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UNITED STATES DEPARTMENT OF AGRICULTURE
BULLETIN No. 354



Contribotion from the Forest Service
HENRY S. GRAVES, Forester



Washington, D. C.



October 20, 1916



FORESTS OF PORTO RICO

PAST, PRESENT, AND FUTURE

AND THEIR PHYSICAL AND ECONOMIC ENVIRONMENT



By
LOUIS S. MURPHY, Forest Examiner

In Cooperation with tlie Goyernment of Porto Rico Board of CommlaaioiMra

of Agriculture. John A. Wilson, Temporary President,

Succeeded by Tulio Larrinaga, President



CONTENTS



Page

Introduction 1

Physical and Economic Features:

Geograpliic Situation 2

Physiography and Soils g

Drainage 7

Climate 7

Land Distribution, Utilization, and

Taxation 9

Population 16

Transportation Ig

The Forest :

Forested Condition and Distribution 21



Page
The Forest— Continued

Forest Formations 23

Forest Influences 36

Commercial Aspects 39

Forest Industries 44

Forest Products 46

Forest Problems 46

Insular Forest Policy 61

The Luquillo National Forest . . . fiS
Appendices:

I. Trees of Porto Rico 66

n. BIbUography »8



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WASHINGTON

GOVERNMENT PRINTING OFFICB

1916



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D. of D.
NOV 18 1916



UNITED STATES DEPARTMENT OF AGRICULTURE




BULLETIN No. 354 ,„,^,,„

^^jf ^- JjSi ^ Contribution from the Forest Service, '^^i^^'S/a^

.^^l^*^S^^ HENRY S. GRAVES, Forester J^<r^^*SU




Washington, D. C.



October 20, 1916



FORESTS OF PORTO RICO; PAST, PRESENT, AND
FUTURE, AND THEIR PHYSICAL AND ECONOMIC
ENVIRONMENT.

By Louis S^ Murphy, Forest Examiner.



CONTENTS.



Page.

Introduction 1

Physical and economic features :

Geograpliic situation 2

Physiography and soils 3

Drainage 7

Climate 7

Land distribution, utilization, and taxa-
tion 9

Population 16

Transportation 18

The Forest:

Forested condition and distribution 21



The Forest— Continued.

Forest formations 23

Forest influences 30

Commercial aspects. .• 39

Forest industries 44

Forest products 46

Forest problems 46

Insular forest policy 51

The I.uquillo National Forest 55

Appendices:

I. Trees of Porto Rico 56

II. Bibliography 98



INTRODUCTION.

Every year the people of Porto Kico consume over three times as
much wood as the forests of the island produce. Great quantities
of timber have beeii cut or burned by the "conuco" to make a clear-
ing, which is abandoned after a few years and becomes a mere waste.
The charcoal burner is still at work destroying the young growth
needed to keep up the forest. Failure to put an end to the destruc-
tive practices that are rapidly reducing the forests or to provide the
means of developing and fully utilizmg them in a scientific manner
has already brought about a shortage in the domestic supply of wood
and consequent hardship to the people. It is the object of this bulle-
tin* to give a complete account of the trees and the forests of Porto

• Tender an informal cooperative arrangement between the Secretary of the U. S. Department of Agri-
culture and the Governor and Board of Commissioners of Agriculture of Porto Rico the author spent sLx
months, from November, 1911, to May, 1912, on the island, making a first-hand study of its forest problems.
A preliminary report of his findings and recommendations regarding these problems was published in the
"First Report of the Board of Commissioners of Agriculture of Porto Rico," San Juan, Jan. 1, 1912, pp.
48-60. In this report it was recommended that the authority of the board be extended to cover the man-
agement of the forests; and that an insular forest service , with a qualified and experienced forester in charge,
be established to carry on the work. This service could be established at a maximum cost of $20,000 and
maintained for $8,000 or less a year, and would effect an annual gain to the island through the scientific
management of its forests amounting to over $350,000.
21871°— Bull. 354—16 1



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BULLETIN 354, U. S. DEPARTMENT OF AGRICULTURE. 'X^Q.



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Rico, to show their vahic to the people of the island, and to suggest
the moans of improving them and making them permanent.^

PHYSICAL AND ECONOMIC FEATURES.

Porto Rico is very sparsely wooded. The impenetrable forest
jungles, commonly associated with the West Indies, are so scarce
that one may cross and recross the island without seeing them, for,
with the exception of those in the Sierra de Luquillo, they are tucked
away in the more inaccessible places into which few except the
"jibaro" ever penetrate. The island is, however, by no means
devoid of wood growth. Around almost every habitation there are
groups of trees, such as the bread fruit and mango; and numerous
scattered single trees, mostly palms, dot the open landscape. The
protective cover of shade trees of the coffee plantations gives a
decidedly forested appearance to many localities.

Porto Rico presents an unusual combination of physical and eco-
nomic conditions. The insular and geograpliic position of the coun-
try, its diminutive size, its restricted area of level lands, and its
density of population, to mention but a few of many influences, have
occasioned unusual demands on the forests. The same cycle of
change is found here as is recorded by civilization everywhere — a
profligate waste and despoliation of the bounties of nature, followed
by an acute need for what has been destroyed.

GEOGRAPHIC SITUATION.

Porto Rico is the easternmost and smallest of the Greater Antilles
and is well within the Tropics. It is situated between latitudes 17° 54'
and 18° 30' north and longitude 65° 35' and 67° 15' west, occupying a
position about midway in the cham of islands connecting Florida and
Venezuela and separating the Carribean Sea from the Atlantic Ocean.
It is about 450 miles east and slightly south of the nearest point of
Cuba; about 500 miles north of the nearest point of Venezuela; about
1,000 miles from Colon (Panama) ; about 1,500 miles from New York
and New Orleans, and a little more than twice that distance from
Gibraltar.



1 In addition to new material the present bulletin revises and brings up to date two pre\aous bulletins
of the Forest Service: "Notes on the Forest Conditions of Porto Rico," by Robert T. Hill. Bulletin 25,
Division of Forestry, Department of Agriculture, 1899, and "The Luquillo Forest Reserve, Porto Rico,"
by John C. GifTord, Bulletin 54, Bureau of Forestry, U. S. Dept. of Agriculture, 1905.

It is appropriate to acknowledge in this place the author's indebtedness to the works enumerated alwve
and in the bibliography. Special acknowledgment is due to the officers and employees of the Insular
Government and of the Porto Rico Agricultural Experiment Station (U. S. Dept. of Agriculture) for giv-
ing the author access to official unpublished data and personal assistance in locating and getting to the
various places \nsited; to Mr. Paul Buffault, Conservateur, Administration des Eaux et Forets, France,
and Mr. Thomas R . Wallace , A merican consul at Fort de France , for valuable Information concerning forest
conditions and legislation in Martinitiue (French West Indies); aKso to the Office of Acclimatization and
Adaption of Crop Plants of the Bureau of Plant Industrj' , Department of Agriculture, for the use of photo-
graphs comprising Plates I, IV, and VI, fig. 1.



FORESTS OF PORTO EICO.



Porto Rico has a total area of 3,435 square miles (2,198,400 acres).*
The maiii island is 3,349 square miles in extent, and the islands of
Vieques, Mona, Culebra, and other adjacent smaller islands witliin
its governmental jurisdiction are 51.5, 19.5, 11, and 4 square miles,
respectively. The territory as a whole is thus about five-sixths
the size of Jamaica or the island of Hawaii, seven-tenths the size of
Connecticut, and four times as large as Long Island.

In general outline it is almost a geometrically regular parallelogram,
approximately 100 miles long and 35 miles wide. Its longest dimen-
sion lies east and west. The sea Ime is nearly straight and the coast
is usually low, especially on the southern side, although there are a
few headlands. The only protected harbors are San Juan on the
north coast, Guanica and Jobos on the south, and Ensenada Honda on
the southeast. The

remaining ports, such connect/ cut

as Arecibo, Mayaguoz,
and Ponce, are scarcely
more than open road-
steads.

PHYSIOGRAPHY AND SOILS.

Porto Rico and the
other islands of the
Antilles and Central
America and northern
South America were
formerly, according to
geologists, a united and
distinct continental
land mass — the Antillean continent. Then came a great subsidence,
which left only the tops of the mountains above water. After a while
the ocean floor was agam thrust up, the old continent reappearing.
The sediment of which it was composed, covered in the meantime
by deep-sea muds and chalks, was then folded into huge mountain
systems, individual peaks reaching as high as 20,000 feet above sea
level. Another but lesser subsidence of the Antillean contment ac-
complished its breaking up into the present island groups, Jamaica
bemg the first to be isolated, then Cuba, and finally Porto Rico and
Haiti.

There are at the present time three main physiographic regions of
the island of Porto Rico — a central mountainous core of volcanic




Fig. 1.— Porto Rico compared in size with Connecticut and Long
Island, New York.



* "Areas of the United States, the States and Territories," Bulletin 302, U. S. Geological Survey. This
area is the one officially determined upon by the U. S. Geological Survey, the General Land Office, and the
Bureau of the Census, and is based on computation from the U. S. Coast Survey map. The detailed
figures concerning the areas of the smaller islands were obtained directly from the Office of the U. S. Coast
and Geodetic Survey.



4 BULLETIN 304, U. S. DEPARTMENT OF AGRICULTURE.

origin, an elevated area of coral limestone (former marginal niarino
deposits) surrounding the mountainous portion, and the coastal plain.



CENTRAL MOUNTAIN AREA.



The central mountain area occupies by far the largest portion of the
island. Viewed from the sea it presents a rugged and serratt^d aspect;
numerous peaks and summits, with no definite crest line, rise from a
general mass, which has been cut by erosion into lateral ridges, sepa-
rated by deep, steep-sided gorges. The drainage divide is approxi-
mately parallel to the southern coast and about 10 or 15 mUes distant
from it. The region thus has a long and relatively gentle inclination
toward the north coast, but falls off rather abruptly toward the south.

The Sierra de Luquillo,^ the most easterly of the three ranges making
up the central mountain mass, is surrounded by low coastal plains, and
is completely isolated, except for a low water-divide wliich crosses near
Las Piedras to the Sierra de Cayey. By thus completely dominating
the landscape it gams t*he appearance of being very liigh ; and one of
its peaks, El Yunque (the anvil), has been credited with being the
highest emmence on the island. According to the most recent
determinations ^ this peak reaches an altitude of 1,062 meters (3,483
feet). The east peak has an elevation of 1,054 meters (3,457 feet)
and the west peak 1,020 meters (3,346 feet).^ These higher peaks are
flanked by numerous lateral ridges which extend in every direction.
The valleys, known as "quebrados," are deep and gorgclike and are
separated one from another by very narrow, almost knife-edged
ridges, "cuchillas." Falls, cascades, and rapids are conspicuous
features of the dramage system here. This range supports the only
large tract of virgin forest growth on the island.

The remaining mountain mass forms an uninterrupted expanse of
broken uplands. The main crest hne extends from Humacao on the east
through Aibonito and Adjuntas to within a short distance of Maya-
guez on the west coast. The portion east of Aibonito is known as the
' ' Sierra de Cayey ; " that to the west, the ' ' CordUlera Central." This
region has an average elevation of about 2,500 feet, above which the
higher peaks project irregularly, a few to an elevation of more than
3,500 feet. The thirteen highest peaks on the island are in the "Cor-
dillera Central." The highest of these (not named on the Coast and
Geodetic Survey chart) situated about due south of Jayuya, has an

> Ilerrera (see lybliography) describes the Luquillo as follows: "Ten leagues East-South-East from the
City of Puerto Rico is a very high and great Mountain, with three Breaks on it, call'd del Luquillo, or of
the little Madman, on Account of a revolted Indian [that withdrew to it. The highest Point of it is
call'd Eurzidi, a Name given by the Blacks, signifying a place always clouded, and the third is call'd of the
Holy Ghost."

'U.S. Coast and Geodetic Survey Chart 920, issued July, 1910.

3 These two together appear to be given the name " El Cacique " (The Indian Chief) by Gifford. De also
names the round mountain to the west "El Toro" (The Bull), and the moimtaui next to it on the south
"El Carnero" (The Sheep).



Bui. 354, U. S. Dept. of Agriculture.



Plate F„




Opening in Virgin Stand of Mixed Tropical Hardwoods.
Near La Isolina (Arecibo).



Rain-Forest Formation



FORESTS OF PORTO RICO. 5

elevation of 1,341 meters (4,398 feet), while "Mt. Guilarte," com-
monly considered second to El Yunque, is 1,204 meters (3,950 feet).

The many lateral ridges which diverge from the central mountains,
mostly from the north side, are commonly very steep-sided and nar-
row-crested, and the valleys are deep, V-shaped, and almost devoid
of level bottom land. Rock outcrop is generally infrequent, except
toward the outer portion, wliere the ridges are often capped with hard
limestone.

The central mountains are composed largely of black or other dark-
colored igneous rocks, which occur in the form of tuffs, conglomerates,
silts, and an occasional dike of diorite. Their volcanic forms have
been destroyed by erosion. The material thus worked over into sedi-
ment in prehistoric ages now occurs in well-defined strata. Two rela-
tively inconspicuous limestone formations also occur, one black, bi-
tuminous, and shaly, and the other light gray and crystalline.

As a result of the almost uninterrupted action of an abundant pre-
cipitation, a high relative humidity, and a warm temperature, rock
weathering at the higher elevations is more rapid than erosion, as
shown by a soil mantle of unusual depth and almost no bare indurated
rock here. The characteristic soOs are deep, reddish clay loams and
tenacious red clays. So cohesive, unctuous, and compact are these
soils that they are able to maintain themselves in an almost vertical
position. Cultivation, in consequence, is in many places carried on
to the very tops of the ridges and on the steepest slopes, yet evidence
of excessive erosion and landslides is surprisingly inconspicuous.
At the lower elevations the sandy character of the soil and the more
common occurrence of outcrop show that the rate of rock erosion has
exceeded that of weathering.

THE CORAL LIMESTONE BELT.

The belt of coral Hmestone is several miles wide in places and on its
interior border overlaps the igneous rocks. This area is of sedimen-
tary origin. Where rock solution has been the most active agent of
decay, it retains the general form of a table-land. Wliere erosion
has been the most active only isolated conical hills remain. In
certain parts of the island the limestone extends directly to the
water's edge, where it terminates in steep scarps, often 100 feet or
more in height, notably on the south coast west of Ponce and on the
north coast west of Quebradillas. Elsewhere on the island the rem-
nants of this formation stand as steep, sloping, solitary mounds or
domes, which rise singly or in chains above the coastal plain.

Along the junction of the central mountains and the limestone belt
is a distinct line of weakness marking the former shore line. Strong
valley lines are developed there, separating the two physiographic
regions. These ' ' parting valleys " are especially well developed on the



G BULLETIN 354, U. S. DEPARTMENT OF AGRICULTURE.

south side of the island in the valley of the Guanajibos at Sabana
Grande, and on the north side at the junction of the Don Alonso (or
Linion) and Arecibo Rivers.

An uninterrupted block of Hmestone formation, known in places as
the Pepino Hills/ occurs along the north side of the island from Ciales
nearly to Aguadilla, and is some 6 to 10 miles wide from north to
south. It offers a marked contrast to the low rounded limestone
hills which flank it to the north, because of its greater elevation,
rough, angular topography, pitlike valleys, bare rock outcrops of
chalky whiteness, and subterranean drainage. Wherever the large
rivers, such as the Rio Grande de Arecibo and the Manati, cross this
area they have cut deep canyonlike valleys whose sheer cliffs of con-
siderable height occasionally rise directly from the water's edge.
Otherwise the area is strikingly devoid of surface drainage features.
The hills are very closely packed together, their connecting ridges
hardly more than rocky septums separating the disconnected pitlike
valleys. The steep-sided depressions show, on a tremendous scale,
to what an enormous extent rock solution takes place under tropical
conditions.

The region, if viewed from above, would look hke a honeycomb.
Not infrequently the "sinks" are 100 feet and occasionally 200 feet
or more deep. The larger pits sometimes contain an acre or more of
bottom w^th a very fertile soil, commonly under cultivation to such
crops as coffee, bananas, and ground provisions. The bottoms of
others are occupied by bogs or small lakes. The crags and summits
are almost invariably wooded. Caves, which mark the early stages
of pit formation, are common.

Travel here is extremely difficult. Roads are out of the question
and the trails are not numerous and are extremely rough. There is
no alternative Ijut to cross the pits in succession, descending to the
bottom of one and then climbing to the rim of the next almost
straight down and straight up again.

THE COASTAL PLAIN.

The sandy ridge fronting the coast forms a barrier between the sea
and a narrow low-lying area scarcely above tidewater level, and
partly marine and partly alluvial in origin. On the north side of
the island there are many swamps and lagoons covered with a thick
growth of mangrove bushes. The most typical are the Cafio y
Laguna de Tiburones between Arecibo and Barceloneta, Laguna del
Tortuguero north and east of Manati, and the string of lagoons east
of and cormected with the harbor of San Juan. On the south side,



I The term "pepino" (cucumber) undoubtedly refers to the appearance of the elongated mammillary
summits of the hills. An eciuaUy characteristic term, "cockpits," applied to a similar formation in Jamaica
is descriptive of the valley bottoms.



I



FOEESTS OF POETO EICO. 7

the mangrove is only slightly developed, but there are in places
extensive saline plains too low and wet for cultivation, where rank
grasses, a few scattered acacias, or low, succulent, salty herbs con-
stitute the oply vegetation.

The coastal plain proper is elevated but a few feet above the sea,
and has but a slight gradient toward the mountains. It termmates
rather abruptly at the foothills, except in the valleys of the larger
rivers. These plains are entirely sedimentary, having been laid
down when the island stood at a somewhat lower level than now.

The coast-plain hills are isolated, low, and dome-shaped. Some
have been nearly buried by the alluvial deposits of the rivers ; others
rise 100 feet or more above the level of the plain.

The soil, except on the hills, is largely a fine, rich alluvium, sandy
in places, and is almost entirely under cultivation or in pasture.

DRAINAGE.

It would be difficult to find another country of its size so well
watered as Porto Rico. Within the mountainous area are many
swift-flowing streams which have cut for themselves deep, steep-
sided valleys. In their upper courses they traverse steep, angular
gorges, where numerous cascades and cataracts are to be found, par-
ticularly in the Sierra de Luquillo. The peculiarity of the drainage
system where it passes from the central mountain into the limestone
region has already been described. Within the coastal plain the
valleys are broad, with considerable areas of bottom land through
whcih the rivers pursue a meandering course. The streams flowing
liorth from the main divide are much more numerous and longer than
those from the south side, and they likewise carry a much greater
and more constant volume of water. The island is reported to have
upward of 1,300 named streams, of which the Rio de la Plata is con-
sidered the longest, about 45 miles. None of the rivers is naviga-
ble, except for small boats, and then chiefly in their tidal reaches.
They, nevertheless, are of tremendous importance as a source of
domestic water supply, and their power possibiUties are also very
considerable.

CLIMATE.



Though Porto Rico is well within the Tropics, it has an equable
and comfortable climate, for the modifying influences of the ocean
are accentuated by its position in the direct path of the North
Atlantic trade winds. These counteract the enervating effect of the
high temperature and humidity, the occasional periods of sultry and
oppressive weather invariably occurring when they fail. They vary
in direction from northeast to southeast, usually coming from east or
east-southeast. Their average velocity from month to month is



8 BULLETIN S'A, U. S. DEPARTMENT OF AGRICULTURE.

remarkably constant, rarely varying more than a mile from the
annual average of 11 miles per hour, excepting in July, when the
velocity rises to 13 miles, and in October and November, when it falls
to 8 or 9 miles.

Hurricanes whose centers pass over the island are rare; in the past
40 years there have been but three, the most recent as weU as the
most destructive being that of August 8, 1899. The recorded
stonns of this character for the entire West Indies average about one
a year and occur chiefly during the months of August, September,
and October.

TEMPERATURE.

The temperature throughout the year is uniform. The records of
the United States Weather Bureau for a period of more than 10 years
show a combined average annual temperature for over 40 stations in
the island of 76°; during the coolest months of winter the average
is 73° and during the warmest months of summer 79°. The daily
range is much more than the seasonal range; thus at San Juan the
difference between the afternoon and early morning temperature is
10° or 11° and at an inland station may be as much as 20° or 25°.
In the afternoon the temperatures along the coast rise to an average
of 84° in the winter months and to 89° in the summer months and in
the early morning fall to 66° and 73°. In the hills and mountains of
the interior the average daily maximum is about 81° in whiter and
87° in summer, while the corresponding minima are 61° and 68°,
respectively.

The extremes of temperature recorded during the past 10 years do
not differ greatly in different portions of the island. At the more
elevated stations the maximum range is between 90° and 95° and
along the coast and in the vaUeys 95° and 100°. The extreme maxi-
mum has reached 100° only three times during the 10 years, at one
time reaching 103°. The minimum temperatures range between 50°
and 55° except for stations on the immediate coast, where the tem-
perature seldom goes below 60°. The lowest recorded temperature
is 43°, and it is probable that on the highest elevations it goes some-
what lower. It is, however, extremely doubtful if it ever approaches
very near to the frost line.

RAINFALL.

The average annual rainfall is much more variable than the
temperature. The average for a 12-year period from 44 stations
shows 77.30 mches; for the year 1901 it was 93.72, and for 1907 but
64.18. The geographic distribution of rainfall shows a still wider
variation. The heaviest is recorded in the Sierra de LuquiUo, which
is exposed to the fuU sweep of the moisture-laden trade winds. Tlie
average annual rainfall here exceeds 135 inches, with a maximum



FORESTS OF PORTO RICO. 9

record in 1901 of 169 inches. There are two other well-defined areas
where the average annual rainfall exceeds 100 inches, namely, the