbol, dominante y codo-
minante, para los primeros 13 afios (hasta
1949) fué 0,0219 pies cuadrados. En los tres
ultimos afios ha sido solamente de 0,0059
pies cuadrados, lo que determina que el ro-
dal esta muy apifado. Casi el 40
por ciento de los arboles eran intermedios o
dominados y crecian a un ritmo de menos de

59

la mitad del de los dominantes y codominan-
tes. Un cuartel de 14 de acre se clareo de
124 a 94 pies cuadrados de area basimétrica
por acre con la remocion de 204 arboles por
acre. Todos los arboles dominados y como la
mitad de los intermedios fueron arrancados.
Se haran mediciones mas tarde para com-
probar el efecto de este aclareo.

La-caoba antiliana sobrepasa al
mesquite en la costa sur

El mesquite (Prosopis juliflora DC) se na-
turalizo en Puerto Rico hace anos y ha inva-
dido los bosaues en los montes calizos secos
de la costa sudoeste. Ahora domina el bos-
que en un valle dentro del Bosque de Guanica
(elevacion, 100 pies; precipitacion, 30 pulga-
das). El hecho de que haya invadido el bos-
que natural de que retofe activamente llevé
a la conclusién de que era de crecimiento ra-
pido y podia ser fuente altamente productiva
de postes y traviesas. Mediciones hechas
hace 4 anos, demostraron que el crecimiento
de este Arbol era menos de lo que se esperaba.
Se llegé a la conclusion de que la rapidez del
crecimiento inicial disminuye temprano, an-
tes de que los arboles hayan alcanzado tama-
no de postes.

Al medirse de nuevo este afio 24 arboles
marcados, dominantes y codominantes, den-
tro del Bosque de Guanica se obtuvieron da-
tos mas confiables en cuanto a su crecimien-
to. Los resultados de estas mediciones com-
parados con los obtenidos con la caoba anti-
llana (Swietenia mahagoni Jacq.) quedan sena-
lados en la Tabla 10. Esta caoba crece en
una plantacién de 20 afios en otro valle se-
mejante del mismo bosque. Los datos indi-
cados se refieren solo a arboles dominantes
y codominantes. Los dos rodales estan ce-
rrados y tienen densidad comparable. Como
puede verse el mesquite crece mas lenta-
mente que la caoba. Como ésta ultima rin-
de productos mucho mas valiosos, debiera re-
emplazar al mesquite, por lo menos en los
suelos mas profundos donde pueden crecer
arboles grandes. No hay proposito de se-
guir estudiando el mesquite por ahora.

60

Tabla 10.—Crecimiento del mesquite y de
la caoba en Guanica

sot Promedio dianretral a lal :
Numero altura del pecho Promedio
crecimiento

anual

Especie de
Arboles

Hace 7 aiios | Ahora

Pugadas Pulgadas Pugadas
Mesquite 24 4,7 5,6 0.13
Caoba 59 4,1 5,4 0,19

La primavera no crece en region caliza

La _ primavera (Vabebuia donnell-smithii
Rose) es una de las maderas mas valiosas de
Centroamérica. Alli, en la costa oeste, cre-
ce rapidamente en buenos sitios, subplantada
o en campo abierto. Semillas importadas
hace 5 anos produjeron algunos arboles que,
cuando se sembraron en suelo profundo y bien
drenado en el Bosque de Luquillo (elevaci6on,
800 pies; precipitacion, 120 pulgadas) cre-
cieron rapidamente, por eso se importaron
mas semillas el ano pasado.

Sembrados para experimentacion, de 400
semillones cada uno se levantaron bajo un do-
sel abierto en el Bosque Experimental de
Cambalache (nivel del mar; precipitacion,
55 pulgadas) y en el Bosque Rio Abajo (ele-
vacion, 500 pies; precipitacion, 80 pulgadas).
En los dos medios estacionales el suelo, aun-
que fértil es somero, entre 6 y 18 pulgadas
de profundidad. Estos arboles no crecieron
durante el primer ano. Las hojas nuevas
son pequenas, delgadas, cloréticas y parecen
atacadas de mosdaico. Con pocas excepcio-
nes esta condicion es universal y no tiene re-
lacion con la cantidad de luz recibida. La
unica aplicacion aparente es el suelo; que es
menos acido (pH 6) y menos profundo que
aquél donde los arboles estan creciendo bien.
Se hara un esfuerzo para establecer la de-
ficiencia.

La plantacion mas vieja en el Bosque de
Luquillo mide ahora de 30 a 40 pies de altura
y esta muy lozana. Los arboles en descu-
bierto tienen un diametro de 3 a 5 pulgadas.
Los arboles en un nuevo plantio en el mismo
sitio fluctuan entre 10 y 15 pies de altura al
finalizar el primer ano.

CARIBBEAN FORESTER
La faima de sombrero resulta lenta

La palma de sombrero puertorriquefa
(Sabal causiarum (Cook) Bececari) ha sido base
importante para una industria local. La
fuente de hojas de palma se redujo grande-
mente con la separaciOn de un gran area de
palmeras para propositos militares. En un
esfuerzo por aumentar la produccién se ha
estudiado la regeneracion artificial de esta
palma. El producto de viveros requiere 24
meses. Parte de este producto se sembr6 en
1946 en el Bosque Experimental de Camba-
lache (nivel del mar; precipitacion, 55 pulga-
das en suelo lomico semejante al de su lu-
gar de origen. El crecimiento ha sido muy
lento, las palmas alcanzaron de 2 a 5 pies de
altura en 6 alos. Durante 3 afios estuvieron
casi inactivas y de un color pobre. A los 5
anos se produjeron las primeras hojas utiliza-
bles. La primera actividad de esta especie
es baja y no justifica mayor estudio por aho-
ra. El Servicio Forestal esta distribuyendo
algunas palmas para piautios pequenos en
hogares rurales.

Importacién de 53 especies de semillas

La necesidad de nuevas y mas producti-
vas cosechas forestales ha hecho deseable
las pruebas con especies exoticas para deter-
minar su adaptabilidad y productividad en
Puerto Rico. “La Estacion ha hecho pruebas
con 120 especies exoticas de arboles durante
los ultimos 13 anos. Durante este ano se-
millas de 53 especies fueron importadas de
las regiones tropicales y subtropicales de todo
el mundo. Veintisiete de éstas son nuevas
en Puerto Rico. Entre las importadas hay
12 gymnosperms y 24 especies de eucalipto.
Se determino el peso de la semilla de 24 es-
pecies.

Para Aumentar la Utilidad de la Madera

Los insectos y la podredumbre importantes

en el estudio de la post-corta

Hay una creencia arraigada en Puerto
Rico(como en otras areas tropicales) de que

JANUARY - APRIL, 1953

la durabilidad de Ja madera varia con ia épo-

ca de corta. Algunas de las explicaciones

ofrecidas son las fases de la luna, las mareas
o las estaciones del aho. Aunque las inves-
tigaciones no han logrado comprobar que la
época de la corta, como tal, afecte en mane-
ra alguna la durabilidad de la madera, un es-
tudio del asunto parecié de valor por lo me-
nos para propositos de demostracion. Hace
un ano la Estacion emprendié un estudio de
esta naturaleza en que se incluian las si-
guientes variantes: medio estacionai, espe-
cie, fases de la luna, estaciones del ano, ma-
reas, el tiempo y si los arboles crecian o re-
posaban. En este experimento se utilizaron
1.800 estacas que se sembraron en los bos-
ques de Toro Negro y Cambalacne.

A los 12 meses se hizo una inspeccion
completa para determinar la presencia, na-
turaleza y grado de deterioro. Se encontro
que ninguna de las estacas estaba inservible
pero no era posible analizar el efecto de los
Sin em-
bargo agentes de destrucciOn estaban acti-
vos en casi la mitad de las estacas. El dano

causado por insectos parecia mas importante

diferentes tratamientos todavia.

que la podredumbre. Los insectos mas co-

munes eran pulverizadores y los barrenado-
res. También habia algunos danos causados

por termes.

Se ha vuelto a examinar un total de 1.300
estacas al cabo de 18 meses (ésto se hara
cada 6 meses). En esta ocasiOn a cada es-
taca se le did un pequeno empuje para deter-

minar si estaba servible. En total se rom-

pieron 75 estacas pero todavia no se nota

La
debilidad de estos postes ya causada por in-

gran diferencia entre los tratamientos.

sectos o por pudricion era mayor a ras de

61

tierra. Solo algunas estacas se perdieron
debido a danos de insectos solamente. pero
la mayor parte de los que se perdieron por
podredumbre habian sido atacados por insec-
tos. Los tuneles hechos por los insectos en
la madera fueron sin duda factor importante

en el desarrollo de la pudricion.

Examenes que se hagan mas adelante da-
ran mas luces en cuanto al deterioro de las
estacas y haran posivdle la comparacién de

los diferentes tratamientos.

Se determina el peso especifico y

encogimiento para varias especies

A falta de datos sobre resistencia obte-
nidos con pruebas reales, el conocimiento del
peso especifico de diferentes maderas es de
valor para caicular aproximadamente algu-
nas de sus propiedades mecanicas y estimar
el encogimiento, peso por pie cibico, volumen
vacio y el maximo porcentaje de humedad
obtenible y resistencia a la extraccion de cla-
vos y tornillos.

Las cifras sobre encogimiento se usan
para determinar los cambios de dimensiones
con los cambios en contenido de humedad,
convirtiendo el peso especifico de verde a se-
cado al horno y vice versa.

Durante varios afios la Estacion ha es-
tado computando el peso especifico de varias
especies de madera. Este ano se ha deter-
minado el peso especifico de 11 especies y el
encogimiento volumétrico de 7 de éstas. Los
datos aparecen en ia Tabla 11. Como se ha
encontrado en otras partes, el encogimiento
volumétrico de estas especies tropicales es
generalmente mas bajo que el de maderas de

densidad comparable de zonas templadas.

°y)
XS)

CARIBBEAN FORESTER

Tabla 11.—Peso especifico y encogimiento volumétrico de 11 maderas

Especies

Casuarina, C. equisetifolia Forst.
Balsa, Ochroma pyremidale Sw.
Primera troza

Duramen
Albura
Ramas

Capa prieto, Cordia allidora (R. & P.)
Cham

jacana, Lucuma multiflora A. DC.
Aguacatillo Meliosma herberti Rolfe

Caimitillo, Micropholis chrysophylloides
Pierre

Laurel avispillo, Nectandra coriaceae (Sw.)

Griseb

Caimitillo verde, Micropholis garcinifolia
Pierre

Guaraguao, Guarea trichilioides L.
Capa blanco, Petitia domingensis Jacq.

Mamey, Mammea americana L.

Peso especifico secado al horno

Encogimiento vo-
lumétrico de verde
a secado al horno
basado en dimen-
siones verdes

basado en volumem

Seeado al

horno Verde
Porcentaje

_— 0,93

— 0,29 —
— 0,24 —
— 0,18 _
0,49 0,58 15,9
0,76 0,88 14,2
0,44 0,51 140
0,69 0,78 11,0
— 0,59 —
os 0,81 —
0,49 0,57 13.6
0,55 0,61 10,2
0,66 0,76 13,1

Se aplicara mayor esfuerzo a este proyec-
to durante los proximos afios. La falta de
equipo para medir el volumen basimétrico ha
dificultado este trabajo en el pasado. Esta
deficiencia quedara corregida el afio pro-
ximo.

Los espeques de Eucalipto sin
tratamiento duran tres anos

E] eucalipto (E. robusta y E. kirtoniana
I’. v. M.) se ha adaptado tan bien en las mon-
tanas del centro de Puerto Rico, que se han
emprendido varios estudios para su utiliza-
cion. Uno de los primeros estudios de esta
naturaleza se ocupa de la durabilidad de es-

tas especies como espeque para cercas. Se
empezo en 1949. Se enterraron 20 espeques
de 4 a 5 pulgadas de diaémetro en suelo pro-
fundo y bien drenado dentro del Bosque de
Guilarte, (elevacion, 3.000 pies; precipita-
cién, 110 pulgadas).

Este ano (3 afios después de instalados)
11 espeques se rompieron bajo empuje mo-
derado y los que resistieron estaban muy dé-
biles. Como los espeques era algo mayores que
los que s2 usan normalmente, puede asegu-
rarse que la duracion promedio de los mismos,
sin tratamiento no es mas de 3 anos en este
ambiente. La necesidad de tratamiento pre-
servativo es clara y estudios para su desarro-
llo, ya descrito en este informe, tienen ese fin.

JANUARY - APRIL, 1953

Tnsectos atacan fostes tratados
con cloruro de cinc

Las practicas de preservacion de madera
en las dreas rurales requieren técnicas
simples, aplicables con un minimo de costo
y en pequena escala. La busqueda de
tales técnicas condujo en 1951 a pruebas del
procedimiento a difusion, que puede aplicarse
a la madera verde sin descortezar. El pre-
servativo que se probo fué cloruro de cine con
cobre y cromio, que se dice es relativamente
resistente a la filtracion.

Se hicieron pruebas con tres especies de
montanas comunes buenas para postes: eu-
calipto (E£. robusta y E. hirtoniana F. v. M.) y
guaba (/nga vera Wild.) Se trataron 16 pos-
tes de cada especie. El producto quimico se
uso al 25 por ciento en solucioOn acuosa. Los
postes se dejaron en la solucién hasta que
hubieron absorbido una libra del compuesto
por pie cubico de madera, un periodo que va-
ri0 de 7 a 21 dias*. Para determinar la pro-
fundidad de la penetracion, se rajaron varios
postes y se rociaron con partes iguales de
una solucion al uno por ciento de ferricianuro
de potasio, una solucién al uno por ciento de
yoduro de potasio y una solucién al 5 por
ciento de almidon soluble. Se encontré que
el preservativo se habia concentrado en la al-
bura y en las 24 pulgadas mas bajas de los
postes; éstos se invertieron y se dejaron se-
car 3 meses antes de colocarlas.

Al cabo de un ano todos los postes de
eucaliptos tratados con preservativos tienen
termes, mientras que los no tratados estan
sanos. No se nota danos por insectos en nin-
guno de los postes de guaba tratados o no
tratados, pero en uno de los tratados se ob-
serva un desarrollo incipiente de hongo.

Aunque son numerosas las notas sobre
material tratado con el cloruro de cine en los
Estados Unidos, no se ha encontrado ningun
apunte sobre el uso de cloruro de cine con
cobre y cromio, que es un producto relativa-
mente nuevo. La evidencia arrojada por
este experimento senala a un desarrollo ma-

* Segin el tiempo, siendo menor el periodo en tiempo

se,

63

yor mas favorable en el tratamiento de ter-
mes en el eucalipto con cloruro de cine con
cobre y cromio. El ataque de los termes
empezo en la corteza y se extendio dentro de
la madera. Se haran mas pruebas con éste
y otros preservativos para averiguar su efec-
tividad en la madera descortezada, y como
obtener mejor penetracion.

Postes de tres especies tratedos
con creosota sanos a los dos anos

La prueba de mayor éxito hecha en la Es-
tacion sobre la conservacion de postes se llevo
a cabo en 1944 cuando varos postes de ca-
suarina (Casuarina equisetifolia Forst) fueron
tratados con carbolineum por el método de
bafios frios y calientes. Estos postes estan
todavia sanos.

Se decidi6 aplicar la misma prueba a tres
especies comunes: Eucaliptus robusta Smith,
E. kirtoniana F. v. M. y Micropholis chrysophyl-
loides Pierre. Se secaron los postes a un con-
tenido de humedad menor del 30 por ciento,
se sumergieron entonces en el carbolineum
caliente (100°C) por 4 horas y luego se pu-
sieron a enfriar por 16 horas. La absorcion
del preservativo varid de 6 a casi 8 libras
por pie cuibico. La mitad de los postes se
colocaron en el Bosque Toro Negro (eleva-
cidn, 2,500 pies; precipitacion, 110 pulgadas)
y la mitad en el Bosque Experimental de
Cambalache (nivel del mar; precipitacion, 55
pulgadas). Se colocaron testigos de E.
robusta sin tratar en los dos ambientes esta-
cionales.

Todos los postes que recibieron trata-
miento estan completamente sanos a los 2
anos después de colocados. El preservativo
parece estarse filtrando de algunos de los
postes. La mitad de los de E. robusta han
fracasado. Probablemente ninguno de los
postes no tratados duraraé mas de un ano.
Por el contrario, la duracién de los postes
tratados sera seguramente mucho mayor.

Los futuros experimentos de esta natu-
raleza utilizaran creosota (es mas barata que
el carbolineum) y se enderezaran al aspecto
economico de tales tratamientos.

64
PLANES PARA 19853

Los desarrollos del ano pasado senalan la
necesidad de mayor esfuerzo en la investiga-
cion de practicas forestales de utilidad para
bosques particulares. Esto comprendera no
solo la repeticidn de pruebas en esos terre-
nos, de especies y técnicas que han sido sa-
tisfactorias en otras partes, sino también ex-
perimentos similares enderezados a abrir
mercados de manera que los arboles puedan
ser considerados cosecha de turno corto.

Se recomiendan especificamente estudios
cooperativos sobre las propiedades para la
produccion de pulpa con eucalipto, los arbo-
les de sombra para cafetales, y algunas otras
especies mas comunes. En terrenos parti-
culares se van a hacer extensas pruebas con
el eucalipto intercultivado con otras cose-
chas. Se debiera ensayar con arboles de
sombra mas productivos en cafetales parti-
culares. También se haran esfuerzos para
conseguir una planta para tratamientos a
presion para la preservacion de vigas, pilotes,
traviesas y maderas de construccion domés-
ticas e importadas. También se recomienda
una exhibicion publica de productos foresta-
les locales, un inventario del consumo y des-

CARIBBEAN FORESTER

perdicio de productos forestales usados por
industrias locales, métodos de secado, utili-
dad de la preservacion de madera y anos de
servicio. Para fomentar la dasonomia en
terrenos particulares se organizaran areas
de demostracion dentro de bosques publicos
comparables a los terrenos_ particulares.
Planes para el desarrollo de estas areas se
formularan conjuntamente con el Selvicultor
de Extension y estas areas se utilizaran prin-
cipalmente por el Servicio de Extension.
Ademas se completara el inventario de los
plantios en terrenos particulares empezados
hace 2 anos y los resultados se incorporaran
a un boletin que tratara sobre la siembra de
arboles.

E] trabajo nuevo propuesto requerira una
reduccion de esfuerzos en algunos proyectos
viejos. Un ntmero grande de pruebas sobre
adaptabilidad se terminara a fines de este
ano y una revision del programa de reexa-
men ha resultado en una economia de tiem-
po adicional. Un manual que regularice al-
gunos de los procedimientos y técnicas de in-
vestigacion basado en las experiencias habi-
das debiera aumentar la eficiencia. Una re-
vision del analisis de este problema y planes
factibles se terminara a principios de ano.

JANUARY - APRIL, 1953

65

The Significance to Puerto Rico of Companhia
Paulista Experience with Eucalyptus «

Frank H. Wadsworth and José Marrero
Tropical Forest Experiment Station
Puerto Rico

The Companhia Paulista de Estradas de
Ferro, centered at Sao Paulo, Brazil, has
carried out what is probably the largest
single forestry project yet attempted in
Latin America. The results are of great
importance not only to the State of Sao Paulo
and to Brazil but to all other countries in the
tropical and subtropical regions of this
hemisphere. It is especially significant that
this project has been carried out by private
industry, and as such has had to be a success
financially as well as technically.

At the turn of this century far-seeing
directors of the Companhia became con-
cerned about the increasing scarcity of
fuelwood along their railways through
the eastern part of the state of Sao Paulo.
In 1903 they appointed Edmundo Navarro
de Andrade, an agronomist, to establish
plantations of trees as a source of fuel for
the Companhia.

Navarro began experiments on a property
owned by the Companhia at Jundiai, a few
miles west of Sao Paulo. He planted 95
different species of trees to determine which
gave the highest yield. Eucalyptus from
the seed of old trees resulting from early
introductions by the Jesuits far ougrew all
of the other species and so was subjected to
more experimentation and planting. The
growth of these plantations so impressed the
directors that additional properties were
bought along the railway, and in 1909 the
center of the work was moved to a larger
area at Rio Claro.

The interest of the Companhia grew as
Navarro‘s work produced spectacular results.
Millions of cruzeiros were invested in the
project. Some 17 plantations have now been

established along the lines of the Companhia.
More than 30,000,000 trees have been planted
on some 12,000 hectares. Recognition by
the directors of the indirect values and the
long-term nature of the project led to invest-
ments far in excess of immediate returns.
However, present assets in land and _ plan-
tations and other benefits are adequate to
assure total recovery. Forest ownership
has so improved the bargaining position of
the Companhia that fuelwood can be
purchased from outside sources at not more
than half the usual market price.

The Companhia has its own Foyest
Service, which is centered at Rio Claro but
has personnel on all of the properties. The
work of this Service has included land
acquisition, regeneration, management,
harvesting, utilization, and research.

One of the most significant aspects of
the forestry project of the Companhia has
been the importance attached to research.
Navarro was by nature an investigator and
at all times had an array of experiments in
progress. He so completely sold the directors
on the value of this research that he was
provided a laboratory and adequate funds to
carry out an extensive investigative program
in the fieid. Since his death in 1941
research has continued to hold its place of
importance under the direction of Armando
Navarro Sampaio, an agronomist and the
nephew of Edmundo. There can be no doubt
that it was largerly this sympathetic attitude
toward reseach which has made the project
a success,

* The description of the Companhia
upon observations made by the senior author during
a visit to Riv Claro in July- 1952. He is indebted to
Armando Navarro Sampaio an his assistants. Rubens
Foot Guimanaes and Jayme Vieira Pinheiro for the
data presented.

project is based

66

The research division now includes two
agronomists and a number of assistants. It
has good laboratory facilities and a fund of
data from the plantations throughout the
State as basis for investigations. The early
work was characterized by remarkably
complete record-taking, the benefits of which
are now readily apparent.

Those observations made in Brazil which
appear to be of some value to Puerto Rico are
here presented. Subsequently Puerto Rican
experience is described, and finally conclu-
sions are drawn as to what should be done
in the future in Puerto Rico, in the light of
results to date in both places.

Selection of Species

The suitability of a tree species for
forestry is dependent upon its adaptability,
productivity, and utility. The selection of
superior species on the basis of these
characteristics has formed an important
part of the work in Brazil and should be of
value elsewhere.

Adaptability

The spectacular growth rate of eucalyptus
trees led to investigation of the home
environment of this genus in Australia and
the introduction of additional species in an
effort to determine which would be most
productive. A total of 143. species of
eucalyptus were tested. A list of these
appears as Appendix I.

The Rio Claro environment is subtropical
and moist. The temperature range is from
35° to 102°F. and the mean is 70°F. Pre-
cipitation average about 53 inches annually.
The winter months are dry, the mean pre-
cipitation por each month from April to
September being not more than 3 inches, and
less than 1.5 inches during July and August.
A period of four rainless weeks or more is
experienced nearly every year. Windstorms
are rare. The soils are mostly lateritic red
clays, usually heavy but sandy in limited
areas. Their pH range is from 4.5 to 6.5.

CARIBBEAN FORESTER

They are generally more than 3 feet in depth
and are well drained. They are degraded,
having been farmed and abandoned prior to
purchase by the Companhia.

The first tests of adaptability were small
plantations of 20 x 20 trees within an
isolation strip. A few trees of nearly all of
the species tested are still to be seen, a fact
which makes possible a complete appraisal
of relative adaptabilities. Of those not
adapted, a few did not survive, whereas
others grew slowly and/or produced trees
of poor from. A significant finding was
that trees which fell behind in the first 6
months after planting never grew satisfac-
tory later. The list of adapted species which
is appended excludes all those of poor form or
which produced trees too small for good
utilization.

Species which proved adapted in the
initial plantings were subsequently planted
widely on other properties of the Companhia

where environmental conditions differed
slightly. These plantings led to certain con-
clusions regarding adaptability, some of

which were of a general nature, and others
concerned individual species. Eucalyptus
generally has proven sensitive to the quality
of the soil, particularly its depth. Poor sites
have been reflected in slow growth. Hardpans
are an adverse factor until the roots
penetrate them. Soil acidity appears to ke
of little importance within the range tested.
All species of Eucalyptus preferred the most
humid climate tested, although the range
was slight. The small temperature range
is of no apparent significance. Alba seems
to be one of the best species for adverse
sites, and on swampy soils robusta,
camaldulensis, and umbellata are most satis-
factory. Additional data of this nature are
available in “O Eucalipto’’!/.

Productivity

_ Productivity is an important factor in the
selection of tree species. Experience of the

1/ Navarro de Andrade, E. 1939. O. Eucalipto. Chacaras
e Quintais, Sao Paulo. Pp. 121.

JANUARY - APRIL, 1953

Companhia is not adequate to fully answer
many questions, since long-range investi-
gations of different management techniques
are required. Nevertheless some important
indications are evident.

Ease of propagation has not yet proven
to be a factor in the selection of species in
Sao Paulo. Differences are of minor im-
portance and do not affect costs or results
materialiy. Germination is generally high,
$9 percent or better. It is highest in
camaldulensis and saligna and lowest in
paniculata (seldom much over 80 percent).
Species with small seeds generally germinate
well but must be transplanted in the nursery.
Of these, camaldulensis and saligna survive
transplanting well and robusta and punctate
poorly. Species with large seeds and not
requiring transplanting in the nursery
include citrviodera, maculata, and
pilularis.

MiCrOcorys,

Ease of establishment in the fieid does
not vary greatly among the different species.
Under local conditions all species must have
a ball of earth about the roots for field
planting. Survival is generally high,
regardless of species. There has also been
no observed difference among the species as
to need for early plantation care. The
plantations are generally quite uniform in
early height growth.

Subsequent growth rates vary consider-
ably. Table 1 shows average diameter
growth in 3-14-year-old eucalyptus planta-
tions with two spacings on a sandy soil.
Greater differences would be expected on
clay soil.

A comparison of older plantations (23
vears) on clay soil showed little difference
in diameter among the adapted species.
About 150 trees of each species formed the
basis of measurement. The most rapid was
kirtoniana with an average diameter of 12.4
inches. Next was saligna, with 10.8 inches.
Other species ranged from 8.4 to 10.0 inches.

Little difference in the tolerance of the
various species has been noted. Species

67

Table 1—Diameter growth of young
Eucalyptus

Average diameter at breast height after
3-ls years

Species x
§.5-foot spacing 6.5-fcot spacing

kirtoniana 4.2

_saligna 4.0
botryoides 3.3
alba out 4.4
punctata 3.3 3.7
robusta 3.0
umbellata 2.8 3.8
camaldulensis 2.8 3:5
propinqua 2.0
resinifera 3.6
maculata 32,
citriodora 3.0
microcorys 3.0
paniculata 2.3

which persist most when suppressed are alba,
kirtoniana, punctata, propinqua, and
umbellata.

saligna,

Susceptibility to disease and insect
attacks does not yet differentiate the species
tested. The most important insect pests,
leaf cutting ants and termites, are not
selective.

None of the species reproduces itself
naturally in sufficient abundance to make
unnecessary periodic replanting. Sparse
natural reproduction of citriodora and maculata
was seen. Absence of natural regeneration
is believed partly due to the dry weather
during the winter months when fruiting
takes place and partly to the difficulty of
seed contact with the soil.

The sprouting capacity of the different
species, a reflection of their vigor, is directly
related to growth rates. The average
diameter of sprouts 15 years after the first
cutting of 8-year old trees on a good clay
soil is shown for several species in Table 2.

68

Additional information is available on page
40 of “O Eucalipto.”

Table 2.—Fifteen-year sprout growth

Average diameter at breast
height after 15 years

Species
| With one With three
sprout sprouts
Inches Inches
paniculata (2 5.2
propingua a2
saligna 6.8 6.0
resinifera 6.4 5.6
robusta 5.6
alba 6.4 5.2
camadulensis 5.2

Data on taper of various species are not
very complete, but in one study of large
trees robusta With an average taper of 0.12
inch per lineal foot was one of the best
formed species.

No important difference in the wind
resistance of the various species has been
noticed. There is a slight indication that
umbellata withstands wind better than the

average, None withstand major storms well.

The average diameter and density of
older plantations of the different species is
indicated in Table 3. Here are listed data
from plantations 400 meters square estab-
lished at an initial spacing of 6.5 feet and
unthinned for 24 years. Table 3 shows a
great uniformity among these species both as
to average diameter and number of trees per
unit of area. The basal area is very low,
considering that no thinning has been done.
This and the small percentage of suppressed
trees shown in the final column are evidence
of the intolerance of these species.

CARIBBEAN FORESTER

Table 3.—Tree diameter and stand density
in old plantations

| Percent cf

| No. of Basal
Species | ev creee ones ee ene spe SOD eee
Inches No. Sq. ft. Wi
alba 10.0 74 40 15
botryoides 9.6 67 34 oi
citriodora 9.2 71 33 i
maculata 10.1 53 29
punctata 9.7 68 35 20
resinifera 9.4 70 34 16
robusta 9.5 71 35 7
saligna 10.5 76 46 20

A consideration of all production factors
leaves the impression that present knowledge
does not indicate that any adapted species
should be eliminated from the list on this
account.

Utility

Among those species which are adapted
and comparatively easy to produce the best
are those with products of greatest utility.
For furniture the best species among those
adapted are botrvoides, camaldulensis, citriodora,
cladocalyx, maculata, piluleris, saligna and
umbelleta. All of these species have
attractive wood which takes a high polish.
They are not all easily worked but can be
used. Robusta heartwood was rejected
because of splitting. Species used _ for
construction include botryoides, camaldulensis,
maculata, paniculata, pilularis, punctata, saligna,
trianthe and umbellata.

For railroad ties there is little preference.
A few woods, such as that of robusta, split
excessively. Nearly all species are on a par
for posts and piling. The untreated heart-
wood of most species (even robusta,) lasts up
to 10 years at Rio Claro. Preservation of the
heartwood has proven difficult at Rio Claro
because it will not absorb preservative by
usual pressure treatment methods..-

JANUARY - APRIL, 1953

The relative suitability of different
species for pulp has not been tested at Sao
Paulo. A number of species, including alba,
grandis and saligna are said to have been found
satisfactory elsewhere and _ undoubtedly
many others deserve study. Essential oils
extracted from globulus and citriodora, were
found satisfactory for medical use and for
perfume. The bark of punctata is about 26
percent tannin.

Propagation

The Companhia has found natural
hybridization common in eucalyptus. As a
result, large isolated plots of each species
have been established as sources of typical
seed. These plots are usually 400 trees square
and are surrounded by a 500-meter isolation
strip of the same species. Trees within
these plots are selected individually for form
and for the conformance of the leaves,
flowers, and fruits with type descriptions
from Australia.

The fruits are dried in long concrete beds
and covered at night for protection from daw.
They are exposed to direct sunlight and in
good weather they release all seeds in 2 days.
The seeds are sown in concrete beds of 1 by
5 meters.About 30,000 seeds are sown at a
time. The bed is covered with grass thatch
during the period of germination.
Subsequently seedlings are covered only for
protection from extremes of insolation or
rainfall.

Pots are made of compressed compost by
a special machine. Seedlings are trans-
planted into them when about 1 inch tall,
except for delicate species such as citriodora,
which are sown directly in these pots.
Planting in the field is done when the stock
is 8 to 12 inches tall.

Selection of seedling and stock is directed
toward greater uniformity of growth in the
field. Because of better growth and form a
selected stand outyielded others by 579 cubic
feet per acre at 8 years of age. Selection
is made on the basis of size and form. Of

69

30,000 seeds sown, about 25,600 germinate,
of which the 10,000 best seedlings are chosen
for transplanting. About 8,000 of these are
selected for field planting. Investigation
showed a field spacing of 6 feet to be
superior in yield to 8 feet.

Management

Eucalyptus is usually planted on recently
abandoned cleared lands. Sometimes a
farmer clears and crops the land for 18
months, giving one third of his crop to the
Companhia. Then he cleans up the crops.
plants the trees at half the usual price and
cares for them for 18 months without crops.
A mixture of agricultural and tree planting
(taungya) has not been tried.

Natural regeneration is most prominent
in citriodora, propinqua, and maculata, but in no
instance does sufficient regeneration take
place to be of silvicultural significance.

The cutting regime for fuelwood is:
1; Gut clear-at 7 year.
2. Thin to 3 or 4 sprouts per stump
8th year.
3. Thin to 1 sprout per stump in
13th year.
4. Cut clear at 20 years.
. Repeat cycle, with step 2
in 21st year.

above

OU

The gradual removal of the sprouts is
believed desirable to avoid a major shock at
short intervals (of 7 years) and a resulting
unbalance between root and tops. The
sprouts come up successfully through light
brush. This cycle may be repeated at least
five times and is discontinued when 35
percent of the stumps are dead. The selection
of sprouts in thinning is based upon
diameter, form, and their isolation from
each other at the base. Height growth
of sprouts is less than for seedlings, as is
the volume of a coppice stand at 7 years.

For power line poles the stand is thinned
at 5, 10, and 15 years and the final cut is at
about 20 years. Such poles are 8 inches in
diameter at the small end and 32 feet long.

70

For saw timber the thinning regime is the
same except that the kest stems are left to
30 to 35 years. Some saw timber is also
produced by coppice with standards. A few
trees may be cut each year late in the saw
timber rotation.

All plantations are cleaned every year
througnout the rotation. The brush (not
the grass) is cut to help tree growth and to
facilitate exploitation. Cleaning costs about
two man-days per acre.

Excessive thinning produces profuse
epicermic branching, except possibly with
umbellata and punctata.

No data are available on soil maintenance
beneath the plantations. Herbaceous
vegetation is persistent and slopes are
gradual, so erosion is no serious problem.
It was estimated that a growing plantation
drops 6 tons of leaves per acre per year. No
chemical analysis of the leaves has been
made.

The trees are utilized to a 1-inch top for
fuelwood, which is extracted in carts. Poles
and logs are skidded with oxen.

Yields

Typical growth on good soil (umbellata)
is as shown in Table 4

Tadle 4.—Growth of Eucalyptus umbellata

i) BeBe

Age Height
Years _ Inches sects
6 5.2 41
12 8.2 64
18 13.0 82
24 18.1

The growth of robusta at Rio Claro on a
good clay soil is as shown in Table 5.

Table 5.— Growth of Eucalyptus robusta

Age DB aes
Years Inches
2 pe
4 4.1
6 4.9
8 6.0
10 6.6
20 8.7

CARIBBEAN FORESTER
The production of a typical species

(witbellata), based upon measurement of
3,340 hectares, was as shown in Table 6.

Table 6.--Volume yield of Eucalyptus umbellata

Age Volume
Years Cu. ft./acre
6 2,300
7 2,830
8 3,480
9 3,600
10 3,720
12 3,950
15 4,250

Utilization

Prior to sawing for lumber, logs are dried
6 months in the shade with ends painted.
The lumber of eucalyptus produced at Rio
Claro is largely of low grade. It is cut with
a gang saw. Warping is serious. Further
investigation is required to improve the
utilization of large trees suited for lumber.

Crossties are cut from logs which will
yield two ties in cross section. This reducés
checking since the center of log is not in the
center of the tie. Then three cuts 14 inch
wide and 14 inch deep are made longitudinal
down the surface nearest the bark to reduce
the tangential tension. This method succes-
sufully controls checking. The ties are cut
from heartwood which in no species absorbs
preservative. Nevertheless they are painted
with carbolineum and are durable for 10
years or more.

Posts are dried 3 months so that checking
is complete before treatment. Small! posts
are made from material quartered green to
avoid checking. Preservative treatment is
done with wolman salts, using vacum and
pressure. The sapwood absorbs the
preservative completely, and when treated,
lasts from 10 to 25 years. With wolman
salts the posts may be treated green if
preferred. Cold soaking with wolman salts
takes about 7 days. In hot and cold bath

‘with creosote, power line pole butts are

treated 8 hours at 120° C and then 2 to 3
hours cold.

JANUARY - APRIL, 1953

Pulp and paper are soon to be made from
eucalyptus in a new plant at Jundiai being
constructed by private capital. Oils and
tannins have proven too costly to extract
commercially.

EXPERIENCE WITH EUCALYPTUS
IN PUERTO RICO

Puerto Rico, in common with most
countries of Latin America, has been
attracted to eucalyptus and has_ tested
various species on a number of different
sites. As in Brazil, the local interest in the
genus came largely as a result of the
spectacularly rapid growth of a few trees
which were introduced into the island prob-
ably for medicinal purposes. The prospect
of high yields per acre of a variety of dif-
ferent types of woods from species adapted
to adverse sites as indicated in literature
descriptive of eucalyptus, is particularly
attractive on a densely populated island.

Eucalyptus is apparently a relatively
recent introduction into Puerto Rico. No
record of its presence in the island could be
found prior to 1900. Between 1920 and 1940
the Puerto Rico Forest Service introduced
some 23 species. Since 1940 an additional
27 species have been introduced by the
Tropical Forest Experiment Station. A
complete list of the species introduced
follows:

. affinis H. D. et J. H. M.

. alba Reinw.

. albens F. v. M.

. bicolor A. Cunn.

. botryoides Smith.

. calophyla R. Br.

. camaldulensis Dehnh.
cinerea F. v. M.

citriodera Hook.

. Cladocalyx F. v. M.

. cornuta Labill.

. diversicolor F. v. M.

. fastigata.

. globulus Labill.

mateo

71

y

- goniocalyx F. v. M.
grandis Maiden.
gummifera (Gaertn.) Hook.
. gunnii Hook.

kemiphloia F.v. M.
kirtoniana F. v. M.
longifolia Link & Otto.
maculata Hook.

maidenii.

marginata Smith.
melliodora A. Cunn.
obliqua L’ Herit.
occidentalis Endl.
paniculata Smith.
pauciflora Sieb.
paulistana.

. pilularis Smith.
polyanthema Schauer.
propinqua, H. D. & J. H. M.
. punctata DC.

. racemose F. v. M.
resinijera Smith.

robusta Smith.

rostrata Schlecht.

rubida H. D. & J. H. M.
rudis Endl.

salicifolia Ca.

saligna Smith.
sideroxvlon A. Cunn.
stricta Sieb.

stuartiana F. v. M.
torrelliana F. v. M.
tricntha Link.

umbellata (Gaertn) Domin.
umbra R. T. Baker.
viminalis Labill.

bobo Poe a Bo

Adaptability

The adaptability of the species of
eucalyptus introduced is not as completely
known in Puerto Rico as in Brazil. Many
of the introductions produced too few
seedlings for extensive trials. In the
beginning, the absence of funds for planting
on public iands made it necessary to dis-
tribute the trees to any farmer interested.
This resulted in concentration in a few areas

12

of the island where many eucalyptus species
have since proven unadapted. In addition,
written records of the results of planting
prior to 1932 were lost in the hurricane of
that year. Only recently has information
begun to accumulate from systematic testing
on a variety of promising sites.

Nearly ail of the plantings of eucalyptus
in Puerto Rico have been made either below
500 feet elevation along the coast or between
2,000 and 3,500 feet elevation in the
mountains. Most of the low elevation sites
are in a tropical moist climate, with tem-
perature between 60° and 90° F and pre-
cipitation between 50 and 120 = inches
annually. Usually at least 3 inches of pre-
cipitation is received during the driest
months, from February to April. Soils are
mostly clay, derived from volcanic and
sedimentary rocks.

In the mountains the climate is sub-
tropical and wet, with temperatures
generally between 50° and 85° F and pre-
cipitation ranging from 85 to 120 inches
annually. Soils are friable to heavy acid
clays, usually deep, and derived from volcanic
rocks.

Studies of relic plantations from early
introductions and of the results from recent
experiments lead to a number of general con-
clusions regarding the adaptability of these
eucalyptus species tested in Puerto Rico.
The most important of these follow.

1. Climatically they seem better suited
to the mountains than the coast.
Judging from the literature on the
natural range of these species, this is
probably as much as _ reaction to
temperature as to precipitation.

2. Where climatic conditions are satis-
factory they are remarkably
adaptable to soils which have been
abused by excessive cultivation.

3. Where adapted they have, by a wide
margin outgrown in diameter and

height nearly all other trees native
or exotic.

CARIBBEAN FORESTER

4. Where adapted they produce trees
of better form than most other
species.

5. No species yet tried, even under
apparently favorable conditions,
develops a sufficiently dense canopy
in 10 years to dominate native vege-
tation, including grass, vines and
trees.

A summary of the adaptability of the
different species of eucalyptus which have
been most extensively tested appears in the
Thirteenth Annual Report of the Tropical
Forest Experiment Station in this same issue
cf this journal and thus need not be repeated
in detail here. Only a few of the most
favorable species-site relationships will be
described.

At low elevation only three species, alba,
kirtoniana, and umbellata, have proven adapted.
In the mountains the well adapted species
are firtoniana, resinifero, and robusta, and
maculata is promising. Other species tested
extensively but nowhere yet found well
adapted include frianthe, botryoides, citriodora,
globulus, pilularis, propinqua, and

Some of these produce a few
good trees per acre, but do not make
uniform stands. Others grow _ slowly.
Several might prove successful if planting
were not limited to soils which have been
degraded by cultivation.

gummiifera,
sideroxvlon.

Propagation

The two species of eucalyptus most
generally planted, robusta and kirtoniana, are
considered easy to propagate and establish
on appropriate sites. Propagation both on
the coast where the mean temperature is
78° F and precipitation is about 70 inches
annually and in the foothills at 500 feet
elevation with a mean temperature of about
749 F and precipitation of 120 inches

annually has shown the latter location most

favorable. Growth is more rapid and
mortality is lower. The following descrip-
tion aplies to the foothills nursery.

JANUARY - APRIL, 1953

The seed is sown in raised seed beds
constructed of concrete (see Fig. 1).. The
soil in these beds is a mixture of equal parts
of clay loam, filter press cake, and coarse
sand. The freshly sown beds are protected
from excessive sun and hard rains by
removable corrugated metal shades. Sowing
is done at the rate of one pound to 50
square feet of bed. As a precaution against
damping off the soil is treated prior to
sowing with formalin or copper sulphate
and later the soil is sometimes treated with
Bordeaux mixture. In spite of this,
damping off is frequently a problem, and
other methods of control are being tested.

This heavy sowing produces a_ very
dense stand of seedlings. The yield
per pound of seed varies between 6,000 and
15,000 seedlings. After 8 to 12 weeks in
the seed beds the trees are from 2 to 4 inches
tall. (See Fig. 2). Then the seedlings are
gradually transplanted over a period of 2 or
3 weeks, selecting the largest first. The soft
soil is moistened throughly so that individuai
seedlings can be pulled up without damaging
the roots.

The seedlings are transpianted to conven-
tional, slightly raised transplant keds (see
Fig. 3) at a spacing of 3x 6 inches. Trans-
planting is done with a dibble. Tests of a
transplant board with these tiny seedlings
have not yet been successsful. Trans-
planting losses are insignificant, and
watering needed. After 8 to 10 weeks in
the transplant beds the stock is 18 to 30
inches tall and is ready for lifting.

The trees are transplanted bare-rooted to
the field and planted at a spacing of from
6 to 8 feet. Planting survival ranges from
75 to 90 percent. Despite the rapid growth
of eucalyptus the young trees must be
weeded twice annually for about 2 years to
free them from competing native vegetation.
All weeds within 18 inches of each tree are
cut back to the ground level. After 2
years the trees are usually at least 2 feet
above the other vegetation and need no
further assistance, except possibly occasional
liberation from vines.

Eucalyptus robusta and _ &irtoniana on
favorable sites are subject to few insect
attacks and disease. The chief probiem of
this nature affecting management is the
dying of single trees throughout the life of
the stand. Usually mortality of this type
is preceded by die-back in teh crowns, and
sometimes by gum exudation and worthless
sprout growth at or near the base of the
trunk. On many sites this type of mortality
keeps the canopy sufficiently open to prolong
the vine problem and encourages a dense
growth of native vegetation to invade
beneath the plantation.

Management

Puerto Rico’s plantations of eucalyptus
cover probably less than 2,000 acres. They
are mostly young and many of them are
merely scattered tests of site adaptability.
Thus no fixed management techniques such
as those of Brazil have been established.
Nevertheless, observations have been made
which indicate a few desirable practices.

On the best sites thinning is apparently
needed before the tenth year. The chief
sympton cf this condition is the early reduc-
tion in the height and size of the crowns.
A canopy sufficiently dense to indicate a
need for thinning never develops, nor does
the thick herbaceous cover beneath the trees
disappear. The growth rate of the upper
canopy trees declines slowly with crown size
and the harvest of subordinate stems
becomes desirable for economic reasons.

The production of the largest timber for
which eucalyptus seems suited in Puerto
Rico, power-line poles, calls for a rotation of
from 15 to 20 years. During this rotation
one or two thinnings will generally proves
desirable.

Artificial reforestation with eucalyptus,
including weeding and vine removal, cost 20
mandays per acre, so the development of
natural methods of regeneration is very
desirable. Prospects for such a method do
not appear bright, however, since natural
seedlings of eucalyptus are almost never
found, and sprouting of trees of 10 inches
cer more in diameter is weak.

~]

CARIBBEAN FORESTER

Fig. 1.—Concrete seed beds with removable shades usted for the propaga-
tion of Eucalyptus, (Lechos de hormigon con cobijas removibles usados
parc la propagacion de Eucalipto).

JANUARY - APRIL, 1953

Fig. 2.—Dense stand of Eucalyptus seedlings 8 weeks old and ready for
transplanting. (Rodal denso de semillones de Eucalipto de 8 semanas y listos
para ser trasplantados ).

Fig. 3—Nursery beds recently planted with Eucalyptus. (Lechos
en el vivero sembrados recientemente con Eucalipto).

75

Growth

No data as to the productivity of
eucalyptus in Puerto Rico are available
except in terms of average tree diameters in
plantations of known ages. <A volume table
is In preparation which will show volumes
in cubic feet to different top diameters.

Important differences in growth rates are
not yet generally evident among the adapted
species. At iow elevation 8-year old planta-
tions of alba, kirtoniana, and umbellata range
from 3 to 9 inches d. b. h. and from 40 to
75 feet tall. In the mountains 13-year old
plantations of kirtoniana, and ,robusta range
from 6 to 16 inches d. b. h., and from 60
to 90 feet tall, the former the taller;
and the latter the larger in diameter.
Additional growth data appear in the
Annual Report elsewhere in this journal.

An encouraging result of growth studies
is that under one condition, a least, rapid
growth continues to a large size. In a
24-year old widely spaced plantation of
robusta on lateritic clay at 2,000 feet elevation
the average annual diameter growth for 48
trees during the past 5 years was 0.31 inch.
For 15 trees of more than 12 inches dbh, it
was 0.41 inch. One 16-inch tree grew at the
rate of 0.82 inch per year.

Utilization

To the present the utilization of euca-
lyptus has not been a problem in Puerto Rico.
The few trees which have reached large size
are used for poles or fuelwood. Nevertheless
a problem of utilization may arise in the
future because an increasing area is being
dedicated to eucalyptus, yet no traditional use
of these species or means for preserving the
wood are available locally. Eucalyptus has
been planted here primarily because it grows
so much faster and straighter on poor sites
than other trees. It has been assumed that
in an area so densely populated as Puerto
Rico, with so few forest resources that
almost any wood, if uniform, cheap, and
available in quantity would find a market.

CARIBBEAN FORESTER

The development of such a market is needed
soon to provide an outlet for the increasing
production of established plantations and to
serve as an incentive for more planting,
particularly on privately owned lands.

The lumber of robusta and kirtoniana,
warps seriously, a fact which apparently
restricts utilization to poles, posts, and
possibly pulpwood. The wood has been
found perishable in the ground. Fence posts
generally remain serviceable only 24 to 36
months, about the same period as most
native posts.

Tests of preservative treatment show
that by the hot and cold bath method an
absorption of 6 to 8 pounds of carbolineum
per cubic foot is possible. The durability
of treated posts is not yet known.

Robusta has recently been used for
subsurface piling. Piling of up to 50 feet
in length have been found as satisfactory in
every respect as imported pine, and they
seem to withstand driving better. This may
prove to be one of the highest uses of
eucalyptus in Puerto Rico.

CONCLUSIONS

A number of conclusions arise from a
comparison of experience with eucalyptus at
Sao Paulo and in Puerto Rico. The greater
fund of knowledge available at Sao Paulo
makes this comparison particularly helpful
to Puerto Rico. The major conclusions
reached are here listed.

1. Fewer species have so far proven
adapted to Puerto Rico than to Sao
Paulo. Nevertheless those adapted
to Puerto Rico are also among the
better species at Sao Paulo.

wo

The investigation of eucalyptus in
Puerto Rico has barely scratched the
surface. Many species have been set
aside on the basis of very limited tests.
More extensive plantings should be
made with the better species,

JANUARY - APRIL, 1953

OU

eiiahve

regardless of past experience. Better
soils, should be tested, because: good
species of eucalyptus might weli
compete in yield with other farm crops
under favorable environmental con-
ditions. Species particularly worthy
of more planting are alba, botryoides,
camaldulensis, triantha and umbellatc.

. More attention should be paid to

species, seed sources, and selection in
the nurseries. Both at Sao Paulo and
in Puerto Rico a number of unknown
species or hybrids exist. These should
be identified and seed sources pro-
tected accordingly. For the present
seed for testing should be obtained
from reliable outside sources. The
results of selection of uniform seedling
in the nursery should be tested locally.

establishment of eucalyptus
plantings immediately subsequent to
cultivation, as is done at Sao Paulo, and
during the cultivation period also
should be tested to make reforestation
with these species simpler and more
attractive for the farmer.

. Management experiments to determine

the results of different thinning
regimes an to explore the posibilities
of reproduction by coppice are also
needed to assure maximum yields.

. Productive understory crops should be

developed. The continuous need for
weeding at Sao Paulo and the invasion
of native trees beneath plantation in
Puerto Rico indicate that there may be
a place for a secondary crop beneath
the trees. Bananas and coffee are
possibilities worthy of trial.

. A local preservation plant such as is

available at Sao Paulo must be set up
soon to make possible the marketing
of the large volume of poles which will
soon be available in the plantations.
Studies of the pulping properties of
local species are also needed if com-
plete utilization is to be achieved.

~
Ee |

APPENDIX I

Species of Eucalyptus Tested by the

Companhia Paulista

acaciaeformis

acervula Hook (syn. ovata)
affinis H. D. et J. H. M.
alba Reinw.

albens Miq.

x algeriensis*

amplifolia Naudin.
andrewsi J. H. M.
angulosa

x antipolitensis

bailevana* F. v. M.
bakert

bicolor A. Cunn.

bosisteana F. v. M.
botrvoides* Smith

caleyi J. H. M.

calophyila* R. Br.
camaldulensis* Dehnh. (syn. rostrata)
x camaldulensis* x resinifera™
cambageana J. H. M.

cam phora

capitellata* Smith

cinerea F. v. M.
citriodora* Hook
cladocalyx* F. v. M. (syn. corynocalyx)
coccifera Hook

conica H. O. & J..H. M.
consideniana J. H. M.
cornuta Labill.

dowsoni R. T. B.

dealbata

deanei J. H. M.

decipiens Endl.

decurva

diversicolor F. v. M.

dives Schauer

drummondi

dumosa (syns. ovata & johnstoni)
elaeophora F. v. M.
erythronema Turez.
eximia™ Schauer

exserta

* Species which have proven well adapted at Rio Claro.

x - hibrid.

fasciculosa F. v. M.

falcata

ficifolia F. v. M.

foecunda Schauer

globulus Labill.
gomphocephala F. v. M.
goniocalyx* F, v. M.
grandifolia

eriffithsi J. H. M.

guilfowei J. H. M.
gummifera* (Gaertn.) Hookr.
gunni* Hook

haematoma DC.

hemiphloia F. v. M.

hubrida J. H. M.

incrassata Lab.

kirtoniana F. v. M. (grandis*)
kirtoniana* F. v. M. (syn. patentinervis)
laevopinea R. T. B.

lehmannii Preiss.

leucoxvlon F. vy. M. (syn creacilipes)
linearis® A, Cunn.

lindlevana* (syns. andreana, numerosa)
longifolia Link & Otto.
loxophleba Benth

macarthure H. D. et J. H. M.
macrocarpa Hook
macrorrhyncha F. v. M.
maculata* Hook

maculosa R. T. B.

maideni*

marginata Smith

megacarpa F. v. M.
melanophloia F. v. M.
melliodora A. Cunn.
microcorys F. v. M.
microtheca F. v. M.

mooret J. H. M. (syn. microphylia)
morisst (morrisit )

muelleriana A. W. Howitt.
obliqua L” Herit

obtusiflora

occidentalis* Endl.
ochrophloia F. v. M.

odorata Behr.

oleosa F. v. M.

CARIBBEAN FORESTER

oranensis*

paniculata* Smith

fatens Benth.

pauciflora Sieb. (svn. coriacea)
x paulistana*

pilularis* Smith

piperita* Smith

planchoniana F. v. M.

platypus Hook (syn. obcordata)
polyanthemos Schauer
populifolia Hook

pressiana Schauer

propinqua* Deane & Maiden
puverulenta Sims (syn. pulvigera)
punctata* DC.

racemosa* F. vy. M. (syn. creba)
redunca Schauer

regnans F. v. M.

resinifera* Smith

robusta* Smith

rubida* Deane & Maiden
rudis* Endl.

salicifolia (Sol.) Cav. (syn. amygdalina)
saligna* Smith

salmonophloia F. v. M.
sdlubris F. v. M.

scabra* (syn. eugenioides )
sieberiana F. v. M.
siderophloia* Benth.
sideroxylon A. Cunn.

smithi* R. T. B.

stellulata Sieb.

stricta Sieb.

stuartiana F. v. M.

squamosa H. D. et J. H. M.
tetragona (syn. pleurocarpa)
umbelleta* (syn. tereticornis )
x trabuti*

triantha Link (syn. acmenioides™ )
umbra* R. T. Baker

uncinata Turez.

urnigera Hook

viminalis® Labill.

viridis (syn. acacioides™ )
woolsiana R. T. B.

JANUARY - APRIL, 1953

~]
ie)

(Traduccién del articulo anterior)

Experiencias de la Companhia Paulista con
Eucalipto
Su Importancia para Puerto Rico ~«

La Companhia Paulista de Estradas de
Ferro centralizada en Sao Paulo ha llevado a
cabo lo que es probablemente el mayor pro-
yecto individual de dasonomia hasta la fecha
emprendido en la América Latina. Los re-
sultados son de gran importancia no solo para
el Estado de Sao Paulo y para el Brasil, sino
para todos los paises en las regiones tropica-
les y subtropicales de este hemisferio. Es
especialmente significativo que este proyecto
haya sido realizado por una empresa privada
que como tal ha tenido que triunfar tanto
en lo econdmico como en lo técnico.

A principios de este siglo directores pre-
visores de la Companhia empezaron a preocu-
parse por la creciente escasez de lefa a lo
largo de sus lineas ferroviarias en la parte
este del estado de Sao Paulo. En 1903 nom-
braron a Edmundo Navarro de Andrade, un
agronomo, para establecer plantaciones de
arboles como fuente de combustible para la
Companhia.

Navarro inicid sus experimentos en una
propiedad de la Companhia en Jundiai, pocas
millas al oeste de Sao Paulo. Sembro 95 es-
pecies distintas de arboles para determinar
cuales daban mayor rendimiento. E! euca-
lipto de semillas de viejos arboles, residuos
de las primitivas plantaciones de los Jesuitas,
sobrepaso a todas las demas especies y por
consiguiente se le sometio a mas experimen-
taciones y plantaciones. El crecimiento de
estas plantaciones impresiono de tal manera
a los directores que se adquirieron mas pro-
piedades a lo largo del ferrocarril y en 1909
el centro de operaciones se traslad6 a un area
mayor en Rio Claro.

* Las notas sobre el proyecto de la Companhia est4n ba-
sadas en las observaciones del Dr. Wadsworth durante
una visita que hizo a Rio Claro en juli: de 1952. Tie-
n2 que agradecer a la bondad de Armando Navarro
Sampaio y a sus ayudantes Rubens F ot Guimanaes ¥
Jayme Viera Pinheiro lcs datos aqui presentados.

El interés de la Companhia crecia segtin
el trabajo de Navarro producia resultados
espectaculares. Millones de cruzeiros se
emplearon en el proyecto. Unas 17 planta-
ciones se han establecido a lo largo de las
lineas de la Companhia. Se han sembrado
mas de 30.000.000 de arboles en alrededor de
12.000 hect4areas. La Junta de Directores
comprendié tan cabalmente las valores indi-
rectos y el largo plazo de los proyectos que
autorizo inversiones en exceso de las ganan-
cias individuales. Sin embargo el capital en
terrenos y plantaciones y otros servicios es
suficiente para asegurar la recuperacion to-
tal. La posesién de bosques ha mejorado de
tal manera el poder de contratacion de la
Companhia que la lena puede comprarse en
fuentes exteriores a no mas de la mitad del
precio en el mercado.

La Companhia tiene su propio Servicio
Forestal que esta establecido en Rio Claro
pero tiene personal en todas las propiedades.
El trabajo de este Servicio ha incluido la ad-
guisiciOn de tierras, regeneracion, ordenacion,
cosechas, utilizacion e investigaciones.

Uno de los aspectos mas significativos del
proyecto ce dasonomia de la Companhia,
ha sido la importancia que se le ha dado
a la investigacion forestal. Navarro era
investigador por naturaleza y a todo mo-
mento tenia un despliegue de experimentos
en progreso. De tal manera convencio a los
directores del valor de estas experimentacio-
nes que éstos le proporcionaron un laborato-
rio y fondos adecuados para llevar a cabo un
extenso programa de investigacion. Des-
pués de su muerte en 1941 el trabajo de in-
vestigacion ha mantenido su importancia
bajo la direccion de Armando Navarro
Sampaio, agrénomo y sobrino de Edmundo.
No hay duda de que es esta actitud favorable

80
hacia el trabajo de investigacion to que
ha hecho del proyecto un éxito.

La division de investigaciones incluye
ahora dos agronomos y varios ayudantes.
Tiene buenas facilidades de laboratorie y un
caudal de datos sobre las plantaciones en to-
co el Estado como base para sus investigacio-
nes. El trabajo en su principio se caracte-
rizo por una notable copilacion de datos cu-
vos beneficios son ahora palpables.

Se presentan aqui las observacicnes he-
chas en el Brasil que parecen tener algun
valor par Puerto Rico y en seguida se descri-
ben las experiencias puertorriquenas; final-
mente se ofrecen conclusiones sobre lo que
debiera hacerse en Puerto Rico a la luz de
los resultados obtenidos hasta la fecha en
ambos sitios.

Seleccion de Especies

La conveniencia de una especie de arbol
para la dasonomia depende de su adaptabili-
dad, productividad y utilidad. La seleccién
de especies superiores desde el punto de vista
de estas caracteristicas, ha sido parte impor-
tante del trabajo en el Brasil y debiera tener
importancia en cualquier otro sitio.

Lo espectacular en el ritmo de crecimiento
del eucalipto condujo a investigaciones en el
lugar de origen de esta especie australiana
y a la introduccion de especies adicionales en
an esfuerzo por determinar cual seria mas
productiva. Se hicieron pruebas con 143
especies de eucalipto. Una lista de éstas
aparece como Apéndice I.

La situacion de Rio Claro es subtropical y
humeda. La temperatura fluctta entre 359
y 102°F; la temperatura media es de 709F.
Tiene un promedio de 53 pulgadas de precipi-
tacion anualmente. Los meses de invierno
son secos con no mas de 3 pulgadas de pre-
cipitacion de abril a septiembre y 1,5 pulga-
das durante julio y agosto. Casi todos los
anes hay una temporada de seca que dura 4
semanas o mas. Vientes tormentosos son
raros. Los suelos son de arcillas lateriticas
rojas, generalmente pesadas pero arenosas

CARIBBEAN FORESTER

en areas limitadas. Su ritmo pH es de 4,5 a
6,5. Generalmente tienen mas de 3 pies de
profundidad y estan bien drenados. Estan
degradados por haber sido cultivados y luego
abandonados con prioridad a la compra por
la Companhia.

Las primeras pruebas para adaptabilidad
se hicieron en plantios pequenos de 20 x 20
arboles en una faja aislada. Todavia se ven
algunos arboles de cada una de las especies
probadas lo que hace posible una evaiuacion
completa de su relativa adaptabilidad. De
las que no se adaptaron, pocas sobrevivieron,
otras crecieron lentamente y/o produjeron
arboles de forma pobre. Un hallazgo sig-
nificativo es que los arvoles que se retarda-
ron durante los primeros 6 meses después de
sembrados nunca crecieron — satisfactoria-
mente. De la lista de las adaptadas que se
anexa se excluyen todas las de forma pobre y
las que dieron arpoles demasiado peqauenos
para su buena utilizacion.

Las especies que se adaptaron en jas pri-
meras plantaciones fueron luego sembradas
en otras propiedades de la Companhia donde
la condici6n ambiental diferia poco. Estas
plantaciones llevaron a ciertas conclusiones
relacionadas con la adaptabilidad, algunas
de caracter general, otras relativas a espe-
cies individuales. El eucalipto siempre ha
demostrado ser suceptible a la calidad del
suelo, particularmente a la _ profundidad.
El estar sembrado en suelos pobres se re-
refleja en crecimiento lento. Bancos du-
ros son factor adverso hasta que las raices
los penetran. La acidez del suelo parece
de poca importancia dentro de las pruebas
hechas. Casi todas las especies de euca-
lipto prefirieron los mas humedos de_ los
climas probados, aunque la diferencia era
poca, la poca diferencia en temperaturas
no parece tener importancia. La _ especie
alba parece ser la mejor para sitios adver-
sos y en suelos pantanosos robusta, camaldu-
lensis y umbellata se dan satisfactoriamen-
te. Datos adicionales sobre este aspecto
se encuentran en “O Eucalipto’’/.

O Eucalipto. Cha-

1/ Navarro de Andrades, E. 1939.
. 121.

caras e Quintais. Sao Paulo. Pp.

JANUARY - APRIL, 1953
Productividad

La productividad es factor importante
en la seleccién de especies. Las experien-
cias de la Companhia no son adecuacas pa-
ra contestar completamente a muchas pre-
guntas, debidc a que se requieren investi-
gaciones de largo alcance sobre muchas
téenicas de ordenacién. Sin embargo
gcunas indicaciones importantes son eviden-
tes.

La facilidad de propagacién no ha sido
hasta ahora factor en la seleccion de espe-
cies en Sao Paulo. Las diferencias son de
poca importancia y no afectan material-
mente ni el costo ni los resultados. La ger-
es generalmente alta, 90 por cien-

Es mas alta en camaldulensis y en
mas baja en la paniculata (rara
Las especies de semilla

1
al-

minacion
to o mas.
saligna ¥
vez mas de 80%).
pequefia generalmente germinan bien pero
hay que trasplantarlas en el vivero. De
éstas camaldulensis y saligna sobreviven a la
transplantaciOn pero robusta y punctata no.
Las especies de semilla grande que no nece-
sitan transplantaciOn en el vivero incluyen

citriodora, maculata, microcorys y_ pilularis.

La facilidad de acomodo en el campo no
varia mucho entre las especies. Bajo con-
diciones locales todas las especies deben te-
ner cepell6n para sembrarse en campo. La
supervivencia es generalmente alta en todas
las especies. No se ha observado diferen-
cia alguna entre las especies en cuanto al
cuido temprano de la plantacion. Las plan-
taciones son generalmente uniformes en
cuanto al crecimiento temprano en altura.
Luego el ritmo de crecimiento varia conside-

rablemente,

La tabla 1 indica el crecimiento diametral
promedio de plantaciones de eucalipto de
5-14 aMos en suelos arenosos espaciadas de
dos distancias. Las diferencias serian ma-
yores en suelos arcillosos.

Tabla 1.—Crecimiento diametral del
eucalipto joven

Diametro promedio a la altura
del pecho a los 3-% anos

; Espaciados Espaciados
Especie de 2 metros de 25 metros
Cms. Cms.
kirtoniana 10,7
saligna 10,2
alba 9.4 11,1
boirvoides 8,4
punctata 8,4 9,4
robusta 7,6
umbellcta real 9,7
camaldulensis Teak 8,9
propingua 51
resinifera 9,1
maculata Si
citriodora 7,6
mMICcrocorys 7,6
paniculata 5,8

Una comparacion con plantaciones viejas
(23 anos) en suelos arcillosos arroj6 poca
diferencia en diametro entre las especies
adaptadas. Unos 150 arboles de cada espe-
cie sirvieron de base para las mediciones.
La mas rapida fué la irtoniana con un diame-
tro promedio de 31,5 centimetros. Le siguio
saligna con 27,4 centimetros. Otras especies
fluctuaron entre 21 y 25 centimetros.

Se ha notado poca diferencia en tolerancia
entre las varias especies. Las especies que
persisten mas cuando dominadas son alba,
kirtoniana, punctata, saligna, propinqua Y
umbellata,

Todavia no puede establecerse diferencia
entre las especies estudiadas en cuanto a su
susceptibilidad a enfermedades y a insectos.
las plagas mas importantes de insectos, las
hormigas corta-hojas y los termes no esco-
gen.

Ninguna de las especies se reproduce na-
turalmente lo suficiente para hacer innecesa-
ria la replantacion periddica. Se noto la re-
produccion natural escasa de la citriodore y la
maculata. Se cree que la ausencia de regene-
racion natural se deba al tiempo seco duran-
te los meses de invierno cuando tiene lugar

82

la fructificacién y en parte a la dificuitad de
contacto de la semilla con el suelo.

La capacidad para retonar de las diferen-
tes especies, lo que refleja su fortaleza, se
relaciona directamente al ritmo de creci-
miento. El promedio diametral de los re-
nuevos a los 15 anos después de la primera
corta, en arboles de 8 afios en buen suelo ar-
cilloso queda indicado para varias especies
en la Tabla 2. Informacion adicionai puede
tenerse en la pagina 40 de “O Eucalipto.”

Tabla 2.—Crecimiento de renuevos a los
15 anos

—
[Promedio diametral a la altura
del pecho a los 15 anos

Con tres

- Con un
Especies renuevo renuevos

paniculata 18,3 13,2
propinqua 18,3

salicna 17,3 15,2
resinifera 16,3 14,2
robusta 14,2
alba 16,3 13,2
camaldulensis 132

Datos sobre la disminucién gradual de
varias especies no son muy completos, pero
en un estudio de arboles, robusta, con un pro-
medio de disminucion de 1 centimetro por
metro lineal, se consideré una de las especies
mejor formadas.

No se ha notado diferencia de importan-
cia en la resistencia al viento entre las varias
especies. Hay una ligera indicacién de que
la uimbcllata soporta el viento mejor que el
promedio de especies. Ninguna soporta bien
las grandes tormentas.

En la tabla 3 se indica el promedio dia-
metral y la densidad de plantaciones viejas
de diferentes especies. “ Aqui se apuntan los
datos sobre plantios de 400 metros cuadra-
dos con espaciamiento inicial de 6,5 pies y
sin clareos por 24 afios. Como se vera en la
Tabla 3 hay uniformidad entre las especies
tanto en el promedio diametral como en el
numero de-arboles por unidad de superficie.

CARIBBEAN FORESTER

El] area basal es muy baja visto que no ha
habido clareo. Esto y el pequefio porcentaje
de arpoles dominados que se sefialan en la
ultima columna, demuestran la intolerancia
de estas especies.

Tabla 3.—Diametro de Arboles y densidad de
rodal en plantaciones vieijas

Promedio | Numero Ae Area basal

| ‘ !
| Por ciento

Especie a la altura} arboles por | por de arboles
del pecho | hectarea | hectarea dominados
Cms. No. Metros %
cuadrados
alba 25,4 183 9,2 15
botirvoides 24,4 165 7,8 27
citriodora 23,4 175 7,6 21
maculata 25,6 131 6,7
punctata 24,6 168 8,0 20
resinifera 23,9 173 7,8 16
robusta 24,1 175 8,0 i
saligna 26,7 188 10,6 20

Una consideracion de los factores relati-
vos a la produccion deja la impresion de que
los conocimientos actuales no indican que
deba eliminarse de la lista ninguna de las es-
pecies adaptadas.

Utilidad

Entre las especies que se han adaptado
y que son relativamente faciles de producir
las mejores son las que dan productos de
mayor utilidad. Para ebanisteria las mejo-
res especies entre las adaptadas son la
botryoides, la camaldulensis, la citriodora, \a
cladocalyx, la maculata, la pilularis, la saligna y
la umbellata. Todas éstas dan madera atrac-
tiva que pule bien. No todas son faciles de
trabajar pero pueden usarse. La_ robusta
(duramen) fué rechazada porque se hiende.
Las especies que se usan para construccion
ineluyen botryoides, camaldulensis,
paniculata, pilularis, punctata, saligwa, iriantha
y umbellata.

Para durmientes casi no hay preferen-
cia. Algunas maderas como la de la robusta
se rajan demasiado. Para postes y pilotes
estan al par. El duramen de madera sin
tratar, de la mayor parte de las especies

maculata,

‘

JANUARY - APRIL, 1953

(aun robusta) dura 10 anos en Rio Claro.
La preservacion de duramen se ha encon-
trado dificil en Rio Claro porque éste no
absorbe los preservativos por el método
usual de tratamiento a presion.

La relativa utilidad de diferentes especies
para pulpa no se ha comprobado en Sao
Paulo. Se dice que un numero de especies
incluyendo alba, grandis, y seligna han resul-
tado satisfactorias en otros sitios, e induda-
blemente hay otras que merecen estudio.
Aceites esenciales extraidos de globulus y
citriodora se han encontrado satisfactorios
para usos medicinales y perfumeria. La
corteza de punctata contiene un 26 por ciento
de tanino.

Propagacion

La Companhia ha descubierto que la hi-
bridizacio6n es comun en el eucalipto. Como
resultado, cuarteles aislados de cada especie
se han establecido como fuentes de semillas
tipicas. Estos cuarteles tienen por lo gene-
ral un cuadro de 400 arboles y estan rodea-
dos de una faja aisladora de 500 metros de
la misma especie. Los Arboles en estos cuar-
teles han sido escogidos individualmente por
su forma y por la conformacion de las hojas,
fleres y frutos a las descripciones de su tipo
en Australia,

Los frutos se ponen a secar en lechos lar-
gos de concreto y se cubren de noche para
protegerlos del rocio. Se exponen a luz di-
recta del sol y en buen tiempo, sueltan las
semillas en dos dias. Las semillas se siem-
bran en lechos de concreto de 1 por 3 metros.
Se siembran unas 30.000 semillas a la vez. Se
cubre el lecho con una cubierta de hierba
durante la germinacion. Mas luego los se-
millones se protegen solamente contra extre-
mos de insolacion o lluvia.

Los tiestos se hacen de composte compri-
mido en una maquina especial. Los semillo-
nes se trasplantan a ellos cuando tienen como
una pulgada de altura, con excepcidn de es-
pecies delicadas, como la citriodora, que se
siembran directamente en los tiestos. Se

83

siembran en el campo cuando el material
tiene de 8 a 12 pulgadas de altura.

La seleccién de semillones y otro mate-
rial de vivero tiende a lograr mayor unifor-
midad de crecimiento en el campo. Debido a
mejor forma y mayor crecimiento, un rodal
seleccionado sobrepas6 en rendimiento a
otros por 570 pies cubicos por acre a los 8
anos. La seleccion se hace a base de tamano
y forma. De 30.000 semillas sembradas
unas 25.000 germinan, de las cuales los
10.000 semillones mejores se escogen para la
trasplantacion. Como 8.000 se seleccionan
para siembra en campo. Las investigacio-
nes han demostrado que un espaciamiento de
6 pies es superior en rendimiento a uno de —
8 pies.

Ordenacion

El eucalipto se siembra usualmente en
terrenos desmontados y de reciente aban-
dono. A veces un agricultor limpia y cul-
tiva la tierra durante 18 meses dandole la
tercera parte de su cosecha a la Companhia.
Entonces recoge su cosecha, siembra los ar-
boles por la mitad del precio usual y los cui-
da durante 18 meses sin cultivos. Una
mezcla de agricultura y plantacion de arbo-
les (método taungya) no se ha ensayado.

La regeneracién natural es mas comun
en citriodora, propingua y maculatc, pero en nin-
gin caso es suficiente para tener valor sel-
vicultural.

El régimen de corta para lena es como
sigue:

1. Corta total a los 7 anos.

2. Aclareo dejando 3 0 4 renuevos por

tocon a los 8 anos.

3. Aclareo dejando 1 renuevo por tocdn a

los 13 anos.

4. Corta total a los 20 anos.

5. Repeticion del ciclo, etapa 2 a los 21

anos.

La remocion gradual de los renuevos se
considera deseable para evitar cambios muy
bruscos a intervalos cortos (de 7 afios) y el
consiguiente desequilibrio entre raiz y tope.
Los renuevos crecen facilmente por entre la

34

maleza. Este ciclo puede repetirse por lo me-
nos cinco veces pero se Gescontinua cuando el
35 por ciento de los tocones estan muertos.
La seleccién de renuevos en el aclareo se basa
en el didametro, la forma y ei aislamiento de
uno del otro en el tronco. El crecimiento en
altura de los renuevos es menor que e! de se-
millones como lo es también el volumen de
un rodal de renuevos a los 7 anos.

Para postes de energia eléctrica el rodal
se aclarea a los 5, 10 y 15 anos y la corta
final es a los 20 anos. Estos postes tienen
didmetro de 8 pulgadas en la punta y miden
32 pies de largo. Para madera de aserraje
el régimen de corta es el mismo excepto que
los mejores tallos se dejan hasta los 30 0 35
anos. Alguna madera de aserraje se produ-
ce también siguiendo el sistema de tallar con
resalvos. Pueden cortarse algunos todos los
anos para fines de la rotacion de madera de
aserraje.

Todas las plantaciones se limpian todos
los anos durante la rotacion. La maleza (no
la hierba) se corta para ayudar en el creci-
miento de los arboles y para facilitar la ex-
plotacion. El coste de limpieza es de dos jor-
nales por acre.

Clareo excesivo produce profusion de ra-
mas de brotes en reposo con excepcion, qui-
zas, en la umbellata y la punctata.

No hay datos sobre la proteccion de sue-
los bajo las plantaciones. La vegetacion
herbacea es persistente y las laderas son lle-
vaderas de manera que la erosion no es pro-
blema serio. Se ha calculado que una plan-
tacion en crecimiento suelta 15 toneladas de
No se ha hecho

un analisis quimico de las hojas.

hojas por hectarea al ano.
Los arbo-
les se utilizan hasta la ultima pulgada de la
Los
pilotes y troncos sen arrastrados por bueyes.

punta para lena que se saca en carretas,

Rendimientos

Se indica en la Tabla 4 el crecimiento ti-
pico cn buen suelo (umbellata).

CARIBBEAN FORESTER

Tabla 4—Crecimiento de Eucalypius umbellata

Diametro a la altura

Edad dele pecho Altura
eae Cnise iletmons
6 13,2 12,5
12 20,8 19,5
18 33,0 25,0
24 45,9

El crecimiento de robusta en Rio Claro en
buen suelo arcilloso se indica en la Tabla 5.

Tabla 5.—Crecimiento de Eucalyptus robusta

Edad Diametro a la altura del pecho
Anos. Cms.
2 5,6
4 10,4
6 12,4
8 15,2
10 16,8
20 225

La produccion de una especie tipica
(umbellata) basada en mediciones de 3.340
hectareas queda indicada en la Tabla 6.

Tabla 6.—Volumen de rendimiento de
Eucalyptus umbellata

Edad Volumen
Anos Metros cubicos por
hectarea_
6 160,8
a 197,8
8 243,3
9 251,6
10 260,0
12 276,1
15 297,1

Utilizacion

Antes de aserrarlos para madera :os trcn-
cos se ponen a sccar a la sombra por 6 me-
ses, con las puntas pintadas. La madera ce
eucalipto que se produce en Rio Claro es ma-
yormente de calidad inferior. La cortan

JANUARY - APRIL, 1953

con una sierra multiple. El alabeo es serio.
Se necesita mayor investigaciOn para mejo-
rar la utilizacion de arboles grandes propios
para madera.

Las traviesas se cortan de troncos tan an-
chos que rinden dos. Esto reduce la tenden-
cla a rajarse visto que el centro del tronco no
esta en el centro de ja traviesa. Entonces
se hacen tres incisiones de 14 pulgada de
ancho y 12 pulgada de profundidad, longitu-
dinalmente a lo largo de la superficie mas
cerca de la corteza, para reducir la tension
tangencial. Este método controla muy bien
esta tendencia. Estas traviesas se cortan
de duramen que en ninguna especie absorbe
el preservativo. Sin embargo se pintan con
un compuesto de creosota y duran 10 afios
o mas.

Los postes se ponen a secar por 3 meses
para dar tiempo a que todas las rajaduras
naturales aparezcan antes del tratamiento.
Los postes pequenos se hacen de material
verde cortado en cuartos para evitar las ra-
jaduras. El tratamiento preservativo se ha-
ce con sales Wolman usando vacio y presion.
La albura absorbe el preservativo completa-
mente y después de tratada dura de 10 a 25
anos. Con sales Wolman los postes pueden
tratarse verdes si se prefiere. La inmersion
con sales Wolman requiere 7 dias mas 0 me-
nos. las bases de los postes de energia eléc-
trica se someten a un tratamiento de banos
calientes y frios con creosota 8 horas a una
temperatura de 120°C y luego 3 horas al frio.

Pronto se haran pulpa y papel del eucalip-
to en la nueva planta en Jundiai que se esta
construyendo con capital privado. Los acei-
tes y el tanino han resultado demasiado cos-
tosos para extraerlos con fines comerciales.

EXPERIENCIAS CON EUCALIPTO EN
PUERTO RICO

Puerto Rico, como la mayor parte de los
paises de la América Latina, se ha interesado
en el eucalipto y ha ensayado con varias es-
pecies en distintos ambientes estacionales.
Como en el Brasil, el interés local en la es-
pecie se debio en gran parte al crecimiento
asombroso de algunos arboles que habian

85

sido introducidos en la isla posiblemente con
fines medicinales. La perspectiva de gran-
des rendimientos por acre de una variedad de
maderas de especies adaptables a medios es-
tacionales adversos como indican los infor-
mes sobre el euacalipto, tiene que ser de par-
ticular interés para una isla densamente po-
blada.

El eucalipto es de introducci6n reciente
en Puerto Rico. No hay datos que indiquen
su presencia en la isla antes de 1900. Entre
1920 y 1940 el Servicio Forestal de Puerto
Rico introdujo 23 especies. Desde 1940
hasta la fecha la Estacio6n de Experimenta-
cién Forestal Tropical ha introducido 27 es-
pecies mas. Sigue la lista completa de estas
especies.

Bap jenis i. Dsset). EM:
E. alba Reinw.

. albens F. v. M.
bicolor A. Cunn.

. botryoides Smith

. calophylla R. Br.

. camaldulensis Dehnh.
cinerea F. v. M.
citriodora Hook.
cladocalyx F. v. M.
cornuta Labill.
diversicolor F. v. M.
. fastigata

globolus Labill.
goniocalyx F. v. M.
grandis Maiden.
gummifera (Gaertn.) Hookr.
. gunnii Hook.
hemiphloia F. v. M.
kirtoniana F.v. M.
longifolia Link & Otto.
maculata Hook
maidenii

. marginata Smith

. melliodora A. Cunn.

. obliqua L’ Herit

. occidentalis Endl.

. paniculata Smith

. pauciflora Sieba

. paulistana

. pilularis Smith

. polyanthema Schauer

Pes fey Des Bes ey yy eB Ds Bt By Be Bs Bee oe yt by by ty ty by oo

E. propinqua Deane & Maiden
E. punctata DC.

E. racemosa F. v. M.

E. resinifera Smith

E. robusta Smith

. rostrata Schlecht

rubida Deanne & Maiden
rudis Endl.

salicifolia Ca.

1S)

ts

scligna Smith

sideroxyvlon A. Cunn.
stricta Sieb.

stuartiana F. v. M.

. torrelliana F. v. M.

E. triantha Link

E.umbellata (Gaertn) Domin.
E. umbra R. T. Baker

E. viminalis Labill.

by by by by by by by

Adaptabilidad

La adaptabilidad de las especies de euca-
lipto introducidas no se conoce tan bien en
Puerto Rico como en el Brasil. Estas espe-
cies muchas de ellas produjeron demasiado
pocos semillones para que se pudieran hacer
extensas pruebas. Al principio la falta de
foncos para hacer plantaciones en terrenos
publicos hizo necesario la distribucién entre
agricultores interesados. Esto tuvo por
resultado la concentracion en algunas areas
de la isla donde luego muchas especies de
eucalipto resultaron inadaptables. Los da-
tos sobre las plantaciones anteriores a 1932
se perdieron debido al huracan que hubo
ese ano. Muy recientemente se ha empe-
zacdo a acumular datos sobre pruebas sis-
tematicas hechas en ambientes estacionales
prometedores.

Casi todas las plantaciones de eucalipto se
han hecho a elevaciones menores de 500 pies
en las costas o a elevaciones de 2.000 a 3.500
pies en las montanas. La mayor parte de
las localidades en elevaciones bajas tienen un
clima tropical himedo con temperaturas en-

tre 69° y 90°F y una precipitacion de 50 a.

129 pulgadas anualmente. Por lo regular
hay una precipitacion de por lo menos 3 pul-
gacdes durante los meses mas secos, de fe-
‘rero a abril. Los suelos son en general ar-

CARIBBEAN FORESTER

rilla derivada de rocas volednicas sedimen-
tarias.

En las montanas el clima es sub-tropical y
lluvioso con temperaturas entre 50° y 85°F y
una precipitacion de 85 a 120 pulgadas anual-
mente. Los suelos varian de friables a ar-
cilla acida dura, casi siempre profundos y
de origen volcanico.

Los estudios sobre residuos de las _ pri-
meras plantaciones y los resultados de ex-
perimentaciones recientes llevan a un nt-
mero de conclusiones sobre la adaptabilidad
de estas especies de eucalipto en Puerto Ri-
co. Las mas importantes son como sigue:

1. Se aclimatan mejor en las monta-
fas que en las costas. Juzgando
por los informes sobre el alcance de
estas especies, esto es probablemen-
te reaccion tanto a la temperatura
como a la precipitacion.

2. Donde las condiciones climaticas son
satisfactorias estas especies se adap-
tan bien a suelos desgastados por cul-
tivo excesivo.

3. Donde se han adaptado han sobrepa-
sado grandemente en diametro y en
altura a casi todos los demas arboles
nativos o exoticos.

4. Donde se adaptan producen Arboles
de mejor forma que la generalidad de
las otras especies.

5. Ninguna de las especies con que se
ha ensayado, aun bajo condiciones fa-
vorables, desarrolla un dosel suficien-
temente grande en 10 anos para do-
minar la vegetacion nativa, incluyen-
do yerbas, trepadoras y arboles.

Un resumen sobre la adaptabilidad de

varias especies de eucalipto con las que se
ha ensayado mas extensamente aparece en el
Décimotercer Informe Anual de la Estacion
de Experimentacion Forestal Tropical en esta
misma edicion y no necesita repeticion deta-
llada aqui. Solo se describiran algunas de
las relaciones mis favorables entre especie
y ambiente estacional.

En altitudes bajas solo tres especies, alba,
kirtoniana y umbellcta se han adaptado. En
las montanas las bien adaptadas son
Lirtoniana, resinifera y robusta; maculata promete.

JANUARY - APRIL, 1953

Otras especie con las que se han hecho
muchas pruebas pero que no se han adaptado
bien en ninguna parte incluyen /riantha,
botryoides, citriodora, gummifera, globulus
pilularis, propinqua y sideroxylon. Algunas de
estas producen algunos arboles buenos por
acre, pero no forman rodales uniformes.
Otras crecen lentamente. Varias podrian
lograrse si las plantaciones no estuviesen li-
mitadas a suelos degradados por cultivo.

Propagacion

Las dos especies de eucalipto que mas se
siembran robusta y kirtoniana se consideran
faciles de propagar y establecer en medios
estacionales apropiados. La propagacion,
tanto en la costa donde la temperatura
media es de 78°F y la precipitacién de
unas 70 pulgadas, como en la falda de las
montanas a 500 pies de elevacion con una
temperatura media de 74°F y precipitacion
de 120 pulgadas anualmente, ha demostrado
que esta ultima es sitio mas favorable. El
crecimiento es mas rapido y la mortalidad
mas baja. La descripcion que sigue se refiere
a los viveros en las faldas de montanas.

La semiijla se siembra en lechos elevados
de hormigén (Véase Ilus. 1). El suelo en
estos lechos es una mezcla de partes iguales
de arcilia jomica, cachaza y arena gruesa.
Los lechos recién sembrados se protegen del
mucho sol y fuertes lluvias con cobijas de
metal corrugado. La siembra se hace a ra-
zon de una libra por cada 50 pies cuadrados.
Como precaucion contra el salcocho se trata
el suelo antes de la siembra con formalina o
sulfato de cobre y mas tarde con la mezcla
de Caldo Bordeles si es necesario. A pesar
de ésto el salcocho es un problema y se estan
ensayando otros medios de control.

Ksta clase de siembra produce un rodal de
semillones muy densos. El rendimiento por
libra fluctua entre 6.000 y 15.000 semillones.
Al cabo de 8 o 12 semanas en los semilleros
miden de 2 a 4 pulgadas de altura (Véase
ilus. 2). Entonces se trasplantan los semi-
llones durante un periodo de 2 0 3 semanas,
escogiendo los mas grandes primero. El

suelo se moja bien para poder extraer
semillones sin que sufran dano las raices.

Los arbolitos se trasplantan a lechos de
trasplantacion algo altos (Véase ilus. 3) y se
espacian de 3 por 6 pulgadas. La trasplan-
tacion se efecttia con un almocafre. Las
pruebas con tablas de trasplante con estos
diminutos arbolitos no han tenido éxito. Se
pierde poco en el trasplante y rara vez se ne-
cesita rociar. A las 8 0 10 semanas de estar
en los lechos de trasplantacion el material
tiene de 18 a 30 pulgadas de altura y ya se
puede plantar.

Los arboles se trasplantan al campo cen
raiz limpia se espacian de 6 a 8 pies. La
supervivencia fluctua entre 75 y 90 por cien-
to. A pesar del crecimiento rapido del euca-
lipto, hay que desyerbar los arbolitos dos ve-
ces al ano durante 2 0 3 afios para liberarlos
de la vegetacion nativa. Toda la maleza den-
tro de 18 pulgadas del arbol debera cortarse
ayras de suelo. A los 2 afios los arboles mi-
den generalmente unos 2 pies mas que el
resto de la vegetacién y-no necesitan mas
atencion excepto una ocasional limpieza de
trepadoras.

El Excalyptus robusta y kirtoniana en sitios
favorables sufren de pocas enfermedades o
insectos. El problema principal de la orde-
nacion en este aspecto es la muerte de arboles
aislados en el rodal mientras dura. Usual-
mente la mortalidad de este tipo va prece-
dida de marchitez descendiente en las copas
y algunas veces por la exudacion de resina y
por crecimiento de renuevos inservibles en la
base del tronco. En algunos sitios este tipo
de mortalidad mantiene el dosel tan abierto
que prolonga el problema con las trepadoras
y favorece un denso crecimiento de la vege-
tacion nativa que invade la plantacion.

Ordenacion

En Puerto Rico hay menos de 2.000 acres
sembrados de eucalipto. Las plantaciones
son mayormente jovenes y muchas son ensa-
yos dispersos para adaptabilidad al ambiente
estacional. Por eso no han aplicado téc-
nicas de ordenacion como las del Brasil. Sin

88

embargo, las observaciones hechas zefhalan
algunas praécticas deseables.

En los mejores sitios se necesita el aclareo
antes de los 10 anos. El sintoma principal
de esta necesidad es la reduccion en altura y
en tamano de las copas. Nunca se desarrolla
un dosel tan denso que indique la necesidad
de aclareo, tampoco desaparece la vegetacion
herbacea bajo los arboles. El ritmo de creci-
miento de los arboles del dosel superior de-
clina gradualmente con el tamano de copas y
la cosecha de tallos subordinados se hace de-
seable por razones economicas.

La produccion de los maderos mas gran-
des para los cuales parece convenir el euca-
lipto, postes de energia eléctrica, necesita una
retacion de 15 a 20 anos. Durante esta ro-
tacion uno o dos clareos son aconsejables.

La reforestacion artificial con eucalipto
incluvyendo desyerbos y remocion de trepa-
doras cuesta 20 jornales por acre, por con-
siguiente el desarrollo de métodos de regene-
racion natural es deseable. Las perspecti-
vas en este particular no son muy brillantes
porque los semillones naturales de eucalipto
son raros y los renuevos de arboles de 10
pulgadas o mas son débiles.

Crecimiento

No hay datos sobre la productividad del
eucalipto en Puerto Rico excepto en término
de promedios diametrales en plantaciones cu-
yas edades se conocen. Esta en preparacion
una tabla volumétrica que indicara el volu-
men en pies cubicos hasta distintos diame-
tros superiores,

No se conocen todavia las diferencias im-
portantes que haya entre los ritmos de cre-
cimiento de las diferentes especies adapta-
das. En altitudes bajas, plantaciones de 8
anos de alba, kirtoniana y umbellata fluctian
entre 3 y 9 pulgadas de d.a.p. y entre 40 y
75 pies de aitura. En las montanas, planta-
ciones de 13 anos de kirtoniana y robusta fluc-
tuan entre 6 y 16 pulgadas de d.a.p. y entre
60 y 90 pies de altura; la primera es la mas
alta y la ultima la de mayor diametro. Da-
tos adicionales sobre crecimiento aparecen en
el informe anual en esta misma edicion.

CARIBBEAN FORESTER

Un resultado halagador de los estudios
sobre crecimiento es que por lo menoss bajo
una condicion el crecimiento rapido continia
hasta gran altura. En una plantacién de
robusta de 24 anos bien espaciada, en arcilla
lateritica, a 2.000 pies de altitud, el ritmo de
crecimiento diametral anual para 48 Arboles
durante los ultimos 5 anos fué de 0,31 pul-
gadas. Para 15 arboles de mas de 12 pul-
gadas de d.a.p., fué 0,41 pulgadas. Un Arbol
de 16 pulgadas crecio a un promedio de 0,82
pulgadas por ano.

Utilizacion

Hasta ahora la utilizacion del eucalipto no
ha sido problema en Puerto Rico. Los po-
cos arboles que han alcanzado gran tamano
se han usado para pilotes o para lena. Sin
embargo, pucde surgir el problema debido a
que se esta dedicando al eucalipto un area
cada vez mayor y a que no existe localmente
ningun uso tradicional para esta especie, ni
medios para su preservacion. Aqui se ha
sembrado el eucalipto principalmente porque
crece mas ligero y mas derecho en sitios po-
bres que ningun otro arbol. Se presume que
en un area tan densamente poblada como
Puerto Rico, con tan pocos recursos foresta-
les, cualquier madera, con tal que sea unifor-
me y barata y obtenible en cantidades en-
contrara mercado. El desarrollo de tal mer-
cado se necesita para proveer salida a la cre-
ciente produccién y para servir de incentivo
para que se plante mas, particularmente en
terrenos privados.

La madera de robusta y kirtoniana se alabea
mucho cosa que restringe su utilizacion a pi-
lotes, postes y posiblemente pasta de madera.
La madera se pudre en el suelo. Los espe-
ques sodlo duran de 24 a 36 meses, casi ei
mismo tiempo que duran los de maderas na-
tivas.

Las pruebas para tratamientos con pre-
servativos han demostrado que con el mé-
todo de banos calientes y frios, una absor-

‘cién de 6 a 8 libras de ecarbolineum (sales)

por pie cubico es posible. No se conoce to-
davia que durabilidad tendrian los espeques
asi tratados.

JANUARY - APRIL, 1953

Robusta se ha usado recientemente para
pilotaje bajo suelo. Pilotajes de hasta 50
pies de longitud han resultado tan satisfac-
torios en todo respecto como los de pino im-
portado, y parecen soportar el encaje mejor.
Este puede que resulte ser uno de los usos
principales del eucalipto en Puerto Rico.

Conclusiones

De la comparacion de las experiencias
con el eucalipto en Sao Paulo y en Puerto Rico
se desprende un numero de observaciones.
Los mayores conocimientos a mano en Sao
Paulo hacen esta comparacion particular-
mente beneficiosa para Puerto Rico. Las
principales conclusiones quedan aqui apun-
tadas.

1. Menos especies se han adaptado en
Puerto Rico que en Sao Paulo. Sin
embargo las adaptadas en Puerto Ri-
co estan entre las mejores especies de
Sao Paulo.

La investigacion del eucalipto ha me-

ramente empezado en Puerto Rico.

Muchas especies se han descartado a

base de muy pocas pruebas. Se debe

sembrar mas extensamente las mejo-
res especies sin tomar en considera-
cidn previas experiencias. Mejores
suelos debieran probarse pues bien
podrian buenas especies de eucalipto
competir en rendimiento con otras co-
sechas de cultivo. Las especies que
merecen mas plantarse son alba,
botryoides, camaldulensis, triantha

V umbellata.

3. Se debe dar mas atencién a especies,
fuentes de semillas y seleccién en los
viveros. Tanto en Sao Paulo como
en Puerto Rico existen algunas espe-
cies hibridas; éstas deberan identifi-
carse para proteger las fuentes de
semilla de acuerdo con lo descubierto.
Por ahora semillas para pruebas de-
ben obtenerse de fuentes exteriores
confiables. Deben probarse local-
mente los resultados de la seleccién
de semillones uniformes en los vive-
ros.

bo

89

. Las plantaciones de eucalipto hechas

inmediatamente después del cultivo
de cosechas como se hace en Sao
Paulo y también durante el cultivo,
se debieron probar para hacer la re-
forestacién con estas especies mas
facil y atractiva para el agricultor.
Experimentos de ordenacion para de-
terminar los resultados de distintos
regimenes de corta y para explorar
las posibilidades de reproducci6n con
renuevos del tronco son necesarios
para asegurar un rendimiento ma-
ximo.

Se deben desarrollar cosechas produc-
tivas del estrato inferior. La conti-
nua necesidad de desyerbo en Sao
Paulo y la invasion de arboles nativos
bajo las plantaciones en Puerto Rico,
indican la posibilidad de una cosecha
secundaria bajo los arboles. El] ba-
nano y el cafeto merecen probarse.

. Una planta local de preservacion co-

mo la tiene Sao Paulo debe estable-
cerse para facilitar el mercadeo del
gran numero de maderos que pronto
habra en las plantaciones. Se necesi-
tan también estudios sobre las posi-
bilidades de la pulpa con especies lo-
cales si se desea alcanzar la completa
utilizacion de la madera.

APENDICE I

Especies de Eucalipto probadas por la

Companhia Paulista

acaciae forms

acervula Hook (syn. ovata)
affinis H. D. et J. H. M.
alba Reinw.

albens Maiq.

x algeriensis*

am plifolia Naudin.
andrewsi J. H. M.
angulosa

x antipolitensis
baileyana* F. v. M.
bakeri

bicolor A. Cunn.

90

* Especies que se han adaptado muy bien en Rio Claro.

bosistoana F. v. M.

botryvoides*™ Smith

calew J. H. M.

calophylla* R. Br.

camaldulensis* Dehnh. (syn rostrata)
x camaldulensis* x resinifera™
cambageana J. H. M.

cam phera

capitellata* Smith

cinerea EF. v. M.

citriodora* Hook

cladocalyx* F. v. M. (syn. corynocalyx)
coccifera Hook
conica H. D. et J. H. M.
consideniana J. H. M.

cornuta Labill.

dawsoni R. T. B.

dealbata

deanei J. H. M.

decipiens Endl.

decurva

diversicolor F. vy. M.

divas Schauer

drummondi

dumosa (syns. ovata & johnston?)
elacophora F. v. M.
erythronema Turez.

eximina™ Schauer

exserta

falcata

fasciculosa F. v. M.

ficifolia F. v. M.

foecunda Schauer

globulus Labill.

gomphocephala F v. M.
goniocalyx* F. v. M.

grandifolia
griffithsi J. A.M,
guilfoylei J. H. M.

gummifera* (Gaerth.) Hookr.

gunnii*™ Hook

haematoma DC.

hemiphloia F. v. M.

hybrida J. H. M.

imcrassata Lab.

kirtoniana* F. v. M. (grandis* )
kirtoniana F. v. M. (syn. patentinervis)

Rio Claro.
x - hibrida.

CARIBBEAN FORESTER

laevopinea R. T. B.

lehmannii Preiss

leucoxylon F. v. M. (syn. cracilipes)
linearis™ A, Cunn.

lidleyana* (syns. andreana, numerosa)
longifolia Link & Otto.
loxophleba Benth.

macarthuri H. D. et J. H. M.
macrocar pa Hook

macrorhyncha FE. vy. M.
maculata* Hook

maculosa R. T. B.

moideni™

marginata Smith

megaccrpa F. v. M.
melanophloia F. v. M.
melliodora A, Cunn.

microcorys F. v. M.

microtheca F. v. M.

moorei J. H. M. (syn. microphylla)
morisii (morrisii)

muclleriana A. W. Howitt.
obliqua VHerit

obtusiflora

occidentalis* Endl.

ochrophloia F. v. M.

odorata Behr.

oleosa F. v. M.

oranensis*™

paniculata* Smith

patens Benth.

pauciflora Sieb (syn. coriacea)
x paulistana*

pilularis* Smith

piperita® Smith

plenchoniana F. v. M.

platypus Hook (syn. obcordata)
polvanthemos Schauer
populifolia Hook

preissiana Schauer

propinqua* Deane & Maiden
puverulenta Sims (syn. pulvigera)
punctata* DC.

racemosa* F. v. M. (syn. creba)
redunca Schauer

regnans F.v. M.

resinifera®* Smith

robusta* Smith

rubida* Deane & Maiden

JANUARY - APRIL, 1953

rudis* Endl.

salicifaite- (sok. Cav: (syn. amygdalina)
saligna* Smith
salmonophloia F. v. M.
salubris F. v. M.

scabra* (syn. eugenioides)
sieberiana F. v. M.
siderophloia* Benth.
sideroxylon A. Cunn.
smithii* R. T. B.
stellulata Sieb.

Stricta Sieb.

stuartiana F. v. M.
squamosa H. D. et J. H. M.
tetragcna (syn pleurocarpa)
umbellata* (syn tereticornis)
x trabuti*™

triantha Link (syn. acmenioides )
umbre* R. T. Baker
uncinata Turez

urnigcra Hook

viminalis* Labill.

viridis (syn. acacioides* )
woolsiana R. T. B.

91

U. S. DEPARTMENT OF AGRICULTURE
FOREST SERVICE’
TROPICAL FOREST EXPERIMENT STATION
RIO PIEDRAS, PUERTO RICO

VOLUME 14, NOS. 3 AND 4 JULY - OCTOBER, 1953
. ‘ pat

> + @~¢

4
.

Caribbean Forester

El “Caribbean Forester”, revista que el
Servicio Forestal del Departamento de Agri-
cultura de los Estados Unidos. comenz6 a pu-
blicar trimestralmente en julio de 1938 es de
distribucién gratuita y esta dedicada a encau-
zar la mejor ordenacion de los recursos fores-
tales de la region del Caribe. Su propdsito es
estrechar las relaciones que existen entre los
cientificos interesados en la Ciencia Forestal
y ciencias afines encarandoles con los proble-
~ mas confrontados, las politicas forestales vi-
gentes y el trabajo que se viene haciendo pa-
ra lograr ese objetivo técnico.

Se solicita aportaciones de no mas de 20
paginas mecanografiadas. Deben ser someti-
das en el lenguaje vernaculo del autor, con el
titulo o posicién que este ocupa. Es impres-
cindible incluir un resumen conciso del estu-
dio efectuado. Los articulos deben ser dirigi-
dos al “Director, Tropical Forest Experiment
Station, Rio Piedras, Puerto Rico.”

Las opiniones expresadas por los autores
de los articulos que aparecen en esta revista
no coinciden necesariamente con las del Ser-
vicio Forestal. Se permite la reproduccion de

los articulos siempre que se indique su proce-

dencia.

The “Caribbean Forester’, published since
July 1938 by the Forest Service, U. S. Depart-
ment of Agriculture, is a free quarterly jour-
nal devoted to the encouragement of im-
proved management of the forest resources
of the Caribbean region by keeping students
of forestry and allied sciences in touch with
the specific problems faced, the policies in

-effect, and the work being done toward this
end throughout the region.

Contributions of not more than 20 type-
written pages in length are solicited. They
should be submitted in the author’s native
tongue, and should include the author’s title
or position and a short summary. Papers
should be sent to the Director, Tropical Fo-
rest Experiment Station, Rio Piedras, Puerto
Rico.

Opinions expressed in this journal are not

necessarily those of the Forest Service. Any

article published may be reproduced provided
that reference is made to the original source.

- Le “Caribbean Forester”, qui a été publié
depuis Julliet 1938 par le Service Forestier du
Département de l’Agriculture des Etats-Unis,
est une revue trimestrielle gratuite, dediée a
encourager l’aménagement rationnel des fo-
réts de la region caraibe. Son but est d’entre-
tenir des relations scientifiques entre ceux
qui s’interéssent aux Sciences Forestiéres, ses
problemes et ses méthodes les plus récentes,
ainsi qu’aux travaux effectués pour réaliser
cet objectif d’amelioration technique.

On accept voluntiers des contributions ne
dépassant pas 20 pages dactilographiées.
Elles doivent étre écrites dans la langue ma-
ternelle de ’auteur qui voudra bien préciser
son titre ou sa position professionnelle et en
les accompagnant d’un résumé de 1|’étude. Les
articles doivent étre addressés au Director,
Tropical Forest Experiment Station, Rio Pie-
dras, Puerto Rico.

La revue laisse aux auteurs la responsibi-
lité de leurs articles. La reproduction est
permise si l’on présice l’origine.

“The printing of this publication has been approved by the Director of the Bureau of the Budget (August

26, 1953)

VoL. 14 Nos. 3 AND 4 JULY - OCTOBER 1953

Wire @aribbcan Forester

Gomire mts

S Uta @ Heine

Hrostdamage im thesPine;Morest: ~~. = _= 5 2s 93
Arthur Pedersen, Haiti

Onnamentalatnees;im: Puerto Rico. 22222 2s. 2a et 97
H. F. Winters and N. Almeyda, Puerto Rico

New observations of tree growth in Tabonuco Forest _____ 106

Frank H. Wadsworth, Puerto Rico
Some observations from the Eucalyptus Study Tour to

PASTS GONE gee Be PR cate DN aa Od hn A 111
J. W. Duffield, United States

canal Om linGian) plant iNaimes) = 22 6 Se SS 120
D. B. Fanshawe, British Guiana

The forests of Darien, Panama ___-_ Sh, Boas eee oe 128

F. Bruce Lamb, Panama
The inhibitory action of organic chemicals on a blue

Stain hUnCUS. =. LR SES Se oe ae ee 136
F. J. Ascorbe, Puerto Rico

Ouprsemorts conconserve: trees: = = 4 Nk ee 140
Frank H. Wadsworth, Puerto Rico

Arboles en la finca __ SAE SR Rs NOD. _ 146
Santiago A. Vivaldi, Puerto Rico

MOUCHATUOlSeMWhahers 2 ee soos we ee ye ee 152
Luis F. Martorell, Puerto Rico

ie tropical-rain forest’= A review ----- -...-_ 161

Frank E. Egler, United States

oy

te
=
.
4
'
1
,
7
—

— eh

JULY - OCTOBER 1953

Frost Damage in the Pine Forest

ARTHUR PEDERSEN
Formerly Logging Engineer
Societe Haitiano-Americaine de Developpement Agricole
Pine Forest, Haiti

The winter of 1950-1951 in the Pine
Forest of the Morne Des Commissaires region
of Haiti was the most severe since regu-
lar recording of weather data was begun by
the SHADA Forest Division in May, 1945.
The direct result of exceptionally low temper-
atures was the killing of pine seedlings (Pi-
nus occidentalis Sw.) and partial injury to
pine saplings over relatively large areas. A
consideration of the weather factors involved
the type of injury, and the location and
extent of the damage, leads to certain recom-
mendations for forest practices to minimize
future damage.

The Nature of Frost Injury

A summary of information concerning
frost injury to forest trees is given here as
a background for a better understanding of
the situation in the Pine Forest. Trees suffer
direct damage from frost. In warm regions
lacking aregular annual cold period, the
freezing of plant tissues usually results

in death. Microscopical examination shows
that the intercellular spaces normally filled
with air contain ice crystals which were
formed at the time of the freezing of the
plant tissues and at the expense of the sap
of the surrounding cells. This loss of water
from the cells, together with the upset of the
colloidal system, may be regarded as the
cause of death. Death may also result when
the very cold or frozen soil around the tree

roots prevents the tree from absorbing ade-
quate moisture to sustain the transpiration
current. In addition to the direct action of
cold in injuring delicate tissues, it is believed
warm weather before freezing increases

damage while cold temperatures lessen it.

Also that rapid freezing or thawing furthers
injury and repeated freezing and thawing is
more harmful still. Moisture on the plant

just before or during freezing augments the
damage.

Frost injury can occur when the temper-
ature falls below 32 degrees Fahrenheit, al-
though experimental evidence indicates that
it must drop at least several degrees below
freezing before forest trees are affected.
The frost-resisting power of trees has not
been adequately studied. It is known that
frost resistance is developed through natu-
ral selection, since frost-hardy races of some
species exist. The point at which temperature
becomes critically low varies widely, de-
pending on the condition of the vegetation.
Resistance is due chiefly to the inherent pe-
culiarities of the protoplasm and to the ad-
mixture of sugar, oils, or resinous bodies
with it. The amount of water present in the
tissues of a tree plays a leading part; resis-
t-nze in gencral being inversely proportional
v2 water content. The succulent tissue
of new growth, having a large amount of free
water and dilute cell sap, may be severely
injured at temperatures only a few degrees
below freezing; whereas the older, lignified
shoots may be uninjured.

Trees in the juvenile stage are much
more subject to injury from cold than older
trees. This is because in youth the roots and
crown are near the ground surface, where
the extremes in temperature are the greatest.
Later in life, when the crown is farther above
the ground, the roots are deeper in the soil,
the tree is relatively safe. Trees growing
in the shade are not injured as badly as those
growing in direct sunlight. The protection
afforded young trees by an overstory is to
render temperature conditions more uniform
and thus to raise the low extremes. Forest
plantations established on grasslands suffer
damage because the number and intensity of
frosts immediately above ground is greater
than elsewhere. In frost hollows or pockets,
which are low areas in which cold air settles
and cannot drain off, frost injury is severe
and often prevents tree establishment.

Frost injury occurs in many forms. The
most conspicuous is the discoloration, wilting,

94

and death of leaves and twigs. In coni-
fers this takes the form of reddening or
browning and death of needles with a charac-
teristic curling downward of the twig or
bunch of needles. Injury to the cambium is
common. The entire cambium may be killed,
thus girdling and killing the tree, or it may
die in localized areas causing cankers, or if
less severe, abnormal tissue will develop, re-
sulting in a frost ring. Cambium damage is
usually confined to young stems with thin
bark. Bud development is influenced by
frost, and in pine four different types of re-
covery have been classified: (a) bunched,
(b) single leader, (c) double leader, and (d)
multiple leader. Repeated killing of shoots
leads to stunted and bushy trees with de-
creased growth.

Frost can cause splitting of tree trunks,
when there is a sudden drop in temperature
during which the outer wood becomes cold
and contracts rapidly before the inner wood
cools to an equal degree. The cracks usual-
ly originate at the base of the trunk, extend
upward from a few to many feet; splitting
the bark and penetrating deeply into the
wood. Healing of the wood produces callous
growth, repeated opening of the crack by
cold or strains induced by wind will result in
a very pronounced protruding callous growth,
known as a frost rib,

Weather

The foregoing summary of frost injury
indicates that air temperature is the signifi-
cant, measurable factor causing frost damage
to forest trees. The low temperatures at Pine
Forest were recorded during the period from
November to April, which includes the more
or less dormant period for Haitian pine. Since
this period is the dry season, but with diurna’
temperatures high enough for plant growth,
dormancy is considered a result of lack of
sufficient moisture. It is presumed then
that cold air currents coming into contact
with pine foliage resulted in their freezing
and subsequent death.

CARIBBEAN FORESTER

Table 1 summarizes weather data for the
SHADA Forest Division headquarters site at
elevation 5,500 feet.

Table 1. — Minimum temperatures at Pine Forest
aay, oe 25 2
| 1945-46 to 1949-50 Ave.) Winter of 1950-51
Month (ao ai | an ee ran
Average Minimum | Average | Minimum
= as
¥ F on F
November 48.5 ANZ 49.0 38.0
December 48.7 39.0 ATA 38.0
January 46.9 37.8 39.9 24.0
February 47.2 39.5 39.4 27.0
March 48.3 40.0 43.8 34.0
April 49.8 43.5 45.4 34.0

The minimum temperatures for the 1950-
1951 winter may be regarded as exceptional-
ly low when compared to the preceding 5
years. The critical temperature of 32°F was
not recorded until 1949. The 1950-51 aver-
age winter minimum is a full 4 degrees be-
low the previously established mean.

The Damage Observed

The low temperatures all occurred during
the night and invariably the air temperature
rose rapidly with daylight, as the days
during this period were clear and dry. This
caused a rapid thawing of frozen foliage
which perhaps increased the amount of
damage. In the early morning the pine need-
les exposed to the freezing temperatures
were covered with frost. After several such
exposures some of the individual fascicles or
bunches of needles curved downward, the
curved portion being at the point of attach-
ment of the fascicle to the main branch. The
individual needles remained normal in shape.

These curled fascicles, with others in their
normal position, turned reddish brown in
color after several days. Some of the droop-
ing fascicles were not frozen sufficiently to

JULY - OCTOBER 1953

kill the needles and remained healthy and
ereen. Seven months later the bulk of the
killed foliage was still on the trees, having
changed to a dull brown color.

Damage appears to be confined to the foli-
age and affected most severely the pine
seedlings and small saplings up to 3 feet high.
Seedlings under a good cover of larger trees
were only rarely affected. Heaviest damage
ocurred in frost pockets, in the open on flat
- terrain ,and on the savannes, where in some
places 90 percent of the seedlings were kii-
led with practically all of the remaining 10
percent partially damaged.

Larger saplings and small poles, ranging
from 1 to 7 inches in diameter, were heavily
damaged on savannes, on open flat areas,
end in frost pockets. Those under an over-
story or larger trecs were little damaged or
not at all. The damage to this size class was
aiso confined to the foliage; the leaders or
top branches being the parts most frequent-
ly hit, especially in dense stands. However, in
all stands individual trees could be found
with any part of the foliage kilied. On some
areas up to 80 percent of the saplings were
damaged with the percentage of trees total-
ly killed ranging up to 20 percent.

The largest tree seen killed was approxi-
mately 35 feet in height. However, trees of
more than 20 feet in height were rarely kil-
led. Damage to large poles and merehant-
able trees consisted of the occasional killine
of an exposed branch or twig, usvaily at the
base of the crown.

Location of Damaged Siands

In the Spring of 1951 a survey was con-
ducted to locate the damaged stands with a
view to determining the areas involved. It
quickly became apparent that damage did not
occur on sloping ground where there exists
no obstruction to the continued downward
flow of cold air. Using this finding and a
knowledge of the topography of the forest
a survey could be made in a very short time.
The areas covered were those reached by the
road system in the forest supplemented by
mule travel.

95

On Morne La Selle at all elevations dead
tufts of needles were seen here and there on
trees of all sizes, At 8,000 feet elevation
the noticeable injury was confined to scatter-
ed trees of 4 feet or less in heignt. The
severity of injury varied from total kill to
dead branches or individual bunches of need-
les. Often only the leader was killed. Most
of the trees totally killed were 1 and 2 year
old seedlings located in low spots where little
or no overstory existed. As few flat, low
spots are present at this elevation little dam-
age was found, The maximum damage was
found between 5,000 and 6,000 feet elevation,
where the large savannes appear: Pistache,
Philippe, Acani, Boucan Pierre. Heavy dam-
age was found on all of these. The total
area subject to frost injury was found to be
800 acres. Of this total 350 acres were heavi-
ly damaged.

Effect on the Tree and Stand

Each individual tree needs as a minimum
number of needles to maintain protosynthe-
sis. Below this amount the tree cannot pro-
vide enough food to sustain life. Many trees
only partially damaged will succumb for this
reason. Others with enough living foliage re-
maining to sustain life, but with lowered re-
sistance, will eventually die through tke in-
vasion of insects, fungi and viruses, Dam-
aged trees surviving all this will grow, but at
a much slower rate that formerly until a
normal crown is again Geveleped. Also, those
trees with the leader killed will be deformed
by having lateral branches curving upward
to form the new leader or epicormic buds
forming multiple leaders.

The resulting stand made up of such trees
will for several years be grow’ng at a sub-
normal rate and some of the growth will be
put on by trees that at maturity will be of
little or no value for lumber. A stand with
most of the trees killed must be re-establish-
ed naturally by the surrounding trees. Such
an area has had 5, 10, or 20 years production
destroyed.

96

One possible beneficial effect of the frost
must be noted, even though of minor impor-
tance. In a few dense stands where the dam-
age was not great, such damage as occurred
has accomplished a natural thinning where
too many stems existed for best growth to
take place. The damaged trees have been
given a handicap in the race for survival and
will now survive for a time in the understory.
Their presence here will force the neigh-
boring dominant trees to shed their lower
branches earlier in life than otherwise.

Logging and Frost Damage

Any logging, no matter how light, will ex-
pose the smaller trees to greater tempera
ture changes, with a consequent increase in
damage when the terrain is flat or depres-
sed. The entire removal of the overstory will
result in widespread damage, as may be seen
in the areas both east and west of the Pine
Forest headquarters site. Small trees were
especially susceptible where patches of the
overstory were harvested. The trees, ac-
customed to shade presumably were damaged
easily. Seedlings established on old skidroads,
even in dense stands, were damaged while
the adjacent stand was untouched. On heavily
logged areas where bracken fern has taken
over the site, that portion of the tree above
the top level or the fern was sometimes da
maged but those portions beneath the fern
were free of damage.

Recommendations

To attain the objectives of forest man-
agement, frost injury must be held to a mini-
mum. The only practical means by which the
forest manager can do this is through wise
selection of harvesting methods. The mana-
ger must recognize that under certain condi-
tions of weather definite areas within the
forest are especially susceptible to frost inju-
ry. These areas must be delineated and so cut
as to provide maximum protection to the
young stands.

CARIBBEAN FORESTER

The ideal to strive for on the susceptible
areas is a uniform overstory of the older age
classes. In the majority of the stands an un-
even-aged condition is present. Such stands
should be cut on a selection basis. This con-
sists of the removal of individual trees. A
sufficient number of trees must be left to
provide protection to the young stand under-
neath, but at the same time giving these
trees enough space por proper development.
Where even aged stands are now on the
ground, under no circumstances should any
large groups of trees be removed. For a work-
ing rule it may be said that any clearcut
areas should be kept to 1 acre or less in
extent. For areas deficient in the older age
classes, the growing stock must be increased
until the desired overstory is attained, Where
unavoidable frost damage occurs, the dam-
aged trees that are deformed may have to be
removed at intervals to allow the better form-
ed trees to gain dominance.

The open, flat areas called savannes are
another matter. Most of these savannes are
devoid of tree cover, but some have a good
cover, Boucan Pierre being one. Frost may
here be one of the main factors prohibiting
the normal establishment of trees. If this is
true, it is possible that a cover can be estab
lished, but such an event would be a slow
process, consisting of a gradual encroach-
ment of the forest onto the savanne from all
sides. Such a process would be a matter of
generations, and therefore as little cutting as
possible should take place on the savannes.
The heavier the overstory left on the border
the more protection will be given the seed-
lings moving onto the savanne.

No damaged areas are at this time in
need of artificial reforestation. If damage
occurs in the future, planting would be one
possible means of bringing the area back in-
to production with the least possible loss of

time.

JULY - OCTOBER 19538

"D
~]

Ornamental Trees in Puerto Rico

H. F. WINTERS AND N. ALMEYDA
Federal Experiment Station
Mayaguez, Puerto Rico

Although there are not always clear-cut
distinctions an ornamental tree may be de-
fined as any tree planted or left for decora-
tive purposes. This would exclude trees plant-
ed purely for orchard, forestry, or windbreak
purposes, although some of the same species
might be used in another place as ornamen-
tal trees. Many trees which are considered
desirable in one section are weeds in another.
Ornamental trees need not bear conspicuous
ilowers. In fact, the most valued temper-
ate climate species such as the maples, elms,
and oaks have inconspicuous flowers. This is
also true of many tropical trees.

For the Tropics and Subtropics a riuch
wider range of tree species is available than
in the Temperate zone. There is also much
more variety in form if we include the palms
and bamboos. A broad classification accord-
ing to growth habit and form might be set
up as follows:

1. Palms. — Some palms are too small
to be classified as trees. The ro-
yal palm is a good example of a
tree size palm.

2. Bamboo. — Grasses which grow to
tree size usually with § soft
feathery foliage.

3. Coniferous evergreen. — Not so com-
mon in the tropics as in temper
ate zones.

4. Broad-leaved trees

a. Deciduous. — even in the tro-
pics many trees shed theic
leaves and stand bare for pe-
riods varying from one week
to several months. Some trees
such as the roble amarillo
(Tabebuia glomerata Urb.

flower during this period.

b. Evergreen. — leaf shed is
gradual throughout the year.
A good example is the indian
laurel. (Ficus nitida Thum.)

The esthetic value of trees has been long
recognized and they have figured prominent-
ly in the religious and folk ways of practical-
ly all peoples. Trees are larger, stronger, lon-
ger lived than man. The ancients workshiped
them, performed ceremonies before them,
and hung offerings on their trunks. Our own
literature is rich in tree lore. The Bible
speaks frequetly of trees, we read of “yule
logs,’ we have our Christmas tree and Arbor
Day ceremonies.

The landscape would be dreary without
trees. The monotony of plains and deserts is
broken by streams and oases where trees may
be found. The predominant color of trees,
green, is pleasing to the eye and the shade
cast by trees is associated with coolness. In
addition many trees are of value because of
their flowers and few sights can equal that
of a grove of flowering trees.

Trees may serve many useful purposes.
In our cities we try to hide ugly sights by
planting them. Here they may be planted
along the streets for shade and to soften the
outline of buildings. Our cities are also
sprinkled with parks and plazas where trees
are the predominant plants. When so planted
trees give relief from summer sun and add to
the recreational value of parks. Trees provide
homes for birds and animals for which we
have an attachment. Perhaps the greatest use
of all is that trees are the most important
components of the landscape and the princi-
pal tool of the landscape gardener. They give
dimension and profile to the landscape.

In the landscape design all trees are or-
namental but may serve a variety of purpo
ses. The first of these is framing. Trees may

98

be used to frame the view of a dwelling or
business buildinz as it is presented to the
public, ie., the view from the road. Likewise,
most landscape views may be improved by
framing with trees. Framing focuses the vi-
sion upon the desired scene. Such a tree
would ke an unpruned Indian-laurel (Ficus
nitida).

Trees may be grown to screen undesira-
ble views of streets, factories, or neighbor-
ing buildings. For this purpose a densely fo-
liaged tree which retains its foliage through-
out the year would be most desirable. In
Puerto Rico the “palo de maria” (Calophyllum
antillanum Brit.) might be used. Trees are
often planted to soften the architectural lines
oft a home or building rather than to screen
it from view. In such a location the jacaran-
da (Jacaranda acutifolia H. & B.) might be util-
ized.

Often trees are used to accent the en-
trances to buildings or grounds and large
trees as a background for the landscape pic-

CARIBBEAN FORESTER

ture. Another important use is to border
walks and drives, for shade, an to outline the
route. Trees will also mark property bounda-
ries effectively because of their permanent
nature .

Ornamental trees are especially well suit-
ed for specimen plants to be grown on lawns
and near houses. In such locations choice of
the subject is very important. Often a flower-
ing tree is desired, but one should be careful
to select a species which will not litter the
ground continously with fallen flowers, seed
pods, or leaves, and which will not grow
quickly out of bounds or remain |<afless for
extended periods.

The following tree species have been se-
lected because of their ornamental value in
Puerto Rico. Not many of them are native
to the island but some such as the flambo-
yant (Delonix regia Bojer) have been so widely

planted that they are considered to be nati-
ves.

Scientific Name

Commen Name

Rem arks

Acrocomia media Cook Puerto Rico Acroecomia

Large spiny palm, pinnate leaves

Areca catechu L. Betel-nut palm

Paima de areca

Large orange to red fruits

Arenga finnata Gomuti sugar palm

Palma de azucar

Very large pinnate leaves

Caryota urens L. Teddy fishtail palm

Palma de cola de pescado

Curious wedge-shaped leaflets

Chrvsalidocerpus lutescens Wendl. Golden-fruited palm

Areca

Clumps of slender to sturdy trunks

Coconut
Coco

Cocos nucifera L. Falling nuts, dangerous

Dictvosperma album var. rubrum

Wendl & Drude

Red palm Graceful, pinnate leaves

JULY - OCTOBER 1953

Scientific Name

Euterpe Globosa Gaertn.

Gaussia attenuata (Cook) Beccari
Livinstona chinensis R. Br.
Phoenix canariensis Chabaud
Roystonea borinquena Cook

Sabal causiarum (Cook) Bec.

Thrinax microcarpa Sarg.

Bambusa reultiplex

Bambusa tulda Roxb.

Bambusa vulgaris Schrad

Araucaria excelsa R. Br.

Cupressus spp.

Pinus spp.

Podocarpus coriaceus L. C. Aich.

Thuja orientalis L.

Adansonia digitata L.

Adenanthera pavonina L.

Albizzia lebbeck (L.) Benth.

Common Name

Mountain palm
Palma de sierra

Puerto Rican llume palm
Llume

Chinese fan palm
Palma de borbon

Canary island date palm
Datiles de jardin

Puerto Rico royal palm
Palma real puertorriquena

Puerto Rican hat palm
Palma de sombrero

Brittle thatch palm

Palma de escoba

Bamboos

Hedge bamboo
Bambu enano

Tulda

Common bamboo
Bambu

99

Remarks

Feather palm native to higher
mountains

Slender, small red fruits

Rather common, fan leaves

Large, pinnate leaves

Tall, stout

Stout trunk, fan leaved

Slender, palmate

Dense growing. Good for tall
foliage

Straight, stout culms, feathery
hedges

Attractive feathery foliage

Narrow-leaved Evergreens

Norfolk-island-pine
Pino Norfolk
Cypress

ciprés

Pines

Pinos

Yacca Podocarpus
Caoba del pais

Oriental Arborvitae
Tuyas

Fir like foliage

Symetrical branching.

Much branched, formal looking.
Needle-like leaves

Spreading branches

Usually cone shaped trees.

Broad-leaved Trees

Baobad

Sandal beadtree
Coralitos

Woman’s tongue
Lengua de mujer

Stout trunk, white flowers

Fern-like foliage

Cream colored flowers

100

Scientific Name

Aleurites moluccana (L.) Willd.

Andira jamaicensis Urb

Artocar pus altilis

Artocarpus heterophyllus

Bauhinia monandra Kurz

Bauhinia purpurea L.

Bauhinia variegata L.

Bixa orellena L.

Brassaia act‘nophylla

Byrsonima crassifolia (L.) H.B.K.

Calophyllum antillanum Brit.

Celycophyllum candidissimun

Cananga odorata

Cassia fistula L.

Cassia grandis L. F.

Cassia multijuga Rich.

Cassia nodosa Hamilt.

Cassia siamea Lam.

Cassia spectabilis (DC) Brit. & Rose

Casuarina equisetifolia Forst.

Cavanillesia platcnifolia

H.B.K.
Ceiba pentandra (L.) Gaertn.

Common Name

Candlenut
Nuez de la India

Cabbage Angelin tree
Moca

Breadfruit

Pana

Jackfruit

Jaca

Napoleon’s Plume
Mariposa

Purple Bauhinia
Palo de orquideas

Orchid tree
Palo de orquideas

Annato
Achiote

CARIBBEAN FORESTER

Remarks

Cream colored flowers
Dense panicles of lavender
flowers

Attractive foliage

Large fruits borne on main
branches and trunk.

Showy pink flowers

Large, showy flowers

Showy lavender flowers

Pink flowers, prickly fruit

Australian umbrella-tree Flowers in terminal red spikes

Byrsonima
Maricao

Calaba beautyleaf
Palo de maria
Degame

Ylang-ylang
Nanilan

Golden shower
Canafistula

Pinkshower Senna
Cana-fistula cimarrona

Senna

Jointwood Senna
Acacia rosada

Bombay blackwood

Calceolaria cassia
Acacia amarilla

Australian pine
Pino

Cuipo

Silk-cotton tree;
Kapok, Ceiba

Yellow flowers -

Shiny, leathery leaves

Lacy white flowers

Extremely fragant flowers

Showy yellow flowers

Dark pink flowers

Yellow flowers

Showy rose-pink flowers

Attractive yellow flowers

Yellow flowers

Intersting branching, showy fruit

Pink flowers, 5-winged capsule

Large, tall, thorny

JULY - OCTOBER 1953

Scientific Name

Chrysobalanus icaco L.

Chrvsophyllum cainito L.

Chrysophyvllum oliviforme L.

Cinnamomum cCéssia

Clusia rosea Jacq.

Coccolobis uvifera (L.) L.

Cochlospermum vitifolium Spreng.

Cordia nitida Vahl.

Cordia sebestena L.

Couroupita guianensis Aubl.

Crescentia cujete L.

Cybistax donnell-smithi

Delonix regia (Bojer) Raf.

Didymopanax morototoni (Aubl.)
Dene.

Dillenia indica L.

Enterolobium cyclocarpum

(Jacq.) Grisb.

Erythrina berteroana Urban
Erythrina glauca Willd.
Erythrina poeppigiana ( Walp.)

O. F. Cook
Eucalyptus spp.

Common Name

Icaco; cocoplum
Icaco

Caimito starapple
Caimito

Satinleaf starapple
Caimitillo
Cassia-bark tree
Canela cimarrona
Pitch apple

Cupey

Seagrape

Uva de playa
Yellowsilk shellseed
Rosa imperial
Glossy cordia
Capa colorada

Geigertree cordia
San Bartolomé

Cannonball tree
Bala de canon

Calabash tree
Higuero

Primavera

Royal poinciana
Flamboyan

Matchwood
Yagrumo macho

India Dillenia
Dilenia

Elephants Ear
Oreja de mono

Dwarf coral tree
Machete

Coralbeam

Bocayo

Bucare Coralbeam
Bucare

Eucalyptus
Eucalipto

101

Remarks

Giossy green foliage

Leaves shiny green above, copper
brown beneath

Silver to brown-backed leaves
Dense foliaged tree

Leathery leaves, attractive

flowers

Rounded, red-veined leaves, clus-
ters of reddish fruits

Showy yellow flowers

Showy red fruits

Orange flowers

Fruit has offensive odor

eee hard-shelled fruits

Yellow flowers when leafless

Showy scarlet flowers
Leaves clustered at the ends of the

branches

Large, white, magnolia-like
flowers

Becomes very large

Dwarf tree, coral flowers
Flowers cream to orange

Orange scarlet flowers

Usually sparse foliage

102

Scientific Name

Eugenia spp.

Ficus benjamina L.

Ficus eldstica Roxb.

Ficus retusa

Ficus sintenisii Warb.
Ficus stahlii Warb.

Gardenia jasminoides Ellis

Gliricidia sepium (Jacq.) Steud.

Grevillea robusta Cunn.

Guaiacum officinale L.

Guaicum sanctnum L.

Guarea trichilioides L.

Haematoxvlon campechianum L.

Hernandia sonora L.

Hibiscus tiliaceus L.

Ixora macrothyrsa

Jacaranda acutifolia H. & B.

Jacaranda filicifolia

Kigelia pinnata DC.

Lagerstroemia speciosa (L.) Pers.

Lucuma multiflora A. DC.

Common Name

CARIBBEAN FORESTER

Remarks

Eugenia
Hoja menuda

Benjamin Fig

India-rubber-tree
Palo de goma

India laurel Fig
Laurel de la India

Higuillo prieto
Jaguey

Cape-jasmine
Gardenia

Madre
Madre de cacao

Silkoak
Roble de seda

Lignumvitae
Guayacan

Holywood Lignum vitae

«€ \ « A
Guayacan

American muskwood
Guaraguao

Logwood
Campeche

Mago

Linden Hibiscus
Emajagua

Malay Ixora
Bola de nieve

Sharpleaf Jacaranda
Flamboyan azul

Fernleaf Jacaranda
Jacaranda

Sausage-tree
Arbol de salchichon

Queen Crapemyrtle
Reina de las flores

Lucuma
Jacana

Dense foliaged trees

Long, drooping branches orange
to red fruits

Shiny, leathery oblong leaves

Often trimmed to umbrella shape

Becomes very large
Very large, spreading

Large, white, fragant flowers
Pale pink flowers

Fern-like foliage

Blue flowers, yellow fruit

Branches spreading or pendulous.
Blue flowers
Large evergreen tree

Pale yellow flowers
Black fruits with longitudinal
groves

Flowers yellow to orange red

Small white flowers in clusters
Blue flowers

Blue flowers

Curious hanging fruits
Lavender flowers

Glossy foliage

JULY - OCTOBER 1953

Scientific Name

Magnolia grandiflora L.
Magnolia portoricensis Bello

Magnolia splendens Urban

Mammea americana L.

Mangifera indica L.

Melaleuca leucadendron L.
Melaleuca genistifolia
Melia azedarach L.
Montezuma speciosissima
Sessé & Moc.

Moringa oleifera Lam.
Ochroma lagopus Sw.
Pachira aquatica Aubl.
Parkinsonia aculeata L. Sp.
Peltophorum inerme (Roxb.) Naves
Polygala cowellii Blake

Pimenta racemosa

Pithecellobium dulce (Roxb.) Benth.

Plumeria alba L.
Plumeria rubra L.

Posoqueria latifolia (Lam.) R. & S.

Pterocarpus indicus Willd.

Common Name

103

Remarks

Southern Magnolia
Magnolia

Magnolia
Acibar

Laurel sabino

Mamey

Mango
Cajeput-tree
Cajeputi
Bottie-brush

Chinaberry
Lilaila

Maga

Horseradish-tree
Ben

Balsa
Guano

Guiana-chestnut
Pachira
Jerusalem-thorn
Palo de rayo
Sogabark Peltophorum
Falmboyan amarillo
Violet-tree

Palo de tortuga
Bayrum-tree
Maiagueta

Manila tamarind
Guama americano
White frangipani
Alheli blanco

Red Frangipani
Alheli rojo
Panama Posoqueria
Café de Panama

Burmacoast Padauk
Palo de pollo

Large, white, fragant flowers
Shiny leaves, showy flowers
Large tree, showy flowers

Shiny, leathery leaves
Brownish fruits

New foliage usually red

Exfoliating paper bark
Red flowers of the characteristic

bottle-brush type

Lavender flowers

Showy red flowers

Fern-like leaves, white flowers
Large leaves and fiowers
Flowers large and very showy
Green twigs, almost leafless
Attractive yellow flowers

Very conspicuous purple flowers
Glossy green leaves

Drooping branchlets, red fruits
Large foliage, white flowers
Pink flowers

Very fragant white flowers

Numerous, small, yellow, fragant
flowers

104 CARIBBEAN FORESTER

Scientific Name Common Name Remarks

Ravenala madagascariensis Travelers-tree Giant fan of leaves

J. F. Gmelin Palma de viajero

Samanea saman Willd. & Merril Raintree Large spreading tree
Dormil6n

Sapindus saponaria L. Soapberry Round, brown-skinned fruits
Jaboncillo

Sesbania grendiflora Agati Sesbania Large white or red edible flowers
Gallito

Sideroxylon foetidissimum Jacq. False mastic Flowers in clusters

Tortugo amarillo

Spathodea campanulata Beauv. African tuliptree Large orange-scarlet flowers
Tulipan
Stenolobium stans Seem. Florida yellowtrumpet Clusters of yellow, slightly

fragrant flowers

Sterculia apetala (Jacq.) Karst Coolie Sterculia Large spreading tree
Anacaguita

Swietenia macrophylla King Honduras tnahogany Tall; dense foliage
Caoba de Honduras

Swietenia mahagoni Jacq. West Indies Mahogany Shiny, dark-green leaves
Caoba dominicana

Syzygium cumini (L.) Skeels Jambolan Clusters of small, black,
Yambolana edible fruits

Syzygium jambos Roseapple Yellowish, roselike odor,
Pomarrosa edible fruits

Syzygium malaccense Malayapple Deep-crimson, edible fruits

Pomarrosa americana

Tabebuia glomerata Urban Trumpet-tree Yellow tlowers when leafless
Roble amarillo

Tabebuia pallida Miers Whitewood trumpet-tree Pink shades
Roble blanco

Tamarindus indica L. Tamarind Fine dense foliage
Tamarindo

Tectona grandis L. Teak Flowers in airy panicles
Teca

Terminalia catappa L. Tropical almond Red winter foliage
Almendra

Thespesia populnea (L.) Soland Seaside mahoe . Yellow flowers
Emajaguilla

Triplaris americana L. Longjohn ant-tree Cerise flowers

Triplaris

JULY - OCTOBER 1953

Scientific Name Common Name

Warscewiczia coccinea (Vahl.) Kl. Orange-gold chaconia

Remarks

Long vermilion sprays

Trees to be Avoided Especially
for Planting near Dwellings

Euphorbia cotinifolia Euphorbia
Hura crepitans L. Sandbox-tree
Havilla
Hymenaea courbaril L. Courbaril
Algarrobo
Jatropha curcas L. Barbados-nut
Tartago
Sterculia foetida L. Hazel Sterculia

Anacaguita

Sap extremely irritating

Sap extremely irritating

Fruit stinks

Fruit poisonous

Flowers stink

CARIBBEAN FORESTER

New Observations of Tree Growth
in Tabonuco Forest

FRANK H. WADSWORTH

Tropical Forest Experiment Station
Puerto Rico

The tabonuco forest type constitutes the
most important relic of natural vegetation in
Puerto Rico. Although probably less than
1,000 acres remain in virgin condition, more
than 25,000 acres of this type of forest still
retain much of their original composition.
These areas he between 500 and 3,000 feet
of elevation. The largest remaining blooks of
forest are in the Sierra de Luquillo and the
Sierra de Cayey.

The tabonuco type has been so named
because of the prominence of the tabonuco
tree (Dacryodes excelsa Vahl.) within it. In
some virgin forests this species made up as
much as 30 percent of the basal area and
more than half of the timber volume. The
type is classified as tropical moist forest by
Holdridge (3) and as lower montane rain
forest by Beard (1).

The importance of this forest type to
Puerto Rico goes far beyond its benefits in
producing timber and conserving soil and wa-
ter on the 25,000 acres it now covers. It ap-
parently is the climax vegetation on no less
than one third of the land surface of the is-
land. At least 300,000 acres within this zone,
because of the need for protection of the soil,
should always remain tree covered. Thus the
results of investigations within the remain-
ing small area of this type can serve as an in-
dication of possibilities and a guide to prac-
tices on a very much larger area.

The tabonuco forest originally was proba-
bly the best developed in the island. Virgin
stands on good sites range between 100 and
110 feet in height, and contain three tree
strata. The upper stratum is not continuous
but consists of emergent groups or indi-
vidual trees with diameters ranging up to 6
feet. The second stratum, at 60 to 70 feet,
produces a closed canopy, beneath which the

less continuous third stratum is found. The
forest is mixed, with 33 species on an aver-
age acre, and a total of about 175 species re-
corded for the type.

Past forestry investigations in the tabo-
nuco type have been largely preliminary in
nature. Outside Puerto Rico the type is limit-
ed to a few thousand acres in the Lesser An-
tilles, so no large fund of information about
it is available from elsewhere. The ecologi-
cal studies of Beard in the Lesser Antilles
(2), however, have provided us with descrip-
tions of the type which are so detailed that
they are helpful in distinguishing primary
from secondary forest in Puerto Rico. De-
scriptions of the type in Puerto Rico have
also been published (9) as have reports on
the first efforts to regenerate and manage
the forest (8, 70, 11). Preliminary data on
tree growth and volume increment have also
appeared (4).

Past studies of growth within the tabo-
nuco type have concerned both virgin and
cutover forest. In the virgin forest, where
great stand density may develop, and where
increment tends to be offset by mortality,
the diameter growth of individual trees was
found to be slow, averaging about 0.09 inch
per year for the entire stand (7). It was also
shown that diameter growth rates of indi-
vidual trees differ with their crown position,
those which are dominant and codominant
tending to grow 50 percent more rapidly than
those which are intermediate or suppressed.
Conservative openning up of such stands by
partial cuttings has been found to increase
average diameter growth 50 percent or more,
even for those trees which remain in the
same position in the canopy.

More recently studies of the relative
growth of different species within the forest
were made (5, 7). Comparable average

JULY = OCLOBER 1953

erowth rates derived for a number of species
showed marked differences, but data have
usually been inadequate to establish mathe-
matical proof of tne validity of these observ-
ed differences. By 1950 six years of growth
records in a 1.8-acre plot had provided an
adequate basis for such a comparison with
intermediate trees of five prominent species.
The data for four of these species, tabonuco
(Dacryedes excelsa Vahl.), ausubo (Manilkara
bidentata (A.DC.) Chev.) motillo (Sloanea ber-
teriana Choisy), and masa (Teiragastris belsa-
mifera (Sw.) Kuntze), showed no significant
difference in growth rate from that of the
stand as a whole or from each other. A fifth
species, yagrumo hembra (Cecropia peltata L.)
was growing somewhat more rapidly (5 per-
cent significance) than the rest of the stand.

Repeated remeasurement of individual
trees has shown clearly that despite these
apparent similarities in growth rates, mark-
ed differ ences do exist in the growth rates of
some individual trees within these groups,
that is, among trees of the same species and
position in the canopy. An attempt made in
1951 (6) to determine visible factors which
were related to this growth variability was
unsuccessful. Correlations with diameter of
the trees, and the apparent vigor of their
crowns were not close. A third factor, the de-
gree of competition, as measured by the ag-
gregate basal area of all trees within 25 feet,
unexpectedly showed virtually no correlation
with growth.

The Need for Additional Growth Information

The few past investigations of tree
growth in the tabonuco type generally con-
firm relationships which were to be expect-
ed on the basis of widespread experience else-
where. For instance, it was to be expect-
ed that virgin forest growth would be slow,
that trees dominating the forest might grow
more rapidly than those suppressed within
it. On the other hand, these studies have con-
tributed new knowledge in showing the order
of magnitude of these relationships under
local conditions. Moreover, past growth data,
even when incomplete, have helped appraise

107

the potential productivity of different trees
as components of managed stands.

The measurement of the growth ratcs
of trees is no isolated objective. The growth
rate is one measure of the productivity of a
tree, but, far more important, it reflects the
ageregate productivity of that complex of
factors which make up what we call site, or
environment. A knowledge of this relative
growth response to different environmental
conditions is basic to silviculture, which in
part is a process of finding and bringing to-
gether productive trees and productive envi-
ronment.

More complete knowledge of tree growth
response to different environments in the
tabonuco forest has at least three important
applications in Puerto Rico.

1. To show possible economic returns
from forestry on the 150,000 acres of
similar lands which are unsuited to
other than tree crops yet are virtual-
ly iddle. This will serve as an incen-
tive for the practice of forestry by the
farmers who own this land.

2. To make possible the intensification
of the management of the tabonuco
forest type on public lands. The re-
moval of overmature an mature trees,
those of poor form, and inferior spe-
cies, is already largely accomplished
on accessible areas. Further improve-
ment requires more critical appraisal
of the potential growth rates of the
trees remaining.

Co

To point the way to better manage-
ment of coffee shade forests, which
cover nearly 200,000 acres and most
of which are located within the tabo-
nuco forest zone. The growth of the
coffee shade trees, and possibly also
that of the coffee itself, is influenced
by the same environmental conditions

that control forest tree productivity.

Additional studies of three growth, as
related to environment, can point to the opti-
mum productive stand density, the best tree

108

species, the maximum size of tree to produce,
and the significance of minor soil and other
environmental differences.

New Observations

The fact that diameter growth measure-
ments of numerous trees within the tabvonu-
co forest showed differences which were not
clearly related to the more obvious character-
istics of environment or of the trees them-
selves, and the fact that these growtn dif-
ferences were of an order of magnitude
which would materially affect productivity
pointed to a need for closer study of theze
trees.

A complete study of the environment of
an adequate number of trees to provide final
conclusions as to the importance of all envi-
ronmental factors in tree growth within the
forest is highly desirable. Because of the
complicated and very long-term nature of
such an investigation, it was decided as a
to study in detail those trees
which represent growth extremes, in order
to determine whether new visible indexes of
growth rates might be discovered. This was
done with 199 trees in four permanent sam-
ple plots comprising an area of about 6 acres
within both virgin and secondary tabonuco
type forest in the Luquillo Mountains,

Trees of Unusually Rapid Growth

The study of factors related to unusual-
ly rapid growth was based upon those trees
growing at a rate of 2 inches in diameter
per decade in virgin forest and 3 inches in
diameter per decade in cutover forest. A total
of 152 trees qualified for this study. They
make up the most ravid growing 5 pereent
of the trees in the plots.

A number of visible environmental fac-
tors were found related to this rapid growth.
One outstanding exception is position in the
canopy. A total of 95 trees, or 63 percent, are
intermediate or suppressed trees. These rapid
growing trees are not more dominant than
the others. This finding bears out the pre-
viously discovered weak relationship be-
tween growth rates and position in the cano-
py.

CARIBBEAN FORESTER

A clear relationship with topography was
evident. Two-thirds of these rapid growing
trees are located on the brink of steep slopes,
on ridges, or on steep upper slopes. Rapid
growing trees of tabonuco, granadillo, va-
grumo macho, palo de matos, masa, and lau-
rel avispillo tend to be limited to this site.
On the other hand, rapid growing trees of
yagrumo hembra, guaba, guaraguao, motillo,
ausubo, and manzanillo are limited to the
concave lower slopes and valley bottoms.
Trees which are cff their preferred sites,
even when other environmental factors ap-
pear favorable, are usually growing slowly.
Differential drainage requirements appar to
be the most probable explanation.

The effects of catastrophes, such as
windfalls are reflected in the growth of ma-
ny trees. One-seventh of the rapid growing
trees are located within 10 feet of rotten
stumps. Many of these are growing in an
environment which otherwise does not appear
favorable to rapid growth. The death of a
nearby large tree evidently relieves the in-
tense competition for nutrients to a degree
that is reflected in the more rapid growth of
adjacent trees for many years thereafter.

There is some evidence to indicate that
trees growing in locations subject to an ex-
ceptionally heavy accumulation of litter are
materially benefited. Seven of these fast
erowing trees are very heavily suppressed
but are growing directly down the slope from
large trees which drop so much litter that a
layer 6 inches deep or more is constantly
present.

Several characteristics of these trees
themselves appear to indicate their rapid
growth. A total of 108, or nearly three-
fourths of those studied are of exceptionally
good form, many with perfect boles almost
to the terminal. This is one of the most uni-
form characteristics of rapid growing trees.
The average diameter of these fast growing
trees is 7.8 inches, or only about 1 inch lar-
ger than that for the stand as a whole. The
range is wide, from 2 to 25 inches d.b.h. This
group thus includes all sizes of trees.

JULY - OCTOBER 1953

Four specics were much better represen-
ted in this group of rapid growing trees than
the others. Whereas this group includes 5
percent of all tre:s, it includes 38 percent of
the granadillo (Buchenavia capiiata Vahl.)
Hichl.) 20 percent of the yagrumo hembra
(Cecropia peltcta L.), 18 percent of the matos
(Ormosia krugii Urban) and 14 percent of the
yagrumo macho (Didymopanax morototoni
(Aubl.) Dene). These differences appear suf-
ficiently large to indicate a more rapid aver-
age growth rate for these species.

One-third of the rapid growing trees had
exceptional bark, usually very smooth and
free of lichens or mosses. Rapid growing trees
of palo de matos have porous bark. On tabo-
nuco the bark is often a rosy tint. Although
these bark characteristics ere not found on
all rapid growing trees they were never seen
on those which are not growing rapidly.

Trees of Unexpectediy Slow Growth

The study of factors related to unexpected-
ly slow growth was based upon those trees
(excluding palms and understory species)
which appeared vigsrous at the beginning of
the period but are growing 0.6 inch in di-
ameter per decade or less. This study was
limited to 3 acres of virgin forest. Only 47
trees, or 2 percent of the total stand quali-
fied for this study.

The study of slow-growing trees yield-
ed less than that of rapid-growing trees Le-
cause it was more difficult to judge as <o
which of many apparent adverse factors
might be the most significant. The most
constant adverse environmental factor affect-
ing these slow growing trees is extreme sup-
pression. Five out of every eight were so
completely overtopped as to receive almost
no direct sunlight at any time of the day.

Certain characteristics of the trees
themselves are apparently typical of slow
growth. Only 5, or one-eight of these trees
are now vigorous in appearance. The larze
deep green leaves of many of these trees were
criginally thought to be a sign of vigor, but
apparently they are only a response to shade,

169

and mean that death is not imminent, but
not necessarily that growth is rapid.

The average diameter of these trees,
4.5 inches, is 2 inches less than that for the
stand as a whole. All are less than 16 inches
in diameter. This bears out observations else-
where that the slowest growing trees in a
stand are generally small.

The inconsistencies between diameter
growth and visible growing conditions led to
a theory that possibly there was an error in
using diameter growth as the sole index of
tree increment. It was conceived that possibly
diameter growth and height growt® rates ars
not directly related. For example, rapid
height growth mignt take place in response
tc an opening in the canopy at a time when
no reserve was left for diameter growth. The
few data collected in this study tend to reject
this theory. Twelve of these slow-growing
trees made during a 5-year period an annual
©,erage height growth of 5.8 feet, compared
with an average of 19.7 feet for 43 trees
growing at the rate of 1 inch or more in di-
ameter per decade.

Other visible factors apparently related
to slow growth are small or thin crowns,
characteristic of 22 percent of the trees, and
disease or accidents which affected the same
proportion .

Additional Observations of Environmenia!
Relations

The preferences of several species for
either the ridges or the valleys is shown even
more clearly in composition than in growth
rates. The species which show strongest
preference for the ridges are comparatively
rare in the valleys, and vice versa. Even
slight local concavity or convexity of the
surface seems to have a profound effect upon
the composition of the seedlings, saplings,
and larger trees.

The effects of hurricanes and windfalls
in the virgin forest were evident in many
parts of the plots. Apparently several large
trees in the area now within the plots were

110

blown over in either the 1928 or the 1932
hurricane. Many rotten stumps and logs lying
parallel are still visible. Along these logs, in
the area wnich must have been the opening
created by the windfall, the stand now, some
20 years later, is still dominated by species
such as camassey (Miccnia sp.), yagrumo
hemtra (Cecropia peltata L.) and achiotillo,
(Alckornca latifolia Sw.), all near the low end of
the successional scale. The camasey and ya-
grumo, now about full size and subject to in-
creasing competition from the sides, are gro-
wing slowly. Seedlings of more advanced spe-
cies are only beginning to invade beneath
tiem ,indicating the long period required for
the restoration of a composition similar to
tnat before the catastrophe.

The large trees are almost invariably
lecated beside rock outcrops on the ridges.
This fact leads to the belief that root anchor-
age in such rocks is a prerequisite to hurri-
cane resistance.

The organic matter in rotten stumps and
logs is apparently an important source of
nutrients for the existing stand. Several
rotten stumps which were opened were
thoroughly penctrated by tree roots some of
which had grown vertically upward for 3 feet
to reach the tops of such stumps.

The buttresses of large trees of some
species, such as motillo and eranadillo, form
on the upper side of the tree effective litter
traps. The litter held by these buttresses may
be more than a foot in depth. Active voots
are abundant in such areas and some of these
arise directly from the lower parts cf tne but-
tresses.

Conclusions

A few new relationships have been un-
covered which serve as indicators of tree
growth rates in the tabonuco forest. The
most important of these may be described as
follows:

1. Trees of any size or position in the
canopy may be growing rapidly.

2. Several tree species show a clear

preference for either moist or well

CARIBBEAN FORESTER

drained sites within the forest and
generally do not grow rapidly off
these sites.

3. Trees of rapid growth usually are of
excellent form, and have smooth boles
and clean bark which is free of lichens
and moss.

rc

Unusually large deep green leaves
generally are not an indicator of rapid
growth of suppressed trees - such as
they are for dominant trees.

5. Height growth tends to be most rapid
in trecs of rapid diameter growth, s9
the latter is probably a good index of
total increment.

Probably the most significant single
finding of this study is the discovery of
strong microenvironmental preferences in
many species, as is shown by separate study
of the upper and lower slopes. More detailed
study of this relationship might well lead to
deliberate modification of the forest compo-
sition to conform with the site preference of
each species within it. If the trees are pro-
duced only on their chosen sites within the
forest, it may then prove possible to induce
all trees to grow at a rapid rate, since it was
shown here that trees of all sizes and posi-
tions in the canopy may grow rapidly under
favorable conditions. The result could con-
ceivably be a tripling of tree growth rates
within this forest.

Literature Cited

1. BEARD, J. 8S. 1944. Climax vegetation
in tropical América. Ecology 25:127-158.

75 ln Ree ___1949. The
vegectation of the Windard and Leeward

Islands. Oxford Forestry Memoirs 21.
Pp. 192:

3. HOLDRIDGE, L. R. 1947. Determina-
tion of world plant formations from sim-
ple climatic data. Science 105 (2727):
367-368.

4, TROPICAL FOREST EXPERIMENT
STATION 1950. Tenth annual report.
Caribbean Forester 11(2) :59-80.

natural

JULY - OCTOBER 1953

5: TROPICAL FOREST EXPERIMENT
STATION. 1951. Eleventh annual report.
Caribbean Forester 12(1) :1-17.

6 1952. Twelfth annual

report. Caribbean Forester 13(1) :1-21.

1953.
nual report. In press.

8. MARRERO, J. 1948. Forest planting in
the Caribbean National Forest. Past ex-

perience as a guide for the future. Carib.
Forester 9(2) :85-148.

Thirteenth an-

“I

telat

. WADSWORTH, F. H. 1951. Forest
management in the Luquillo Mountains I.
The setting. Carib. Forester 12(3) :93-114.

ics)

10. 1952. Forest

management in the Luquillo Mountains,
ill. Selection of products and silvicultu-
ral policies. Carib. Forester 13(3):
93-119

ik : 1947. Growth in the
lower montane rain forest of Puerto Rico.
Carib. Forester 8(1) :27-35

Some Observations from the Eucalyptus
Study Tour to Australia’

J. W. DUFFIELD

Institute of Forest Genetics

California Forest and Range Experiment Station

The Eucalyptus Study Tour, sponsored
by the Food and Agriculture Organization of
the United Nations and the Commonwealth
of Australia, occupied fully the months of
September and October, 1952, and took the
participants into all the states of Australia.

The genus Eucalyptus dominates all the
principal forest and woodland formaticns of
Australia, with the exception of the rain
forests. The harvesting and conversion of
forest products in Australia is likewise prin-
cipally a matter of harvesting and converting
eucalypt products. Therefore, a complete ac-
count of the forest resources and industvies
studied in the course of the tour would
amount to a fairly complete survey of the
forest situation in Australia. This is not the
purpose of the present report, which will te
jimited to those species and procedures which
may be of value in the forest economy of cer-
tain .selected areas.

Ecology
Climate
Eucalyptus forests are restricted to
three principal areas in Australia (7) all of
which receive at least 30 inches of rainfall

(78) annually. These areas are the southwest
corner of Western Australia, Tasmania, and
eastern Australia from the southeast tip
of South Australia along the coast of Victo-
ria, New South Wales and south and central
Queensland. A fourth eucalyptus forest. in
a region of less than 20 inches of rainfall,
lies along the Murray River between Victoria
and New South Wales. This forest depends
cn the almost annual flooding of the Murray
River for the major part of its water supply,
and is known as riverain forest, being com-
posed entirely of one species, E. camaldulensis
Dehn.

Within this forest area are wide climatic
veriations associated with latitude and
altitude, but generally the climate is control-
led by proximity to the coast. Variations in
temperature are, therefore, rather minor.
Few areas experience temperatures lower
than 10°F., and such temperatures are found
cnly in parts of Tasmania and the Austra-
lian Alps in New South Wales. The signif-
icant variations are in amount, distribution

Extracted from an official report on the Study Tour

112

and effectiveness ,of precipitation. The ex
tremes in amount are 30 and 60 inches. West-
ern Australia and parts of the forest area
in South Australia and southwestern Victoria
have winter rainfall. Most of the forest areas
of eastern Australia have uniform rainfall
(9). Only in central Queensland are eucalyp-
tus forests found in a region of true summ=r
rainfall. Effectiveness of precipitation is
gauged in Australia by the ratio of precipi-
tation to evaporation, and that rainfall which
equals or exceeds one-third of the evapo-
ration from a free water surface is consider-
ed effective (14). All of the eucalyptus forest
area falls within the area in which 5 months
per year have a P/E ratio in excess of 1/3
and all of the higher-grade commercial
forests, with the exception of the Jarrah and
Tuart forests of Western Australia, fall with-
in the area in which there are 9 or more
months annually with P/E greater than 1/3.

Soils

The soils of the eucalyptus forest area
are podsols or podsolized (74). This classifi-
cation caused some discussion on the part of
some of the silviculturists from Europe, since
the typical Australian podsols do not show
the clearly developed horizons of the classi-
cal northern European and North American
podsols. The litter and humus layers are often
very slight or completely lacking in Aus-
tralian podsol profiles, and the demarcation
between the leached layer and the layer of
deposition is seldom distinct.

Vegetation Types

Broadly described the eucalyptus forest,
in the sense in which the term is used here,
occurs in two formations, the dry sclerophyll
forest and the wet sclerophyll forest (1/4)
In Western Australia, the only wet sclero-
phyll forest is the Karri (Eucalyptus diversico-
lor) forest on the plateau of the extreme
southwest. The finest forests of eastern Aus-
tralia, mountain ash and the blackbutt-blood-
wood-gum forests of New South Wales, are
also classified as wet sclerophyll formations.

CARIBBEAN FORESTER

In both formations, eucalypts generally are
deminant, but are by no means the only
woody plants. Acacia, Ccsuarina, tree ferns,
and palms, as well as trees of Myrtaceous
genera (related to Eucalyptus) such as Trista-
nia, Syncarpia, Angophora, and Melaleuca are
abundant in many of the eucalypt forests.

The Genus Eucalyptus

The genus Eucalyptus is found in Aus-
tralia, Celebes, Moluccas, New Guinea, New
Britain, New Ireland, Timor and the Phillip-
pines. Although many genera of the Myrta-
ceae are found in New Zealand, eucalypts are
not native there. The great majority of spe-
cies of eucalyptus are extra-tropical, the
greatest number —more than 300— being
found in New South Wales. One rather ambi-
tious work on the geographic distribution of
the eucalypts has been commenced (5), and
separate Maps snowing species distributions
in Western Australia and Victoria have been
published. Species distributions may general-
ly be characterized as rather localized. Only
two species are found in both Western and
Eastern Australia. These are E. camaldulensis
Dehn. and £. transcontinentalis Maiden.

Related to the distribution of species is
their occurrence in the various forest forma-
tions. In general, although a region may con-
tain a large number of eucalyptus species, a
given forest stand rarely contains more than
six or eight — usually fewer. This is true
even in rather complex stands such as are
found in northern New South Wales and
Queensland where the complexity is largely
due to admixture of rain forest species in
the eucalypt forest.

Within eucalypt forests, plant succes-
sion is not particularly apparent; rather a
large forested area is likely to be mosaic of
fairly simple eucalypt associations, the com-
position of each apparently a function of lo-
calized soil and climatic conditions. In the
moister areas of Victoria and Tasmania, how-
ever, one can see eucalypt forests being suc-
ceeded by rain forest.

JULY - OCTOBER 1953

The taxoncimy of the genus is inherentiy
difficuit. Tre political, cultural and botanical
histery of Australia includes few features
calculated to mitigate this difficulty. Tre
extent of Australia, its sparse population and
relatively underdeveloped transportation sys-
tem, and the firm adherence to “states
rignts” by each of the states, have all render-
ed a comprehensive treatment of the genus
difficult. The Critical Revision of Maiden was
the last attempt. Blakely’s “Key” (3) based
on Maiden’s work remains the only usable
treatment of the genus as a whole. Biekely’s
Key sets forth a scheme of subg<neric rela-
tionship groupings, with sections and sub-
sections based on anther characters and
series and sub-series based on other re-
productive and vegetative characters. To
what extent Blakeley’s scheme corresponds
to phylogeny is difficult to determine. The
smaller categories, such as sub-series, might
well be equated to species by botanists less
inclined to accord species rank to each
variant type.

Nomenclature is no less a problem than
taxonomy. One finds that numerous entities
change their names as one pursues them
across state boundaries. Though stable and
uniform nomenclature is not particularly es-
sential for taxonomic purposes, those con-
cerned with utilization prefer intellectual
exercises of a different sort, and have estab-
lished a set of standard nile EUS, which
often correspond to the “common” names
(6). Common names are particularly confus-
ing to the newcomer to Australia, since many
of them appear to refer to totally unre-
lated northern hemisphere genera, such as
ash, box .apple, and gum. Western Australia
is a welcome exception; its principal euca-
lypts have aboriginal or local epithets, such

Karri, jarrah, tuart, wandoo, marri, mallet,

gimlet and tingle.

Utilization

An excellent illustrated account of euca-
lypt utilization has recently been published
(19) by R. F. Turnbull of the Division of

115

Forest Products, Commonwealth Scientific

and Industrial Research Organization. There-

fore, the present account will touch principal-

ly on those aspects of utilization of particular

interest in the actual or potential eucalyptus
growing regions of Sub-Tropical Mexico and
the Caribbean.

Aside from the ornamental and protec-
tion applications of eucalyptus, the chief po-
tential importance of this group for the area
in question appears to be in the production of
high-grade hardwood lumber. As a source of
pulp, eucalypts appear at a disadvantage in
competition with conifers because the euca-
lypts have relatively short fibers. Therefore,
eucalypt pulps are customarily siisencnted
by conifer pulps, koth domestic and imported,
in Australian paper mills.

The utilization of eucalyptus for limber
is beset by two principal difficulties, both of
which have long been familiar to mill oper-
etors. These difficulties are the growth stres-
s<és, common to all hardwoods (10), but most
prozounced in young, rapidly-grown euca-
lypts ,and seasoning difficulties, particularly
collapse. Tiemann early and clearly recog-
nized these difficulties (17), and pointed out
that unwisely chosen species and small young
trees might account for much of the difficul-
ty in seasoning California-grown eucalyvis.
A third cause of degrade in the timber of
many Australian-grown eucalyptus is the
presence of gum veins. Jacobs (Ji) has

shown that this defect, which may te
extremely serious in certain species and
localities, is most frequently an indire_t

consequence of fire.

Research

It is not appropriate to attempt a review
of the whole field of eucalyptus research in
Australia. Some botanical, silvicultural, and
utilization studies in progress may be of
interest, however.

Botanical study proceeds along two lines.
First, conventional taxonomic studies which
result in name changes and rapid increase in
the number of named entities. This tenden-
cy, annoying enough elsewhere, is particular-
ly frustrating in Australia, where a number
of botanists work more or less independent-
ly on the same genus. Recently, a number of
workers, who appear to be more interested
in exploring relationships than in naming
each variant entity, have started to study the
genus experimentally. Pryor (16) has star-
ted a program of openpollinated progeny
testing of hybrid swarms and of controlled
hybridization, working with the highland
species of New South Wales and Victoria.
Similar work is being done in Tasmania.

The development of a punched-card sort-
ing field key to the genus, with a card for
each of 638 named entities is one of the more
interesting current stuaies. This is largely
the work of Norman Hall of the Common-
wealth Forestry and Timber Bureau. Several
sets of this key were being tested by the vari-
ous State forestry organizations during the
tour, and early reactions were generally fa-
vorable.

Silvicultural studies of interest deal large-
ly with techniques for improving the com-
position and quality of fire-damaged and im-
properly-logged stands and with growth stu-
dies. The latter are of particular interest in
the warmer, uniform rainfall areas where
ring formation is weak or is otherwise an
unreliable criterion of age. Fire is a widely
used silvicultural tool in many of the Aus-
tralian forests. Sometimes its use appears to
be not too discriminating, but many instances
are quite instructive. Regeneration ap-
pears to be less of a problem in many euca-
lypt forests than in most North American
forests. Often the control of regeneration is
the problem, and thining studies are a promi-
nent feature of Australian silvicultural re-
search. Very little planting of eucalypts has
been done in Australia, but a number of good
small plantations may be seen in various
parts of the country.

CARIBBEAN FORESTER

A conspicuous gap in biological research
in the eucalypt forests is in entomology and
pathology. In the foothill forests, insects
take what appears to be a large toll in incre-
ment, while in many of the forests, termites
and heart-rotting fungi destroy large vol-
umes of high-grade timber. There appear to
be a wide species differences in the extent
of loss due to these causes,

The program of research in eucalypt uti-
lization carried on by the Division of Forest
Products of the Commonwealth Scientific
and Industrial Research Organization at the
Forest Products Laboratory in South Mel-
bourne is quite broad. The staff includes a
number of highly qualified people working on
basic problems as well as a number who are
making contributions of immediate applica-
bility in industry.

One field of studies being conducted at
the Laboratory deals with the relation be-
tween wood anatomy and properties. The
complex inter-relations between growth
stresses, brittle heart and reaction wood
constitute one phase of this study. Studies of
the structural basis for collapse during
drying are under way. Relatively little study
seems to be devoted to low-temperature sea-
soning techniques, such as solvent and azio-
tropic seasoning.

Recommended Species Trials

It would be unwise to recomend any eu-
calyptus species for use in any given area
where these species have not already been
cultivated. As California experience with E.
globulus has shown, even successful growth
does not guarantee the harvest of a useful
product. All recommendations, therefore, are
for tests of species. For the sake of concise-
ness, these recommendations are incorporat-
ed in Tables 1 and 2.

Recommendations for species tests in
certain sub-tropical areas in Mexico and in
the Caribbean region are based on rather
slight personal acquaintance with these re-
gions. Some of the recommendations are of a
highly hypothetical nature, for example the

JULY - OCTOBER 1953

suggestion that E. bosistoana should be tried
in subtropical Mexico. Most of the species
listed were seen in the field by the writer.
Species not seen, or briefly seen and indis-
tinctly recollected include clba, deglupta, gom-
phocephala, macarthuri, and torelliana. In all
cases however, personal notes and recollec-
tions have been backed up by reference to
two principal sources (2, 3).

There are several omissions from these
tables which will be immediately apparent to
anyone familiar with eucalypts. These are
E. globulus and viminalis, omitted because they
are so well, and, in general, unfavorably,
known in this country. There is also E. citrio-
well known as an ornamental and
source of essential oils in California and else-
where. E. maideni has been omitted as it is
quite similar to E. globulus.. No doubt the
writer’s selections will be subject to many
justified criticisms. Some of the species
included may not seem of outstanding value.
Some species were suggested not for any
particular merits other than the possibility
that they might form an acceptable type of
vegetative cover in an area dominated by
chaparral.

dora,

Tables 1 and 2 are intended only to serve
as a basis for the studies which should
precede programs of eucalyptus tests in the
various regions discussed. To facilitate the
use of Tables 1 and 2, Table 3, which lists
more familiar synonyms and common names,
has been compiled. Before actually proceed-
ing with such tests, the individuals planning
them would be well advised to familiarize

115

themselves with the outcome of eucalyptus
introductions in other regions of generally
similar climate and economy. Table 4, based
largely on reports submitted to F.A.O. by
the participants in the tour gives a
general impression of experience in
the western hemisphere with eucalyptus.
The species in this table are limited to those
included in Tables 1 and 2. Successful surviv-
al, denoted by “S” in Table 4, obviously does
not imply a successful introduction; a species
which survives may grow slowly, have poor
form, or yield products of little value in a giv-
en economy. Nevertheless, reference to
Table 4 may be a useful starting point in eva-
luating various species as candidates for
testing. Following this, the reports on which
pertinent sections of Table 4 are based should
be consulted.

A word of caution should be added con-
cerning the identity of eucalyptus species
mentioned in reports from countries where
this genus is exotic. Identification of euca-
lypts is difficult, especially when materials is
taken from young plants or in new environ-
ments and when the person making the iden-
tification is not generally familiar with eu-
calypts in their native habitats. A rather
striking example of mis-identification ap-
pears in Zon and Briscoe’s study of Euca-
lypts in Florida (27). In this publication, two
excellent protographs, captioned E. resiniferu
show this species with strikingly smooth
white bark. In fact, E. resinifera is most read-
ily recognized by its “rough, reddish fibrous”
bark, “‘persistent to the small branches” (3).

CARIBBEAN FORESTER

‘WIOF pOos ‘poom atqeinq sax W z q 19 T ‘PIO DIDYIQuin
: : é : MS UN DUSIDS
YMors prdey ‘sops TeLp ‘“aaySIpT sox W g da aS st ON 10 “pI® ‘og
as seat e-7 q ca 1 ‘DID ‘ON DUDIYIALO}
‘poom od4q , Aursoyryp,, — W e-7 q 6G 1 DIO DAI{MISIL
‘aTqRanp ‘Suo1s poom — Y I v 99 7 DID onbuidosgd
‘WHOF poos ‘YZMoIS prdey — YW e-2 q 9¢ T ‘PIO stapynpd
‘SU0T]S POOM ‘SvaIe AIP “pout st SMOIN — Y T Vv OL 1 ‘PIO DDN IUDg
“‘SBVOIB OUITRS-qns [RISvOD UL SMOIN, — — = = = W ‘PID DAOD{IZINUL
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‘So[puvY [00} TOF pasn ‘Ysn0y poom — H e-% q-V 29 1 ‘PIO DID]NIDUW
‘poom o[qvanp ‘YyMOoTs MOTG = — — a — se W ‘DId DAd{uwuns
*pooM podio[od-9sor ‘YAMOIS pidey — UW FP 9 IP T ‘PIO sIpuDssd
‘yyMors pider Ajowoemyxqy — — — ax — T sourddyiyg DIqdn}s9p
“ULLOT poos ‘YAMOLS pidey soz YW z q 29 T ‘PIO DUDIZIOII
= =. = = — W wave ‘ended ‘Ouwty, Dq]D
‘osng deg Jeo yyBueng | Aqsuaq oe peos ureyqo 03 é
. = ea Selde
‘ayo “sosn ‘soryaedoad [eledg. te ARG aod], ene gee i
sotytodord poor, AYTRIOT
(6) : (8) ze) (9) (g) (F) (s) (2) (1)
(SSuIpvoy ULUNTOD Jo UoTeUR[dxo IOF TT os8vd a0g)
Ureqque) [Rodory, UL SuIyse} 10} papuswUMOdaa Satsadg — ‘T a[qQvI,

116

ti

aes I [ Vv Vv “Vv OM OOPUDar
“ULLOF POO — POOM o[ Gun SOA IN 6 ad 19 ‘I “PLU DIDI]IQUn
= — ar al = al ‘PID ‘ON DUDIJIAO}
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“ULLOF Pood ‘YAMO.LS pLdey = Y e-Z ra 9G rT ‘PIO seappnyid
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YAMOLd prdvt APOWoIXG] — — — — _— rT sourddipiyg pad npsop
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= = = = = vaue ‘ended “tow DQ )D
an) ce ==> = —$—________
3 ‘osng “dug qavo TT
om nee | yydu9.4g ASU poos ureyqo o4
fs ‘ayo ‘sosn ‘sorjtodoad [Uroodg AVY LQRan(y, WALOJ YoryM Wor soloadg
8 soljtodoad poor ge AY BOOT
3
Sa a ae ee (2) me) (gy ) Ghee on 3) RGD)
'
> (sduipvoy uLunjoo Fo UoLywUR[dxo LOZ QTL odud vag)
B OOLXOPA, [WOdOA}-Gng UL SULYSO} OJ PopuowoOdT SoLodg — °*Z [GL

118

CARIBBEAN FORESTER

Table 1 and 2 Column Headings and Footnotes

(1) Name as given in Blakeley (3). See

Table 3 for synonymy and common

Average Properties of Timbers in Four
Strength Groups at 12 Percent Moisture

: Content
SNL oe ; Modulus of Modulus of Saehe Shent
(2) Where several localities are noted, this rupture elasticity ‘Daralell —gtrenzth
implies that various origins should be eh a ii ee eee SR TM mse y
tested. State abbreviations are:
' A 24,000 3,000,000 12,000 2,500
N.S. W. — New South Wales B 20,000 2,600,000 10,000 1,900
Vic. — Victoria a 16,000 2,200,000 8,000 1,600
: : D — 12,000 1,900,000 6,000 1.100
Tas. — Tasmania (6) Resistance to heartwood decay and ter-
Qld. — Queensland minate attack. Class 1 should give 20
W.A. — Western Australia years’ service as poles or ties. Class 4
S. 0A, — South Australia _. is the least durable.
ACT ee: Capital T (7) Refers to susceptibility to attack by Lyc-
.C.T. — ee ian Capital Te- fae heeuede
(3) Based on personal notes and on (2, 3) Hi Ulehly suecephivle
oS) R Ss O . “
(4) Densit t : M — moderately susceptible
ensity in lbs./cu. ft. at 12 percent mois- R ae ry
¥ : 5 : — rarely susceptible
ture content. Data from Div. For Prod. be :
CSIRO [ > immune 8 ae
: . (8) Based on list of species in which pro-
(5) Strength groupings are those adopted nounced collapse occur (7).
by the Div. For. Prod. CSIRO, as shown (9) Based on (2, 3) and personal notes and
in the following tabulation: observations.
Table 3. — Synonymy and common names of eucalyptus
; discussed in this report
Gracias Most familiar Standard trade Other common
pecies
synonym name 1/ names
elha Reinw.

bosistoana F. v. M.
cloeziana F. v. M.

deglupta Blume naudiniana F.v M.
diversicolor F. v. M. colossea F. v M.
gomphocephala DC aan
grandis Maid.

gummifera ( Gaertn.)

Hochr.

Maid

macarthuri Deane ae

macrorrhyncha F. v M.
maculata Hook. =
marginata Sm. =

microcorys F. v. M.

multiflora Poir. robusta Sm

paniculata Sm. drepanophylla F. v. M 2/
pilularis Sm.

propinqua Deane

& Maid.

resinifera Sm. a
saligna Sm. —

Coast grey box —_
Gympie messmate ——s
Mindanao gum
Karri ——
Tuart a

Rose gum Flooded gum
Red bloadwood

Camden wooly butt

Red stringybark ———
Spotted gum ae
Jarrah as
Tallowwood —
Swamp mahogany 22 sew
Grey ironbark eee
Blackbutt ee
Grey gum eae
Red mahogany

Sydney blue gum ssc ealll

torelliana F. v. M. tereticornis Sm. Cadagi
unbellata ( Gaertn.) Forest red gum Blue gum
Domin. ~ yedunca var. elata Wandoo
Blakeley (Schau.) Benth. BEES

/ CSIRO. (1948) Nomenclature of Australian Timbers.

a/ Not strictly a synonym, but the name for a slightly dictinct’ Queensland Penn:

JULY - OCTOBER 1953

Table 4. — Summary of successful outcomes
of eucalypt introductions into the
Western Hemisphere based on re-

ports of four participants

F.A.O., except as noted.

Species

Brazil 1/

Chile

Uruguay

to

9/

alba
diversicolor
gomphocephala
grandis
gummifera
macrorrhyncha
maculata
marginata
mMmICrOCOrys
multiflora
pilularis
resinifera
saligna
umbellata
wandoo

nn |

RANRRNRANRADM |

1/ Incomplete listing—for complete information see works of Nava-

rro de Andrade (13).

2/ See Tuset (20).

Bibliography

1. ANONYMOUS. 1942. Collapse and the
reconditioning of collapsed timber. Com-
monwealth of Australia. Council for Sci.
and Ind. Res., Div. of For. Prod. Trade

Circular No. 20, 23 pp.

currence of the eucalypts.
wealth of Australia. Forestry and Timber

Bureau. 105 pp. Mimeo.

3. BLAKELEY, W. F. 1934. A key to the
Eucalypts. 339 pp. Sydney.

1952. The natural oc-

Common-

~]

10.

lle

12.

13.

119

. BRYAN, L. W. 1947. Twenty-five years

of forestry work on the island of Hawaii.
Hawaiian Planters’ Record 51:1-80.

. CARTER, C. E. 1945. The distribution

of the more important timber trees of
Eucalyptus.
Forestry Bureau. Atlas No. 1. 8 pp. 34
pl.

the genus Commonwealth

. COMMONWEALTH SCIENTIFIC AND

INDUSTRIAL RESEARCH ORGANIZA-
TION. 1948. Nomenclature of
lian timbers, Trade Circular No. 47, Part
Ill. pp. 45-82.

Austra-

. CROMER, D.A.N. 1951. The forest

resources of Australia and their potent-
ialities. Australian Jour. Sci. 13:130-134.

. ELLIS, L. M. 1925. Eucalypts in New

Zealand, N. Z, State Forest Service. Cir-
cular No. 20. 14 pp.

. GENTILLI, J. Australian climates and

resources. Whitcombe and Tombs. Syd-
ney. 333 pp.

JACOBS, M. R. 1945. The growth stres-
ses of woody stems. Commonwealth For-
estry Bureau, Bulletin No. 28, 67 pp.

(No date). Field studies

on the gum veins of the eucalypts. Com-

monwealth Forestry Bureau. Bulletin

No. 20. 36 pp.

KOTZE, J.J. and C.S. HUBBARD. 1928.
The growth of eucalypts on the high veld
and southeastern mountain veld of the
Transvaal. Union of South Africa. Forest
Department, Bulletin No. 21. 59 pp.

NAVARRO DE ANDRADE, E. 1941.
The eucalyptus in Brazil. Jour. Heredity
32:215-220.

120

14. NOBLE, N. S. 1950. The Australian

environment. Melbourne. 183 pp.

1b JAVARI, A. and A; .DE. PHILIPPIS:
1941. La sperimentazione di especie
forestali esotiche in Italia. Annali della
Sperimentaziones Agraria 38:1-646.

16. PRIOR, L. D. 1951. A genetic analysis

Eucalyptus species. Proc. Linnean Soc.

N.S.W. 76:140-148.

17. TIEMANN, H. D. 1913. Is Eucalyptus suit-
able for lumber? Proc, Soc. Amer. For.
8:301-316.

CARIBBEAN FORESTER

18. TIMCKE, E. W. 1949. The climate and
meteorology of Australia. Commonwealth
of Australia, Official Yearbook No. 38.
pp. 30-70.

19. TURNBULL, R. F. 1950. The taxonomy,
harvesting, processing and utilization of
Eucalyptus trees in Australia. Econ. Bot.
4:99-131,

20. TUSET, R. 1951. Panorama forestal del
Uruguay. Silvicultura 1:13-28.

21. ZON, R. and J. M. BRISCOE. 1911. Eu-
calypts in Florida. U.S.D.A. Forest Ser-
vice Bull, 87.

Akawaio Indian Plant Names

D. B. FANSHAWE
Deputy Conservator of Forests
British Guiana

The Akawaios are a branch of the Ca-
rib tribe of Amerindians related to the Ma-
cushis, Arekunas, Patamonas, and true Ca-
ribs. They speak a dialect of a language com-
mon to them all and can readily understand
each other. A list of plant names for the Ma-
cushi, Arekuna, and Patamona branches par-
ticularly would be almost identical with the
present akawaio list. The Carib list is some-
what different.

The akawaios migrated to British Guia-
na from the West Indian islands at some
undefined period and passed along the coast
rather than up the Orinoco River. They were
unable to drive out the Arawaks who were
settled immediately behind the coastal belt
so passed through their territory and settled
in the forest region behind.

At the present day they inhabit the Pa-
karaima plateau west of Ayanganna on the
upper Mazaruni River and its tributaries the
Kako and the Kukui. They may however, be

found working on the gold and diamond
fields and timber grants north and east of
this territory as far north as Bartica at the
junction of the Mazaruni and Essequibo
Rivers .

The akawaios are, in common with other
Amerindian tribes, of a retiring nature with
short, thickset bodies and rather unattrac-
tive, coarse features. They are shorter and
slighter in build than the true Caribs. They
were, possibly still are, sly and underhand in
their dealings with other Amerindian tribes.
Like other Amerindians they have weak
constitutions and usually die young.

The Pakaraima plateau is a region of
flat, gently sloping or undulating plateau
between 1,200 and 3,000 feet above sea level
broken by flat-topped sandstone mountains
which rise in bold escarpments from 3,500
feet to 7,000 feet. The plateau is formed by
horizontally bedded sediments —sandstone,
conglomerates, quartzites, and shales—

JULY - OCTOBER 1953

hundreds of feet thick intruded by dykes and
sills of gabbro and dolerite. The sandstones,
conglomerates, and quartzites produce an in-
fertile coarse white sandy soil, the shales and
the volcanic intrusives tropical red earths
some of which are reasonably fertile.

Rainfall varies from 150 inches per annum
on the north east escarpment face to per-
haps 100 inches per annum on the borders
with Venezuela and Brazil. As a result the
area is largely forest covered and the few
savannas appear to be natural and not fire
induced. Savannas occur on the upper Maza-
runi between the Karaurieng Creek and the
mouth of the Kukui, between the Kamarang
and the Kako Rivers near the Venezuelan
border, between the Kako and the Kukui
Rivers around Roraima and near the Yene-
zuelan and Brazilian borders.

The forest belt consists largely of two
main types —rain forest on the tropicai red
earths and dry evergreen forest on the coarse
white sands. The rain forest is largely domi-
nated by Mora bukea (Moragonggrijpii) with
a few areas of Clump Wallaba (Dycymbe alto-
sonii) forest. The Mora Bukea forest scarcely
differs from its lowland counterpart except
in composition. The Clump wallaba forest is
typical of the plateau and only occurs in the
lowlands as an invasive type. Dry evergreen
forest is more varied from Wallaba (Eperua)
forest hardly differing from its lowland
counterpart through Suruwai (Cunuria glabra)
forest apparently peculiar to the Pakaraimas
to gallery forest along the edges of the rivers
characterized by Dimorphandra congestiflora.
Where the soils are too shallow to carry high
forest, savanna woodland and scrub savanna
occur. The savannas are of a moist type on
very shallow soils overlying sandstone or
conglomerate. They flood with very little rain
and are wet throughout the rainy season.
They are essentially bunch grass-sedge sa-
vannas with multitudes of tiny herbs and
clumps of low shrubs characterized by Cyvilla
antillana. These savannas are an extension of
the Venezuelan Gran Sabana. Areas of sheet
rock occupy square miles west of Ayanganna

121

and carry a heathlike vegetation composed al-
most entirely of Vellozia tubiflora.

Outside the sandstone belt the rivers are
fronged by swamp forest of Macrolobium
bifolium in the upper reaches and by Mora
forest in the lower reaches or where the al-
luvial flats are wider.

Many of the rapids in the smaller
streams are almost chocked with dense mas-
ses of Eviocaulon capillaris.

The system of spelling is the same as
that adopted for the Arawak Indian Plant
Names published in The Caribbean Forester,
Vol. 8, No. 3: pps. 165-180, July 1947.

Aia, Lonchocarpus chrysophyllus Wleinh.

Aiarl, Tephrosia toxiccria (Sw.) Pers.

Aibia (k)

Aibia-warai, Bejaria glauca HBK

Aima-eno, Chrysophyllum auratuim Mig.

Aipo, Dipteryx odorcta (Aubl.) Willd.

Ajikerai, Fagara spp.

Akaikara. Ananas spp.
Aechmea spp.

Akiau, Astrocarvum munbaca Mart.
Akmon, Achrouteria pomifera Eyma
Aku, Simaruba cmara Aubl.
Aku-morombo, Cowepia spp.
Aku-paira

Aku-wako, Silverballi - general name
Aku-wenupo, Cissam pelos

Akwoto, Dimorphandra congestiflora Spra-
gue & Sandw.

Amario-krokai, Mikania spp.
Amonai, Bactris oligloclada Burret
Aneo, Silverballi

Anike, Zeea mays L.

Anonde, Bixa orellana L.

Apak, Persea gratissima Gaertn. f.
Apak- warai

Apang, Anisophyllea

Miconia spp.

122

Aporuma, Satyra penurensis Bth. & Hk. f.

Arabo, Crescentia cujete L.

Araira, Duguetia decurrens R, E. Fr.

Arakaka, Vatairea guianensis Aubl.

Arapipo Anaxagorea spp.

Arauin, Tabebuia serratofolia (Fahl) Nichols
Tabebuic capitata (Bur. & K.
Schum.) Sandw.

Arauta-kwaiko, Pouteria sp.

Arawintru, Rheedia spp.

Ara-ya, Psidium guajcva L.

Arosa

Asare, Bombax flaviflorum Pulle

Ashik, Pterocarpus spp.

Aurosai, Phytolacca icosandra L.

Aurosaurai, Alchorneopsis floribunda (Bth.)

Mull. Arg.

( Aurosai-waral )
Awai-emo, Bonafousia undulata A. DC.
Stemnadenia cerea Woodson

Awaparepu, Yuyba spp.

Awara, Astrocaryvum tucumoides Drude

Awatakai, Centrosema spp.

Buke, Maranta arundinacea L.

Chiko-eno, Miconia marginata Tr.

Ekekewai, Rollinia exsucca (Dun.) A.DC.

Ekik, Manihot utilissima L.

Ekwai, Mussaenda speciosa Poir.

Epewo, Pithecellobium sp.

Epikirik, Ormosia spp.

Eriwi

Eriwi-yurai (Eriwiwarai) Xylopia aromdti-

ca (Lamb.) Mart.

CARIBBEAN FORESTER

Ero Anacardium occidentale L.

Es-eno-poko, Toulicia spp.

Iba, Musa sapientum L.

Ikorik, Liriosma

Imbaima, Bertholletia excelsa HBK

Imbo, Caryocar nuciferum L.

Ireng Ocotea canaliculata (Rich.) Mez

Irik, Licaria canella (Meissn.) Kostern.

Irumai, Ficus spp.

[ruwai, Mouriric spp.

Ito, Ternstroemia spp.

Kaikai, Panopsis sessilifolia (Rich.) Sandw.

Kaikara, Guedua

Kaikushi-ramutun, Cladonia rengifer

Kairaimai, Pithecellobium pedicellare (DC.)
Bth.

Kaishak, Dicymbe jenmenii Sandw.

Kaka, Pradosia schomburgkiana (DC) Cron-
quist

Kamang, Cecropia angulata I. W. Bailey

Kamarai, Licaria camara (Schomb.) Kostern.

Kamarupo, Bactris trichospatha Trail

Kambai (k) Pteris aquilina L.

Kambang, Hemitelia spp.

Kami (k), Heteropsis jenmanii Oliv.

Kamaratakang, Cassia apoucouita Aubl.

Kamasimo, Xanthosoma

Kamboto, Drvopteris spp.

Kamwo, Byrsonima stipulacea Juss.

Kanau, Peltogyne spp.

Kanawai, Dimorphandra congestiflora Spra-
gue & Sandw.

Kangaro-mabon, Mauritia aculeata HBK

Kapai, Alexa imperatricis (Schomb.) Baill.

JULY - OCTOBER 1953

Kapaia, Carica papaya L.

Kapaichan, Socratea exhorrhiza (Martt.)
Wendl.

Kapo, Calophyllum lucidum Bth.

Kapui-engo, Bauhinia spp.

Karai, Unonopsis glaucopetala R E Fr.

Karaikarai, Conomorpha spp.
Ouratea spp.

Karamik, Micropholis melinoniana Pierre

Karapai, Carapa guianensis Aubl.

Karapipo, Sterculia pruriens (Aubl.) Schum.

Kararapo, Mimosa mvyriadena Bth.

Karaweru, Retiniphyllum schomburgkii Bth.

Karibang

Karimora, Talisic squarrosa Radlk.
Karipo, Couratavi sp. nov.

Kartapang, Bactris

Karte, Guadua sp.

Karuk, Genipa americana L.
Karukumang, J/ex Jenmani Loes.
Karwasai, Brocchinia reducta Baker
Kasakoro, Lagenaric vulgaris Ser.
Katama, Catostemma commune Sandw.

Katuwai, Doliocarpus
Davilla
Tetracera

Kauwik, Swartzia sprucei Bth

Kauyama, Cucurbita pepo L.

Kawisi, Aniba ovalifolia Mez

Kayau-eno-mio Cephaelis tomentosa (Aubl.)
Vahl.

Kinoto, Sloanea

Kirichak, Pegamea guianensis Aubl.

Kobare, Peperomia spp.

Komwa

125

Konopia, Reanealmia spp.

Konowai, Bonnetia sessilis Bth.

Koperek, Cedrela odorata L.

Koraiok, Azenas sativus Schult var.

Koreko, Cecropia.

Koroware eriko, Chelonanthus chclonoides
(L. £.) Gilg.

Koshirik, Ischnosiphen surinamensis (Miq.)
Koern.

Kosing. Parkia nitida Miq.

Kot Ocotea rodiaei (Schomb.) Mez

Koto, Alexa imperatricis (Schomb.) Baill.

Kotik, Hymenolobium spp.

Kotnare, Manihot utilissima L.

Kotokwa, Gossypium berbadense L.

Kotokwa-warai, Weltheria americana L.

Kotore, Sacoglottis

Kowo

Kriporsen, Tapura guianensis Aubl.

Kuama, Bambusa vulgaris Wendl.

Kukwi, Peltogyne venosa Bth.

Kumak, Ceiba occidentalis (L) Burkill

Kumarawa, Strvchnos spp.

Kumatara, Dolichos lablab L.

Kume, Lecythis davisii Sanaw.

Kume-warai, Terminalia quintalata Magui-
re

Kunali-mulai (Kunali-warai) Casecria silves-
tris Sw.

Kunami, Clibadium spp.

Kunawaru Miconia spp.

Kung-waia, Oenocarpus becaba Mart.

Kupo, Piper spp.

Kurachikang, Macralobium bifolium (Aubl.)

Pers.

124

Kuradana, Musa paradisiaca L.
Kurakai, Arrabidaea chica Verl.
Kurarema, Peperomia spp.
Kurashi-urupoe, Hirtella spp.
Kurubedan, Eschweilera

Kurumbenbeo, Ormosia coutinhoi, Ducke
Kusapo, Croton matourensis Aubl.

Kuwaka, Nanthosoma

Kwabanai, Rapatea spp.
Stegolepis spp.

Kwai (Kowai), Mauritia flexuosa L.
Kwari (Kowari), Inga
Kwaturu, Eschweilera grata Sandw.

Kwiawi, Solanum paludosum Moric.
Solanum rugosum Dun.

Kwikpai, Pouteria spp.

Kwina, Sapium spp.
Hevea spp.

Kwipari, Loxoptervgium sagotii Hk. f.
Mai Licania laxiflora Fritsch

Maikwak-esere, Andira grandistifpula Amsh.
Tabebuia

Maitakin, Symphonia globulifera L. i.

Mai-warai, Licania spp.
Parinari spp.

Makang, Sandwithia guianensis Lan}.
Makarin, Tapiriva guianensis Aubl.
Makwaiyare

Man, Clusia spp.

Manare (Monare), Jschnosiphon obliquus
(Rudge) Koern.

Manasara, (Palmaceae )

Manau Qualea albiflora Warm.
Qualea polyvchroma Stafl.

Mangoro, Rhizophora mangle L.

Mapuru (Maporo), Gynerium sagittatum

(Aubl.) Beauv.

CARIBBEAN FORESTER
Maranyo, Copaifera
Marbuk, /ryanthera spp.
Maripa, Maximiliana regia Mart.
Marsupai, Pouteria spp.
Maruk-ewan-tepu, Eperua jenmanii Oliv.
Masai, Inga lateriflora Miq.
Masapre
Masawi, Pausandra martini Baill.
Matak, Silverballi sp.
Maumau, Bombax aquaticum (Aubl.) Schum.
Mekuru, Musa sapientum L.
Meniya, Euterpe
Mirikawai
Mo, Peliogyne venosa Bth. var.
Moniki, Trema micranthum (L) Blume
Mope (Mopa), Arachis hypogaea L.
Mope, Cyperus rotundus L.
Mope, Spondias
More, Byrsonima incarnata Sandw. var.
Morino

Moro, Hunvria floribunda Mart.

Morombaurai (Morombo-warai) Moronobea
jermani Engl.

Morombo

Moro-warai, Ouvratea spp.

Mosai, Monotagma parkerii (Roscoe) Schum.
Mosok, Cassia pteridophylla Sandw.

Mukruk, Solanum

Muruk, Ouiina guianensis Aubl.

Mutuwari, Clathorotropis macrocarpa Ducke
Nak Xanthosoma sagittifolium (L) Schott.
Napo, Hieronyma oblonga (Tul.) Mull. Arg.

Napui, Dioscorea

JULY - OCTOBER 1953

Nosodomai, MJiconia spp.

Nutsak, Swartzia, Blackheart

Ojipipo, Duguetia yeskidan Sandw.
Okoro, Sloanea guianensis (Aubl.) Bth.
Okoromai, Eschweilera alata ACSm.
Ombang, Duroia eriopile L. f.

Ore, (Sterculiaceae)

Oriikorong, Pithecellobium jupumba
( Willd.) Urb.

Pithecellobium corymbosum

(Rich.) Bth.
Osowai, Guatteria spp.
Otoshimik, Pterocarpus spp.
Paira, Piretinera guianensis Aubl.
Paiwatopo, Emmotum fagifolium Desv.
Pakarunda, Dalbergia
Pakira-wenupo, /nga
Pakorai- (Myrtaceae )
Panamwi, Trichilia schomburgkii C. DC.
Panatoro, Parinari spp.

Pandara, Aniba kapplerii Mez.
Ocotea schomburgkiana (Nees)
Bth. & Hk. f.

Parakwai, Mora gonggrijpii (Kleinh.) Sandw.

Parakwaurai (Parakwaiwarai), Meateyba
Paramana, Chaetocarpus

Parawakashi, Pentaclethra macroloba
( Willd.) Kze.

Pareyu, Sélverballi

Parupa, Hortia regia Sandw.
Paruruwaka, Neea spp.

Paruwe, Dicymbe corymbosa Bth.

Pasai, Jacaranda copaia (Aubl.) D. Don.

Patawaia. Jessenia bataua (Mart.) Burret

Patia, Citrullus vulgaris Schrad.
Paui-eno, Pouteria cladantha Sandw.

Paui-semu, Avistolochia daemoninoxia Mas-
ters.

Pembutu, Cephaelis violacea, (Aubl) Sw.
Petakorok, Diospyros, spp.
Piaima-pomo, Cordia nodosa Lam.
Piat, Amanoa guianensis Aubl.

Pio, Duguetia yeshidan Sandw.

Piriwo, Morantea guianensis Aubl.
Pokerewe, Heliconia spp.

Poko, Eschweilera segotiana Miers
Eschweilera odora (Poepp.) Miers

Pomo, Capsicum frutescens

Ponai, Didymopanax morototoni (Aubl.)
Dene & Pl.

Ponjik, Rhynchanthera spp.
Popo
Porek, Pouteria spp.

Porekai (Poredai) Aspidosperma ecxcelsum
Bth.
Aspidosperma oblongum
ALD EC:

Poro, Inga nobilis Willd.

Powa

Pratakik, Powrouma guianensis Aubl.
Purue, Manilkara bidentata (A.DC.) Chev.
Rek, Eviocaulon capillaris Bong.
Reko, Himatanthus spp.

Remona, Citrus medica L. var. acida
Sak, Ipomoea batatas Lam.

Sakarai

Sakau, Miconia spp.

Samalung, Pouteria spp

Saparau, Myrcicria vismeifolia (Bth.)- Berg.

Sara, Scleria spp.
Sarakang, Bromelia karatas L.
Sararai, Cecropia juranyiana Alad. Richt.
Sekerende, Musa sapientum L. var.
Sengwede, Colocasia esculenta Schott.
Seregwe, Palicourea spp.
Sha (k) Byrsonima aerugo Sagot
Shakari, Bellucia spp.
Shiba, (Caesalpiniaceae )
Shimaila, Cespedesia amazonica Huber
Shimi, Terminalia spp.

Buchenavia spp.
Shimiri, Hymenaea courbaril L.
Shipok, Dioscorea spp.
Shipotai, Smilax spp.

Shirimo, Piptadenia suaveolens Miq.
Mimosa

Shiroda, Saxofridericia regalis Rich Schomb.

Spathanthus unilateralis (Rudge)
Desv.

Sikaru, Saccharum officinarum L.
Simana, Catostemma altsonii Sandw.
Suruwai, Cunuria glabra R. E. Schuites
Suruwa-pari, Cunuria

Takuna, VYuvyba spp.

Takapia, Geonoma spp.

Takariwa, Hernandia sonora L.

Tamaren, Mazeta spp.
Leandra spp
Tococa spp.

Tamu, Nicotiana

Tangwaiyang (Tamwaiya), Anthuriim
nobile, Engl.

Tashi, Tachigalia spp.

Tatang, Aldina insignis (Bth.) Engl.

CARIBBEAN FORESTER

Tekereu, Sterculia rugosa R. Br.
Tekureng, Pouteria spp.

Tensing, Licania heteromorpha Bth. var.
Tira, Clathrotropis paradoxa Sandw.
To, Coutoubea ramosa Aubl.
Tokwit-nanko, Notopora schomburgkii Hk.
Toro, Mora excelsa Bth.

Tumoreng, Sclerolobium spp.

Tun, Aspidosperma sandwithianum Mfg.
Tuwo, ( Moraceae )

Uramik, Wulffia baccata (L.f.) Ktze
Urapa, Piratinera guianensis Aubl.
Urari, Strychnos spp.

Urumak, Clusia spp.

Urumaropo, Licania mollis Bth.

Uruwe, Panicum spp.

Usariwara-yauku, Vriesia splendens

(Brongn.) Lem.
Ute
Wai, Ocotea guianensis Aubl.
Wai, Lagenaria vulgaris Ser.
Waiabilo, Desmoncus spp.
Waiawa, Trattinickia spp.
Waiking, Poecilandra
Waiking-pomo, Cyrilla antillana Michx.
Waila
Waila-miru, Silverballi
Waila-warai, Silverballi
Waila-wok: Inga splendens Willd.
Waimasayare, Philodendron
Wakawipa, Micropholis melinoniana Pierre
Wakukwapai, Cephcelis altsonii Sandw.

Wakwama, Carludovica sarmentosa Sagot

JULY - OCTOBER 1953

Wakwamik, Tovomita spp.
Clusia jermanti Engl.
Clusia fockeana Mig. etc.

Walama, Vismia spp.

Wambitona

Wana, Apeiba echinata Gaertn.
Wananai, Ravenala guianensis Steud.

Wanauboma, Andropogon citratum Hort ex
DE

Wa:amia, Geonoma spp.

Waranaku, Couratari pulchra Sandw.
Warapari, Sclerolobium spo.
Warayu, Psychotria

Wargo, Caryocar

Wariki, Couefia exflexa Tanshawe &
Maguire

Warkamicho, Quiina indigofera, Sandw.

Warobai, Xanthosoma

Warumai, Henriettea multiflora Naud.
Waruwa, Protium spp.

Wasang, Cordia exaltata var. melanoneura

Johnston

Wasewia (Wasia), Euterpe edulis Mart.

Watopari (Watopate), Pera bicolor (KI1.)
Mull. Arg.

Watuwai, Laetia procera (Poepp. & Endl.)
Eichl.

We, Virole surinamensis (Rol.) Warb.
Weruwe, Palicourea guianensis Aubl.
Wopa, Eperua falcata, Aubl.

Wiuttik, WWarlierea schomburgkiana Berg

Yarak, Graffenrieda ovalifolia Naud.

Miconia spp.

Yorong, Pradosia

CARIBBEAN FORESTER

\ The Forests of Darien, Panama’

F. BRUCE LAMB

United States Plywood Corporation

Panama

The forests of Panama are one of the
country’s most important natural resources.
Mr. R. D. Garver of the U. 8. Forest Service
in his report proposing a ‘“‘National Survey of
the Forest Resources of the Republic of Pa-
nama” estimated that the forested area of
Panama amounts to 5,000,000 hectares, or 70
percent of the total land area of the Repub-
lic. However, it is estimated that such fac-
tors as inaccessibility and poor forest growth
limit the total commercial forest area to
3,500,000 hectares. The bulk of the commer-
cial forests of Panama are in the Provinces
of Bocas del Toro and Darien. The forests of
Darien cover an area of approximately
1,522,000 hectares.

FOREST TYPES

The forests below an elevation of 500
meters on the Pacific slope of the Cordille-
ra that divides Panama, are Tropical Dry
Forest. The mean annual rainfall of this area
is less than 2,000 mm. distributed over eight
months of the year, from May to December.
A dry season from January through April
limits the composition of the forest to
drought-resistant species. In certain areas
where edaphic conditions modify the effect
of the weather specialized types of forest
appear.

Upland Forest

The bulk of the forests of Darien belong
to this forest type. However, no surveys have
been made upon which to base area esti-
mates. The composition of this forest is very
complex, being made up of a great many
species of trees, of which few have at the
present time a commercial value. The
general character of this forest is similar
throughout the type but the distribution of

1/ The writer spent approximately 2 years, from 1951 to
1953, studying the forest of Darien for the Panama _ For-
est Products Company, developing log supply sources and
determining the voluy,e of timber available.

individual species varies considerably from
one section to another.

So far as is known to the writer, no de-
tailed botanical studies have been made of
this type of forest in Panama. General obser-
vations of forest composition show the fol-
lowing important forest trees in their ap-
proximate descending order of abundance,

Quipo (Ccvanillesia platanifolia) (H. & B.)
HBR.)

Espave (Anacardium excelsum)

Cedro espino (Bombacopsis quinatum)

Bongo (Ceiva pentandra) (L.) Gaertn)

Caoba or mahogany (Swietenia macrophylla

King)

Cedro amargo (Cedrela mexicana L.)

Cedro cibolla (Cedrela sp.)

Tachuela (Zanthoxylum sp.)

Nazareno (Peltogyne purpurea)

Roble (Tabebuia penthaphylia)

Higueren (Ficus sp.)

Caucho (Castille elastica Cerv.)

Maria (Calophvilum brasilense)
Mahogany

The most important timber tree of Pa-
nama is mahogany. The natural distribution
of this species in the forest of the Pacific
side of Panama extends from Costa Rica to
Colombia. However, the tree is not distribut-
ed uniformly over this area. In many places
it has been completely eliminated by logging
or clearing for agriculture. The average
stocking of commercial sized mahogany trees

in the forests where found is less than one-
tree to the hectare. Isolated instances are

JULY - OCTOBER 1953

reported of groups of 35 to 50 mahogany
trees to the hectare, but these occurrences
are rare.

The distribution of the remaining stands
of mahogany in Darien extends from the
area drained by the upper Rio Congo east-
ward to the Rio Cucunati and Rio Sabana
including the headwaters of the Rio Bayano
in the Province of Panama, then southward
along the tributaries of the Rio Chucunaque
to the headwaters of the Rio Tuira on the
Colombian border and then westward to the
headwaters of the Rio Balsas and the sea
coast and then northward between Cerro
Sapo and the sea coast to Garachine Point
(See map.)

Mahogany is not evenly distributed
througout this area. Arecs that sv» oport
enough trees to justify loszing operstions
alternate with areas that Fave no m*#hoga-
ny. The organization of mechanical lovging
operations requires carefu! field werk to
locate commercial stands.

It is estimated on the basis of field studies
that the net volume of mahsgany remaining
in the area described is approximately
60,000,000 board feet. Based on limited obser-
vations in other areas of Panama it is esti-
mated that the total net volume of mahogany
existing in the entire country is 75,000,000
board feet. When deductions are made for
trees too widely scattered to be logged eco-
nomically and timber that is inaccessible, the
net volume available to log is approximately
60,000,000 board feet for all of Panama, of
which 50,000,000 board feet are located in
Darien.

Espave

Espave is one cf the most abundant trees
in the upland forests. It is concentrated in
moist, well drained river valleys and on gen-
tle slopes. Locations where heavy stocking of
espave was seen in Darien are in the Sete-
ganti, Sambu, and Iglesias valleys. Volumes
up to 25,000 board feet per hectare were
found and the vailey of the Seteganti was
estimated to contain 8,000,000 board feet of
espave.

129

Ouipo

Quipo is the most abundant tree in the
upland forests of Darien. It grows to large
sizes, 2 meters in diameter and 20 meters to
the first branch. Volumes as high as 50,090
board feet to the hectare have been observed.

At present there is no industrial outlet
for this soft balsa-like wood. During World
War II certain quantities were shipped to
England as a substitute for balsa in the pro-
duction of life-jackets and life-rafts. It is
possible that in the future some industrial
use for quipo wood will be found.

Lowiand Forest

In areas affected by tidal overflow or
subject to continuous flooding during the
wet season from May until January speci-
alized types of lowland forest have developed.

Cativo

Cativo is found in great abundance in
Darien on low flooded areas along streams
and around shallow lagoons. It occurs in al-
most pure stands in many areas. Associated
species are tangare (Carapa sp.) and coco
(Lecythis sp.) Cativo reaches its optimum de-
velopment on the natural levees along me-
andering streams where there is always an
abundance of water and frequent flooding
takes place during the rainy season. The best
stands of cativo occur above the influence
of salt water.

A survey of the cativo stands on sever-
al of the rivers in Darien showed it to grow
along the lower Rio Chucunaque, Rio Tuira,
Rio Balsas, Rio Sambu, Rio Congo, Rio Cu-
panati, and around the Laguna de la Pita.
(See map)

The Rio Balsas, flowing through its
meander belt, has built up natural levees on
both banks which are higher than the sur-
rounding country. The best drained land is
along the river, gradually sloping off to for-
ested swamp 1 to 2 kilometers from the
stream. Excellent nearly pure stands of cati-
vo occur on both banks of Rio Balsas from

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JULY - OCTOBER 1953

Piriaqui up river approximately 20 kilome-
ters. It was found that the greatest concen-
trations of this timber occur on the levee
near the river, and that volume and timber
size diminish as swampy ground is approach-
ed further inland. The belt of commercial ca-
tivo forest averages 1 kilometer in depth on
each bank of the river, giving a total area of
high quality cativo forest of 40,000 square
kilometers. The stand varies from 35,000
board feet per hectare in the best areas near
the river to 12,000 board feet per hectare
further inland. The average stand for the
area was estimated to be 30,000 board feet
giving a total volume of 60,000,000 board feet
for the valley.

Judging from an examination of felled
trees in the area and the quality of logs re-
ceived at the plywood plant, at least one-half
of this volume, or 40,000,000 board feet, is
face veneer quality material. Of the remain-
der approximately 30,000,000 board feet is
suitable for core stock and 10,000,000 board
feet for lumber.

On Rio Tuira the first cativo is encoun-
tered approximately 25 kilometers up river
from the mouth of the Rio Balsas at a loca-
tion also called Piriaqui. From this point
up river to the mouth of the Rio Chucuna-
que, a distance of 25 kilometers, the river
bank forest is made up largely of cativo.
However, a cruise of this forest shows that
the volume of timber per hectare is con-
siderably below that in the cativo forest on
Rio Balsas. In many places the strip of for-
est is quite narrow, with the land sloping
off into a shallow lagune. This timber volume
of the strip along this river averages
10,000 board feet per hectare, and the high-
est volume per hectare found was 20,000
board feet. The 4,000 hectares of forest land
between Piriaqui and the mouth of the Chu-
cunaque extending 1 kilometer back from the
river bank contain 40,000,000 board feet of
cativo, Cativo forest is found on the Rio Tui-
ra above the mouth of the Chucunaque as far
South as Boca Cupe. These forests have not

131

been examinated. However, the total stand of
cativo on the Rio Tuira is probably in ex-
cess of 100,000,000 board feet.

On Rio Sambu the first cativo is
encountered approximately 10 kilometers up
from the river mouth at the confluence of
Rio Jesus with the Sambu. <A continuous
stand of cativo occurs along the river from
this point up river for a distance of 8 kilo-
meters or to a point where the Quebrada Mo-
robichi flows into the river, The timber in
this area was examined and was found to
extend at least 1,500 meters inland from the
river bank on either side of the river. The
timber volume varies from 5,000 to 30,000
board feet per hectare. In the 3,000 hectares
cruised the average stand is 15,000 board
feet per hectare giving a total volume of
42,000,000 board feet. From the mouth of the
Morobichi upstream the former river bank
stands of cativo have been cleared for agri-
culture. However, this clearing is only a nar-
2oW Strip along the river, and cativo remains
further inland. It is estimated from infor-
mation obtained from local residents and
cruise data that the total volume of cativo
available from the Rio Sambu is approxi-

mately 100,000,000 board feet.

Rio Chucunaque, flowing into the Rio
Tuira just below El Real, is reported to have
extensive stands of cativo along its meander-
ing course for a distance of 80 kilometers.
Some of the best quality cativo logs received
at the plant came from this river. No sur-
veys have been made in this area. However,
all available sources of information indicate
a volume in excess of 200,000,000 board feet
existing in this drainage.

There are several smaller areas of cati-
vo in Darien that have not been surveyed
(See map). From the information available
it is estimated that the total volume of cativo
in Darien is in excess of 500,000,000 board
feet.

During recent years considerable inter-
est has developed in the use of cativo for
both face veneer and core stock in the fabri-
cation of plywood. At the present time ap-
proximately 1,000,000 board feet per month
are being shipped to the United States from
Costa Rica and Colombia. At the plywood
plant in Panama as much as 400,000 board
feet of cativo a month has been used for
both core stock and face veneer. Highly de-
corative face veneers have been made on
both the rotary lathe and the slicer. Deco-
rative cativo plywood is sold with the light
colored woods and probably could be made
competitive with birch. An interesting archi-
tectural application of cativo plywood can be
seen in the Chase National Bank in Panama,

Cativo is also suitable for box boards,
and an effort should be made in Panama to
fabricate out of cativo the boxes used local-
ly. All of the cases used for beer and ecar-
bonated drinks could be made out of cativo
iif local manufacturing facilities were es-
tablished. The boards should be treated with
pentachlorophenol and benzene hexachloride
while green to make them more durable.

The nature of the cativo forest is such
that selective cutting can take place without
destroying the productive capacity of the
forest. This tree is a prolific seed producer,
and reproduction in all stages of develop-
ment is abundant in the cativo forest. No
detailed studies have been made to determine
what proportion of the stand can be cut be-
fore a significant change in composition
takes place. However, it has been observed
that where up to 50 percent of the total vol-
ume was cut stands closed up and remain-
ed pure cativo. On the other hand, where the
cativo forest is felled in order to plant rice,
cativo does not inmediately reoccupy the land
after cultivation ceases. A temporary asso-
ciation of short-lived species such as guaru-
mo (Cecropia sp.) and balsa (Ochroma sp.) oc-
cupies the site first and is probably gradual-
ly replaced by cativo.

In the cativo forest where no cutting
takes place growth balances the mortality,
and the forest remains more or less stable.

CARIBBEAN FORESTER

it is only through utilization of the mature
trees that this type of forest can be made
to contribute to the local economy. Cutting
makes possible an increased rate of growth
by providing more growing space for the
young trees left behind. No studies have
been made to cGetermine what rate of cut-
ting the cativo forest will support. However,
in the best cativo stands where cutting re-
moves the mature trees a growth rate of at
least 1,000 board feet per hectare per year
should be achieved.

The cativo forests of Darien represent a
tremendous source of industrial raw matevi-
al, and general observations indicate that
with a minimum of control over cutting oper-
ations the forest can be maintained in a
continuously productive state. It should be
the policy of the government to do every-
thing possible to encourage the utilization
of cativo.

Mangrove

Since a use has been found for ground
mangrove bark in the mud conditioning che-
micals used in drilling oil wells this tree pro-
vides an important source of income for Pa-
nama. Extensive pure stands of mangrove
(Rhizophora mangle Lu.) extend all along the
Pacific Coast of Panama. No surveys of this
type of forest have been made. However, be-
cause of its potential importance estimates
should be made of the volume of bark availa-
ble. Harvesting of the bark results in the
death of the tree. However, natural repro-
duction will replace the trees cut and provide
a continuous source of raw material so long
as the rate of harvest does not exceed the
growth of new trees.

THE PRODUCTION OF MAHOGANY

Logging

Except for a few locations on Rio Chu-
cunaque all the mahogany that can be cut
and rolled into the rivers by hand methods
has already been logged. Logging operations
now and in the future will depend on mechan-
ical equipment such as tractors and trucks

JULY — OCTOBER, 1953

to bring the logs out to streams where they
can be rafted for towing to sawmills or log
boats.

Present day logging operations on Rio
Sabana and elsewhere are organized on the
basis of skidding the mahogany logs as far
as 2 kilometers to truck loading points and
hauling by truck from 8 to 25 kilometers tu
the jog dump on a stream bank. In other ma-
hogany producing countries in Centrai Amé-
rica logs are being transported by truck as
far as 100 kilometers to stream banks.

A large proportion of the mahogany
timber in Darien is over-mature and defec-
tive. The most common defects encountered
are termite damage and heart rot, which are
most often found in over-mature trees. Oa
the logging operations organized by the Pa-
nama Forest Products Company througn lo-
cal contractors on Rio Sabana as manv as
one-half of the trees were found defective.
This greatly increased the cost of logging
since more trees had to be felled than was
planned and logging operations had te be
spread over a greater area than expected.

Because of the high cost of transporta-
tion it does not pay to bring defective logs
out of the forest. Some contractors save a
part of the defective logs by putting crews
to whipsaw heavy planks out of the good
portion of defective logs. Whether or not this
operation pays depends on the local market
for whipsawn planks. Everything possible
should be done to promote the sale of this
type of material to provide for more com-
plete utilization of defective logs.

Future Supplies of Mahogany

Production of mahogany in Panama
during the last 10 years averages approxi-
mately 3,000,000 board feet of which one-
third is used locally and two-thirds is export-
ed. Based on this rate of cutting the remain-
ing stands of mahogany in Panama can be
expected to last approximately 25 years.

The possibility of providing a continuous
supply of mahogany lumber at this level of
production on the basis of the mahogany

153

growing stock left in Panama does not ap-
pear to be feasible since it will require at
least 40 years and probably 50 years for
planted mahogany to reach commercial size.
The mahogany timber now being cut 1s an
acumulation of mature and over-mature trees
that has been developing over a period of
several hundred years. On the other hand,
it does not seem advisable to restrict the
cutting of this timber in order to balance
cutting against growth because much a high
percentage is overmature and defective. If
this timber is not cut promptly it will com-
pletely deteriorate.

Plantation Costs

Based on observations of planted maho-
gany in various countries in Central Anieri-
ca the results to be expected from mahoga-
ny plantations are shown in the following
calculations.

Cost per hectare

Operation Dollars
Preparing planting lines $ 12.50
Planting including seed 12.50
Care Ist. year - 3 cleanings 12.50
Care 2nd. year - 2 cleanings 7.40
Care 3rd. year - 1 cleaning 5.00
Care 4th. year - 1 cleaning 5.00
Care 5th. year - cleaning and pruning 5.00
Care each year thereafter 2.50

Care, average for 50 years including

$1.20 for administration and protection 3.97

Since mahogany is a light-demanding
species, the most successful plantations have
been established in second growth that
springs up in abandoned agricultural clear-
ings. This type of vegetation provides some
protection for the young plants but does not
create deep shade. Work expended on care
cf plantations shouJd aim to keep the maho-
gany tree crowns free from interference
above, If nursery stocks is transplanted it
should be approximately 1 meter tall and all
the leaves should be removed transplant-
ing.

134

Planting should take place during the
early part of the rainy season. Some success
has also resulted from sowing seed directly
in the forest. Planting should be at the rate
of 250 trees per hectare, with the expecta-
tion of 125 crop trees at the end of the reta-
tion.

The average annual volume increment
based on available data will be approximate-
ly 1,235 board feet per hectare per year, or
61,750 board feet per hectare at the end of
50 years. The value of this harvest, based

CARIBBEAN FORESTER

on present log values of $125.00 per thousand
board feet is $7,718.75. If plantations are es-
tablished in accessible areas the logging cost
should not be more than $50.00 per thousand
board feet leaving a net yield of $75.00 per
thousand board feet or $4,631.35 per hec-
tare.

The expectation value of 1 hectare of
forest land planted to mahogany with the
costs and yield just presented and a com-
pound interest rate of 3.5 percent may be
found by the following formula:

Seta, Vie tai ae PES) ee DE
(1 + pvr — 1)
Yr. Yield at rotation age $ 4,631.35
r. Rotation — 50 years
ta. Thinnings. At the age of 25 years thinnings should
be removed producing small sawtimber worth $40.50 per
hectare. This amount prolonged to the end of the
rotation is 40 (1.03525 = (2.363) = 94.52
Total periodic yield 4,725.87
ce. Cost of planting
Clearing planting lines $ 12.50
Planting 12.50
Planting cost prolonged to the end of rotation 25.00
25(1.03559) = 25 (5.585) = 139.62
Periodic yield less planting cost 4,586.25
Periodic yield discounted to the present:
4586.25 = 4586.25 = 1,000.21
103559 — 1 4585
E. The capitalized value of the average annual expense.
That is, e/p where “c” is the annual expense and ‘“p”
the rate of interest.
e = 3.97 = 113.43
p .035
Se. Soil expectation value $ 886.78

This calculation is for 1 hectare only.
Assuming that a regulated forest property
has been established that is capable of conti-
nuous production of mahogany, then for
comparative calculations a sample of 50 hec-

tares can be chosen on which each year 1
hectare of mature mohogany timber will be
cut and 1 hectare planted. The value of a
50-hectare sample of such a regulated forest
property would be as follows:

JULY - OCTOBER 1953

Income:
Timber value from 1 hectare cut each year
Thinnings from 1 hectare each year

Total annual income

Cests:

Planting 1 hectare each year
Annual expense on 50 hectares at $3.97

Tocal cost

Net annual income
Capital value of net annual income

4,447.85
-035

Value per hectare

127,081.48
50

The 3.5 percent rate of interest used in
these calculations represents a reasonable
rate of return in a relatively risk free mar-

ket. When the values developed here are ad-
justed to compensate for special risks such
as fire, wind damage and unstable land poli-
cies comparisons can be made with values
calculated for other tropical crops or plans
for land use. The values shown for mahogany
should be of interest to both public and pri-

vate investors .

$ 4,631.35
40.00
$ 4,671.35
$ 25.00
198.50
223.50
§ 4,447.85
$ 127,081.48
$ 2,541.62
RECOMENDATIONS

A complete inventory of the forests of
Panama should be made in order to gather
the information to provide an adequate ba-
sis for long range economic planning and for
framing and adequate legislative program
for the control of the exploitation of the for-
est resources. The forest laws should be so
designed that they will encourage the utili-
zation of the forest resources. Steps should
be taken to study the administrative needs
in controlling the use of the forest resources,
and plans made for the establishment of an
administrative organization.

CARIBBEAN FORESTER

The Inhibitory Action of Organic Chemicals
on a Blue Stain Fungus

F, J.

ASCORBE

Agricultural Experiment Station

University of Puerto Rico

As a result of the work of Wolcott’
with different organic chemicais in search
of suitable repellents for the West Indian
dry-wood termite, (Crvptotermes brevis Walker)
the possibility that some of the termite-re-
pellent organic chemicais might have inhibi-
tory action on wood staining fungi was in-
vestigated, Obviously such a substance would
be the ideal wood preservative.

Most of the substances tested are syn-
thetic organic chemicals. Pinosylvin (38, 5-di-
hydroxy stilbene) was extracted from the
heartwood of Scotch pine by Erdtman:’.
Substituted derivatives of pinosylvin were
made in the laboratory. Usnic, physodic, sala-
zinic, and vulpinic acids are naturally occur-
ring products of mold metabolism. 5, 7-dihy-
droxy flavone (chrysin) was obtained from
buds of several varieties of poplar.

Methods

The indicator organism used in this stu-
dy is a species of Trichosporium, obtained on
primary isolation from stained (blue-green}
commercially available wood. It was kept in
stock cultures in Sabourad dextrose agar.

The basal medium to which the test
substances were added has the following com-
position:

Substance Percent
Dextrose 3.0
Ammonium nitrate 0.1

Potassium dihydrogen phosphate 0.1
Magnesium sulfate 0

Manganese sulfate 0.0002
Zinc sulfate 0.0002
Ferric chloride 0.001
Cobalt chloride 0.0002
Copper sulfate 0.0002

1/ Wolcott, George N. 1950. The termite resistance of pinosylvin,
stilbene and other new insecticides. P. R. Journ. Agr. Univ. P. R.
34(4):338-342.

2/ Erdtman, H. 1959. Heartwood extractives of conifers: their
fungicidal and insect-repellent properties and taxonomic inter-
est. TAPP! 29(7):305-310.

Most of the test substances were dissolv-
ed in acetone. Exceptions were: 5, 7-dihydro-
xy flavone, disolved in pyridine; 2,4-dichloro
benzalaniline, 4-chlorobenzalaniline, and 2,4.-
2,4-tetranitro stilbene which were dissolved
in benzene. Anthragallol, anthracene, ace-
naphtene, copaivic acid, triphenyl stibine,
phenanthrene quinhydrome, beta-chloro an-
thraquinone, 1-2-naphthoquinone, 2-methyl-1,
4-naphthoquinone, and 3-pheny!] salycilice acid
(cupric salt) were dissolved in ethyl alcohol
due to their insolubility in acetone.

The controls consisted of basal medium
witn an equivalent amount of the solvent
used in adding the test substance. During
sterilization the solvents were completely
evaporated. Addition of solutions of the test
substance to the basal medium resulted in
perfect soluti ns, but those dissolved in ben-
zene and ethyl alcohol generally floculated,
producing a suspension. The concentration of
test substance used was 100 and 200 gam-
mas per ml. They correspond to 0.01 and 0.02
percent, respectively.

After sterilization the pH of the basal
medium was 4.5. It was assumed that the
addition of the test substance did not change
the pH of the medium, considering that it
was well buffered, and that the concentra-
tion of the test substance was very low. Two
procedures were used for inoculation and for
growing. For Treatment No. 1 the following
procedure was used: Pieces of mycelium
grown in liquid basal medium were added to

JULY - OCTOBER 1953

the flask containing the test substance and
the culture was allowed to grow for a period
of 9 to 10 days with an occasional shaking.
For Treatment No. 2 the inoculum consisted
of 0.2 ml. of a spore suspension in 0.1 percent
sodium lauryl sulfate. They were grown for
7 days in a rotary action flask shaker machi-
ne operating at 240 oscillations per minute.
In both cases the temperature was 30°C (+)
2°. After the growth period the mycelium
was filtered through a Buchner funnz! and
dried in the oven for 24 hours at 70°C. After
drying the mycelium with the filter paper
was weighed and by differences (from the
weight of the filter paper before filtering)

the ‘Weight of the mycelium was obtained.

Table i.

Results and Discussion

Table 1 shows that pinosylvin and its

derivatives are very good inhibitors of

growth of Trichosporium sp. under the condi-
tions of the test. It is of interest to note that
when the hydrogen of the hydroxy] radicals
is displaced by methyl groups (pinosylvin,
dimethyl ether) the activity is reduced. It
is apparent that some of the activity of pino-
sylvin resides in the presence of at least one
free hydroxyl group. The substituted, 2,6-
dibromo pinosylvin lacks inhibiting activity,
whic is possibly due to the fact that it is
the dimethyl ether form.

— Myceli-m weights from Treatment No. 1

Test substance

Weight of mycelium

100 gammas 200 gammas

per ml. per ml.
Mg. Mg.
1. Pinosylvin Det: 1.6
2. Pinosylvin (monomethyl] ether) 2.4 4
3. Pinosylvin (dimethyl ether) 37.4 36.2
4. Dihydro pinosylvin (monomethy] ether) Salk 3.8
5. 3, 4, 6 — trinitro stilbene 20.0 10.5
6. Vulpinic acid 29.8 21.4
7. Salazinic acid 33.6 61.6
8. Usnic acid 41.7 8.1
9. Physodie acid allarl 13.3
10. Phenanthracuinone 1.8 5.1
11. 1-1-di (2-hydroxy-3,5-dichloro phenyl 2, 2, 2-trichloroethane 5.4
Control for substances 1-11 87.4 93.1
12. 5, 7-dihydroxy flavone 8.2 11.4
Control for substance 12 5.8 3.0
13. 2, 4, 2,’, 4’ tetranitro stilbene 63.3 64.5
Control for substance 13 4.9 iby
14, 2, 4-dichloro benzalaniline 55.7 61.7
15. 4-chloro benzalaniline 95.4 89.5
Control for substances 14 and 15 7.4 4.9

Complete medium alone

80.4

Other substances tested as a part of the
first group of eleven, but which showed lit-
tle or no inhibitory action (40 + mg.) are as
follows:

2,6-dibromo pinosylvin (dimethy] ether)
Benzalaniline

4-hydroxy benzaniline
4-methoxy benzalaniline
2-hydroxy benzalaniline
2,4-dihydroxy benzalaniline
3,4-dimethoxy benzalaniline
3,4-dehydroxy benzalaniline
2,4-dichloro stilbene
3,4-dimethoxy stilbene

3,4-methylene dioxy stilbene

2,4-dichloro-2’, 4’-dinitro stilbene

Azobenzere

Dibenzyl

Dipheny] octatetraene

3,4,3’4’-tetramethoxy dibenzy]

2,3,6,7-tetramethoxy-9,10-dihydro-
phenanthrene

Dimethy] tetarachloro phthalate

P-cholorophenyl-p-chlorobenzene_ sulfo-
nate

CARIBBEAN FORESTER

With the exception of 3-methoxy-4-hy-
droxy-5-chloro benzalaniline and 2,4,6,-trini-
tro stilbene, the substituted benzalanilines
and stilbenes lack inhibitory action.

Usnic, physodic, salazinic and vulpinic
acids are high molecular aromatic compounds
with more than one ring and several side
chains. As expected they proved to be inhi-
bitory in varying degrees. The same is true
for phenanthraquinone and for 1,1-di (2-hy-
droxy-3,-5-dichloro phenyl) 2,2,2-trichloro
ethane, an analogue of D.D.T. Inhibitory ac-
tion of chrysin is probably due to piridine,
which in general is very toxic to molds. Ben-
zene, as seen from the controls, is very toxic,
in the presence of 2,4-dichloro and 4-chloro
benzalaniline and 2,4,2’,4’-tetranitro stilbene,
which were dissolved in benzene, the orga-
nism was able to grow.

From Table 2 it can be seen that under
the conditions of the experiment the follow-
ing substances proved to be the best inhibi-
tors for the species of Trichosporium: dinitro
-O-cycloexyl phenol, dinitro-O-cresol, chlor-
anil cyclopentadiene, para chloro-meta

Table 2. — Mycelium weights from Treatment No. 2

Test Substance

| Weight of mycelium

100 gammas

200 gammas

per ml. per ml.

Mg. Mg.

1. 3 - methoxy - 4 - hydroxy - 5 - chloro benzalaniline 140.9 1.9

Control for substance No. 1 230.8 235.7

2. Dinitro - O - phenyl phenol 85.5 86.1

3. Dinistro - O - cyclohexyl phenol 3.0 24.1

4. Dinitro O - cresol 4.2 3.

5. Chloranil vyclopentadiene 40.0 1.6

6. Para chloro-meta xylenol 0.8 0.9

7. Quinone cyclooctatetraene 162.0 86.6

8. Dibenzoyl ethylene Val 1.0

Control for substances 2 to 8 218.6 212.9

9. Phenanthrene quinhydrome 2.5 2

10. 2 - methyl - 1, 4 - naphthoquinone 2.0 1.6

Control for substances 9 and 10 197.2 195.6
Complete medium alone 214.2

JULY «= OCTOBER 1953

xylenol, dibenzoyl ethylene, phenanthrene
quinhydrome, and 2-methyl-1,4-naphthoqui-
none. Other substances tested in Treatment
No. 2 showed little or no inhibitory action
(80 + ml.) These are as follows:

3,4-methylene dioxy benzalaniline

2,3,4-trihydroxy benzalaniline

2-nitro benzalaniline

dihydroxy anthraquinone

Secdium tetrahydro naphthalene-
beta-sulfonate

Resorcinol-acetone (Condensation

product)
Alpha-penyl-4-hydroxycinnamic acid
Quinone cyclooctatetraene
Fhenanthrene
Anthragallol

Anthracene

1,2-naphthoquinone

Beta-chloro anthraguinone

Tripheny]! stibine

Acenaphtene

Copaivic acid

With these the inhibitory action is
somewhat lower than for those of Treatment
No. 1. Probably, an increase in concentration
would result in an increase in inhibitory ac-
tion.

In vitro inhibitory action of any of these
substances may be due to several causes.
Among those possible are the following:

1. Interference with a normal synthesi-
zing enzyme system. A form of com-
petitive inhibition in which the an-
tagonist competes with a metabolite
for the enzyme system.

2. Interference with membrane perme-
ability, in which the antagonistic
substances causes a change rendering
the cell wall incapable of taking or
disposing the necessary substance
(one or series of them).

3. Interference with the reproductive
mechanism of the organism resulting
in cessation of reproduction and con-
sequent death.

4. Radical changes in the physical en-
vironment of the cell brought about

139

by the antagonistic substance outside
or inside the cell which will finally
result in no growth and death.

Possible conversion of the antagonist,
by sterilization or other process, into
the actual antagonistic substance.

OV

Concerning the last possible cause it is
of interest to note that Rennerfelt:’ conduct-
ing a series of experiments with pinosylvin
and different microorganisms, thought that
these compounds might be converted into
phenol (or derivatives) and benzoic acid,
both being poisonous to fungi. He concluded
that for certain organisms the concentration
of phenol required to produce an equivalent
inhibition to that of pinosylvin was consider-
ably higher.

The stilbene derivatives are synthesized
from stilbene which is the parent compound
of stilbestrol and diethyl stilbestrol, two of
the synthetic sex hormones used by humans.
With respect to this, Brownlee et al4¢/ syn-
thesized a series of stilbene derivatives simi-
lar to sex hormones and they all had activity
against staphylococci and streptococci. The
best substance they found was 4-hydroxy
diethy] stilbene.

The best in vitro inhibitors should be
tried in field tests. Observations could be
made on how they behave under actual worx-
ing conditions. The possibility that higher
concentrations of the non-inhibitory subs-
tances could inhibit is not excluded, They
were not made mainly because the amounts
were very small.

In a similar series of experiments made
by the author’ with Fusarium oxysporum vay.
cubense and var. vanillae, the same general
results were obtained. Field trials are now
being conducted with some of these
substances .

3/ Rennerfelt, E. 1945. The influence of the phenolic com-
pounds in the heartwood of Scots pine (Pinus silvestris L.)
on the growth of some decay fungi in nutrient solutions.
Svensk Botanisk fids Krift Bd. 39, H 4.

4/ Brownlee, G., Copp., F. C. Duffin, W.M., and Tonkins,
I. M. 1943. The antibacterial action of some stilbene deri-
vatives. Biochem. J. 37,572-7.

5/ Ascorbe, F. J. 1952. Unpublished data.

140

CARIBBEAN FORESTER

OUR EFFORTS TO CONSERVE TREES

FRANK H. WADSWORTH

Tropical Forest Experiment Station
Rio Piedras, Puerto Rico

Previous papers in this symposium have
shown the importance of trees to Puerto Ri-
co. They are of importance for much move
than merely the wood they produce. Tney
may yield fruits or fibers or may serve tor
beautification. Considered in the aggregate,
forests of trees also are of value for the con-
trol of soil erosion and the runoff of water,
as refuges for beneficial or attractive wild-
life, or as peaceful environment for outdoor
vecreation.

In spite of all of these values nearly all
of the island has been deforested, some areas
several times. Generally this has been done
to permit settlement, for the production of
cultivated crops or forage, or to harvest the
ivees them-elves. The necessity and impor-
tance of these activities on many areas is
generally recognized, but what has been, is
being, and should be done to perpetuate the
benefits of trees where trees are needed?

Tree Conservation in the Past

The effort to conserve trees in Puerto
Rico is not a new activity. A number of the
early Spanish laws which applied to Puerto
Rico reflected the scarcity of forest products
in that country. Later, when Puerto Rico’s
forests retreated so far that building mate-
rials became locally scarce and some of the
streams disappeared during dry weather a
numbey of local laws were passed to conserve
the trees.

In the “Ley Primera,” in 1513, Ferdi-
nand V offered the people land, a part of
which was to be planted to trees (3). In 1536
Charles I ordered settlers to whom lands
were distributed to plant trees along their
boundaries, so that it would be possible to
use the timber (3). The first indication of
interest. within Puerto Rico in forest conser-
vation was government Circular No. 493 in

1/ Paper presented at the Symposium of the American So-
ciety of Agricu!tural Sciences, he'd in Rio Piedras, Puer‘o
Rico, on November 14, 1952.

1824 presenting the recommendation of Mi-
guel de la Torre that strips of trees be left
along and at the source of the stream (5).

In 1839 Isabelia II ordered the establish-
ment of a board in Puerto Rico to protect
forest, fish, and wildlife (6). In 1843 this
board approved a number of r-solutions,
among which some were about as follows:

1. Timber cutting on lands best suited
for forest should be only in the form
of thinnings.

2. In the cutting of the Crown forests
care must be taken to maintain con-
ditions satisfactory for reproduction.

3. Where necessary the Crown forests
should be reforested after cutting.

4. Palms should be planted near dwell-
ings because of their proven effect
in keeping lightning away.

5. No cutting is permitted on the mar-
gins or in the headwaters of rivers,
on either Crown or private land.

or)

Ucar, capa blanco, capa prieto, man-
gle botoncillo, mangle colorado, ma-
ria, ausubo, algarrobo, cébana, roble,
laurel, and cedro are to be reserved
for naval use.

Circular No. 34 of the Puerto Rican
government in 1844 required that each
municipality plant trees on the boundaries of
Crown lands and along roads. This may mark
the beginning of our roadside trees. It aiso
called for the establishment of a public forest-
ry agency, The mayors were to locate and
determine the area of public lands w.thia
their municipalities which should be kept
forested by this agency. (5).

By royal order in 1850 those lands which
reverted to the Crown because they -had not

JULY - OCTOBER 1953

been cultivated in accordance with the terms
of the concession were, if best suited for for-
est, to be withheld from further sale and
placed under the administration of a govern-
ment forest engineer.

A royal order in 1853 ordered the prepa-
ration of a forest law, the location and
marking of Crown lands, and the collection
of data as to the amounts and methods of
cutting. Two foresters were sent from Spain
on a 3-year mission to help set up the pro-
ject (6). In 1859 a circular prohibited the
cutting of the best trees for fuelwood, as
they were to be dedicated to higher uses (5).

A budget for public forestry, 2,800
pesos, first appears in the record in 1860 (5),
although reference is made in legislation 10
years earlier to the position of public forest
engineer. Nevertheless, in 1870 the forestry
appropriation was discontinued by the local
government as an economy measure, since it
was thought that forestry was not necessary
in a country where forests were scarce. Al-
most immediately thereafter a large area of
Crown lands passed into private ownership,
including Guilarte Peak.

In 1875 the Governor General signed 2
decree prohibiting clearing and burning on
all lands private as well as public, unless a
permit was obtained from the mayor. The
mayors were to follow the instructions of a
government forest inspector. In 1876 a royal
order put a stop to the free distribution of
land and specified that before land sales were
made the forest inspector should examine 2i1
Crown lands to prevent the alienation of
those which should remain in forest. Ten
percent of the receipts from the sales of the
Crown lands and of forest products from
them was to be used for reforestation and
forest improvement.

A forest law was promulgated by Alfon-
so XII in 1876 establishing forest reserves
and providing for their protection (2). Crown
forest reserves were to be set aside where
needed for erosion control, conservation of
well levels, regulation of rivers, maintenance
of rains, and protection against wind. Munici-

141

pal forests were to be set aside from Crown
lands for each village. These were to be ad-
ministered locally by the mayors; all others
by the Forest Inspector, who was in charge
throughout the island. The Forest Inspector
was to decide jointly with the local mayor,
a year ahead, which trees should be cut from
the municipal forests and was to make plans
for forest improvement. The royal mark was
to be placed on all trees to be cut.

To assist in the carrying out of this for-
est law an office of the Spanish “Cuerpo
Nacional de Ingenieros de Montes” was main-
tained in Puerto Rico for at least the next
nine years, and an apropriation for forestry
was restored by the local government. A new
Puerto Rican forestry organization was set
up under the “Negociado de Obras Publicas,
Construcciones Civiles, Montes y Minas” and
was referred to as the ‘“‘Inspeccion de Montes
de Puerto Rico” or the “Servicio de Vigilan-
cia de Montes’. In 1877-78, 3,800 pesos were
assigned for personnel, divided among an
inspector, two asistants, a clerk, and an or-
cerly. Sixteen-hundred pesos were provided
for location of boundaries, office rent, boos,
and instruments. The following year the
same personnel carried on, but the total ap-
propriation was cut to 5,100 pesos. The man-
groves, historically of value for naval con-
struction, were transferred from the Navy to
the “Inspeccion de Montes” in 1877 in spite
of dissention by the Navy.

Tne first forest region, containing about
26,000 acres in the Luquillo Mountains and
the eastern mangroves ,had been established
by 1885 and was protected by one guard. A
second region apparently centered at Utuado.
About a dozen timber trespass cases were
heard in 1885 before the mayor of Luquillo
and several were won by the government.
From 1877 to 1888 detailed plans were mace
for exploitation of public timber, based upon
estimates of volume, age classes, and rota-
tion. These plans contemplated cutting more
than 17,000 acres of forest annually. How-
ever, few cutting records are to be found,
and descriptions of the different Crown for-
est areas by the “Inspeccidn’”’ were so vague

142

as to indicate that the Forest Inspector was
not well acauainted with conditions in the
field and that plans were far ahead of pro-
gress. At least 20 auctions of standing tim-
ber were held in the first region from 1885
to 1288. Some of the timber sale contract
clauses were essentially the same as those
of today.

It is evident that Puerto Rico had pro-
eressive forestry legislation during the 19th
century. Although the historical record is not
all clear, the extent and condition of the is-
land’s forest rezources as described at the
end of that century testify to the fact that
conservation efforts were not very effective.

Following the Spanish-American War
the Ameyican government at first paid even
less attention to forest conservation. On Jan-
uary 17, 1903 President Theodore Roosevelt
set aside most of the former Spanish Crown
lands within the Luquillo Mountains as the
Luquillo Forest Reserve, to be administered
by the Federal Bureau of Forestry. However,
the area was not provided protection until
15 years later.

In 1909 the Puerto Rico Comissioner of
Aericulture and Labor wrote the Forester in
Washington, recommending that guards se
hired. He stated that charcoal makers were
deforesting to the tops of the mountains.
The Forest Service, which had by then re-
placed the Bureau of Forestry, sent a repre-
sentative to Puerto Rico in 1910 who report-
ed, however, that the area was too small to
administer efficiently as a National Forest
and suggested that it be turned over to the
local government. The Governor objected on
the grounds that the help of the Forest Ser-
vice was needed, and stated that its with-
drawal would be “exceedingly regretted”. He
offered forested tracts east of the reserve
area to the Federal government if the Forest
Service would send a superintendent.

In 1911 the Insular government again
petitioned the Forest Service to send experts
to rectudy the area. J. G. Peters and L. S.

CARIBBEAN FORESTER

Murphy came and made a reconnaissance of
the forests and forest problems of the entire
island. They found records of land ownership
chaotic in the Luquillo Mountains and again
recommended that the Forest Service with-
draw. The Insular government again object-
ed, upon which Murphy recomended a bound-
ary survey, using Insular engineers and
Federal funds. The survey was completed in
1916 and showed the public forest to contain
12,445 acres. A Federal forest supervisor was
put in charge in 1917, and two guards were
hired in 1918.

Upon Murphy’s recommendation an un-
successful attempt was made to set up a local
forest service in 1912. Finally, in 1917, a Por-
to Rico Forest Service was established in the
Department of Agriculture and Labor. In
1918 this Service was assigned the adminis-
tration of some 15,000 acres of unalienated
mangrove forest. In 1919 blocks of public
nonagricultural land at Guanica and Maricao,
and on Mona Island were added.

Expansion of the original public forest
areas has taken place in various ways. Since
1931 an additional 13,888 acres have been ac-
quired in the Luquillo Mountains, partly by
transfer from the local government but most-
ly by purchase, by the Federal government.

In 1935 the Federal Forest Service estab-

lished a Purchase Unit in the Cordillera
Central, the Toro Negro, containing a gross
area of 120,000 acres, Since that time 6,625

acres have been acquired there.

In 1935, the Puerto Rico Reconstruction
Administration of the U. 8. Department of
the Interior set up a third Forest Service.
This Service established five forests —Cari-
te, Rio Abajo, Guajataca, Guilarte, and Su-
sua— containing a total area of about 21,750
acres. In 1943 the PRRA Forest Service was
discontinued, and its lands were divided be-
tween the other two Services. In 1946 Mona
Island was transferred from the Puerto Rico
Forest Service to the Agricultural Develop-
ment Company.

JULY - OCTOBER 1953

It has been the objective of the public
forest agencies to develop and to use conser-
vatively all of the resources of the forest re-
serves. Planting began in about 1922, and
many exotic tree species were tested. A total
of about 37,000,000 trees have been planted
and there are now about 16,000 acres of satis-
factory plantations. About 7,500 acres of
forest have been improved by silvicultural
cuttings. Approximately 3,700,000 cubic feet
of timber have been cut in accordance with
the principles of silviculture. One hundred
and sixty miles of developmental roads and
259 miles of trails have been constructed.
Recreation facilities and trails have been
constructed at six different sites on the is-
land. About 1,600 acres of land suitable for
farming have been made available in small
parcels to 270 families. To date, the total ex-
penditure on the public forests (and their
cevelopment) exceeds $15,000,000.

The government has alco been interest-
ed in encouraging better practices on p-ivate
forest lands. A law passed in 1925 provides
for a fixed assessment of 1 dollar per czerda
annually for 5 years for deforested lands
which are planted with at least 600 trees ver
cuerda. Another law, passed in 1930, exempts
from taxation properties of not less than 50
cuerdas devoted to the production of trees
for commercial purposes or the conservation
of river sources and banks. Neither of these
laws has been very effective, apparently be-
cause the saving in taxes is not sufficient *o
offset the “retirement” of the land from
subsistence farming.

Since 1921 the local government has pro-
vided an apropriation for propagation of tree
seedlings for distribution to farmers. This
appropriation has been augmented by Feder-
al funds under the Clarke-McNary Act since
1926, and the Norris-Doxey Act since 1937.
The total expenditure to 1952, both State
and Federal, is about $785,000. More than
50,000,000 trees have been propagated and
distributed.

The position of Extension Forester has
existed in the Agricultural Extension Ser-

143

vice since 1928. The Extension Forester has
been active in distributing trees to farmers
and in dissemination of forestry information
to rural people through the agents of that
Service.

Forest research has been conducted on
a small scaie in Puerto Rico almost since the
Forest Services were established. Planting
studies began as early as 1920 (7) In 1939,
the Southern Forest Experiment Station laid
out a regeneration research program. At the
end of that year the Tropical Forest Experi-
men* Station was established at Rio Piedras.
Since tnat time this Station has had at least
two professional foresters conducting re-
search on the problems of both private and
pubile forest lands. The present program in-
clides chiefly studies of regeneration and
silviculture, but through the cooperation of
the Division of Forests of the Commonwealth
wood utilization research is now being ini-
tiated.

Another recent step toward better nmian-
agement of Puerto Rico’s forests is an
island-wide forest survey conducted by the
Division of Forests of the Commonwealth to
determine the character and quantity of
Puerto Rico’s forest resources. This survey
is nearly completed.

Quite apart from forest conservation
considerable areas have been planted to tree
crops and managed to our benefit. Coconuts,
coffee, and citrus were introduced early and
all are important crops today. The bay rum
tree was also placed under cultivation at an
early date. Systematic roadside tree planting
was begun more than 100 years ago, in
recognition of shade as an important tree
product.

Some Elements of a Future Tree

Conservation Program
The production of a maximum of tree
products consistent with proper land use re-
quires a continued effort on the part of the
government and landowners.

Recognition of Tree Land

On paper, tree land might be defined as
that on which the best suited crop is a closed

144

tree cover, or forest, without regard to its
present cover or use: where trees produce a
higher sustained yield, in terms of economic
and/or social benefits, than other crops, On
the ground, on the other hand, definition is
not so simple. It is at present usually impos-
sible to compare the returns from tree and
nontree crops. We do not yet know from ex-
perience the costs of producing forests of
any specified size or volume. Even were these
known the future value of such yield, when
it becomes available, is still an unknown.

One category of lands, however, should
be recognized by all as tree land: those areas
which because of excessive slope (nearly all
lands of more than 50 percent slope, accord-
ing to the Soil Conservation Service) ; heavy
rainfall; or shallow, infertile, or poorly-drain-
ed soil cannot be cultivated or pastured con-
tinuously without soil deterioration and/or
very low yields, yet which can produce trees
as a permanent crop. The area of such tree
land, estimated from studies of topographic
and soil maps, is not less than 600,000 acres,
or about one quarter of the land surface of
the island. For the present we might well
limit our efforts largely to this area.

Sharing the Responsibility

In the past the greatest effort to conserve
trees has been that of the government. It
is necessary that the government assume
this leadership because of the social values
involved in forestry, the uncertainty and
long time character of tree production, and
the degraded condition of large areas of tree
lands, the betterment of which involves an
investment which does not interest private
capital.

Nevertheless, it should be recognized
that the government cannot do the whole
job or even any large part of it. Nearly 90
percent of the tree lands are in private
ownership, many of them in small scattered
tracts. The government cannot afford to pur-
chase and manage all of these tree lands.
Wherever returns from tree crops (such as
coffee) are adequate to interest private pro-
duction this should be encouraged.

CARIBBEAN FORESTER

The program should be a joint one, with
the landowner fully aware of the need for
trees and willing to plant and manage them
wherever there is a reasonable opportunity
for returns. The government, on the other
hand, should do everything reasonable to
make tree culture an enterprise which is at-
tractive to landowners.

The Task of the Government

The future of tree conservation, al-
though it requires the cooperation of land-
owners, is at present largely in the hands of
the government. It is the government, which
through education, research, demonstration,
and legislation, must induce the farmer to
produce tree crops.

The first step is undoubtedly and acceler-
ation of the educational program. Although
two or three million forest trees are planted
annually by farmers, the species selected and
planting methods often are based upon in-
adequate knowledge and result either in com-
plete failure or something less than could
have been expected. It may be true that the
best tree crops we know, including coffee,
are not attractive to many farmers, but still
more regrettable is the fact that the farmers,
are often not fully aware of even those pos-
sibilities which do exist. It seems safe to
say that a large proportion of the 50,000,000
timber trees planted by farmers in past years
were planted because the farmer had an in-
nate love for trees from the aesthetic stand-
point, not because he was counting on a pro-
fitable harvest. We must show the economic
side much more effectively.

If the farmer is eventually to carry the
chief responsibility for tree culture we must
make it much more attractive to him than
present knowledge permits. This calls for an
accelerated public forest research program.
New, and more profitable tree crops must be
introduced or developed. This may include
fruits, nuts, fibers, and other nontimber prod-
ucts as well as timber. Better production
methods with existing crops must be devel-
oped to permit earlier harvesting, greater
yields, and cheaper management. Better

JULY - OCTOBER 1953

include processing of fruits and coffee, new
uses for timber, and wood preservation.

The government must asure protection
of soil and water resources and the produc-
tivity of critical tree lands where private tree
culture is non-existent and unlikely before
social values ave lost. This calls for an ac-
celerated public land acquisition program.
Of the 600,000 acres of tree lands steeper
than 50 percent slope, some 427,000 acres are
in blocks of 10,000 acres or more, where
population tends to be sparse and roads,
schools, and other comunity services are
expensive. This area, which includes poor
soils and critical watershed lands, lends it-
self to efficient large scale tree or forest man-
agement. Part of the area is today produc-
ing coffee under tree shade, Nevertheless,
more than half of the area is deforestea and
subject to shifting cultivation. Where tree
can be made attractive to private
owners on these lands, they should be induc-
ed to produce them. Elsewhere the only re-
course appears to be the acquisition and con-
servation of these areas by the public. In
this category are more than 100,000 acres in
the Sierra de Cayey, on the south slope of
the Cordillera, in the Atalaya Mountains
near AMnasco, in the northern limestone
region, and in the watersheds of the Arecibo,
Manati, and La Plata rivers. The eventual
total which must be acquired depends large-
ly on the progress which can be made
through research, extension, and incentives
to obtain satisfactory tree culture on the

moa

private lands in these areas.

On public forest lands the government
must do more than to merely protect the
soil, water, 2nd tree resources. These lands
should serve as demonstrations of good tim-
ber management. They should serve as ref-
uges for beneficial wildlife and their natural
beauty should be made available to all in well
planned public recreation areas.

Another aspect of public responsibility for
tree culture is roadside beautification. As a
result of the appreciation of trees by our

145

techniques for processing and utilizing tree
products must be worked out to make the
most of what is produced. This should
forefathers we have received a precious heri-
tage in our roadside trees, estimated to
cover at least 15,000 acres. We are in an en-
vironment much more favorable to road-
side tree planting than that when they began
this work. There are now more roads, more
road planning is being done, more money is
available for road maintenance, more people
uce and see the roads, and many new orna-
mental trees have been introduced into the
island. Under these conditions we should be
able to maintain our better roadside trees
and to gradually replace some of them with
more atiractive species,

Literature Cited

1. BRUNER, E. M. 1920. La importancia de
la silvicultura para los agricultores de
Puerto Rico. Rev. de Agr. y Com. (Puerto
Rico) 5(3) :19-24.

2. CUBA. 1907. Disposiciones vigentes rela-
tivas al servicio del Ramo de Montes en la
Isla de Cuba. Havana.

GO

PEYTON, J. S:.-and PETERS, J. G:. 1912.
Forest timber and tree laws in general of
Porto Rico, U. S. Forest Service. Wash-
ington. (Unpublished).

4. PUERTO RICO. 1860-1868 and 1874-1879.
Presupuestos generales de ingresos y gas-
tos correspondientes al ano econdmico. San
Juan.

5. RAMOS, F. 1866. Prontuario de disposi-
ciones oficiales del gobierno superior de la
isla de Puerto Rico. San Juan: Imp. de J.
Gonzalez Font. Pp. 531.

6. RODRIGUEZ SAN PEDRO, J. 1865. Le-
gislacion ultramarina. Vol. IV. Madrid:
Impr. de los Senores Viote, Cubas y Vi-
cente. Pp. 708. ~

146

CARIBBEAN FORESTER

ARBOLES EN LA FINCA +

/
SANTIAGO A. VIVALDI

Servicio de Extension Agricola

Universidad de Puerto Rico

Hoy se ha tratado y se seguira tratando
de ja importancia y el papel que juega el
arbol como conjunto y como individuo en di-
ferentes aspectos de la economia y vida agri-
cola y social de la isla. Entre estos aspectos
hay uno que esta, podriamos decir, mas ata-
do directamente al agricultor y a su finca.
Que por ser mas palpable y por resaltar mas
au la vista de todos, quizas puede despertar
mas interés en nuestro agricultor y mAs em-
peno en ser mejorado por éste. Nos referi-
mos al papel que juegan los arboles en la fin-
ea. A la silvicultura aplicada a la finca. Al
pequeno predio dedicado a bosque de subsis-
tencia que debe existir en todo negocio agri-
cola, no importa su tamano o la cosecha a que
se dedique.

El manejo adecuado de una arboleda de
subsistencia en la finca puede hacer al agyi-
cultor autosuficiente en sus necesidades or-
dinarias y corrientes por productos foresta-
les. Puede suplir sus necesidades en madera
de construccion, espeques para las cercas, le-
na para quemar, carbon, frutas, etc., y hasta
puede haber un sobrante que muy bien puede
venderse en los alrededores. No solamente
producirian un bosque de subsistencia, estos
productos forestales palpables, sino que daria
al agricultor un sinnuimero de beneficios in-
tangibles pero no menos valiosos como la pro-
teccion de sus cosechas agricolas, sirviéndo-
le como rompevientos, y como una barrera
positiva y permanente contra los arrastres;
mejorando y rehaciendo suelo; conservando
la humedad; y embelleciendo la finca para
suplir un sitio apropiado para recreo y espar-
cimiento del espiritu.

Las arboledas no necesitan ocupar terre-
nos valiosos, terrenos agricolas, donde crece-
rian bien y producirian rendimiento econ6-
mico otras cosechas agricolas. Los Arboles,

1/ Conferencia dictada como parte de un symposium de la
Sociedad Americana de Ciencias Agricolas, Rio Piedras,
Puerto Rico, Nov. 14, 1952.

por regla general se siembran en los pedazos
menos fértiles, mas abruptos, mas erodados y
menos productivos de la finca. Predios que no
rinden provecho alguno por ser improducti-
vos, agricolamente hablando. En fincas pe-
quenas, que estén enteramente bajo cultivo
agricola, podria muy bien usarse las colindan-
clas, mediante la siembra de cercas vivas de
especies apropiadas para la produccion por el
agricultor de muchos de los productos fores-
tales que necesita.

Ein las fincas de Puerto Rico son muchos
los predios que caen de lleno en la clase de
suelos no agricolas, severamente erodados,
incapaces de producir alguna cosecha econo-
micamente. Cerca de un 15 por ciento de toda
la tierra en fincas es ticrra de bosque, y en
aleunas isivas la proporcion de terrenos de
bosque llega hasta un 60 por ciento. Esto re-
presenta un area total de alrededor de 85,000
cuerdas. Un cuerdaje similar al que actual-
mente poseen y manejan los Servicios Estatal
v Federal de Bosques. Esto naturalmente no
incluye un numero positivamente mayor de
terrenos forestales que por estar en bloques
extensos no los consideramos como terrenos
en fincas. Toda esta tierra es potencialmen-
te valicsa y esta potencialidad podria reali-
zarse si se sometieran a un manejo adecua-
do. Seria bueno que antes de seguir adelan-
te definieramos lo que nosotros entendemos
por tierra de bosques o terreno forestal.
Por tierra de bosque queremos significar
toda aquella tierra donde la cosecha Optima
seria una cubierta forestal completa sin im-
portarnos para nada el uso actual que se le
esté dando al terreno. Tierra donde el bosque
seria la cosecha permanente mas productiva
en términos tanto econdmicos, de pesos y cen-
tavos, como en términos de beneficios socia-
les. Si una gran parte de esta tierra se de-
dicase a su uso l6ogico, nuestro agricultor

JULY - OCTOBER 1953

podria tener una gran parte de la madera ne-
cesaria para las construcciones de su finca
sin tener que obtenerlas de afuera. El agri-
cultor podria tener estos productos forestales
a la mano y al tiempo en que los necesita.
Podria tener estos productos del bosque y
ademas estaria conservando y mejorando
esos suelos y aprovechando los distintos be-
neficios en el orden estético y biologico que
una arboleda proporciona,

Ejemplo palpable de esta situacion de
mal uso del terreno podemos verlo claramen-
te en los terrenos Tanama y Aguilita del cen-
tro y noroeste de la isla. No solamente en
esta zona la situaciOn es alarmante, sino que
en toda la isla es en general desalentadora.
Con excepcién hecha de algunas areas aisla-
das en diferentes puntes de la isla como Ci-
dra, Barranquitas, Cayey, Maricao y otros
pocos, las fincas de café son practicamente
las Unicas arboledas que existen en terrenos
privados en la isla. Los terrenos forestales
estan abandonados y cuando mas producien-
cdo una fraccion muy pequena de su capaci-
dad, y naturalmente, tienen un valor real ac-
tual muy por debajo de su valor potencial,
siendo su aportaciOn al ingreso de la finca
completamente insignificante.

Esta situacion ha traido naturalmente
una escasez aguda de productos forestales.
Esta escasez ha hecho que el consumidor
haya tenido que mirar hacia productos subs-
titutos para llenar sus necesidades aunque es-
tos sean mas costosos. Asi vemos el aumento
progresivo del gas Kerosina como combusti-
ble. Asi vemos el uso de especies muy infe-
riores como espeques y postes. Asi vemos que
cada dia se hace menor uso de la madera.
Asi vemos también que dia a dia y a pesar
de los esfuerzos del Servicio de Conservacion
de Suelos se va agravando el problema de los
arrastres y de la pérdida rapida del agua en
los suelos.

Aunque nos place grandemente, por jus-

ticia, hacer reconocimiento del trabajo hecho
por jos Agentes Agricolas, Agentes de Cam-
po del Servicio de Conservacion de Suelos y
del Servicio de Bosques Insular y Federal, en

147

el mejoramiento y multiplicacion de los pre-
dios de bosque en las fincas, no podemos, sin
embargo, dejar de traer a vuestra atencion
el hecho de que por desgracia, nuestro agri-
cultor no parece darse verdadera cuenta de
la importancia de dedicar parte de su finca
a la produccion de productos forestales que
él mismo necesita y consume en su negocio
agricola y en su hogar. No parece nuestro
agricultor darse cuenta de la magnitud de
los problemas relacionados con la escasez de
estos productos forestales. Con excepcion de
la arboleda necesaria para proteger las plan-
taciones de café y otras situaciones aisladas
mencionadas antes, hasta la fecha no parece
haber sido posible vender la idea de que la
siembra de arboles puede llegar a ser una
empresa econodmicamente atractiva al agri-
cultor privado.

Creemos logico enumerar para ustedes
algunos de los problemas mas importantes
con que nos hemos encontrado en el desarro-
llo de nuestro trabajo por tratar de mejorar
los bosques privades de la isla.

En primer término la escasez de tierra
cultivable en Puerto Rico unida a la densidad
enorme de nuestra poblacion hace que la pre-
sion por el cultivo de la tierra sea demasia-
do fuerte. Hace que el agricultor trate de po-
ner bajo cultivo agricola, tierras que sabemos
deberian estar dedicadas a2 pasto o a bosques.
Esta situacion hace que el agricultor, muchas
veces, aunque comprenda la bondad del con-
sejo de que dedique parte de estas tierras a
bosque se vea en la necesidad de tratar de
hacerlas producir alguna cosecha por la cual
pueda conseguir crédito o alguna entrada in-
mediata. Asi vemos como una cantidad cre-
cida de cuerdas de tierra estan sembradas de
cana y frutos menores sin que podamos no-
sotros comprender como pueden rendir be-
neficio econdmico alguno a quien las cultiva.
Tierras que logicamente deberian estar dedi-
cadas a arboledas para producir parte de los
productos forestales y frutales necesarios y
que tanto escasean en muchas zonas de la
isla.

En segundo término se nos viene a la
mente la mala seleccioén de especies. Cuando

148

el agricultor se decide a dedicar parte de su
finca a bosque, en lo primero que piensa es
en talar la maleza que crece en la parte mas
inservible, desgastada y probablemente mas

d

erodada de su finca y sembrarla de arboles.
Pero, y aqui esta quizas una de las fallas mas
importantes del trabajo hecho hasta la fecha,
solo piensa en especies valiosas, generalmen-
te exdticas que de crecer bien podrian pro-
ducirle maderas valiosas. Especies climax.
Pero, {son esos terrenos apropiados para es-
tas especies? ; Esta el medioambiente prepa-
rado para que estas especies climax puedan
sobrevivir y desarrollarse? Generalmente no.
Estas tierras degradadas, desnudas y eroda-
das han perdido todas las caracteristicas co-
munes al bosque y para tener éxito en su re-
poblacion hay que empezar mucho mas abajo
en la ecologia. Hay que empezar con especies
agresivas, peleadoras, fuertes, que puedan
soportar y vencer esas condiciones adversas.
Estas son las especies que pueden preparar
el camino para el establecimiento y desarro-
llo de las especies valiosas que son mas exi-
gentes tanto en nutrientes como en condicio-
nes ambientales. Es necesario pues conven-
cer al agricultor de que por el momento, cuan-
do éste sea su caso tiene que olvidarse de
esas especies valiosas y conformarse con
otras que aunque no de tanto valor, van siem-
pre a producirle lo que él necesita: lefia, es-
peques, postes y lo que es mas importante
aun, van a protegerle su suelo y van a prepa-
rar el terreno para que luego pueda venir la
invasion por aquellas otras especies que el
pretferia. Las especiess climax.

Otro problema que frecuentemente con-
frontamos en el campo es e! mal uso de las
pocas arboledas que nos quedan. En este as-
pecto tenemos los dos extremos. Aquellos
que creen que su bosque es un santuario don-
de no puede hacerse corta alguna y aquellos
que cortan sin consideracion alguna hasta
que solo dejan una maleza inservible que
apenas si les produce algun espeque regular
y generalmente de especie inferior. Ambas
practicas son pobres e indeseables, En el pri-
mer caso ademas de ser una pérdida innece-
saria de madera en los arboles que van mu-

CARIBBEAN FORESTER

riendo y desapareciendo sin que nadie haga
uso de ellos, las condiciones ambientales que
cbligatoriamente se desarrollan son tales que
inhiben el crecimiento de los arboles jéve-
nes que puedan estar medrando bajo la som-
bra de los arboles mas viejos. Este medioam-
biente caracteristico de un predio de bosque
bajo estas condiciones no solamente inhiben
el crecimiento de los arboles jOvenes, sino que
hacen que las condiciones sean muy poco
apropiadas para la reproduccion. En otras pa-
labras, anulan dos de las caracteristicas ba-
sicas de cualquier buen manejo forestal: con-
seguir el mayor crecimiento por unidad de
terreno y conseguir una reproduccion natu-
ral adecuada.

En el segundo caso, cuando se corta sin
seguir normas aceptables de manejo, caso
muy comun y corriente, los resultados seran
un bosque futuro de especies inferiores, cali-
dad y forma indeseable y una poblacion de-
fectuosa.

No cabe duda que cuando se cuenta ya
con un predio de bosque natural para empe-
zar, no debiera nunca pensarse como se ha
hecho tantas veces en suplantar este bosque
por uno artificial. Debe si pensarse en mejo-
rarlo poniéndolo bajo un buen manejo. Para
esto, naturalmente tiene que existir un lide-
rato adiestrado que pueda guiar al agricultor
en estas situaciones. Un liderato que por un
medio u otro pueda convencer al agricultor
de la necesidad para él y para su comunidad
de que su pequeno bosque subsista. Que sub-
sista y se mejore para que pueda llenar las
necesidades del buen manejo y utilizacion de
sus tierras. Para que produzca para él mu-
chos de los productos forestales que él nece-
sita en su hogar y en su fineca.

La situacion que hemos descrito en la
isla, en cuanto al uso de los terrenos fores-
tales o de bosque en las fincas privadas, ne-
cesita urgentemente de un liderato adicional
inteligente y consciente del problema y que
pueda interesar a nuestro agricultor en el
restablecimiento de estos predios forestales.
La motivacion tiene que ser mas amplia y

mejor coordinada que hasta el presente. El

JUG = OCTOBER, 1953

esfuerzo mayor tiene que ser hacia un mejor
uso y ampliacion de los recursos de que dis-
ponemos. Este esfuerzo puede traducirse en
educacion y ayuda técnica a los agricultores.

La educacién, que la consideramos el
punto clave, la piedra angular del éxito de
cualquier campafa 0 programa que se implan-
tase debe extenderse hasta incluir y dar én-
fasis al reconocimiento de los terrenos fores-
tales dentro de la finca, las diferentes poten-
cialidades de la cubierta forestal como pro-
ductora de madera, frutas, fibras y otros pro-
ductos del bosque. La proteccion de las cuen-
cas; la conservacion del suelo y la humedad;
la estabilizacion del caudal de los cuerpos de
agua para que podamos disponer de ellos,
tanto en tiempos de sequia como en tiempo
de lluvias y la provision de un medioambien-
te propicio para un desarrollo mas vasto de
recreacion al aire libre y un mejor estable-
cimiento de nuestra fauna silvestre,

La ayuda técnica debera, a su vez, in-
cluir un programa amplio de investigacion
que llene las lagunas que existen actualmen-
te en la informacion que podemos dar a nues-
tros agricultores. Debera extenderse ademas
hasta poder aconsejar al agricultor en la so-
lucion de sus problemas individuales, inclu-
yendo ante todo demostraciones donde poda-
mos demostrarle lo que le aconsejamos. Si
es que vamos a continuar suministrando como
hasta la fecha el material de propagacion a
usarse en la repoblacion forestal en nuestras
fincas, debemos investigar detalladamente
las fallas enumeradas y hacer todo lo huma-
namente posible porque este material llegue
a manos del agricultor en las mejores condi-
ciones y en la época mas apropiada. Unica
manera de que la reforestacion tenga una
base solida. Un principio adecuado.

Nos consta, por haber estado en relacién
directa con estos programas por muchos
anos, que nuestro gobierno se ha dado cuenta
cabal y exacta del problema que nos ocupa.
No nos cabe duda alguna de que hay cierta
inquietud en todas las agencias al mirar y
enfocar este problema. Podemos darnos cuen-
ta de este creciente interés, por las solicitu-

149

des que nos llegan a diario recabando nues-
tra cooperacion y ayuda en la formulacion
de planes para la siembra de pequenos pre-
dios en proyectos de las diferentes agencias
gubernamentales como la Autoridad de Tie-
rras, Autoridad de Hogares, Secretarias de
Instruccion y Educacion, etc. Esto sin lugar
a dudas, sirve como medio de propaganda y
divulgacion. Pero es el estimulo en el agri-
cultor, en el campesino lo que mas nos debe
de interesar. Es al agricultor, al campesino,
al que vive en el campo y esta diariamente2
viendo esa parte de su finca improductiva y
desnuda a quien debemos interesar y estimu-
lar para que se convenza de que a él, a su
finca, a su comunidad, a nuestro pais tcdo,
le conviene que él ponga a producir e2a tie-
rra que él cree inservible. Que la ponga a pre-
ducir lo que, segun la mas basica reglamen
tacion de la utilizaciOn racional de la tierra,
debiera estar produciendo; arboles.

Esto solo puede conseguirse de manera
permanente mediante una campana amplia,
Lien organizada y coordinada de educacion.
Una campana que enfatize y realce la impor-
tancia del desarollo de un liderato adiestrado
y consciente de la importancia de aumentar
los recursos forestales de la isla, a través de
la seleccion, adiestramiento y reconocimiento
del mayor numero de lideres voluntarios po-
sible. Una campana educativa que despierte
la conciencia de nuestra juventud rural y jo-
venes agricultores hacia una mejor compren-
sion de la importancia de los bosques.

Hemos dejado para discutirlo separada-
mente, por considerarlo de suma importancia,
el problema de la sombra del café. Decidimos
incluirlo porque como hemos dicho antes, las
fincas de café son practicamente las unicas
arboledas que quedan en las fincas de nues-
tra isla y por considerar que los problemas
de manejo de la sombra de una plantacion de
café, son basicamente problemas silvicultu-
rales. La sombra en los cafetales, tiene por
objeto principal mantener las condiciones
climatologicas mas 0 menos invariables, prin-
cipalmente en humedad. Esto equivale a ha-
cer menos sensibles y bruscos los cambios del
clima, asegurando los requisitos ideales para

150

el mejor mantenimiento de las plantas. Para
que el agricultor pueda graduar su sombra
de manera racional, es necesario que conozca
las condiciones climatolégicas del sitio, y las
condiciones atmosféricas que reinan en la ma-
yor parte del ano, de la altura de su finca,
condiciones actuales de sus arboles de sombra
y las diferencias individuales de cada una de
sus piezas de café. Es necesario que conozca
las especies que tiene y las caracteristicas
ce cada una de elias. En fin, tiene que tener
un conocimiento amplio de un buen numero
de arvoles y de las condiciones y factores que
afectan su desarrollo, manejo y reproduccion.

Durante los ultimos anos se ha notado un
resurgimiento del caficultor. Se ha notado
una mejoria halagadora en la industria del
café en nuestra isla. Y naturalmente, el cafi-
cultor ha fijado sus ojos en el silvicultor para
que le resuelva sus problemas de la sombra
Generalmente el cultivo del café se ha, mira-
co solamente desde el punto de vista tipica-
mente agricola. Practicamente todos los tra-
bajos de experimentacion llevados a cabo,
han sido trabajos sobre el crecimiento, con-
ducta y requerimientos del arbusto de café
en si. Es muy poco el trabajo que se ha hecho
con la sombra que protege esas plantaciones
de café. Es muy poca la importancia que se le
ha dado a los problemas que existen con esta
fase tan importante de ese cultivo.

Verdad es que podemos aconsejar al
agricultor dandoles reglas generales que pue-
den servirle de guia para el manejo de su
sombra. Verdad es que podemos decirle que
para tierras bajas, de temperaturas altas y
suelos resecos la sombra debe de ser muy tu-
pida y de arboles de ramaje extenso; que
para las tierras de temperatura fresca y hu-
meda la sombra debe ser menos espesa; y
que para los sitios muy frios y humedos la
sombra debe ser muy rala. También es ver-
dad que podemos aconsejarlos en otros as-
pectos generales casi siempre en relacion
con la densidad de la sombra, Pero, { podemos
acaso aconsejarlos sin duda ni titubeos sobre
el combate de los males que afectan sus 4r-
boles de sombra? ~Podemos ofrecerle algo
nuevo, de lo cual estemos seguros, en espe-

CARIBBEAN FORESTER

cies y su adaptacion? ~En utilizacion de los
tantos miles de pies cubicos de madera que
se pierden anualmente en las fincas de café?
No nos cabe la menor duda de que hay mucho
que hacer en la solucion de los problemas sil-
viculturales en la zona cafetalera de la isla.
Tampoco nos cabe duda aiguna de que es ai
silvicultor a quien toca resolver estos prosle-
mas y ofrecer una solucion al agricultor de
cafe.

Quizas la contribucion mas importante
hecha al cafetal en los ultimos anos haya sido
la introduccion del guama venezolano y su
distribucion entre los agricultores. No cree-
mos, como ha llegado a creerse por algunos
agricultores y hasta por algunos técnicos,
que el guama venezolano sea una panacea que
nos venga a resolver todos los problemas de
sombra, pero si creemos que en ciertos y de-
terminados casos y para determinadas zonas,
si ha resuelto un problema de importancia.
Durante los ultimos anos se han distribuido
3% millones de arbolitos de guama venezo-
lano entre los agricultores de la region cafe-
talera y actualmente a la propagacion de esta
especie se le esta dando gran importancia y
auge en los viveros forestales.

Quizas también la solucion de muchos de
los problemas que afectan las fincas de café
podria lograrse por los mismos medios usa-
dos en el manejo de los bosques. Deben in-
vestigarse las posibilidades del control biol¢-
gico en la lucha contra enfermedades e insec-
tos. Si la proporcion de luz y agua y las con-
diciones del suelo mejoran estimulando el
crecimiento rapido de todos los Arboles del
cafetal, los riesgos de enfermedades se redu-
cen. Asi mismo si se eliminan los arboles que
han pasado su madurez biologica, se reducen
erandemente las enfermedades.

Solo nos queda recordar que las genera-
lizaciones en la preservacion de maderas, en
la importancia e influencia de los bosques y
en la necesidad de conservar los recursos fo-.
restales ya se han vulgarizado lo suficiente
en nuestro pueblo. Que si seguimos trayen-
do ante nuestra clase agricola este tema sin
una informacion estadistica mas convineente,

JULY - OCTOBER 1953

podemos caer en el error de matar su interés
y hasta crear en ellos la sospecha de que no
podemos probar lo que les decimos. Necesita-
mos presentarles datos, datos locales convin-
centes y de facil comprobacion. Necesita-
mos mostrarles ejemplos confiables de de-
mostraciones donde se hayan resuelto sus
problemas de una manera practica. Nuestro
agricultor cree cuando ve. La cosa mas natu-
ral del mundo. Ejemplo palpable de esto es
el caso de los agricultores de tabaco de la zo-
na este de Puerto Rico. Estos agricultores
han reconocido, viendo el ejemplo, la utili-
dad de la siembra de pino australiano en sus
fincas. Han liegado a darse cuenta en tal for-
ma que el pino podia resolverle uno de sus
grandes problemas que ya la inmensa mayo-
ria de los agricultores de Yabucoa, San Lo-
renzo, Juncos, Gurabo, etc. consideran la
siembra de pinos, una siembra complemen-
taria a la de tabaco. Han echado por el sue-
le el dicho de que cuando uno siembra Arbo-
les los siembra para sus hijos o nietos. Ellos
han aprendido a hacer uso del pino desde que
apenas el arbolito tiene una pulgada de dia-
metro. No queremos entrar en detalles sobre
el uso verdaderamente intensivo que estos
agricultores han aprendido a hacer de esta
especie porque entendemos que el Agente

151

Agricola de uno de estos pueblos, les explica-
ra en detalles el éxito obtenido por él en la
siembra de arboles en su distrito. El Sr. Le-
guillou, Agente Agricola de Yabucoa es un
ejemplo tipico de ese liderato inteligente,
consciente del problema de nuestra isla, de
cuya necesidad hice mencion con anxteriori-
cad. El] éxito alcanzado por el Sr. Leguillou
nos demuestra lo que puede hacerse y nos
alienta en nuestro trabajo al demostrarnos
que nuestro agricultor responde cuando pue-
de palpar las ventajas de lo que se le demues-
tra vy aconseja.

No queremos terminar sin hacer un me-
recido reconocimiento del trabajo que esta
lievando a cabo el Servicio de Bosques Fede-
ral en el Bosque Experimental de Cambala-
che. Tenemos la bien fundada esperanza de
gue como resultado de estos trabajos en
adaptabilidad de especies, costos, produccion,
rendimiento y usos, se puedan contestar con
aceptable exactitud muchas de las pregun-
tes que hace nuestro agricultor. Preguntas
que tendremos que aprender a contestar si
no queremos perder su confianza y hacer que

ellos pierdan el interés que puedan desarro-
llar en el establecimiento y mantenimiento de
predios forestales en sus fincas.

152

CARIBBEAN FORESTER

{QUE ARBOL SEMBRARE :

LUIS F. MARTORELL, Entomélogo

Estacion Experimental Agricola

Universidad de Puerto Rico

i Qué especie de arbol sembraré frente a
mi casa? {Que especies de arboles sembraré
en mi finca? Estas, y otras preguntas pare-
cidas, las hacen a diario muchas personas en
la Isla. Desconocen los arboles a sembrar que
embellezean sus hogares, den sombra a la
finca y a las casas de campo y sus alrededo-
res.

La seleccion de una especie de arbol,
para fines ornamentales parece ser tarea
muy dificil para la mayoria de las personas,
probablemente, por tener escasos conocimien-
tos sobre la serie de factores que determinan
las cualidades buenas o malas de las especies
de arboles ornamentales o para sombra.

En la Isla se cultivan muchas especies
de arboles que se codican a fines ornamenta-
les y para sombra, las cuales, desde el punto
de vista entomologico, patol6gico o por condi-
ciones propias de la especie no son las mas
recomendables, constituyendo asi, un error
e! cultivarlas. No sdlo cometen ese error los
desconocedores de la materia, sino también
algunas personas con conocimientos agrico-
las y aun alguna que otra agencia del gobier-
no.

El proposito de este breve articulo, es
dar a cooncer un numero de arboles que no
deben sembrarse en Puerto Rico y al mismo
tiempo recomendar aquellos que pueden ser
de mayor beneficio al ornato de la Isla.

Arboles Que no Deben Sembrarse

Los siguientes arboles los considera el
entomologo indeseables para fines ornamen-
tales o de sombra:

1/ Conferencia dictada como parte de un symposium de la Socie-
dad Americana de Ciencias Agricolas, Rio Piedras, Puerto Rico,
celebrada el 14 de noviembre de 1952.

Canatfistula, Cassia fistula L.
Roble de plata, Grevillea robusta A. Cunn

Cassia amarilla, Sciacassia siamea (Lamb.)
Britton

Maga, Montezuma speciosissima Sessé & Moc.
Flamboyan, Delonix regia (Bojer) Raf.

africano,
Béauv.

Tulipan Spathodea campanuiata

Capa prieto, Cordia alliodora (R. & P.)
Cham,

Roble bianco, Tabebuia pallida Miers
Laurel de la India, Ficus nitida Thumb.

Almendro, Terminalia catappa L.

Cedro, Cedrela odorata L., Cedrela mexica-
na Roem.

Acacia, Albizzia procere (Willd.) Benth.

Oreja de mono, Enterolobium cyclocarpum
(Jacq.) Griseb.

Pino Australiano, Casuarina equisetifolia
Forst.

Péndula, Citharexvlum fruticosum L.

Madre de cacao, Gliricidia sepium ( Jacq.)
Steud.

Angela o Bén, Moringa oleifera Lam.
Aleli, Plumeria alba L., Plumeria rubra L.
Emajaguilla, Thespesia populnea (L.) Soland

Sin embargo, las especies, arriba men-
cionadas, son las que mas se observan en las
carreteras, jardines, parques y fincas priva-
das,

JULY - OCTOBER 1953

Las razones que existen en contra del
cultivo de estos arboles, son las siguientes:

La canafistula, el roble de plata, la cas-
sia amarilla y la maga son especies muy sus-
ceptibles a los ataques de la queresa pustuic-
sa, (Asterolecanium pustulans (Cockerell) ). Esta
queresa no solo ataca los troncos y ramas,
deformandolos y causando una fea aparien-
cia en los mismos, sino que les causa la muer-
te, no importa el tamano, ni lo desarrollados
que estén. Este insecto atac6d severamente al
roble de plata en la Isla y caus6 la desapari-
cidn total de esta especie. El autor ha podido
observar hileras de hasta 60 arboles de cassia
amarilla, completamente destruidos por la
queresa pustulosa. Hace afius (6) se ovserva-
ron muchos Arboles de maga en el area entre
Dorado e Isabela, los cuales en su mayoria
venian sucumbiendo a los ateques de ecte in-
secto.

El] Dr. George N. Wolcott, Entomologo
de la Estacion Experimental, ha notado que
ultimamente no han aparecido ataques o bro-
tes infecciosos de la queresa pustulosa, pero
hay que considerar que toda vez que el in-
secto esta presente en la Isla, resulta suma-
mente arriesgado sembrar estas especies en
grande escala. No se puede perder de vista la
posibilidad de que ocurra en cualquier mo-
mento un brote o incidencia de este insecto y
cause la destruccion de millares de Arboles de
las especies arriba mencionadas, como ya ha
sucedido en el pasado.

El flamboyan es uno de los Arboles mas
comunes en la Isia. Se encuentra en los pa-
tios y jardines y también en las orillas de los
caminos y carreteras. El flamboyan en flor
es un espectaculo impresionante como todo el
mundo sabe, pero una vez que pasa este pe-
riodo, el arbol se torna poco atractivo, pués
pierde sus hojas, y se llena de vainas secas.
Entonces es cuando mas se le notan los ttine-
les y nidos del comején, lo que contribuye a
afear su aspecto. Por ser esta especie muy
susceptible a los ataques del comején comun,
(Nasutitermes (N) costalis (Holmgren)). Es
raro el arbol de flamboydn que no sufra los
ataques de este insecto.

153

También sufre frecuentemente de las de-
predaciones de un insecto defoliador. Se trata
de la oruga, o larva de la mariposa nocturna,
(Melipotis acontioides (Gueneé), la cual se mul-
tiplica rapidamente. El] autor ha visto milla-
res de arboles en el Valle de Lajas y en los
alrededores de Guanica completamente defo-
liados por este insecto. Estas orugas atacan
los arboles en ntimero tal y con tanta voraci-
dad, que pueden eliminarles las hojas a un
aérbol en menos de 12 horas. Fué en el afio
1633 que se informaron casos de Arboles
atacados en el area del Condado y Hato
Rey. El periddico “El Mundo”’, durante los ul-
timos dias del mes de agosto del 1933, di6 un
informe detallado sobre el ataque severo de
esta plaga en los sitios mencionados y segun
fué informado por el Sr. Francisco Sein, En-
tcenclogo de la Estacion Experimental Agri-
cola.

E] sistema de raices del flamboyan es
tan superficial que hace desventajosa su
siembra como ornamental en los alrededores
de las casas y aceras. Este arbol cuando se
desarrolla normalmente, extiende sus raices,
casi siempre por sobre la superficie del te-
rreno, causando asi la rotura de las aceras,
encintados, verjas de concreto y hasta de las
paredes de las casas. La Unica bondad de esta
especie, su bella florecida, se aminora cuan-
do se consideran todas sus desventajas.

E] tulipan africano no ofrece inconve-

nientes, desde el punto de vista entomoloégico,
ya que los pocos insectos que lo atacan, nin-
guno causa danos de mayor importancia que
puedan restarle méritos a la belleza de este
arbol. Sin embargo al igual que el flambo-
yan, tiene un sistema de raices, quizas muy
superficial, y por lo tanto tampoco es reco-
mendable para sembrar cerca de las residen-
clas, aceras o verjas de concreto. De haber
espacio disponible, el tulipan africano puede
ser una de las especies para ornato y sombra
mas recomendables para Puerto Rico.

E] capa prieto, es un arbol de gran utili-
dad, no solo por la excelente calidad de su
madera que se prefiera para la construccion
de muebles finos, sino por la belleza de sus
ramilletes de flores blancas enmarcadas en

154

el fondo verde obscuro del follaje. Es de
admirar los caps prietos de las cercanias del
Pcfion dei Collao entre 1,800 y 2,300 pies de
altura, en la carretera de Cayey a Salinas
cuando estan en flor. A pesar de su extrema
belleza no es recomendable como ornamen-
tal o para sombra por ser atacado, desgra-
ciadamente, por una chinche de ala de encaje.
Esta chinche, (Monanthia monotropidia Stal) no
solo descolora el follaje, sino que eventual-
mente causa la caida de las hojas. El ataque
es constante, pues las generaciones del insec-
to se suceden sin cesar. Sin embargo puede
ser un buen arbol de madera, si se siembra
conjuntamente con otras especies en los bos-
ques o fincas de cafe.

El roble blanco y su especie hermana, el
roble prieto (Tabebuia heterophylla (DC.) Brit-
ton) se usan en Puerto Rico como arboles or-
namentales y de sombra, Se pueden observar
generalmente en los patios, jardines, y calles
de las ciudades y pueblos de la Isla. El roble
blanco muy comtm en las montanas de la
Isla, es una de las especies mas vistosas du-
rante su florecida. Todo el arbol se cubre de
un manto de flores, las cuales varian del
color rosa palido hasta el rosa subido. Las
flores al caer, forman una alfombra alrede-
dor del arbol y la combinacion de flores en
las ramas y sobre el suelo resulta muy agra-
dable a la vista del viajero.

La enfermedad, “‘escoba de bruja” ataca
al roble blanco. De acuerdo con las investi-
gaciones del Dr. M. T. Cook (3) quién estu-
dio esta enfermedad, la misma es causada
por un virus, cuyo posible vector es el salt6n
de las hojas (Protelebra tabebuiac Dozier). Un
arbol que sufra severamente de esta enfer-
medad pierde toda su belleza y se convierte
en un manojo de escobillas, lo que no es lo
mejor para el ornato. La enfermedad preva-
lece mayormente en los arboles de roble que
crecen en los terrenos llanos.

También, durante las épocas de sequia,
los saltones de las hojas se alimentan del fo-
llaje de los robles, causdndoles una clorosis o
amarillez a las hojas. Llega el momento en
que las hojas se desprenden y el arbol se que-

CARIBBEAN FORESTER

da completamente defoliado. Cuando los ata-
ques de este insecto coinciden con la “escoba
de bruja’, el arbol cobra un aspecto por de-
mas indeseable.

Esta especie podria substituirse por el
roble de plata, (Tabebuia argentea) o por el
roble amarillo (Tabebuia glomerata Urb. Poui)
que son inmunes a la “escoba de bruja.”

1 laurel de la India es un arbol favorito
de las plazas y parques, pues es corpulento y
ofrece excelente sombra. Es una de las espe-
cies menos recomendables para la Isla, Sus
hojas sucumben al tripido o candelilla (Gynai-
kothrips ficorum (Marchal), que es un insecto
de reproduccion rapida especialmente duran-
te los largos periodos de la sequia. Deforma
las hojas y las enrosca con preferencia a las
de los retonos o tallos tiernos. Dentro de las
hojas asi enroscadas, viven estos pequenos
insectos que al mas leve movimiento se dejan
caer muchas veces en los ojos de los tran-
seuntes, para causarles una gran irritacion,
con el mismo efecto de una chispa de cande-
la o de gotas de alcohol. Miles y miles de es-
tos pequefos insectos vuelan o los lleva el
viento de arbol en arbol. Este arbol no debe
sembrarse en los parques de recreo, ya que el
insecto que se alberga en el mismo es nocivo.

Podria substituirse por otra especie del
mismo género, el Ficus benjamina L., que es
completamente inmune a los ataques del
tripido o candelilla. Habria entonces, que
propagar esta ultima especie de material acli-
matado a la Isla pués se sabe que en Santo
Domingo esta especie alberga otra especie de
tripido muy parecido al que ataca aqui al
laurel de la India y podria introducirse a
nuestro pais ese indeseable insecto. También
se podria substituir el laurel de la India, por
el palo de pollo (Pterocarpus officinalis Jacq.)
El Pterocarpus es un arbol que se asemeja mu-
cho al laurel y es resistente a las enfermeda-
des e insectos. Produce muy buena sombra
y adquiere gran tamano lo cual, lo hace muy
adecuado para los parques y residencias.

d

Las otras especies de Ficus que existen
en la Isla son inmunes al tripido. Pueden sem-
brarse en lugar del Ficus nitida.

JULY - OCTOBER 1953

El almendro y el cedro son dos especies
indeseables como arboles de sombra u orna-
to.

El almendro lo ataca un tripido o cande-
lilla (Selenothrips rubrocinctus (Giard), gene-
ralmente durante los meses del otono y del
invierno. El insecto se multiplica rapidamen-
te, ataca las hojas tornandolas amarillentas
algunas y plateadas o blancuzcas otras, y fi-
nalmente deshoja todo el arbol. Debido al in-
cesante ataque de este insecto el arbol de al-
mendro se queda, la mayor parte del tiempo,
sin hojas y por lo tanto sus funciones como
arbol de sombra resultan nulas.

Lo mismo le ocurre a los cedros cuando
estos son atacados por el salt6n de las hojas
(Dikraneura cedrelae Oman). Los ataques scn
consecutivos perdiendo el arbol toda su be-
lleza. El cedro es un magnifico arbol de bue-
na madera, pero no tiene valor ornamental,
debido en gran parte al ataque de esta plaga.

La acacia y la oreja de mono a pesar de
ser magnificos arboles ornamentales y de
sombra, son susceptibles a una enfermedad
muy parecida al “mal de la guaba”’. El Sr. L.
Alvarez Garcia (1) Fitopatologo de la Esta-
cion Experimental, estudio esta enfermedad,
causada por el hongo, Fuscrium oxyosporum
var. perniciosum, raza 2. El autor noto una
enfermedad similar durante el mes de junio
del 1952 en arboles de oreja de mono, en los
alrededores del Hospital de Distrito de Baya-
mon.

Esta enfermedad produce una abundan-
te exudacion de un liquido amarillento por
las rajaduras de la corteza del tronco de las
ramas de los arboles enfermos. Ataques se-
cundarios de insectos de la corteza y del

tronco tales como cermabicidos, bupréstidos
y escolitidos siguen a la enfermedad. Estos
ataques contribuyen a destruir el arbol que,
finalmente, en el momento menos esperado,
se cae. Si el arbol padece de la enfermedad
es recomendable cortarlo inmediatamente.
Asi se evitara la propagacion de la enferme-
dad a los arboles vecinos. En las cercanias

155

del lago del Guayabal, en Villalba, el autor
obkservO una enfermedad similar en el flam-
boyan.

Ei Sr. Alvarez Garcia recomienda el uso
de otra especie de acacia, la Albizia lebbeck
(L.) Benth., por que es resistente a la refe-
rida enfermedad. Durante los ultimos afios,
el autor ha observado numerosos 4rboles de
esta especie que han sido atacados y destrui-
dos por la enfermedad, en el area de Rio Pie-
dras a Guaynabo y también en Villalba.

Debido a la susceptibilidad de los ante-
riores arboles a las enfermedades menciona-
das no es recomendable su siembra.

El pino australiano se usa mucho como
arbol ornamental en la Isla. Existe una en-
fermedad desconocida hasta la fecha, que
destruye los arboles de esta especie estando
alin bien desarrollados. Durante los anos 1940
y 1941 muchos arboles de Casuarina enfermos
tuvieron que ser destruidos para evitar que
cayeran sobre las casas y plantios de cana.
La enfermedad se parece mucho a la c& la
acacla y oreja de mono, e igualmente la Ca-
suarina sufre de los ataques secundarios de
insectos taladradores de la corteza y el tallo,
Gespués de tener la enfermedad.

El uso del pino australiano con fines de
sombra permanente puede limitarse debido a
esta enfermedad, aun no estudiada. Esta es-
pecie puede sembrarse para otros fines, tales
como para obtener espeques, largueros para
ranchoncs, etc., donde el arbol se corta por
lo regular antes de llegar a su madurez.

La péndula se siembra en las orillas de
las carreteras y en algunos jardines. La larva
de una mariposa (Pyrausta cerata (Fabricius)
ataca el follaje de este arbol. Esta larva u
oruga, forma unos mazos 0 manojos de hojas,
las cuales pegan unas con otras. Cuando las
hojas se secan, el arbol queda finalmente des-
nudo. El arbol, algunas semanas después, ad-
quiere nuevo follaje, pero si las con-
diciones son satisfactorias, el insecto vuelve
a infestar de nuevo al arbol, El aspecto de un
Arbol de péndula bajo el ataque de este in-
secto no ayuda en nada al ornato.

156

La madre de cacao es uno de nuestros
arboles ornamentales mas Utiles. Su flor se
asemeja mucho a la de los cerezos japoneses,
ya que es rosada o violacea y se adhiere a
las ramas y al tronco. El follaje sin embargo,
lo ataca un afido o pulgoén, (Aphis medicaginis
Koch.), el cual se propaga rapidamente cu-
briendo grandes areas e infestando cientos
de arboles. El liquido dulce que segrega este
pulgon, no solo atrae a las hormigas sino
también a una clase de hongo negro, cono-
cido por hollin. Las hojas se cubren con este
hongo- negro y muchas se caen. En general,
el aspecto en este estado resulta lugubre.
Cuando se estacionan automoviles debajo de
los arboles atacados por el pulgon, todo el
carro se cubre del liquido dulce segregado
por los pulgones. Esto lo han sufrido los que
estacionan automoviles bajo estos arboles en
los terrenos de las casetas de la PRRA en
Puerta de Tierra.

Tanto los arboles que se encuentran en
las alturas de la Isla, como también en las
llanuras, son atacados por este insecto. Su
siembra como ornamental no deberia conti-
nuarse.

El angela o ben se siembra a las orillas
de las carreteras y en muchos jardines, en el
sur de la Isla. El Arbol en flor es muy atrac-
tivo y su fruto es una vaina larga muy vis-
tosa. Esta especie es muy susceptible a los
ataques del comején, y sus ttineles se en-
cuentran en todas las ramas ,tronco y hasta
en las vainas secas del arbol. Este adquiere
una apariencia muy pobre. Su susceptibilidad
a los ataques de este insecto tan comtn, lo
hace indeseable como ornamental.

Los alelies son arbustos ornamentales
que se siembran usualmente en los jardines y
patios de las residencias. Sus flores blancas
y rosadas son muy bonitas. Una oruga negra
con franjas amarillas 0 cremosas, con la ca-
beza y parte porterior rojas ataca el follaje
de estos arboles. La oruga adquiere un tama-
no considerable, a veces hasta de 6 pulgadas
de largo. Es muy voraz y causa la completa
defoliacion de los arboles atacados. En mu-
chas partes de la Isla el insecto persiste en

CARIBBEAN FORESTER

sus ataques constantes y hace al arbol poco

d

deseable como ornamental.

La emajaguilla o Santa Maria se encuen-
tra en las orillas de las carreteras y en mu-
chos patios en las residencias por todo el sur
de la Isla. Pertenece a la familia Malvaceae,
igual que la maga y se considera planta hos-
pedera de la oruga rosada de la capsula del
algodon. La emajaguilla y la maga deben ser
eliminadas totalmente del area algodonera de
Puerto Rico. En estudios verificados por el
autor (4) en el area algodonera del norte de
Puerto Rico, se demostro que la presencia de
gran cantidad de arboles de maga y emaja-
guilla contribuian a mantener un alto pro-
medio de infestacion de la oruga rosada de la
capsula del algodon (Pectinophora gossypiella
Saunders) en los algodonales comerciales.

La emajaguilla es también la principal
planta hospedera de los manchadores de la
fibra del algodon (Dysdercus andreae (.) y
D. sanguinarius Stal). Estos insectos, aunque
no causan en Puerto Rico danos de importan-
cia economica al algodon, en cualesquier mo-
mento pueden constituir una amenaza para
la industria algodonera.

Las especies de arboles arriba mencio-
nados, le dan una idea al lector de los errores
que se cometen a diario en Puerto Rico cuan-
do se siembran arboles en las carreteras, ca-
minos, patios, parques, jJardines, etc., sin an-
tes estudiar detenidamente sus cualidades
buenas o malas.

Arboles Propios para Sombra y

Ornamentacion

Actualmente tenemos aqui, infinidad de
especies nativas e importadas que sirven per-
fectamente para ornamentar y dar sombra
a nuestras carreteras y residencias, sin los
inconvenientes que poseen las especies arri-
ba mencionadas.

La lista seria bastante extensa, pero
para abreviar citaré las especies mas comu-
nes y mas adaptables a nuestro clima tropi-
cal. La lista incluye el nombre comtn en

JULY - OCTOBER 1953 157

espanol, igual que el nombre técnico de cada___usos y fines para los cuales pueden utilizarse
arbol. En la tercer columna se indican los los Arboles.

Nombre Vulgar Nombre Cientifico Usos ?
Aceitillo Zanthoxvlum jlavum Vahl SM
Achiote Bixa orellana L. SF
Alelaila Melia azedarach L. O
Algarrobo Hymenaea courbaril L. SM
Anacaguitas Sterculia apetala (Jacq.) Karst. SO
Ausubo Manilkara bidendata (A.DC.) Chev. SM
Bala de canon Couroupita guianensis Aubl. O
Balsamo de cayeput Melaleuca leucodendron L. SO
Bayahonda Prosopis juliflora (Sw.) DC. SO
Bucayo Erythrina glauca Willd. SO
Bucayo enano Erythrina berteroana Urban SO
Bucayo gigante Erythrina poeppigicna (Walp.) O. F. Cook SO
Burro Capparis coccolobifolia Mart. SO
Burro blanco Capparis portoricensis Urban SO
Burro prieto Capparis cvnophallophora L. SO
Canafistula cimarrona Cassia grandis L. F. SO
Caoba de Honduras wietenia macrophylla King SM
Caoba dominicana Swietenia mahagoni Jacq. SM
Caoba venezolana Swietenia candollei Pittier SM
Cassia rosada Cassia nodosa Hamilt. O
Cerezo 0 mufieca Cordia nitida Vahl SO
Cobana Stahlia monosperma (Tul.) Urban SM
Cojoba o cojobana Pithecolobium arboreum (L.) Urban SO
Coco marino Barringtonia speciosa Forst SO
Cupey Clusia rosea Jacq. O
Dilenia Dillenia indica L. SO
Emajagua Pariti tiliaceum (L.) Hil. O
Eucalipto oloroso Eucalyptus citriodora Hook O
Eucalipto Eucalyptus robusta Smith SO
Genogeno Lonchocarpus domingensis (Pers.) DC SO

2/ En esta columna por medio de simbolos clasificaremos los arboles segUn sus usos mas comunes. Para otros usos y
fines particulares consUltese la obra del autor. Véase bibliografia (3). S—sombra; M—madera; F—fruto; O—ornamental,
ya por sus flores, frutos o apariencia del arbol.

Nombre Vulgar

Geno

Goma

Granadillo

Guara
Guaraguao
Guama

Guama americano
Guano

Guasavara
Guayacan
Guayacan de vera
Tlan-ilan

Jacana

Jagua

Jagueyes

Javillo

Mago

Laureles
Malagueta
Mamey

Mango

Manzana malaya
Maria

Maricao
Mariposa

Mesquite =

Nombre Cientifico

CARIBBEAN FORESTER

Usos
Lonchocarpus glaucifolius Urban SO
Castilla elastica Cerv. SO
Buchencvia capitata (Vahl) Eichl. O
Cupania americana L. SO
Guarea trichilioides L. SM
Inga laurina (Sw.) Willd. 5
Pithecolobium dulce (Roxb) Benth SO
Ochroma lagopus Sw. O
Eugenia aeruginea DC SO
Guaiacum officinale L: SOM
Guaicum sanctum L. O
Canangium odoratum (Lam.) King O
Lucuma multiflora A. DC. SO
Genita amcricana L. SOF
Ficus benjamina L. SO
Ficus Stahlii Warb. SO
Ficus sintenisii Warb. O
Ficus laevigata Vahl. SO
Ficus lyrata Watb. SO
Ficus nekbuda Watb. SO
Hura crepitans L. SO
Hernandia sonora L. SO
Ocotea y Nectandra spp. SOM
Amomis caryophyllata (Jacq.) Krug & Urban SO
Mammea americana L. SOF
Mangifera indica L. oF
Jambos malaccensis (L.) DC. SOF
Calophyllum calaba Jacq. S.
Byrsonima spicata (Cav.) DC. SO ;
Caspareopsis monandra (Kurz) Britton ia O =
- Prosopis glandulosa Torrey S

JULY - OCTOBER 1953
Nombre Vulgar

Moea
Moral
Palo de doncella

Palo de pollo

Pana

Peronia

Pana cimarrona
Pomarrosa
Quenepa

Reina de las flores
Reseda

Roble amarillo
Rosa de maximiliano
Saman

Sapota de costa
Sauce

Sisso

Tamarindo

Teca

Triplaria

Ucar

Uva de playa
Vomitel colorado

Yagrumo macho

Nombre Cientifico

Andira jamaicensis (W. Wright) Urb.
Cordia sulcata DC

Byrsonima cuneata (Turcz.) P. Wilson
Pterocarpus officinalis Jacq.
Pterocarpus indicus Willd.
Artocarpus com:1unis Forst.

Ormosia krugit Urban

Artocarpus integrifolia L.

Eugenia jambos L.

Melicocca bijuga L.

Lagerstroemia speciosa (L.) Pers.
Lawsonia inermis L.

Tecoma stans (L.) H.B.K.
Max‘milianea vitifolia (Wild) Krug & Urb.
Samanea saman (Jacq.) Merrill
Manilkara pleena (Pierre) Cronquist
Salix chilensis Molina

Dalbergia sissoo Roxb.

Tamarindus indicus L

Tectona grandis L.

Triplaris caracasana Cham.

Bucida buceras L.

Coccolobis uvifera L.

Cordia sebestena L.

Didymopanax morototoni (Aubl.) Dene & PI.

160

i)

bibliografia

. ALVAREZ GARCIA, L. 1950. Enferme-

dad de la Albizia procera. Informacion Ofi-
cial No. 10 Est. Expt. Agr. Univ. P. R.
Oct. 5, 1950.

. COOK, T. 1938. The whitches’ broom of

Tabebuia pallida in Puerto Rico. Jour. Agr.
Univ. P. R. 22(3) :441-443.

. MARTORELL, F. 1945. A survey of the

forest insects of Puerto Rico. Jour. Agr.
Univ. P. R, 29(38-4) :69-608.

CARIBBEAN FORESTER

. MARTORELL, F. 1951. Cotton pink boll-

worm control in Puerto Rico. Bull. 93, Agr.
Expt. sta. Univ. Pe Rip: 1-40.

. OTERO, J. I. TORO, R. A. y OTERO de

PAGAN L. 1945. Nombres vulgares y
cientificos de algunas plantas puertorri-
quenas, Bol. 37, Est. Expt. Agr. Univ.
POR, pe 1-280:

. WOLCOTT, G. N. 1940. An outbreak of

the scale insect (Asterolecanium pustulans
Cockerell) on maga (Montezuma speciosissi-
ma Sessé & Moc). The Carib. Forester,
Trop. For. Expt. Sta., Rio Piedras, 2(1):
Ga%6

JULY - OCTOBER 1953

161

The Tropical Rain Forest —

A REVIEW
FRANK E. EGLER

American Museum

of Natural History

New York

It is a pleasure to record the appearance
of an impressive volume which at once takes
its place in the field of vegetation study.
This book will serve the technical reader for
an authoritative and well-balanced source of
reference, even as it will serve the lay public
for an interesting and readable account of a
forest region which holds an unequalled fa-
cination. In so many ways does this volume
allow us new, and rather overdue, perspec-
tives on the scattered literature of the trop-
ical rain forest and in turn set the stage
for new developments, that i feel it worthy
of extended consideration. Certainly an in-
tensive perusal is essential for all temperate
ecologists who are striving to formuiate a
science of world-wide applicability.

The author approaches his subject with
laudable modesty, His ‘main qualification
tor such a formidable task is first-hand ex-
perience of rainforest vegetation adding up
to nearly two years’, but extending through
7 years in Borneo, British Guiana, and Nige-
ria. He admits this qualification is “painfully
inadequate”. Although examples from these
three territories are perhaps too constant-
ly brought to the attention of the reader,
the “inadequacy”, if such it is, is more than
amply compensated by -a remarkable grasp
of the tropical rain forest literature, the in-
tegration of which is the volume’s chief con-
tribution. In this literature, the author has
ranged widely, apparently in complete dis-
regard of the languages involved and in a
manner that would be difficult for most
Americans.

This volume is dedicated to the memory
of Carl Schroeter, and thus is expressed the
root of its author’s approach to the study of
vegetation. To many of us, the book is a lin-
eal descendant of the tropical rain forest

ee

1/ Richards, P. W. 1952. The tropical rain forest, an ecologi
cal study. Cambridge University Press. New York and
London. 450 pp.

sections of Shimper’s Pflanzengeographie,
brought up to date in facts and concepts.
Relegated to the past, with barely an excuse
for their omission, are the discussions of far-
fetched “adaptations” and teleological inter-
pietations, ideas which though “scientific”
in their heyday now seem to us more akin to
that earlier era when ‘natural philosophy”
was often undertaken to reveal and to mar-
vel at the glories of God, and to discover the
uses for man of all his creations, uses which
he seemed adept at hiding from the creature
for which he created them. The author claims
to follow the general principles of the Anglo-
American school of ecologists. We appreciate
this fraternal hand-clasp across the North
Atlantic, certainly expressed in good faith.
Actually however, the American influence is
obviously at a minimum throughout the book,
and where it is apparent (as in discussions of
climate climax, and of monoclimax versus
polyclimax) it appears strangely irrelevant,
almost like an atheist saying grace at table
when dining with theologians. Words like
consociation, association and formation are
frequently in quotation marks, implying on-
ly usages of the authors he quotes. An
“etum”’ is mentioned but once. Such elastic
terms as “primary”, “community” and “sin-
gle-dominant” are used and preferred. True,
he does use the term climatic climax, but un-
objectionably, in general reference to virgin
or primary vegetation. In only one instance
does he attempt a definition, and that one
sentence pinpoints precisely the irrationality
and illogic of the argument: “The English
school of plant ecologists have compromised
between the Monoclimax and Polyclimax
theories of vegetational development by re-
garding one climax formation in each climat-
ic region (that found on the most wide-
spread or ‘normal’ combination of soil and

162

topography) as the climatic climax and
others in the same region as edaphic or physi
ographic climaxes.” In short, the sole eriteri-
on for raising the one virgin and primary
community to the dignity and superiority of
the climax climax, and for debasing all the
others to the stigma of inferiority and im-
maturity, is the completely arbitrary one of
which occupies the most area and thus
which is ‘normal’ (democracy-with a ven-
geance). I suspect furthermore that if the
vote is a tie, we all would be astrongly in-
fluenced by which community subjectively
impresses us the most with its lushness, flo-
ristic complexity and simple American big-
ger-ness and better-ness. If this policy were
to be adhered to strictly, I maintain that if
one deals, e.g., with areas of shrub-covered
rocky cuestas, and grass-covered horizontal
strata, and if these two landforms occur
areally in all proportions, then the edaphic
shrub climax would become a climatic climax
(with all implications of different climate,
and of climax soil) wherever we step over
such a political or other boundary that the
relative area changes from 49 to 51 percent.
We need not leave this country to find many
such examples.

Dr. Richards’ volume concerns all the
tropical rain forests of the world, which he
recognizes as related in many and various
ways, ways customarily lumped under the
term “ecological”. He recognizes their divi-
sion into three formations, the American, the
African, and the Indo-Malayan, differenti-
ated in terms of their floras. It is upon dif-
ferences and similarities between these three
territories that the book is constructed. It
was not the intent to describe the forests of
smaller areas, country by country. Many will
be disappointed that the Hawaiian islands
were purposely omitted from discussion, for
even though they are the farthest outpost of
the Indo-Malayan tropics, their abundant
literature is time and again apropos of the
arguments he develops.

The volume is divided into five parts,
each composed of separate chapters. Part I,
“Structure and Physiognomy” includes dis-

CARIBBEAN FORESTER

ussions of synusiae (not communities, but
loristic aggregates of piants similar in their
caroonydrate requirements, like epiphytes,
and saprophytes), and oi stratification
(which he finds universally to tend to three
layers of trees, not more). Profile diagrams
are included, a graphic technique which Dr,
Richards has developed, the original sugges-
tion for which he credits to Sir Edward Sa-
lisbury, and which certainly deserves further
application, in temperate regions as well. The
chapter on regeneration (a matter of func-
tions, rather than of structure) has much of
general interest in the data on age-class re-
presentation, the death of one tree or small
groups, and development in the resulting
gaps. Aubreville’s Mosaic Theory is here dis-
cussed, which should crystallize for many
what may have been but vaguely perceived.
The theory refers to a dynamic equilibrium,
a constancy-in-change, on a time-scale and
a space-scale much greater than most of us
are inclined to adopt. Spot-wise on the land,
this means a succession of combinations of
dominant species. This approach certainly
deserves consideration even beyond Dr. Ri-
chards’ regional discussion of it. The theory
may well embrace what in certain temperate
climates has been simplified and distorted
into a 2-phase cycle of conifers and hara-
woods. And where the flora is somewhat
more complex, it may include what has been
called an ‘association segregate” (though
such a segregate would not then have the
continuous historical community-phylogeny
overtones). Furthermore, it seems to this re-
viewer that such an approach to the inter-
pretation of a large forest region has always
been the viewpoint of those who recog-
nize that there are species which are ef-
fective ecological equivalents, especially with
complex floras, and that matters of chance
and coincidence are operative in vegetation
—the niceties of ecological theory notwith-
standing. This Part I also includes discus-
sions of such physiognomic features as bark,
buttresses, neumatophores, leaf shapes, and
special features of flowers and fruits. The
last chapter is concerned with the ground
layer herbs, and the various synusiae.

Cc
4
1

JULY - OCTOBER 1953

Part II, “The Environment” has sepa-
rate chapters on climate, microclimates, sea-
sonal changes and soil conditions. In the pre-
face, Dr. Richards indicates that the absence
of a discussion of biotic factors is due only
to the lack of available data. What new in-
sights and outlooks we may anticipate when
we will have progressed beyond the present
edapho-climatic determinism! One thinks of
the high-altitute supra-mossy-forest grass-
lands of New Guinea, once thought to be a
climatic climax, but eventually recognized as
a favored home of the wallaby, who was
hunted by the indigenes, who burned the ve-
getation, who left the region —but the ve-
getation lingered on. Perhaps that type of
“climatic climax’ is not so unusual. The
chapter on soils will be welcomed by many
for whom the complicated and conflicting l-
terature has been a stumbling block. Dr. Ri-
chards leaves us with the impression that re-
latively little is known (though soil scientists
have a most impressive and complicated way
of saying that little). Of one thing we all fee!
more sure, that for a region which has had
aeons of time to appnroach a single homoge-
neous end-stage, there are remarkable and
striking diversities, involving contrasting la-
teritic and podzolic processes, reflected with
equal diversity in their respective vegeta-
tions. He quotes one discontinuum that
should end all arguments for the universali-
ty of continua. This occurred in British Guia-
na, where the division between the white-
soil wallaba forest and the brown-soil green-
heart forest clove the fresh soil of an ant-
hill, with the two appropriate trees, last re-
presentatives of their respective communi-
ties, growing out of the sides, so close to
each other that one had to turn sidewise to
slip between the two communities.

Part III discusses the “Floristic Compo-
sition of Climax Communities”, based on
sample plot data from the literature. Some
readers will be surprised at the relatively
numerous examples of single-dominant pri-
mary communities in the tropics. On the
other hand, data from the “mixed communi-

ties” only emphasize the high degree of their

163

mixedness, and make us realize that most of
our association concepts would not have ari-
sen in the tropics, and cannot be applied in
the tropics.

Part IV, “Primary Succesions”’ is compo-
sed of three chapters. The first is on the pri-
mary xerosere, almost entirely an excellent
review of the recolonization of Krakatau. The
second, on hydroseres, points up a general
pan-tropical development that bears many
similarities to the development in tempera-
te regions, with two trends, for eutrophic wa-
ters, and for peat-accumulating oligotrophic
waters. I would have liked to have seen a
discussion here of the principle exemplified
by our own Everglades, where the erosive
force of water movement is insufficient to
offset the development of peat, and thus an
upland can be succeeded by a swamp. The
third chapter on coastal successions is a brief
treatment of sandy-snore vegetation, and a
more extended discussion of mangrove vege-
tation (thankfully with no comments what-
ever on the seedlings so prefectly ‘‘adapted”’
to plunk into the mud below). It is here that
I feei that the American influence has been
unfortunate. A belting of vegetation types in
space is not ipso facto reason for consider-
ing them successions in time. In this instan-
ce I have a personal knowledge of the Sout
Florida conditions he describes in detail. The
field evidence appears to indicate that tne
belts are distinctive site types, and that if
a succession must be assumed, it is related
to a gradually rising sea level. The elaborate
succession diagram would then be acceptable
—if all the arrows were reversed, Certainly
there is development within any one belt, but
the one example of his quoted author that
actually suppports the succession theory,
puzzles that author, and he leaves it as an
anomaly.

Part V, “Tropical Rain Forest under Li-
miting Conditions” is an impartial document-
ed review of the literature, in two chapters.
The first concerns those studies that inclu-
de, in addition to rain forest, other vegeta-
tion types variously called monsoon forest,
savanna forest, thorn forest, savanna, and

164

desert. (Dr. Richards neither proposes nor
adopts any system of classification for tropi-
eal vegetation types). His conclusions will
come as a surprise only to those who have
kept to the older books, and who are loth to
part with the older theories. He states that
“there is no such thing as a ‘tropical grass-
land climate’, and that apparently all lowland
tropical grasslands are due to anthropic or
very local edaphic conditions. Evidence exists
everywhere for the recognition of one or
more ‘‘montane” forests on tropical moun-
tains, although I looked in vain for an ela-
boration of the idea that Chipp used in his
discussion of the Gold Coast Forest (and
which is inherent in many ideas of vegeta-
tion relationships), that some of the vere-
tation types adjacent to the rain forest are
composed of species occurring, but rarely, in
that rain forest, and emerging into dominan-
ce where freed from competition of the other
trees.

Part Vi, “Man and the Tropical Rain Fo-
rest”, is meant only to introduce a field wor-
thy of a separate volume. It contains never-
theless a good summary of the vegetation
developments on the lands of shifting agri-
cultures. Here too the general picture emer-
ges that although grasslands receive an im-
petus from fires and can become relatively
stable, the forest will again take the land if
fires are eliminated.

In a postscript on ‘The Future of the
Tropical Rain Forest”, the author paints an
alarming picture of the tremendous accele-
ration with which these forests are being
destroyed. In commenting on the effects of
this destruction he indicates that it “has

CARIBBEAN FORESTER

changed fundamentally the future course of
plant evolution, and closed many avenues of
evolutionary development”, since the tropics
have served as a centre of evolutionary activ-
ity for the entire world. Such a viewpoint
would be opposed to Edgar Anderson’s docu-
mented thesis that this very destruction has
hybridized the habitats, and may well result
in evolutionary outbursts to fill the new vac-
uum. As another consequence, the author
mentions, but does not deal with the contro-
versial subject of the effects on macro-clim-
ate. One might wish he had applied his know-
ledge to this field, for the known data, though
fragmentary, are not only of great academic
interest, but of high economic importance. He
closes with a rational and eloquent plea for
preservation of more such extensive areas as
the Albert National Park in the Belgian Con-
go, areas to serve for needed an important
biological research in the present, and for the
study and admiration of future generations.

Thus we come to the end of this praise-
worthy contribution to knowledge of the
world’s vegetation. Its author is the first to
say that it is destined to be superseded as
new information casts new lights. “No bet-
ter prospect for... (his) work can be wish-
ed than that it may soon become out of
date”. When so, it will only move sidewise

to a favored niche in history. In the mean-
time, like the dwarf of Didacus Stella, we
can scramble to the giant’s shoulders, com-
placently sweep the new horizons, and peer
into the distance with considerable self-satis-
faction at the ease with which we think we
can see one mite farther.

JULY - OCTOBER 1953

TONED Shes oO
VOLUMES 13 AND 14 OF THE CARIBBEAN FORESTER

January 1952 to October 1953

ACGIMatiZatONEOleSPCClCS == ie ge ee ee See XIII,
Fi GLIMALACTOU CERES Pe CIOS hee at gee ee ee ee en ee ae XIII,
Akawalominigianenlantenames eo ese he es a Se ee Pe Sy eS XIV,
NUANCE DN ep ee XIV,
ENT DO LES R eli cant ln Celemony a ee XIV,
Argentina, Forest management in the subtropical rain forests of Misiones, -_ ~~ xe
Argentina, Ordenacion de los bo-ques higrofiticos y subiropicales de Misiones __ ~~ XIII,
NSCORD Crm Lean | pene een geen See ee ee re Ee ee Se Ee eS XIV,
Australia, Some observations from the Eucalyptus Study Tour to __ __ _-~ —_ ~-- XIV,
Blue stain fungus, The inhibitory action of organic chemicals on a -- -- ~~ -- XIV,
BritisheGuiana —-A: Review, Lhe vegetation of -— —=—— == == _=.-— ~~ -2 == XIII,
@hintemHelixg © sere = peeewen -S aeee te SOS ees eee SR ns XIII,
Comisi6n Forestal Latinoamericana, Cuarta reunion de la __ __ __ _~ __ ~~ ~~ ST,
Compania Paulista experience with Eucalyptus, The Significance to Puerto Rico of — XIV,
(C0ZZO%s Donn COR tte eestor ee Oe Ae eS Le XIII, 145,
Cuarta reunion de la Comision Foresta] Latinoamericana __ __ -- __ -- ~~ -- NII,

Decimotercer informe anual de la Estacion de Experimentacion

165

ROLES Ca las OP iCal erste er eran emerson Ett fe ge XIV, 34
Duodécimo informe anual de La Estacion de Experimentacién

Forestal Tropical Mo 21

AS) Ube lan fron eee ee ne ee Ee ee ey SE ee XIV, 111

Gel ae ran ke been eee ine Alay a SS pee eS, oe A SR A ee he oe DmOWNE, aAleh tkrko

XIV, 161

Estacionede: Experimentacion’ Horestal Tropical —- (== =~ == —~ == == =~ —> =~ XM, 21; XIV, 34

Estacion de Experimentacion Forestal Tropical, Décimotercer

IMLOMeCANU alec e Ml aye ee Seen ee ey ee XIV, 34

166 CARIBBEAN FORESTER

Estacion de Experimentacion Ferestal Tropical, Duodécimo
intormeantial Génlay wt: 2S) ot, See ee en ep eget on See XM 21

Eucalyptus, The significance to Puerto Rico of Companhia
Paulista; experience with, 22.2) 2a Se ee ee ee eee KTV 65

Eucalyptus Study Tour to Australia, Some observations
inom the ss: a ee Beha a eta eee ge ees Ree ee ee XIV, 111

Experiencias de la Companhia Paulista con Eucalipto, su
IMportancia, para Puerto: Rice te) es, oe ee eyes eee XIV; a7

Panshawe dW). (Bo 24-25 2225 r= sane ae Se eg en ae eee | XIV, 120

Filipinas, Siembra de prueba de la caoba hondurena

(Swietenia macrophylla King) en ~~ ~~ __ __ _ ee ee Si Bk XS 85
Forests of Darien, Panama, The __ _ Seas Pe, ae XIV, 128
Forest management in the Luquillo Mountains, 11° .. -. 22 22 22,252 22. 52022 XIII, 49
Forest management in) thesLuquillo Mountains, IM 222) 2) os ee es ee XU, 93
Forest management in the subtropical rain forests of Misiones, Argentina __ __ __ XII, 165
Prost damace i “the Pine Morest\= 5 2O 2s (eee ee ee eee cee XIV, 93
(Inhibitory action of organic chemicals on a blue stain fungus, The __ __ __ __ —~_ XIV, 136
Islas Barlovento y Sotavento — Juicio critico sobre la obra de J. S. Beard,

Vegetacion maturaldeudlas* ete we eae eee ne ek ees XIII, 176

Juicio critico scbre la obra de J. S. Beard ‘‘Vegetacién natural de las

Islas Barlovento y Sotavento” __ __ __ -_ 2. ~~ ~~ ~~ __ ~~ _2 LL LL XIII, 176

lb ehoolloe IDA phen es ee ee ee = ge ee XIV, 128
Luquillo Mountains, Forest management in the, IT _. __ __ Sue 2 Pure ee XI, 49
Luquillo Mountains, Forest managementim the; fil. 2472-222 2S ee ee ee XIII, 93
Martorell, Luis F. _- __ __ — Mega eee SND eA epee aes Ce aL XIV, 152
Miarrenon OSG 02 en ae ee ee ee ee ee pe ee Gye Es RR XIV, 65
79

Montafias de Luquillo, Ordenacién forestal en las, I] -..2- 2. .2 2. L--22 == XIII, 62
PUG EO)

Natural vegetacion of the Windward and Leeward
Iislands!—A: Reviews: They2 20232222 Gee Be oe eee ee ee cee XIII, 173

New observations of tree growth in? Wabonuco” Rorest; 2202255" es See XIV, 106

JULY - OCTOBER 1953

Ordenacion de los bosques higrofiticos y subtropicales de

IMASIONES WALZ enUINa) sea ee, ee a ah eo se eG XIII, 145
Ordenacion forestal en las Montanas de Luquillo, Il -- -_ __ ~_ ~~ -- -_ —~ —- DIA ES ey
Ordenacion forestal en las Montanas de Luquillo, HI ~. ~~ ~~ ~~ ~~ ~~ .. .. XIII, 120
@Ornamentaletreestine BUeLLOWRICOns te ee ee SS ee se XIV, 97
OurgentontsecOecODSeLvieg ree Spe penne ee en ee eS pa Te ee ee XIV, 140
anamamwlhesrorestSnO tw) aries r= esa my cee eee ee en ee NSS 28
BEGET SETA TUN U Tal aie eee gee ee ed a eee Se ee Se ay Se SIV 93
inephoresveunoOstsdamacenmrthey =a, ae ee Pe ee DNV 93
RuertOomRacOm Ornamental etheespin == = ene ee ee XIV, 97
E@uegatbolesembrateg ses e— 9 weeny 2 a Seen Se SoS AAV 2152
Siembra de prueba de la caoba hondurena

(GSwierenwamac op iy losing, rene bilipinaSee == ee et XITI, 85
Significance to Puerto Rico of Companhia Paulista

Espen encemwithelucalyp tussle, se ee ey ee GIVE” 65
SHI L Lieg @ege rere ee ort Se oe ee he ee SS Se SOD 45 47
Some observations from the Eucalyptus Study Tour to Australia _. __ __ ~~ ~~ Nee
Swietenia macrophylla King en Filipinas, Siembra de prueba

cewlaxcaoDaBhOondurenasgety ee p aen e ee en S h XIII, 85
Swietenia macrophylla King, Trial planting of large leaf mahogany, __ __ __ ~~ SOURS SS
Tabonuco Forest, New observations of tree growth in —- __ __ __ —_ ~~ ~~ ~~ =- XIV, 106
siihinteenthkannualgre pong nee ee eee a ee ee oS XIV i
Trial planting of large leaf mahogany (Swietenia macrophylla King) __ __ __ __ eR 7/5
itopicalRorestel xpeLimentestatione =.) ae ee ee SS ae eS > GUO Rarer iho)3

XIV = 1
liropicalaramptoreste——raaReviewsbhe) Seen ee ws ee LL XIV, 161
sikwel theannialerep ole yn a ee ee Se Shae 1
“Vegetacion natural de las Islas Barlovento y Sotavento’,

juicioucriticossobreslavobrasde syn S4 beatd, === = 2 22 ee eT 1716
lMezetationsolebmtishyGiianat se aurevicwe hem = 2 oe Ee Se XIII, 179
Wivald ime San tlag Op Neg: eagerness eet eee a ER Fe meet no) EN we XIV, 146
WiadSwortiiahnan kes iameeae mien ae Pe eR Se ee SSS XGITL, 49; 62

93, 120

XIV, 65, 79

106, 140

Windward and Leeward Islands - A review, The natural vegetation of the __ __ __ NEE 173
Wi CES ae laa ep nee et, footie a See ee er de XIV, 97

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