Cover: Bromeliads festoon the

trunks and branches of dwarf

trees found in the cloud forests of

the Luquillo Mountains in Puerto

Rico. (photo by John Parrotta)

SUMMARY

The world’s tropical forests, which

circle the globe, are interestingly

diverse. Ranging from the steamy

jungles of the rain forests to the dry

forests and savannas, they provide

habitat for millions of species of

plants and animals. Once covering

some 15.3 billion acres (6.2 billion

ha), these tropical forests have been

reduced through cutting and clearing by 210 million acres (85 million

ha) between 1985 and 1990. All

types of tropical forests are defined

and their products and benefits to

the environment are presented and

discussed. Modern forest practices

are shown as a means of halting forest destruction while still providing

valuable forest products and protecting and preserving the habitats

of many endangered species of

plants and wildlife. The Luquillo

Experimental Forest is presented as

a possible model to exemplify forestry practices and research that

could manage and ultimately protect the tropical forests throughout

the world.

October 1997

Southern Research Station

PO. Box 2680

Asheville, NC 28802
J. Louise Mastrantonio

and John K. Francis

J. Louirse Mastrantonio is a freelance science writer in Portland, OR;

John K. Francis is a research forester at the International Institute

of Tropical Forestry, U.S. Department of Agriculture, Forest Service,

Rio Piedras, PR 00928-5000, in cooperation with the University or

Puerto Rico, Rio Piedras, PR 00936-4984.
Figure l.- The worldwide distribution of tropical wet (green) and dry (gold) forests.

Figure. 2- The Africo.n tulip tree (Spathodea campanulata)was spread around the

world as an ornamental and now grows in disturbed natural forests in

Puerto Rico and other moist tropical countries.
Wet Tropical Forest

Dry Tropical Forest

he world’s tropical forests circle the globe in a ring around the

Equator. They are surprisingly diverse, ranging from lush rain

forests to dry savannas and containing millions of species of

plants and animals (fig. 1). Dopical forests once covered some

15.3 billion acres (6.2 billion ha). In recent times, however, they have

been cut at a rapid rate to make room for agriculture and to obtain

their many valuable products. Between 1985 and 1990,

210 million acres (85 million ha) of tropical forests were destroyed.

This guide shows how modern forest practices can help stem the tide

of forest destruction while providing valuable forest products for people.

The tropical forests of Puerto Rico, which were abused for centuries,

were badly depleted by the early 1900’s. Widespread abandonment of

poor agricultural lands has allowed natural reforestation and planting

programs to create a patchwork of private, Commonwealth, and Federal

forests across the land (fig. 2). The most frequent example in this

publication is the Luquillo Experimental Forest, which could be a model

rotecting and managing tropical forests worldwide.
About half of all the world’s forests are in the Tropics, the area between the Tropic of Cancer and the

Tropic of Capricorn. This region

may be best known for its rain forests-lush, steamy jungles with

towering trees, epiphytes, and

dense u.nderstories of smaller trees,

shrubs, and vines.

Tropical forests are surprisingly

diverse. In addition to rain forests,

there are mangroves, moist forests,

dry forests, and savannas. Such

classifications, however, give only a

slight indication of the diversity of

tropical forests. One study by the

Food and Agriculture Organization

(FAO) of the United Nations, which

considered 23 countries in tropical

America, 37 in tropical Africa, and

16 in tropical Asia, identified dozens of types of tropical forests: open

and closed canopy forests, broadleaved trees and conifer forests,

closed forests and mixed forestgrasslands, and forests where agriculture has made inroads.

Rain Forests

The largest remaining areas of

tropical rain forests are in Brazil,

Congo, Indonesia, and Malaysia.

Precipitation generally exceeds 60

inches (150 cm) per year and may

be as high as 400 inches (1000 cm).

Lowland rain forests are among the

world’s most productive of plant

communities. Giant trees may

tower 200 feet (60 m) in height and

support thousands of other species

of plants and animals. Montane

(mountain) rain forests grow at

higher elevations where the climate

y and wet for optimum

tree growth.

Figure 3.-Wetland forests (swamps and

mangroves) are critical habitats

for many plant and animal species.

Whole wetland ecosystems are being lost through development.

Mangrove forests grow in the

swampy, intertidal margin between

sea and shore and are often considered part of the rain forest complex.

The roots of mangrove trees help

stabilize the shoreline and trap

sediment and decaying vegetation

that contribute to ecosystem productivity (fig. 3).

Dry Forests

Large areas of tropical dry forests

are found in India, Australia, Central and South America, the Caribbean, Mexico, Africa, and Madagascar. Dry forests receive low rainfall amounts, as little as 20 inches

(50 cm) per year, and are characterized by species well adapted to

drought. Trees of dry tropical forests are usually smaller than those

in rain forests, and many lose their

leaves during the dry season. Although they are still amazingly diverse, dry forests often have fewer

species than rain forests.

Savanna is a transitional type

between forest and grassland. Trees

are often very scattered and tend to

be well adapted to drought and tolerant of fire and grazing. If fire is

excluded, trees eventually begin to

grow and the savanna is converted

to dry forest. With too much fire or

grazing, dry forest becomes savanna

(fig. 4). This vegetation type has

fewer species of trees and shrubs

but more grasses and forbs than

other forest types in the Tropics.

Figure 4.-Tropical grasslands and savannas are created from tropical dry forests by fire

and to a lesser extent by grazing. In the absence of fire, dry forest reinvades

grasslands and savannas.

2
All forests have both economic

and ecological value, but tropical

forests are especially important in

global economy. These forests cover

less than 6 percent of the Earth’s

land area, but they contain the vast

majority of the world’s plant and

animal genetic resources. The diversity of life is astonishing. The original forests of Puerto Rico, for

example, contain more than 500

species of trees in 70 botanical families. By comparison, temperate forests have relatively few. Such

diversity is attributed to variations

in elevation, climate, and soil, and

to the lack of frost.

There is also diversity in other life

forms: shrubs, herbs, epiphytes,

mammals, birds, reptiles, amphibians, and insects. One study suggests that tropical rain forests may

contain as many as 30 million different kinds of plants and animals,

most of which are insects (fig. 5).

Figure 5.-The number of arthropod species

is far greater than the number of

species of all other life forms combined. The majority of arthropods

are tropical.

Figure 6. -Harvest of wood products from the tropical forests is essential to maintain our

present lifestyle, but it should be planned and conducted carefully to prevent

damage to the environment and loss ofproductivity of the land.

Wood and Other Products

Tropical forests provide many

valuable products including rubber,

fruits and nuts, meat, rattan, medicinal herbs, floral greenery, lumber, firewood, and charcoal. Such

forests are used by local people for

subsistence hunting and fishing.

They provide income and jobs for

hundreds of millions of people in

small, medium, and large industries.

Tropical forests are noted for their

beautiful woods (fig. 6). Four important commercial woods are mahogany, teak, melina, and okoume.

onduras mahogany (Swietenia

acro~~yZla), grows in the Americas from

wood of medium density, mahogany

is easy to work, is long lasting, and

has good color and grain. It is commonly used for furniture, molding,

paneling, and trim. Because of its

resistance to decay, it is a popular

wood used in boats. Teak (Tectona

grandis) is native to India and

Southeast Asia. Its wood has medium density, is strong, polishes

well, and has a warm yellow-brown

color. Also prized for resistance to

insects and rot, teak is commonly

used in cabinets, trim, flooring, furniture, and boats (fig. 7). Melina

(Gmelina arboreal grows naturally

from India through Vietnam. Noted

3
Figure 7.-- Teak (Tectona grandis) is one of the most valuable tropical hardwoods.

This young plantation is growing in St. Croix, U.S. Virgin Islands.

for fast growth, melina has lightcolored wood that is used mainly for

pulp and particleboard, matches,

and carpentry. Okoume (Aucoumea

klaineana) is native to Gabon and

the Congo in west Africa. A large,

fast-growing tree, the wood has moderately low density, good strength-todensity ratio, and low shrinkage

during drying. It is commonly used

for plywood, paneling, interior furniture parts, and light construction.

Other Economic Values

Tropical forests are home for

tribal hunter-gatherers whose way

of life has been relatively unchanged for centuries. These people

depend on the forests for their livelihood. More than 2.5 million people

also live in areas adjacent to tropical forests. They rely on the forests

for their water, fuelwood, and other

resources and on its shrinking land

base for their shifting agriculture.

For urban dwellers, tropical forests

provide water for domestic use and

hydroelectric power. Their scenic

beauty, educational value, and opportunities for outdoor recreation support tourist industries.

Many medicines and drugs come

from plants found only in tropical

rain forests. Some of the best known

are quinine, an ancient drug used

for malaria; curare, an anesthetic

and muscle relaxant used in surgery; and rosy periwinkle, a treatment for Hodgkin’s disease and

leukemia. Research has identified

other potential drugs that may have

value as contraceptives or in treating a multitude of maladies such as

arthritis, hepatitis, insect bites, fever, coughs, and colds. Many more

may be found. In all, only a few

thousand species have been evaluated for their medicinal value.

In addition, many plants of tropical forests find uses in homes and

gardens: ferns and palms, the hardy

split-leaf philodendron, marantas,

bromeliads, and orchids (fig. 8), to

name just a few.

4
Environmental Benefits

Tropical forests do more than respond to local climatic conditions;

they actually influence the climate.

Through transpiration, the enormous number of plants found in

rain forests return huge amounts of

water to the atmosphere, increasing humidity and rainfall, and cooling the air for miles around. In

addition, tropical forests replenish

the air by utilizing carbon dioxide

and giving off oxygen. By fixing carbon they help maintain the atmospheric carbon dioxide levels low

and counteract the global “greenhouse” effect.

Forests also moderate streamflow. Trees slow the onslaught of

tropical downpours, use and store

vast quantities of water, and help

hold the soil in place. When trees

are cleared, rainfall runs off more

quickly, contributing to floods and

erosion.

Before the dawn of agriculture

approximately 10,000 years ago,

forests and open woodland covered

about 15.3 billion acres (6.2 billion

ha) of the globe. Over the centuries,

however, about one-third of these

natural forests has been destroyed.

According to a 1982 study by FAO,

about 27.9 million acres (11.3 million ha) of tropical forests are cut

each year-an area about the size

of the States of Ohio or Virginia.

Between 1985 and 1990, an estimated 210 million acres (85 million

ha) of tropical forests were cut or

cleared. In India, Malaysia, and the

Philippines, the best commercial

forests are gone, and cutting is increasing in South America. If deforestation is not stopped soon, the

world will lose most of its tropical

forests in the next several decades.

Reasons for Deforestation

Several factors are responsible for

deforestation in the Tropics: clearing for agriculture, fuelwood cutting,

and harvesting of wood products. By

far the most important of these is

clearing for agriculture. In the Tropics, the age-old practice of shifting,

sometimes called “slash-and-burn,”

agriculture has been used for centuries. In this primitive system, local people cut a small patch of forest

to make way for subsistence farming. After a few years, soil fertility

declines and people move on, usually to cut another patch of trees

and begin another garden.

In the abandoned garden plot, the

degraded soil at first supports only

weeds and shrubby trees. Later, soil

fertility and trees return, but that

may take decades. As population

pressure increases, the fallow (rest)

period between cycles of gardening

is shortened, agricultural yields decrease, and the forest region is finther degraded to small trees, brush,

or eroded savama.

Conversion to sedentary agriculture is an even greater threat to

tropical forests. Vast areas that once

supported tropical forests are now

permanently occupied by subsistence farmers and ranchers and by

commercial farmers who produce

sugar, cocoa, palm oil, and other

products.

In many tropical countries there

is a critical shortage of firewood. For

millions of rural poor, survival depends on finding enough wood to

cook the evening meal. Every year

more of the forest is destroyed, and

the distance from home to the forest increases. Not only do people

suffer by having to spend much of

their time in the search for wood,

but so does the land. Damage is

Figure 8.-Cultivated orchids of today were selected and bred from tropical forest species.

This Vanda sp. probably originated in Southeast Asia.
greatest in dry tropical forests

where firewood cutting converts forests to savannas and grasslands.

The global demand for tropical

hardwoods, an $&billion-a-year industry, also contributes to forest

loss. Tropical forests are usually

selectively logged rather than

clearcut. Selective logging leaves

the forest cover intact but usually

reduces its commercial value because the biggest and best trees are

removed. Selective logging also

damages remaining trees and soil,

increases the likelihood of fire, and

degrades the habitat for wildlife

species that require large, old

trees-the ones usually cut. In addition, logging roads open up the

forests to shifting cultivation and

permanent settlement.

In the past, logging was done primarily by primitive means-trees

were cut with axes and logs were

moved with animals such as oxen.

Today the use of modern machinery-chain saws, tractors, and trucks

-makes logging easier, faster, and

potentially more destructive.

Endangered Wildlife

Forests are biological communities-complex associations of trees

with other plants and animals that

have evolved together over millions

of years. Because of the worldwide

loss of tropical forests, thousands of

species of birds and animals are

threatened with extinction. The list

includes many unique and fascinating animals, among them the orangutan, mountain gorilla, manatee,

jaguar, and Puerto Rican parrot.

Although diverse and widely separated around the globe, these species have one important thing in

common. They, along with many

other endangered species, rely on

tropical forests for all or part of their

habitat.

6

Figure 9.-The rare and endangered Puerto Rican parrot (Amazona vittata) is found

today in small wild and captive flocks in the Luquillo Experimental Forest.

Orangutans (Pongo pygmaeus)

are totally dependent on small and

isolated patches of tropical forests

remaining in Borneo and Sumatra,

Indonesia. Orangutans spend most

of their time in the forest canopy

where they feed on leaves, figs and

other fruit, bark, nuts, and insects.

Large trees of the old-growth forests

support woody vines that serve as

aerial ladders, enabling the animals

to move about, build their nests, and

forage for food. When the old forests

are cut, orangutans disappear.

The largest of all primates, the

gorilla, is one of man’s closest relatives in the animal kingdom. Too

large and clumsy to move about in

the forest canopy, the gorilla lives

on the forest floor where it forages

for a variety of plant materials. Loss

of tropical forests in central and

west Africa is a major reason for the

decreasing numbers of mountain

gorillas (Gorillagorilla). Some habitat has been secured, but the future

of this gentle giant is in grave danger as a result of habitat loss and

poaching.

The jaguar (Leo onca), a resident

of the Southwestern United States

and Central and South America, is

closely associated with forests. Its

endangered status is the result of

hunting and habitat loss.

The Puerto Rican parrot (Amazona vittata), a medium-sized, green

bird with blue wing feathers, once

inhabited the entire island of Puerto

Rico and the neighboring islands of

Mona and Culebra. Forest destruction is the principal reason for the

decline of this species. Hunting also

contributed. Today, only a few

Puerto Rican parrots remain in the

wild and their survival may depend

on the success of a captive breeding

program (fig. 9).

In addition to species that reside

in tropical forests year round, others depend on such forests for part

of the year. Many species of migrant

birds journey 1,000 miles or more

between their summer breeding

grounds in the north and their tropical wintering grounds. These birds

are also threatened by tropical forest destruction.
Forestry-loosely defined as the

systematic management and use of

forests and their natural resources

for human benefit-has been practiced for centuries. Most often, forestry efforts have been initiated in

response to indiscriminate timber

cutting that denuded the land and

caused erosion, floods, or a shortage of wood products.

Ancient Forestry Practices

In ancient Persia (now Iran), forest protection and nature conservation laws were in effect as early as

1,700 B.C. Two thousand years ago

the Chinese practiced what they

called “four sides” forestry-trees

were planted on house side, village

side, road side, and water side. More

than 1,000 years ago, Javanese maharajahs brought in teak and began

to cultivate it. In the African Tropics, agroforestry (growing of food

crops in association with trees) has

been practiced for hundreds of

years.

In the Yucatan Peninsula of

southern Mexico, the ancient Mayas

cultivated fruit and nut trees along

with such staples as corn, beans,

and squash. Bark, fibers, and resin

were obtained from plants grown in

fields, kitchen gardens, and orchards. Early in their civilization,

the Mayas practiced slash-and-burn

agriculture. As their population

grew, they found more efficient

methods of growing crops. They terraced hillsides, learned how to decrease the time between “rotations”

of agricultural land with native forests, dug drainage channels and

canals to move water to and from

cultivated areas, and filled in

swampland to plant crops.

The agricultural sophistication of

the Mayas enabled their civilization

to grow and flourish. What brought

about their decline about A.D. 820

is not fully known, but some believe

that as their society developed,

the Mayas made unsustainable demands on their environment.

Relatively little is known about

tropical forestry before the mid1800’s in most places. At that time,

the European colonial empiresnotably the Dutch, English, and

Spanish-brought modern forest

management practices to Indonesia,

India, Africa, and the Caribbean.

Centers for forestry and forestry

research were established, and

more careful records were kept.

Sustainable Forestry

Modern forestry has its basis in

l&h-century Germany. Like the

Chinese and the Mayan forest practices, German forestry is essentially

agricultural. Trees are managed as

a crop. Two concepts are important:

renewability and sustainability.

Renewability means that trees can

be replanted and seeded and harvested over and over again on the

same tract of land in what are

known as crop “rotations.” Sustainability means that forest harvest can be sustained over the long

term. How far into the future were

foresters expected to plan? As long

as there were vast acres of virgin

(original) forests remaining, this

question was somewhat academic.

Today, however, sustainability is a

vital issue in forestry. Most of the

world’s virgin forests are gone, and

people must rely more and more on

second- growth or managed forests.

Perhaps we now face, as never before,

the limits to long-term productivity.

In the German forest model, forestry is viewed as a continual process of harvest and regeneration.

Harvest of wood products is a goal,

but a forester’s principal tasks are

to assure long-term productivity.

That is achieved by cutting the

older, mature, and slow-growing

timber to make way for a new crop

of young, fast-growing trees.

Harvest-Regeneration

Methods

Three examples of timber harvest-regeneration methods (silvicultural systems) illustrate how

foresters manage stands to produce

timber on a sustained basis.

Selection

Individual trees or small groups

of trees are harvested as they become mature. Numerous small

openings in the forest are created

in which saplings or new seedlings

can grow. The resulting forest has

a continuous forest canopy and

trees of all ages. Such systems favor slow-growing species that are

shade tolerant.

Clearcutting

In clearcutting, an entire stand of

trees is removed in one operation.

From the forester’s point of view,

clearcutting is the easiest way to

manage a forest-and the most economical. Regeneration may come

from sprouts on stumps, from seedlings that survive the logging operation, or from seeds that germinate

after the harvest. If natural regeneration is delayed longer than desired, the area is planted or seeded.

Clearcutting systems are often

used to manage fast-growing species that require a lot of light. Resulting stands are even aged because all

the trees in an area are cut-and regenerated-at the same time. Clearcutting has become controversial in

7
recent years because it has the potential to damage watersheds and

because it tends to eliminate species of wildlife dependent on oldgrowth trees. If clear-cuts are kept

small and the cutting interval is

long enough, however, biological

diversity may not be impaired.

Shelterwood

In shelterwood systems, the forest canopy is removed over a period

of years, usually in two cuttings.

After the first harvest, natural regeneration begins in the understory.

By the time the second harvest is

made, enough young trees have

grown to assure adequate regeneration. Shelterwood systems favor

species that are intermediate in tolerance to shade. Such systems are

difficult to use successfully and are

the least used of the three silvicultural methods described.

Multiple-Use Forestry

Gifford Pinchot, the first Chief of

the U.S. Forest Service, was also

this country’s first professional forester. Pinchot advocated the use of

forest resources-all resources, not

just timber-for human benefit.

Pinchot was a strong and charismatic leader, and his ideas helped

shape the course of forestry in the

United States.

Pinchot had a vocal opponent in

John Muir, a young naturalist from

California who believed that public

lands should be preserved rather

than used. Eventually Muir and

Pinchot became rivals for public approval. Oddly enough, there was no

loser in this early conservation

battle. Muir’s preservation ethic became embodied in the philosophy of

the National Parks, and Pinchot’s

concept of wise use became the guiding principle of the National Forests.

National Forests are still managed under the concepts of multiple

use and sustained yield. The dominant uses of National Forests are

considered to be wood, water, wildlife, forage (for domestic cattle and

wildlife), and recreation. Extraction

of minerals and other valuable products is also considered a legitimate

use of National Forests. Because

Pinchot’s philosophy left room for

the “highest and best use” of a given

area, the U.S. National Forests now

include a wilderness system of more

than 32 million acres (13 million ha)

in which timber harvest is not allowed.

Today it is generally recognized

that most, if not all, nondestructive

uses of forest are valid. Some areas

may be set aside as parks; others

for wildlife habitat or as wilderness.

Still others will be managed for timber harvest or multiple benefits.

Today, conflicts arise primarily over

where these different uses will be

dominant. In the National Forests,

such decisions are made through a

land-use planning process in which

the public has ample opportunities

for input and involvement.

At the turn of the century, very

little was known about the worlds

native forests or how to manage

them. In the United States, foresters were quick to recognize the

value of information about forests

and a branch of research was established in the Forest Service in 1915.

Early research was done primarily

in support of reforestation efforts,

but, as forestry grew in size and

complexity, so did the research.

Today, the USDA Forest Service

has six regional experiment stations

located in important forest regions.

Each experiment station has several field laboratories generally

with specialized assignments for a

geographic region or a specific subject area, and numerous sites for

field research. In addition, the Forest Products ILaboratory in Madison, WI, serves as a nationwide

center for research and development of new technology relating to

wood, including tropical woods. Two

laboratories are dedicated exclusively to tropical forest research: the

International Institute of Tropical

Forestry in Puerto Rico and the Institute of Pacific Islands Forestry in

Hawaii.

Research is vital for modern forest management, which is information intensive. Today’s foresters

require vast quantities of data and

a knowledge of ecology: they must

understand not only the parts of

ecosystems but how different parts

of the environment interact. Scientific investigations are conducted in

support of all kinds of forestry activities: silviculture, forest insect

and disease control, wildlife habitat management, fire prevention

and control, range and watershed

management, forest products utilization, forest survey, reforestation,

ecology, and economics.

8
In the past, timber harvest in the

Tropics has seldom been followed by

regeneration. Conversion to agriculture is often permanent or results

in soil erosion. Timber harvest contracts have usually been short term

and have provided little or no incentive for timber companies to replant. So little reforestation has

been done in the Tropics that many

people believe these forests cannot

be restored. However, there are

many examples of successful reforestation in India, Indonesia, and the

Caribbean.

In the Tropics, as elsewhere, forestry is a mixture of modern innovations and ancient techniques

borrowed from local tradition. Plantation forestry is common. Forest

reserves have been established for

timber harvest, wildlife habitat,

scenery, outdoor recreation, or watershed protection. And in the Tropics, agroforestry-tree growing

combined with agricultural cropping-is much more common than

elsewhere.

Figure lO.-Forest scientists are working to determine which trees will grow well

in plantations and how best to manage them.

Plantation Forestry

In the Tropics, trees are often

planted and grown in plantations

for wood production. Often, many

species must be tried to determine

which will grow best (fig. 10). Plantations must also be supported by

major investments in forest management and research. Forest nurseries must be established, and

planting techniques and cultural

practices (spacing and thinning,

pruning, fertilization, insect and

disease control, and genetic improvement) must be developed.

Extensive pine plantations, have

been established in the moist Tropics, mainly in South Africa and Australia. Species most often planted

include Caribbean pine (Pinus

caribaea), ocote pine (I! oocarpa),

slash pine (l? elliottii), and benguet

pine (P. kesiya). Pines are popular

plantation trees because they are

generally fast growing, have good

survival rates, and are adapted to

a wide variety of environments, including degraded forest sites.

Eucalypts, including species such

as Euealyptusgrandis, E. deglupta,

E. tereticornis, E. globulus, and E.

camaldulensis are favored for the

same reasons. Eucalypts are commonly grown for pulp, fuel, and lumber. Other species commonly planted

include teak (Tectona grandis), Honduras mahogany (Swietenia macrophylla), melina (Gmelina arboreal,

beefwood (Casuarina equisetifolia),

and Mexican cypress (Cupressus

lusitanica).

9
Forest Reserves

There are many reasons for establishing forest reserves in the Tropics. They can restore watersheds

and wildlife habitat, improve scenic

beauty and opportunities for outdoor recreation, and produce wood

and other products for local use and

export. Many forest products contribute to the sustenance and income of local people: wildlife and

fish, firewood, rubber, fruits and

nuts, rattan, medicinal herbs, floral greenery, and charcoal.

Perhaps the most famous of these

reserves is the 5,600 square mile

(14,500 k2) Serengeti National Park

in Tanzania. With its vast herds of

grazing ungulates (hoofed animals)

and predators, including several endangered species, the Serengeti is

a showcase of a savanna ecosystem

that has long been protected and

managed for wildlife and other

natural resources (fig. 11). Although

plagued with poachers, the Serengeti

promotes the cause of wildlife conservation to the many thousands of

“ecotourists” who pay to experience

nature each year.

Another type of forest reserve is

the “extractive” reserve, which is

dedicated to the production of useful products. Large reserves of this

type have been established recently

in Brazil. Local residents use them

for tapping rubber, for gathering

fruits and nuts, for hunting, and for

harvesting wood on a sustainedyield basis. Such uses provide a sustainable income while maintaining

the ecological integrity of the forest.

1 0

Figure ll.-Giraffes (Giraffe cameloparadalis) are dependent on Acacia spp. and other

savanna trees and shrubs for sustenance. (photo by Ariel Lugo).

Agroforestry

The practice growing of trees in

combination with agricultural crops

is fairly common in the Tropics. It

is possible to grow food crops year

around in many forested areas, and

rural poor depend on this source of

food as nowhere else on Earth.

Taungya System

Various systems have been developed for combining forestry with

agriculture. “Taungya” is a Burmese word meaning cultivated hill

plot. This system of agroforestry

was developed in Europe during the

Middle Ages and probably independently in a number of places in the

Tropics. After existing forest or

ground cover is removed by burning,

trees are planted along with agricultural crops. Both are cultivated until

the tree canopy closes. Then the area

is left to grow trees, and another site

is located for combined forestryagriculture.

Shade Cropping

An overstory of trees is often used

to provide shade for agricultural

crops. A common practice is to grow

tree species such as guaba (Inga

uera) over coffee. In Puerto Rico,

many forests developed where coffee was once grown in this manner.
Support Crops

Trees can be planted to provide

support (and sometimes shade) for

vine crops. Vines such as pepper

and vanilla need support.

Alley Cropping

Nitrogen-fixing trees are planted

in hedges in widely-space parallel

rows along the contour of slopes.

Food crops are grown in the “alley”

between the rows. The trees add

nitrogen and organic matter, protect

the soil from erosion, and provide

wood and animal forage.

Living Fences

Green fenceposts that will root

and sprout often are planted in a

closely spaced row. When they

sprout, they create a “living fence”

that provides shade and forage for

cattle.

Windbreaks

Trees are often planted as windbreaks for agricultural crops, farms,

or homesites. Such plantings can

eventually contribute wood products as well as shelter. Food trees

such as citrus, rubber, and mango

can also provide fuel, lumber, and

other wood products when they have

outlived their original usefulness.

The conservation issues of the

past seem simple compared with

those of today. As we move toward

the 21st century, human societies

are concerned with global warming,

deforestation, species extinction,

and rising expectations. Growing

populations must be fed, clothed,

and sheltered, and people everywhere want higher standards of

living.

Global Warming

Warming of the earth’s atmosphere is a major environmental

issue. Air pollution, deforestation,

and widespread burning of coal, oil,

and natural gas have increased atmospheric concentrations of carbon

dioxide, methane, nitrous oxide,

and chlorofluorocarbons. These

gases trap heat from the sun and

prevent it from radiating harmlessly back into space. Thus, the

“greenhouse” or warming effect is

created.

Because of natural variations in

climate, it is difficult to measure

warming over large areas. Scientists agree, however, that increases

in atmospheric concentrations of

greenhouse gases will cause higher

temperatures worldwide. Even an

increase of a few degrees might

cause serious melting of the polar

icecaps, a gradual rise in sea level,

a disruption in normal weather patterns, a possible increase in forest

fires, and the extinction of species.

Role of Forests

Trees, the largest of all land

plants, act as a kind of environmental “buffer” for the ecosystem they

dominate. They help ameliorate the

extremes of climate (heat, cold, and

wind) and create an environment

where large land mammals, including people, can live comfortably,

Trees complement animals in the

global environment. Mammals take

in oxygen from the air and exhale

carbon dioxide. Plants use the carbon dioxide in their growth processes, store the carbon in woody

tissues, and return oxygen to the

atmosphere as a waste product.

This process, known as photosynthesis, is essential to life. Carbon

captured from the atmosphere by

photosynthesis is eventually recycled through the environment in

a process known as the carbon cycle.

Trees have an especially important

role in the carbon cycle.

Tree leaves also act as filters to

remove atmospheric pollutants

from the air. This effect is particularly beneficial in urban areas.

Forestry Issues

Two key issues will dominate forestry in the years ahead: (1) maintaining long-term productivity of

managed forests, and (2) preventing further loss of tropical forests.

Both problems will require new approaches to forest management.

Traditionally, forestry has focused

on growing crops of wood in plantations or in managed natural stands.

In this “agricultural mode,” other

benefits of forest such as watershed

protection, wildlife habitat, climate

moderation, and outdoor recreation,

have received less attention than

wood production.

Perhaps more importantly, the

sustainability of the full range of

forest benefits has not been mea11
sured. There is no question that

trees can be grown for crops of wood

in managed stands. With intensive

management-short rotations, species selection, genetic improvement,

fertilization, thinning, and other

cultural treatments-more wood

can be produced in less time than

in natural forests. But for how long?

And at what cost in other benefits?

As more and more of the world’s

original forests have been cut, the

ecological value of forests has come

to be more appreciated. In recent

years, increased emphasis has been

put on what some are calling “ecosystem management.” In this

model, the health and long-term

stability of the forest are paramount, and timber production is

considered a byproduct of good forest management rather than the

principal product. In Puerto Rico,

for example, wood production is a

relatively minor aspect of forestry.

Since the 1930’s when timber harvests were curtailed, the forests

have been managed primarily for

watershed protection, wildlife habitat, and outdoor recreation.

There are no easy solutions to the

problem of tropical forest destruction, but most experts agree that the

problems cannot be solved simply

by locking up the forests in reserves.

The forests are too important to local people for that to be a workable

solution. There is no doubt that

tropical forests will be cut. It is better for them to be cut in an ecologically sound manner than to be

cleared for poor-quality farmland or

wasted by poor harvest practices

(fig. 12).

The only real long-term solutions

are: (1) more efficient agriculture on

suitable farmland, (2) efficient forestry practice including plantations,

and (3) reserves to protect species

and ecosystems. Many forestry experts believe that we have only begun to tap the potential for wise use

of tropical forests. Many uses have

yet to be fully explored. We are only

starting to learn the value of tropical forests for medicines, house and

garden plants, food and fiber, tourism, and natural resource education.

Figure 12.-Vast areas of tropical forests have

been and are still being converted

to marginally productive farmland to feed agrowingpopulation.
From Mt. Britton Tower at an el-
14
Early Conservation Efforts 35 percent of Puerto Rico is forested. outdoor recreation, watershed proThese forests give Puerto Rico much tection, wildlife habitat, or growing

As in other parts of the world, of its current beauty and may some- trees.

widespread forest cutting in Puerto day be a rich source of timber and

Rico eventually led to conservation other forest products.

efforts. The sale of wood was re- Outdoor R,ecreaClon‘ *

stricted by the Spanish in 1816, primarily because some species were A Forest of Many Names In the for--L A.%-..-- --^ -

considered necessary for naval use portunities

Luquillo Forest -I-’ -- ‘---= m, 1

during the colonial wars for independence. In 1824, alarmed by the ex- that was par+ ,c+L*

tent of deforestation, Governor reserves set

Miguel De la Torre issued a decree to in 1876. Originany JI

plant trees for watershed improve- (5,020 ha), t% -*on

men&-the first real conservation law.

mOre than 21:

Spain draftedits first comprehensive It includes t

forest laws in 1839 and set up fordisturbed f

estry commissions that led to the

Unique in th

first forest inventory on the island

est is the old

in 1843.

National Fl

In the next several decades, gov- been under

ernment protection of the forests

merit c. .

decreased, but enough interest in

conservation remained for King

UFDT;ii,

m-* __^^* A. ci...-2.

~DL, b~ltxt: ii~-t: many opfor outdoor recreation.

contains lana ‘lne coolness of the mountains

(, oI bile original forest draws people from the urban cenaside by the Spanish ters of San Juan and other towns

--- -“-- %t 12,400 acres in the warm and humid coastal lowlllu zGsudrve now covers lands. Access is excellent. From San

3,000 acres (11,300 ha). Juan, the Caribbean National Forhe largest block of un- est is less than an hour’s drive on

‘orest on the island. paved roads. Three highways trae Tropics, Luquillo For- verse the Forest: one on the northest forest reserve in the eastern boundary, another along the

nest System and has western edge, and still another

some form of manage- through the interior that provides

; ror more than 100 years. access to El Yunque Recreation Area

A *n”A+ve is managed by the with its many foot trails and picnic

tment of Agriculture, shelters. For visitors, the first conAlfonso XII to create the first forest c W-~SL nervlce, and has two primary tact with the Forest Service is ofreserves in 1876. Their purposes

functions-management and re- ten with interpretive displays and

were to ensure water quality, to pre- ~~~~nh ‘l”+s, its two names: Lu- ““4’ cI1l’ 1 ‘lW a fine film at the splendid new visivent soil erosion, and to assure an qulllo Experimental Forest and tors center “El Portal de1 Yunque” f-i--.‘l..L--- *

adequate supply of wood for roofing C/~X-MX~U i?ational Forest. Actu- near the entrance of the forest on

material, fuelwood, and sawtimber. ally, the forest has had many names Highway 191. Interpretive naturalBecause of those early set-asides over the years, names that reflect a ists are stationed at several points in

and later purchases, Puerto Rico long and colorful history. First the forest to assist visitors and to

now has a fine system of Common- called El Yunque after a prominent point out local features of interest.

wealth Forests. These forests are peak in the vicinity, the name was

brrarrgGL&

nh‘BnmnA 111. L administered by the Department of ;n 1903 to Luquillo Forest

Reserve andI again in 1935 to Car- Watershed Protection

Natural Resources, an agency of the

Commonwealth of Puerto Rico. Al- ibbean Nat%ma1 Forest (in Spanish,

“Bosque Nacional de1 Caribe”). In Eight major rivers have their

though small, they are widely scat- 1956, the FoiUUv braa+ ~XTQ “.- s designated as headwaters in the Luquillo Forest

tered around the island and preserve and provide water and hydroelectric

representative samples of several the Luquillo Exnerir ---r ----nental Forest in

recognition of the growing impor- power for towns and rural areas in

native forest types (mangroves, dry tance of rel:search in the reserve. eastern Puerto Rico. In the past,

forests, and rain forests) as well as Often, however; ---- LLLW- forest is simply unregulated timber cutting contribplantations of pine, mahogany, and uted to flooding and erosion, but

teak. referred to as “El Yumque, its oldest

Three-fourths of Puerto Rico’s for- and perhaps mos t picturesque today, critical watersheds-peaks,

name. ridges, and steep slopes-are off

ests are privately owned. A few

plantations of pine and mahogany The Caribbean N:itional Forest is limits to timber harvesting. As a

part of the National1 Forest System result, the water that flows from the

have been established, but most forests have regenerated naturally on and is managed by 1:aw for multiple- forest is relatively clean and free of

abandoned farmland. Today, nearly use benefits I. -van A *__* within the for- sediment.

est are dedicated to what is considered their best uses-whether for

15
Wildlife Habitat

The entire forest is also a wildlife

refuge. It has 68 species of native

birds, many migratory birds, and

numerous reptiles and amphibians.

At night, the rain forest resounds

with a loud chorus that may include

16 different species of frogs-the

beloved coquis of Puerto Rico (fig.

14). The only native mammals are

bats. However, mongooses, rats, and

domestic cats have been introduced

and now run wild.

Figure 14.-The tiny Puerto Rican coqui frog

(Eleutherodactylus spp.) courts

with a musical and surprisingly

loud “koki-koki” song.

Baiio de Oro Natural Area

Three-fourths of all the virgin

(primary) forests that remain in

Puerto Rico are located in the experimental forest. To protect this

unique and valuable resource, some

2,100 acres (850 ha) have been set

aside as the Baiio de Oro Natural

Area. Timber harvest is not allowed

in this area, and no roads or trails

may be built.

Important Trees which splits off in thin plates or

scales. Large, old palo Colorado trees

Although timber is considered to are important nest trees for the

be an important use of the forest, Puerto Rican parrot. Many of these

very little has been cut in recent trees support complete communities

years. In fact, the Forest Reserve of other plants: vines, mosses,

was created in response to defores- herbs, ferns, liverwarts, and even

tation, and emphasis has been on seedlings of other tree species.

reforesting cutover areas. Over the l Tabonuco (Ducryodes excelsa)

years, many acres have been is perhaps the most stately tree in

planted to trees. In the future, these “El Yunque.” These forest giants ofplantations will be an important ten reach a height of 100 feet (30

and sustainable source of timber for m) and a diameter of 40 inches (1

local use. m). The smooth, pale bark often

Luquillo Forest has 225 different exudes a white resin useful for

species of trees and a highly diverse starting fires and for incense. The

plant community typical of tropical wood of tabonuco was formerly used

rain forests around the world. Some to make furniture and boxes, but

of the most important or interest- today it is rarely cut.

ing native trees are listed here: * Sierra palm (Prestoea monl Ausubo (Munilkaru bidentata) tuna) is a striking feature of the

is a large, slow-growing tree with a Luquillo Experimental Forest. Aldense crown of dark-green ellipti- though palms are slow growing,

cal leaves. The wood of ausubo is they reproduce in abundance in the

beautiful, resistant to termites and shade on the forest floor and surrot, and highly desirable for furni- vive hurricanes that topple many

ture and construction purposes. broad-leaved forest trees. Palm

This was once one of the most im- fruits are produced all year and are

portant timber trees in Puerto Rico. a staple food of the Puerto Rican

Now, few large, old trees remain. parrot.

l Fern trees (Cyutheu urboreu

and C. uquilinu) are among the

most beautiful and fascinating

plants of tropical forests. These

small, evergreen trees have slender

trunks and feathery, lacy leaves

called fronds. The Carib Indians

used the hollow stems to carry and

preserve fire. Now these stems are

cut for use as planters for orchids

and bromeliads or for potting material. Fern trees are also used in

home and commercial gardens. Unfortunately, most of the fern trees

harvested are stolen from along

roads.

l Palo colorado (Cyrilla rucemifloru) is a very large tree that

may live to be 1,000 years old. Its

name comes from its reddish bark,

1 6
International Institute of the national forest. Subsequently, a Plans and programs

Tropical Forestry monitoring and research program developed to improve al

was begun, and the parrot was the benefits from this vah

Establishment of a forestry re- given protection under the Endan- Efforts include: (1) refining the ensearch station in Puerto Rico was gered Species Act. Over the years, viromnental education presentation

are being

nd extend

Iable area.

authorized by Congress in 1927, but the captive flock has continued to at “El Portal de1 Yunque” visitor’s

it was not until 1939 that the Tropi- increase, giving hope that the wild center, (2) improve recreational opcal Forest Experiment Station, now population can eventually be rees- portunities in other parts of the forcalled the International Institute of tablished. est, (3) acquire small pieces of

Tropical Forestry, was created. Lo- Over the years, the International property around the periphery of

cated on the grounds of the Agricul- Institute of Tropical Forestry has the forest that suffer from heavy

ture Experiment Station at the enjoyed a growing reputation in for- recreational impact, (4) develop a

University of Puerto Rico in Rio estry extension and education. A small-scale logging demonstration

Piedras, the institute has become a technical journal, “The Caribbean using the most environmentalfocal point for forestry research and Forester,” was published between friendly techniques available to proeducation in tropical America. The 1939 and 1963. Thousands of people vide wood to local artisans, (5) assist

designation as the Luqnillo Experi- have participated in training state and nongovernment agencies

mental Forest in 1956 reflected the courses and technical meetings, and with land management problems

growing importance of forestry re- the library has one of the best col- through technical assistance, (6)

search in the region. lections of tropical forestry informa- extend activities to promote the reTogether, the International Insti- tion in the world. In 1989, the covery of endangered species of

tute of Tropical Forestry and the experimental forest was designated plants as well as animals, and (7)

Caribbean National Forest have for a long-term ecological research promote sound urban forestry propioneered the application of sound by the National Science Founda- grams throughout the island.

forest management principles in tion. As a result, scientists are now Changes are also planned in the

tropical America. Between 1931 and learning more about the native flora research program. In the past 50

1956, the amount of land in the and fauna and how they react to years, many advances have been

Luquillo Forest was increased and natural and human-caused distur- made, particula&y in plantation forconsolidated from surrounding bances. estry. Foresters now have extensive

farmlands, and trespass was essen- Recreation facilities have been knowledge about how to reforest

tially eliminated. By 1975, 10,000 developed, including trails, picnic tropical sites. In the future, more

acres (4,000 ha) of land had been sites, visitor centers, and scenic emphasis will be placed on learnreplanted. Today, plantation forests overlooks. More than half a million ing how tropical forests fimctionlook so much like the native forests visitors a year now enjoy the Carib- how plants and animals interact in

that few people can tell them apart, bean National Forest. complex ecosystems and in global

and they have many of the same ecology Such information will help

benefits. In 1934, as an aid to refor- ~~~Directions to restore damaged forests, plan forestation efforts, research was initi- estry programs for local economies,

ated on natural regeneration, and The Caribbean National Forest is and show how to mitigate the glospecies trials were begun. Growth a small fraction of the original for- bal effects of air and water pollurecords have been kept on approxi- ests of Puerto Rico and very small tion,

mately 20,000 trees for nearly 50 compared to the national forests of While research in the Caribbean

years. will always be an important part of

Researchers at the institute were

the United States, Brazil, and else- the institute’s program, studies are

the first to report decrease in the where. But this forest is very spePuerto Rican parrot population in cial. Since the 1930’s, work done also being initiated elsewhere in

there helped to reverse the trend of Latin America. Emphasis will be on

forest destruction in Puerto Rico. The forest hydrology and ecology, forest

result is a living treasure-an exrehabilitation and management,

ample of how tropical forests can be the causes of species loss, and improtected and managed for human provement of access to technical

benefit. information.

1 7
HIGHLIGHTS IN THE

HISTORY OF THX LUQUILLO

EXPERIME3PiXL FOREST

1839-First Spanish forest conservation law for Puerto Rico.

1876-The Spanish Crown proclaims El Yunque and other

areas in Puerto Rico as forest reserves.

1903-President Roosevelt designates the Luquillo Forest

Reserve (now called the Caribbean National Forest).

1905-The Bureau of Forestry, U.S.

Department of Agriculture,

publishes the first detailed

report about the forest and

its resources.

1931-The first forest plantations

(mahogany) are established.

1933-The Emergency Conservation Program began. With

the Civilian Conservation

Corps (1937), extensive work

is accomplished in reforestation, road construction, and

other improvements.

1935-Name changed to the Caribbean National Forest.

1937-First timber inventory completed.

1939-Tropical Forest Experiment

Station (now the International Institute of Tropical

Forestry) established.

1946-Forest designated as a wildlife refuge.

1956-Entire forest designated as

the Luquillo Experimental

Forest in recognition of the

growing importance of research.

1968-Conservation efforts began

for the Puerto Rican parrot.

1976-The Luquillo Experimental

Forest is designated as a

Biosphere Reserve.

1988-Experiment Station receives

a grant from the National

Science Foundation for longterm ecological research.

1 8

SUGGESTED REXDING

Birdsey, Richard A.; Weaver, Peter Wadsworth, Frmk H. 1981. ManL. 1982. The forest resources of agement of forest lands in the

Puerto Rico. Resour. Bull. SO-85 himi d Tonics under sound ecoNew Orleans, LA U.S. Depart- es. In: Mergen,

ment of Agriculture, Forest Serlogical princinl

Francois, ed. Tropical forests: utivice, Southern fi’orest Experiment lization and conservation. New

Station. 59 p. Haven. CT: Yale University: 168-

Collins, Mark, ed. 1990. The last 180. ’

rain forests, a ‘c?rorld consemt2.m weaver, P.L. 1979. Tree growth in

atlas. Emmaus, PA: Rodale Press. several tropical forests of Puerto

200 p. 50-152. New OrEwel, J.J.; Whitmore, J.L. 1973.

Ecological life zones of Puerto

Rico. Res. Pap. 1

leans, LA: U.S. Department of

A&eultu

Rico and the U.S. Virgin Islands.

--D---.~-. -Lre, Forest Service,

Southern Forest Experiment StaRes. Pap. ITF-18. Rio Piedras, tion. 15 p.

PR U.S. Department of Agricul- Weaver, P.L. 1986. Hurricane damture, Forest Service, Institute of age and recovery in the montane

Tropical Forestry. 79 p. forests of the Luquillo Mountains

Little, E.L., Jr.; Woodbury, R.O.; of Puerto Rico. Caribbean JourWadsworth, F.H. 1974. Common nal of Science. 5

trees of Puerto Rico and the Vir- Whitemore. Jack

gin Islands. Agric. Handb. 449.

Washington, DC: U.S. Department of Agriculture. 1024 p.

Lugo, A.E. 1585.1ILn introduction to

the forests of Puerto Rico. Rio

!2( l-2): 53-70.

; L.; Hartshorn,

G.S. 1969. Literature review of

common tropical trees. Trop. For.

Series Contrib. 8. Seattle, WA:

Institute of Forest Products, College of Forest Resources, UniverPiedras, PR: U.S. Department of shington. 113 p.

Agriculture, Forest Service,

sity of Wa

Southern Forest Experiment Station. 20 p.

Snyder, N.F.; Wiley, J.W.; Kepler, Note:

C.B. 1987. The parrots of Lu- Publications may be reviewed in the

quillo: natural history and conser- library at the International Instivation of the Puerto Rican parrot. tute of Tropical Forestry, Rio

Los Angeles: Western Foundation Piedras, PR, or are available on loan

of Vertebrate Zoology. 384 p. from some public libraries.
The Forest Service, United States Department of

Agriculture (USDA), is dedicated to the principle of

multiple use management of the Nation’s forest

resources for sustained yields of wood, water, forage, wildlife, and

recreation. Through forestry research, cooperation with the States

and private forest owners, and management of the National Forests

and National Grasslands, it strives-as directed by Congress-to

provide increasingly greater service to a growing Nation.

The USDA prohibits discrimination in its programs on the basis of

race, color, national origin, sex, religion, age, disability, political

beliefs, and marital or familial status. (Not all prohibited bases

apply to all programs.) Persons with disabilities who require

alternative means for communication of program information

(braille, large print, audiotape, etc.) should contact the USDA’s

TARGET Center at (202) 720-2600 (Voice and TDD).

To tile a complaint, write the Secretary of Agriculture, U.S.

Department of Agriculture, Washington, DC 20250, or call l-800-

245-6340 (voice) or (202) 720-l 127 (TDD). USDA is an equal

employment opportunity employer.

Mastrantononio, J. Louise; Francis, John K. 1997. A student guide to tropical forest conservation. Gen. Tech. Rep. SO-123. Asheville, NC: U.S.

Department ofAgriculture, Forest Service, Southern Research Station.

20 p.

Tropical forests, which circle the globe, are surprisingly diverse, ranging from rain forests to savannas. Tropical forests are disappearing at

an alarming rate as they are converted to farmland and other uses.

Modern forest management practices can help stem the tide by providing income and valuable products while maintaining forest cover. Puerto

Rico has already gone through deforestation and partial reforestation.

The Luquillo Experimental Forest is an interesting example of a protected and managed tropical forest.

Keywords: Deforestation, forest management, Luquillo Experimental Forest, tropical forest.