Cover: Bromeliads festoon thetrunks and branches of dwarftrees found in the cloud forests ofthe Luquillo Mountains in PuertoRico. (photo by John Parrotta)

SUMMARY

The world’s tropical forests, whichcircle the globe, are interestinglydiverse. Ranging from the steamyjungles of the rain forests to the dryforests and savannas, they providehabitat for millions of species ofplants and animals. Once coveringsome 15.3 billion acres (6.2 billionha), these tropical forests have beenreduced through cutting and clear-ing by 210 million acres (85 millionha) between 1985 and 1990. Alltypes of tropical forests are definedand their products and benefits tothe environment are presented anddiscussed. Modern forest practicesare shown as a means of halting for-est destruction while still providingvaluable forest products and pro-tecting and preserving the habitatsof many endangered species ofplants and wildlife. The LuquilloExperimental Forest is presented asa possible model to exemplify for-estry practices and research thatcould manage and ultimately pro-tect the tropical forests throughoutthe world.

October 1997

Southern Research StationPO. 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 Instituteof Tropical Forestry, U.S. Department of Agriculture, Forest Service,Rio Piedras, PR 00928-5000, in cooperation with the University orPuerto 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 theworld as an ornamental and now grows in disturbed natural forests inPuerto Rico and other moist tropical countries.

Wet Tropical ForestDry Tropical Forest

he world’s tropical forests circle the globe in a ring around theEquator. They are surprisingly diverse, ranging from lush rainforests to dry savannas and containing millions of species of

plants and animals (fig. 1). Dopical forests once covered some15.3 billion acres (6.2 billion ha). In recent times, however, they havebeen 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 tideof 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 plantingprograms to create a patchwork of private, Commonwealth, and Federal

forests across the land (fig. 2). The most frequent example in thispublication is the Luquillo Experimental Forest, which could be a model

rotecting and managing tropical forests worldwide.

About half of all the world’s for-ests are in the Tropics, the area be-tween the Tropic of Cancer and theTropic of Capricorn. This regionmay be best known for its rain for-ests-lush, steamy jungles withtowering trees, epiphytes, anddense u.nderstories of smaller trees,shrubs, and vines.

Tropical forests are surprisinglydiverse. In addition to rain forests,there are mangroves, moist forests,dry forests, and savannas. Suchclassifications, however, give only aslight indication of the diversity oftropical forests. One study by theFood and Agriculture Organization(FAO) of the United Nations, whichconsidered 23 countries in tropicalAmerica, 37 in tropical Africa, and16 in tropical Asia, identified doz-ens of types of tropical forests: openand closed canopy forests, broad-leaved trees and conifer forests,closed forests and mixed forest-grasslands, and forests where agri-culture has made inroads.

Rain Forests

The largest remaining areas oftropical rain forests are in Brazil,Congo, Indonesia, and Malaysia.Precipitation generally exceeds 60inches (150 cm) per year and maybe as high as 400 inches (1000 cm).Lowland rain forests are among theworld’s most productive of plantcommunities. Giant trees maytower 200 feet (60 m) in height andsupport thousands of other speciesof plants and animals. Montane(mountain) rain forests grow athigher elevations where the climate

y and wet for optimumtree growth.

Figure 3.-Wetland forests (swamps andmangroves) are critical habitatsfor many plant and animal species.Whole wetland ecosystems are be-ing lost through development.

Mangrove forests grow in theswampy, intertidal margin betweensea and shore and are often consid-ered part of the rain forest complex.The roots of mangrove trees helpstabilize the shoreline and trapsediment and decaying vegetationthat contribute to ecosystem pro-ductivity (fig. 3).

Dry Forests

Large areas of tropical dry forestsare found in India, Australia, Cen-tral and South America, the Carib-bean, Mexico, Africa, and Mada-gascar. Dry forests receive low rain-fall amounts, as little as 20 inches(50 cm) per year, and are character-ized by species well adapted todrought. Trees of dry tropical for-ests are usually smaller than thosein rain forests, and many lose theirleaves during the dry season. Al-though they are still amazingly di-verse, dry forests often have fewerspecies than rain forests.

Savanna is a transitional typebetween forest and grassland. Treesare often very scattered and tend tobe well adapted to drought and tol-erant of fire and grazing. If fire isexcluded, trees eventually begin togrow and the savanna is convertedto dry forest. With too much fire orgrazing, dry forest becomes savanna(fig. 4). This vegetation type hasfewer species of trees and shrubsbut more grasses and forbs thanother forest types in the Tropics.

Figure 4.-Tropical grasslands and savannas are created from tropical dry forests by fireand to a lesser extent by grazing. In the absence of fire, dry forest reinvadesgrasslands and savannas.

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All forests have both economicand ecological value, but tropicalforests are especially important inglobal economy. These forests coverless than 6 percent of the Earth’sland area, but they contain the vastmajority of the world’s plant andanimal genetic resources. The diver-sity of life is astonishing. The origi-nal forests of Puerto Rico, forexample, contain more than 500species of trees in 70 botanical fami-lies. By comparison, temperate for-ests have relatively few. Suchdiversity is attributed to variationsin elevation, climate, and soil, andto the lack of frost.

There is also diversity in other lifeforms: shrubs, herbs, epiphytes,mammals, birds, reptiles, amphib-ians, and insects. One study sug-gests that tropical rain forests maycontain as many as 30 million dif-ferent kinds of plants and animals,most of which are insects (fig. 5).

Figure 5.-The number of arthropod speciesis far greater than the number ofspecies of all other life forms com-bined. The majority of arthropodsare tropical.

Figure 6. -Harvest of wood products from the tropical forests is essential to maintain ourpresent lifestyle, but it should be planned and conducted carefully to preventdamage to the environment and loss ofproductivity of the land.

Wood and Other Products

Tropical forests provide manyvaluable products including rubber,fruits and nuts, meat, rattan, me-dicinal herbs, floral greenery, lum-ber, firewood, and charcoal. Suchforests are used by local people forsubsistence hunting and fishing.They provide income and jobs forhundreds of millions of people insmall, medium, and large industries.

Tropical forests are noted for theirbeautiful woods (fig. 6). Four impor-tant commercial woods are ma-hogany, teak, melina, and okoume.

onduras mahogany (Swieteniaacro~~yZla), grows in the Ameri-

cas from

wood of medium density, mahoganyis easy to work, is long lasting, andhas good color and grain. It is com-monly used for furniture, molding,paneling, and trim. Because of itsresistance to decay, it is a popularwood used in boats. Teak (Tectonagrandis) is native to India andSoutheast Asia. Its wood has me-dium density, is strong, polisheswell, and has a warm yellow-browncolor. Also prized for resistance toinsects and rot, teak is commonlyused in cabinets, trim, flooring, fur-niture, and boats (fig. 7). Melina(Gmelina arboreal grows naturallyfrom India through Vietnam. Noted

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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 light-colored wood that is used mainly forpulp and particleboard, matches,and carpentry. Okoume (Aucoumeaklaineana) is native to Gabon andthe Congo in west Africa. A large,fast-growing tree, the wood has mod-erately low density, good strength-to-density ratio, and low shrinkageduring drying. It is commonly usedfor plywood, paneling, interior fur-niture parts, and light construction.

Other Economic Values

Tropical forests are home fortribal hunter-gatherers whose wayof life has been relatively un-changed for centuries. These peopledepend on the forests for their live-lihood. More than 2.5 million peoplealso live in areas adjacent to tropi-cal forests. They rely on the forestsfor their water, fuelwood, and otherresources and on its shrinking landbase for their shifting agriculture.For urban dwellers, tropical forestsprovide water for domestic use andhydroelectric power. Their scenicbeauty, educational value, and oppor-tunities for outdoor recreation sup-port tourist industries.

Many medicines and drugs comefrom plants found only in tropicalrain forests. Some of the best known

are quinine, an ancient drug usedfor malaria; curare, an anestheticand muscle relaxant used in sur-gery; and rosy periwinkle, a treat-ment for Hodgkin’s disease andleukemia. Research has identifiedother potential drugs that may havevalue as contraceptives or in treat-ing a multitude of maladies such asarthritis, hepatitis, insect bites, fe-ver, coughs, and colds. Many moremay be found. In all, only a fewthousand species have been evalu-ated for their medicinal value.

In addition, many plants of tropi-cal forests find uses in homes andgardens: ferns and palms, the hardysplit-leaf philodendron, marantas,bromeliads, and orchids (fig. 8), toname just a few.

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Environmental Benefits

Tropical forests do more than re-spond to local climatic conditions;they actually influence the climate.Through transpiration, the enor-mous number of plants found inrain forests return huge amounts ofwater to the atmosphere, increas-ing humidity and rainfall, and cool-ing the air for miles around. Inaddition, tropical forests replenishthe air by utilizing carbon dioxideand giving off oxygen. By fixing car-bon they help maintain the atmo-spheric carbon dioxide levels lowand counteract the global “green-house” effect.

Forests also moderate stream-flow. Trees slow the onslaught oftropical downpours, use and storevast quantities of water, and helphold the soil in place. When treesare cleared, rainfall runs off morequickly, contributing to floods anderosion.

Before the dawn of agricultureapproximately 10,000 years ago,forests and open woodland coveredabout 15.3 billion acres (6.2 billionha) of the globe. Over the centuries,however, about one-third of thesenatural forests has been destroyed.According to a 1982 study by FAO,about 27.9 million acres (11.3 mil-lion ha) of tropical forests are cuteach year-an area about the sizeof the States of Ohio or Virginia.Between 1985 and 1990, an esti-mated 210 million acres (85 millionha) of tropical forests were cut orcleared. In India, Malaysia, and thePhilippines, the best commercialforests are gone, and cutting is in-creasing in South America. If defor-estation is not stopped soon, theworld will lose most of its tropicalforests in the next several decades.

Reasons for Deforestation

Several factors are responsible fordeforestation in the Tropics: clear-ing for agriculture, fuelwood cutting,and harvesting of wood products. Byfar the most important of these isclearing for agriculture. In the Trop-ics, the age-old practice of shifting,sometimes called “slash-and-burn,”agriculture has been used for cen-turies. In this primitive system, lo-cal people cut a small patch of forestto make way for subsistence farm-ing. After a few years, soil fertilitydeclines and people move on, usu-ally to cut another patch of treesand begin another garden.

In the abandoned garden plot, thedegraded soil at first supports onlyweeds and shrubby trees. Later, soilfertility and trees return, but thatmay take decades. As populationpressure increases, the fallow (rest)period between cycles of gardeningis shortened, agricultural yields de-crease, and the forest region is fin-ther degraded to small trees, brush,or eroded savama.

Conversion to sedentary agricul-ture is an even greater threat totropical forests. Vast areas that oncesupported tropical forests are nowpermanently occupied by subsis-tence farmers and ranchers and bycommercial farmers who producesugar, cocoa, palm oil, and otherproducts.

In many tropical countries thereis a critical shortage of firewood. Formillions of rural poor, survival de-pends on finding enough wood tocook the evening meal. Every yearmore of the forest is destroyed, andthe distance from home to the for-est increases. Not only do peoplesuffer by having to spend much oftheir 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 forestswhere firewood cutting converts for-ests to savannas and grasslands.

The global demand for tropicalhardwoods, an $&billion-a-year in-dustry, also contributes to forestloss. Tropical forests are usuallyselectively logged rather thanclearcut. Selective logging leavesthe forest cover intact but usuallyreduces its commercial value be-cause the biggest and best trees areremoved. Selective logging alsodamages remaining trees and soil,increases the likelihood of fire, anddegrades the habitat for wildlifespecies that require large, oldtrees-the ones usually cut. In ad-dition, logging roads open up theforests to shifting cultivation andpermanent settlement.

In the past, logging was done pri-marily by primitive means-treeswere cut with axes and logs weremoved with animals such as oxen.Today the use of modern machin-ery-chain saws, tractors, and trucks-makes logging easier, faster, andpotentially more destructive.

Endangered Wildlife

Forests are biological communi-ties-complex associations of treeswith other plants and animals thathave evolved together over millionsof years. Because of the worldwideloss of tropical forests, thousands ofspecies of birds and animals arethreatened with extinction. The listincludes many unique and fascinat-ing animals, among them the oran-gutan, mountain gorilla, manatee,jaguar, and Puerto Rican parrot.Although diverse and widely sepa-rated around the globe, these spe-cies have one important thing incommon. They, along with manyother endangered species, rely ontropical forests for all or part of theirhabitat.

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Figure 9.-The rare and endangered Puerto Rican parrot (Amazona vittata) is foundtoday in small wild and captive flocks in the Luquillo Experimental Forest.

Orangutans (Pongo pygmaeus)are totally dependent on small andisolated patches of tropical forestsremaining in Borneo and Sumatra,Indonesia. Orangutans spend mostof their time in the forest canopywhere they feed on leaves, figs andother fruit, bark, nuts, and insects.Large trees of the old-growth forestssupport woody vines that serve asaerial ladders, enabling the animalsto move about, build their nests, andforage for food. When the old forestsare cut, orangutans disappear.

The largest of all primates, thegorilla, is one of man’s closest rela-tives in the animal kingdom. Toolarge and clumsy to move about inthe forest canopy, the gorilla liveson the forest floor where it foragesfor a variety of plant materials. Lossof tropical forests in central andwest Africa is a major reason for thedecreasing numbers of mountaingorillas (Gorillagorilla). Some habi-tat has been secured, but the futureof this gentle giant is in grave dan-ger as a result of habitat loss andpoaching.

The jaguar (Leo onca), a residentof the Southwestern United Statesand Central and South America, isclosely associated with forests. Itsendangered status is the result ofhunting and habitat loss.

The Puerto Rican parrot (Ama-zona vittata), a medium-sized, greenbird with blue wing feathers, onceinhabited the entire island of PuertoRico and the neighboring islands ofMona and Culebra. Forest destruc-tion is the principal reason for thedecline of this species. Hunting alsocontributed. Today, only a fewPuerto Rican parrots remain in thewild and their survival may dependon the success of a captive breedingprogram (fig. 9).

In addition to species that residein tropical forests year round, oth-ers depend on such forests for partof the year. Many species of migrantbirds journey 1,000 miles or morebetween their summer breedinggrounds in the north and their tropi-cal wintering grounds. These birdsare also threatened by tropical for-est destruction.

Forestry-loosely defined as thesystematic management and use offorests and their natural resourcesfor human benefit-has been prac-ticed for centuries. Most often, for-estry efforts have been initiated inresponse to indiscriminate timbercutting that denuded the land andcaused erosion, floods, or a short-age of wood products.

Ancient Forestry Practices

In ancient Persia (now Iran), for-est protection and nature conserva-tion laws were in effect as early as1,700 B.C. Two thousand years agothe Chinese practiced what theycalled “four sides” forestry-treeswere planted on house side, villageside, road side, and water side. Morethan 1,000 years ago, Javanese ma-harajahs brought in teak and beganto cultivate it. In the African Trop-ics, agroforestry (growing of foodcrops in association with trees) hasbeen practiced for hundreds ofyears.

In the Yucatan Peninsula ofsouthern Mexico, the ancient Mayascultivated fruit and nut trees alongwith such staples as corn, beans,and squash. Bark, fibers, and resinwere obtained from plants grown infields, kitchen gardens, and or-chards. Early in their civilization,the Mayas practiced slash-and-burnagriculture. As their populationgrew, they found more efficientmethods of growing crops. They ter-raced hillsides, learned how to de-crease the time between “rotations”of agricultural land with native for-ests, dug drainage channels andcanals to move water to and fromcultivated areas, and filled inswampland to plant crops.

The agricultural sophistication ofthe Mayas enabled their civilizationto grow and flourish. What broughtabout their decline about A.D. 820is not fully known, but some believethat as their society developed,the Mayas made unsustainable de-mands on their environment.

Relatively little is known abouttropical forestry before the mid-1800’s in most places. At that time,the European colonial empires-notably the Dutch, English, andSpanish-brought modern forestmanagement practices to Indonesia,India, Africa, and the Caribbean.Centers for forestry and forestryresearch were established, andmore careful records were kept.

Sustainable Forestry

Modern forestry has its basis inl&h-century Germany. Like theChinese and the Mayan forest prac-tices, German forestry is essentiallyagricultural. Trees are managed asa crop. Two concepts are important:renewability and sustainability.Renewability means that trees canbe replanted and seeded and har-vested over and over again on thesame tract of land in what areknown as crop “rotations.” Sus-tainability means that forest har-vest can be sustained over the longterm. How far into the future wereforesters expected to plan? As longas there were vast acres of virgin(original) forests remaining, thisquestion was somewhat academic.Today, however, sustainability is avital issue in forestry. Most of theworld’s virgin forests are gone, andpeople must rely more and more onsecond- growth or managed forests.Perhaps we now face, as never before,the limits to long-term productivity.

In the German forest model, for-estry is viewed as a continual pro-cess of harvest and regeneration.Harvest of wood products is a goal,

but a forester’s principal tasks areto assure long-term productivity.That is achieved by cutting theolder, mature, and slow-growingtimber to make way for a new cropof young, fast-growing trees.

Harvest-RegenerationMethods

Three examples of timber har-vest-regeneration methods (silvicul-tural systems) illustrate howforesters manage stands to producetimber on a sustained basis.

Selection

Individual trees or small groupsof trees are harvested as they be-come mature. Numerous smallopenings in the forest are createdin which saplings or new seedlingscan grow. The resulting forest hasa continuous forest canopy andtrees of all ages. Such systems fa-vor slow-growing species that areshade tolerant.

Clearcutting

In clearcutting, an entire stand oftrees is removed in one operation.From the forester’s point of view,clearcutting is the easiest way tomanage a forest-and the most eco-nomical. Regeneration may comefrom sprouts on stumps, from seed-lings that survive the logging opera-tion, or from seeds that germinateafter the harvest. If natural regen-eration is delayed longer than de-sired, the area is planted or seeded.

Clearcutting systems are oftenused to manage fast-growing spe-cies that require a lot of light. Result-ing stands are even aged because allthe trees in an area are cut-and re-generated-at the same time. Clear-cutting has become controversial in

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recent years because it has the po-tential to damage watersheds andbecause it tends to eliminate spe-cies of wildlife dependent on old-growth trees. If clear-cuts are keptsmall and the cutting interval islong enough, however, biologicaldiversity may not be impaired.

Shelterwood

In shelterwood systems, the for-est canopy is removed over a periodof years, usually in two cuttings.After the first harvest, natural re-generation begins in the understory.By the time the second harvest ismade, enough young trees havegrown to assure adequate regenera-tion. Shelterwood systems favorspecies that are intermediate in tol-erance to shade. Such systems aredifficult to use successfully and arethe least used of the three silvicul-tural methods described.

Multiple-Use Forestry

Gifford Pinchot, the first Chief ofthe U.S. Forest Service, was alsothis country’s first professional for-ester. Pinchot advocated the use offorest resources-all resources, notjust timber-for human benefit.Pinchot was a strong and charis-matic leader, and his ideas helpedshape the course of forestry in theUnited States.

Pinchot had a vocal opponent inJohn Muir, a young naturalist fromCalifornia who believed that publiclands should be preserved ratherthan used. Eventually Muir andPinchot became rivals for public ap-proval. Oddly enough, there was no

loser in this early conservationbattle. Muir’s preservation ethic be-came embodied in the philosophy ofthe National Parks, and Pinchot’sconcept of wise use became the guid-ing principle of the National Forests.

National Forests are still man-aged under the concepts of multipleuse and sustained yield. The domi-nant uses of National Forests areconsidered to be wood, water, wild-life, forage (for domestic cattle andwildlife), and recreation. Extractionof minerals and other valuable prod-ucts is also considered a legitimateuse of National Forests. BecausePinchot’s philosophy left room forthe “highest and best use” of a givenarea, the U.S. National Forests nowinclude a wilderness system of morethan 32 million acres (13 million ha)in which timber harvest is not al-lowed.

Today it is generally recognizedthat most, if not all, nondestructiveuses of forest are valid. Some areasmay be set aside as parks; othersfor wildlife habitat or as wilderness.Still others will be managed for tim-ber harvest or multiple benefits.Today, conflicts arise primarily overwhere these different uses will bedominant. In the National Forests,such decisions are made through aland-use planning process in whichthe public has ample opportunitiesfor input and involvement.

At the turn of the century, verylittle was known about the worldsnative forests or how to managethem. In the United States, forest-ers were quick to recognize thevalue of information about forestsand a branch of research was estab-lished in the Forest Service in 1915.Early research was done primarilyin support of reforestation efforts,but, as forestry grew in size andcomplexity, so did the research.

Today, the USDA Forest Servicehas six regional experiment stationslocated in important forest regions.Each experiment station has sev-eral field laboratories generallywith specialized assignments for ageographic region or a specific sub-ject area, and numerous sites forfield research. In addition, the For-est Products ILaboratory in Madi-son, WI, serves as a nationwidecenter for research and develop-ment of new technology relating towood, including tropical woods. Twolaboratories are dedicated exclu-sively to tropical forest research: theInternational Institute of TropicalForestry in Puerto Rico and the In-stitute of Pacific Islands Forestry inHawaii.

Research is vital for modern for-est management, which is informa-tion intensive. Today’s forestersrequire vast quantities of data anda knowledge of ecology: they mustunderstand not only the parts ofecosystems but how different partsof the environment interact. Scien-tific investigations are conducted insupport of all kinds of forestry ac-tivities: silviculture, forest insectand disease control, wildlife habi-tat management, fire preventionand control, range and watershedmanagement, forest products utili-zation, forest survey, reforestation,ecology, and economics.

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In the past, timber harvest in theTropics has seldom been followed byregeneration. Conversion to agricul-ture is often permanent or resultsin soil erosion. Timber harvest con-tracts have usually been short termand have provided little or no incen-tive for timber companies to re-plant. So little reforestation hasbeen done in the Tropics that manypeople believe these forests cannotbe restored. However, there aremany examples of successful refor-estation in India, Indonesia, and theCaribbean.

In the Tropics, as elsewhere, for-estry is a mixture of modern inno-vations and ancient techniquesborrowed from local tradition. Plan-tation forestry is common. Forestreserves have been established fortimber harvest, wildlife habitat,scenery, outdoor recreation, or wa-tershed protection. And in the Trop-ics, agroforestry-tree growingcombined with agricultural crop-ping-is much more common thanelsewhere.

Figure lO.-Forest scientists are working to determine which trees will grow wellin plantations and how best to manage them.

Plantation Forestry

In the Tropics, trees are oftenplanted and grown in plantationsfor wood production. Often, manyspecies must be tried to determinewhich will grow best (fig. 10). Plan-tations must also be supported bymajor investments in forest man-agement and research. Forest nurs-eries must be established, andplanting techniques and culturalpractices (spacing and thinning,

pruning, fertilization, insect anddisease control, and genetic im-provement) must be developed.

Extensive pine plantations, havebeen established in the moist Trop-ics, mainly in South Africa and Aus-tralia. Species most often plantedinclude Caribbean pine (Pinuscaribaea), ocote pine (I! oocarpa),slash pine (l? elliottii), and benguetpine (P. kesiya). Pines are popularplantation trees because they aregenerally fast growing, have goodsurvival rates, and are adapted toa wide variety of environments, in-cluding degraded forest sites.

Eucalypts, including species suchas Euealyptusgrandis, E. deglupta,E. tereticornis, E. globulus, and E.camaldulensis are favored for thesame reasons. Eucalypts are com-monly grown for pulp, fuel, and lum-ber. Other species commonly plantedinclude teak (Tectona grandis), Hon-duras mahogany (Swietenia macro-phylla), melina (Gmelina arboreal,beefwood (Casuarina equisetifolia),and Mexican cypress (Cupressuslusitanica).

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Forest Reserves

There are many reasons for estab-lishing forest reserves in the Trop-ics. They can restore watershedsand wildlife habitat, improve scenicbeauty and opportunities for out-door recreation, and produce woodand other products for local use andexport. Many forest products con-tribute to the sustenance and in-come of local people: wildlife andfish, firewood, rubber, fruits andnuts, rattan, medicinal herbs, flo-ral greenery, and charcoal.

Perhaps the most famous of thesereserves is the 5,600 square mile(14,500 k2) Serengeti National Parkin Tanzania. With its vast herds ofgrazing ungulates (hoofed animals)and predators, including several en-dangered species, the Serengeti isa showcase of a savanna ecosystemthat has long been protected andmanaged for wildlife and othernatural resources (fig. 11). Althoughplagued with poachers, the Serengetipromotes the cause of wildlife conser-vation to the many thousands of“ecotourists” who pay to experiencenature each year.

Another type of forest reserve isthe “extractive” reserve, which isdedicated to the production of use-ful products. Large reserves of thistype have been established recentlyin Brazil. Local residents use themfor tapping rubber, for gatheringfruits and nuts, for hunting, and forharvesting wood on a sustained-yield basis. Such uses provide a sus-tainable income while maintainingthe ecological integrity of the forest.

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Figure ll.-Giraffes (Giraffe cameloparadalis) are dependent on Acacia spp. and othersavanna trees and shrubs for sustenance. (photo by Ariel Lugo).

Agroforestry

The practice growing of trees incombination with agricultural cropsis fairly common in the Tropics. Itis possible to grow food crops yeararound in many forested areas, andrural poor depend on this source offood as nowhere else on Earth.

Taungya System

Various systems have been devel-oped for combining forestry withagriculture. “Taungya” is a Bur-mese word meaning cultivated hillplot. This system of agroforestrywas developed in Europe during theMiddle Ages and probably indepen-

dently in a number of places in theTropics. After existing forest orground cover is removed by burning,trees are planted along with agricul-tural crops. Both are cultivated untilthe tree canopy closes. Then the areais left to grow trees, and another siteis located for combined forestry-agriculture.

Shade Cropping

An overstory of trees is often usedto provide shade for agriculturalcrops. A common practice is to growtree species such as guaba (Ingauera) over coffee. In Puerto Rico,many forests developed where cof-fee was once grown in this manner.

Support Crops

Trees can be planted to providesupport (and sometimes shade) forvine crops. Vines such as pepperand vanilla need support.

Alley Cropping

Nitrogen-fixing trees are plantedin hedges in widely-space parallelrows along the contour of slopes.Food crops are grown in the “alley”between the rows. The trees addnitrogen and organic matter, protectthe soil from erosion, and providewood and animal forage.

Living Fences

Green fenceposts that will rootand sprout often are planted in aclosely spaced row. When theysprout, they create a “living fence”that provides shade and forage forcattle.

Windbreaks

Trees are often planted as wind-breaks for agricultural crops, farms,or homesites. Such plantings caneventually contribute wood prod-ucts as well as shelter. Food treessuch as citrus, rubber, and mangocan also provide fuel, lumber, andother wood products when they haveoutlived their original usefulness.

The conservation issues of thepast seem simple compared withthose of today. As we move towardthe 21st century, human societiesare concerned with global warming,deforestation, species extinction,and rising expectations. Growingpopulations must be fed, clothed,and sheltered, and people every-where want higher standards ofliving.

Global Warming

Warming of the earth’s atmo-sphere is a major environmentalissue. Air pollution, deforestation,and widespread burning of coal, oil,and natural gas have increased at-mospheric concentrations of carbondioxide, methane, nitrous oxide,and chlorofluorocarbons. Thesegases trap heat from the sun andprevent it from radiating harm-lessly back into space. Thus, the“greenhouse” or warming effect iscreated.

Because of natural variations inclimate, it is difficult to measurewarming over large areas. Scien-tists agree, however, that increasesin atmospheric concentrations ofgreenhouse gases will cause highertemperatures worldwide. Even anincrease of a few degrees mightcause serious melting of the polaricecaps, a gradual rise in sea level,a disruption in normal weather pat-terns, a possible increase in forestfires, and the extinction of species.

Role of Forests

Trees, the largest of all landplants, act as a kind of environmen-tal “buffer” for the ecosystem theydominate. They help ameliorate the

extremes of climate (heat, cold, andwind) and create an environmentwhere large land mammals, includ-ing people, can live comfortably,

Trees complement animals in theglobal environment. Mammals takein oxygen from the air and exhalecarbon dioxide. Plants use the car-bon dioxide in their growth pro-cesses, store the carbon in woodytissues, and return oxygen to theatmosphere as a waste product.This process, known as photosyn-thesis, is essential to life. Carboncaptured from the atmosphere byphotosynthesis is eventually re-cycled through the environment ina process known as the carbon cycle.Trees have an especially importantrole in the carbon cycle.

Tree leaves also act as filters toremove atmospheric pollutantsfrom the air. This effect is particu-larly beneficial in urban areas.

Forestry Issues

Two key issues will dominate for-estry in the years ahead: (1) main-taining long-term productivity ofmanaged forests, and (2) prevent-ing further loss of tropical forests.Both problems will require new ap-proaches to forest management.

Traditionally, forestry has focusedon growing crops of wood in planta-tions or in managed natural stands.In this “agricultural mode,” otherbenefits of forest such as watershedprotection, wildlife habitat, climatemoderation, and outdoor recreation,have received less attention thanwood production.

Perhaps more importantly, thesustainability of the full range offorest benefits has not been mea-

11

sured. There is no question thattrees can be grown for crops of woodin managed stands. With intensivemanagement-short rotations, spe-cies selection, genetic improvement,fertilization, thinning, and othercultural treatments-more woodcan be produced in less time thanin natural forests. But for how long?And at what cost in other benefits?

As more and more of the world’soriginal forests have been cut, theecological value of forests has cometo be more appreciated. In recentyears, increased emphasis has beenput on what some are calling “eco-system management.” In thismodel, the health and long-termstability of the forest are para-mount, and timber production isconsidered a byproduct of good for-est management rather than theprincipal product. In Puerto Rico,for example, wood production is arelatively minor aspect of forestry.

Since the 1930’s when timber har-vests were curtailed, the forestshave been managed primarily forwatershed protection, wildlife habi-tat, and outdoor recreation.

There are no easy solutions to theproblem of tropical forest destruc-tion, but most experts agree that theproblems cannot be solved simplyby locking up the forests in reserves.The forests are too important to lo-cal people for that to be a workable

solution. There is no doubt thattropical forests will be cut. It is bet-ter for them to be cut in an ecologi-cally sound manner than to becleared for poor-quality farmland orwasted by poor harvest practices(fig. 12).

The only real long-term solutionsare: (1) more efficient agriculture onsuitable farmland, (2) efficient for-estry practice including plantations,and (3) reserves to protect speciesand ecosystems. Many forestry ex-perts believe that we have only be-gun to tap the potential for wise useof tropical forests. Many uses haveyet to be fully explored. We are onlystarting to learn the value of tropi-cal forests for medicines, house andgarden plants, food and fiber, tour-ism, and natural resource education.

Figure 12.-Vast areas of tropical forests havebeen and are still being convertedto marginally productive farm-land to feed agrowingpopulation.

From Mt. Britton Tower at an el-

14

Rico is forested. outdoor recreation, watershed pro-Early Conservation Efforts 35 percent of PuertoThese 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 andRico eventually led to conservation other forest products.efforts. The sale of wood was re-

Outdoor R ‘ *,ecreaClon

stricted by the Spanish in 1816, pri-marily because some species were

A Forest of Many Names In the for--L A.%-..-- -- ̂-

considered necessary for naval useportunities

Luquillo Forest -I-’ -- ‘---= m, 1during the colonial wars for indepen-dence. In 1824, alarmed by the ex-

that was par+ ,c+L*

tent of deforestation, Governorreserves set

Miguel De la Torre issued a decree toin 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 comprehensiveIt includes t

forest laws in 1839 and set up for-disturbed f

estry commissions that led to theUnique in th

first forest inventory on the islandest is the old

in 1843.National Fl

In the next several decades, gov-been under

ernment protection of the forestsmerit c. .

decreased, but enough interest inconservation remained for King

UFDT;ii,* *m- __^^ A. ci...-2.

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

contains lana ‘lne coolness of the mountains(, oI bile original forest draws people from the urban cen-aside by the Spanish ters of San Juan and other towns

--- -“-- %t 12,400 acres in the warm and humid coastal low-lllu zGsudrve now covers lands. Access is excellent. From San3,000 acres (11,300 ha). Juan, the Caribbean National For-he largest block of un- est is less than an hour’s drive on‘orest on the island. paved roads. Three highways tra-e Tropics, Luquillo For- verse the Forest: one on the north-est forest reserve in the eastern boundary, another along thenest System and has western edge, and still anothersome form of manage- through the interior that provides

; ror more than 100 years. access to El Yunque Recreation AreaA *n”A+ve is managed by the with its many foot trails and picnic

tment of Agriculture, shelters. For visitors, the first con-

Alfonso XII to create the first forestc W-~SL nervlce, and has two primary tact with the Forest Service is of-

reserves in 1876. Their purposesfunctions-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 visi-

vent soil erosion, and to assure anqulllo Experimental Forest and tors center “El Portal de1 Yunque”f-i--.‘l..L--- *

adequate supply of wood for roofingC/~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 natural-

Because of those early set-asidesover the years, names that reflect a ists are stationed at several points in

and later purchases, Puerto Ricolong 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 arepeak in the vicinity, the name wasnh‘BnmnA

brrarrgGL& 111. L

administered by the Department of;n 1903 to Luquillo Forest

Reserve andI again in 1935 to Car- Watershed ProtectionNatural Resources, an agency of theCommonwealth 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 Foresttered around the island and preserve and provide water and hydroelectricrepresentative samples of several

the Luquillo Exnerir---r ----nental Forest inrecognition 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; LW---- LL - forest is simply unregulated timber cutting contrib-plantations of pine, mahogany, and uted to flooding and erosion, butteak.

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 fewplantations 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 thehave been established, but most for-ests 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 A *__*I. -van within the for- sediment.

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

15

Wildlife Habitat

The entire forest is also a wildliferefuge. It has 68 species of nativebirds, many migratory birds, andnumerous reptiles and amphibians.At night, the rain forest resoundswith a loud chorus that may include16 different species of frogs-thebeloved coquis of Puerto Rico (fig.14). The only native mammals arebats. However, mongooses, rats, anddomestic cats have been introducedand now run wild.

Figure 14.-The tiny Puerto Rican coqui frog(Eleutherodactylus spp.) courts

with a musical and surprisinglyloud “koki-koki” song.

Baiio de Oro Natural Area

Three-fourths of all the virgin(primary) forests that remain inPuerto Rico are located in the ex-perimental forest. To protect thisunique and valuable resource, some2,100 acres (850 ha) have been setaside as the Baiio de Oro NaturalArea. Timber harvest is not allowedin this area, and no roads or trailsmay be built.

Important Trees which splits off in thin plates orscales. Large, old palo Colorado trees

Although timber is considered to are important nest trees for thebe an important use of the forest, Puerto Rican parrot. Many of thesevery little has been cut in recent trees support complete communitiesyears. In fact, the Forest Reserve of other plants: vines, mosses,was created in response to defores- herbs, ferns, liverwarts, and eventation, 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 inplanted to trees. In the future, these “El Yunque.” These forest giants of-plantations will be an important ten reach a height of 100 feet (30and sustainable source of timber for m) and a diameter of 40 inches (1local use. m). The smooth, pale bark often

Luquillo Forest has 225 different exudes a white resin useful forspecies of trees and a highly diverse starting fires and for incense. Theplant community typical of tropical wood of tabonuco was formerly usedrain forests around the world. Some to make furniture and boxes, butof the most important or interest- today it is rarely cut.ing native trees are listed here: * Sierra palm (Prestoea mon-

l Ausubo (Munilkaru bidentata) tuna) is a striking feature of the

is a large, slow-growing tree with a Luquillo Experimental Forest. Al-

dense 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 sur-

rot, 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 urboreuand C. uquilinu) are among themost beautiful and fascinatingplants of tropical forests. Thesesmall, evergreen trees have slendertrunks and feathery, lacy leavescalled fronds. The Carib Indiansused the hollow stems to carry andpreserve fire. Now these stems arecut for use as planters for orchidsand bromeliads or for potting ma-terial. Fern trees are also used inhome and commercial gardens. Un-fortunately, most of the fern treesharvested are stolen from alongroads.

l Palo colorado (Cyrilla ruce-mifloru) is a very large tree thatmay live to be 1,000 years old. Itsname comes from its reddish bark,

16

International Institute of the national forest. Subsequently, a Plans and programsTropical Forestry monitoring and research program developed to improve al

was begun, and the parrot was the benefits from this vahEstablishment of a forestry re- given protection under the Endan- Efforts include: (1) refining the en-

search station in Puerto Rico was gered Species Act. Over the years, viromnental education presentation

are beingnd extendIable area.

authorized by Congress in 1927, but the captive flock has continued to at “El Portal de1 Yunque” visitor’sit was not until 1939 that the Tropi- increase, giving hope that the wild center, (2) improve recreational op-cal Forest Experiment Station, now population can eventually be rees- portunities in other parts of the for-called the International Institute of tablished. est, (3) acquire small pieces ofTropical Forestry, was created. Lo- Over the years, the International property around the periphery ofcated on the grounds of the Agricul- Institute of Tropical Forestry has the forest that suffer from heavyture Experiment Station at the enjoyed a growing reputation in for- recreational impact, (4) develop aUniversity of Puerto Rico in Rio estry extension and education. A small-scale logging demonstrationPiedras, the institute has become a technical journal, “The Caribbean using the most environmental-focal point for forestry research and Forester,” was published between friendly techniques available to pro-education in tropical America. The 1939 and 1963. Thousands of people vide wood to local artisans, (5) assistdesignation as the Luqnillo Experi- have participated in training state and nongovernment agenciesmental Forest in 1956 reflected the courses and technical meetings, and with land management problemsgrowing 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 re-

Together, the International Insti- tion in the world. In 1989, the covery of endangered species oftute 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 pro-pioneered 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 thetropical America. Between 1931 and learning more about the native flora research program. In the past 501956, the amount of land in the and fauna and how they react to years, many advances have beenLuquillo Forest was increased and natural and human-caused distur- made, particula&y in plantation for-consolidated from surrounding bances. estry. Foresters now have extensivefarmlands, and trespass was essen- Recreation facilities have been knowledge about how to reforesttially eliminated. By 1975, 10,000 developed, including trails, picnic tropical sites. In the future, moreacres (4,000 ha) of land had been sites, visitor centers, and scenic emphasis will be placed on learn-replanted. Today, plantation forests overlooks. More than half a million ing how tropical forests fimction-look so much like the native forests visitors a year now enjoy the Carib- how plants and animals interact inthat few people can tell them apart, bean National Forest. complex ecosystems and in globaland they have many of the same ecology Such information will helpbenefits. In 1934, as an aid to refor- ~~~ Directions to restore damaged forests, plan for-estation 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 glo-species trials were begun. Growth a small fraction of the original for- bal effects of air and water pollu-records 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 Caribbeanyears. will always be an important part of

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

the first to report decrease in thewhere. But this forest is very spe-

Puerto Rican parrot population incial. Since the 1930’s, work done

also being initiated elsewhere in

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

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

result is a living treasure-an ex-rehabilitation and management,

ample of how tropical forests can bethe causes of species loss, and im-

protected and managed for humanprovement of access to technical

benefit.information.

1 7

HIGHLIGHTS IN THEHISTORY OF THX LUQUILLO

EXPERIME3PiXL FOREST

1839-First Spanish forest conser-vation law for Puerto Rico.

1876-The Spanish Crown pro-claims El Yunque and otherareas in Puerto Rico as for-est reserves.

1903-President Roosevelt desig-nates the Luquillo ForestReserve (now called the Car-ibbean National Forest).

1905-The Bureau of Forestry, U.S.Department of Agriculture,publishes the first detailedreport about the forest andits resources.

1931-The first forest plantations(mahogany) are established.

1933-The Emergency Conserva-tion Program began. Withthe Civilian ConservationCorps (1937), extensive workis accomplished in reforesta-tion, road construction, andother improvements.

1935-Name changed to the Carib-bean National Forest.

1937-First timber inventory com-pleted.

1939-Tropical Forest ExperimentStation (now the Interna-tional Institute of TropicalForestry) established.

1946-Forest designated as a wild-life refuge.

1956-Entire forest designated asthe Luquillo ExperimentalForest in recognition of thegrowing importance of re-search.

1968-Conservation efforts beganfor the Puerto Rican parrot.

1976-The Luquillo ExperimentalForest is designated as aBiosphere Reserve.

1988-Experiment Station receivesa grant from the NationalScience Foundation for long-term ecological research.

1 8

SUGGESTED REXDING

Birdsey, Richard A.; Weaver, Peter Wadsworth, Frmk H. 1981. Man-L. 1982. The forest resources of agement of forest lands in thePuerto Rico. Resour. Bull. SO-85 himi d Tonics under sound eco-New Orleans, LA U.S. Depart- es. In: Mergen,ment of Agriculture, Forest Ser-

logical princinlFrancois, ed. Tropical forests: uti-

vice, Southern f i’orest Experiment lization and conservation. NewStation. 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 inatlas. Emmaus, PA: Rodale Press. several tropical forests of Puerto

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

Ecological life zones of Puerto

Rico. Res. Pap. 1leans, LA: U.S. Department ofA&eultu

Rico and the U.S. Virgin Islands.--D---.~-. -Lre, Forest Service,Southern Forest Experiment Sta-

Res. Pap. ITF-18. Rio Piedras, tion. 15 p.PR U.S. Department of Agricul- Weaver, P.L. 1986. Hurricane dam-ture, Forest Service, Institute of age and recovery in the montaneTropical Forestry. 79 p. forests of the Luquillo Mountains

Little, E.L., Jr.; Woodbury, R.O.; of Puerto Rico. Caribbean Jour-Wadsworth, F.H. 1974. Common nal of Science. 5trees of Puerto Rico and the Vir- Whitemore. Jackgin Islands. Agric. Handb. 449.Washington, DC: U.S. Depart-ment of Agriculture. 1024 p.

Lugo, A.E. 1585.1ILn introduction tothe forests of Puerto Rico. Rio

!2( l-2): 53-70.; L.; Hartshorn,

G.S. 1969. Literature review ofcommon tropical trees. Trop. For.Series Contrib. 8. Seattle, WA:Institute of Forest Products, Col-lege of Forest Resources, Univer-

shington. 113 p.Piedras, PR: U.S. Department ofAgriculture, Forest Service,

sity of Wa

Southern Forest Experiment Sta-tion. 20 p.

Snyder, N.F.; Wiley, J.W.; Kepler, Note:C.B. 1987. The parrots of Lu- Publications may be reviewed in thequillo: natural history and conser- library at the International Insti-vation of the Puerto Rican parrot. tute of Tropical Forestry, RioLos Angeles: Western Foundation Piedras, PR, or are available on loanof Vertebrate Zoology. 384 p. from some public libraries.

The Forest Service, United States Department ofAgriculture (USDA), is dedicated to the principle ofmultiple use management of the Nation’s forest

resources for sustained yields of wood, water, forage, wildlife, andrecreation. Through forestry research, cooperation with the Statesand private forest owners, and management of the National Forestsand National Grasslands, it strives-as directed by Congress-toprovide increasingly greater service to a growing Nation.

The USDA prohibits discrimination in its programs on the basis ofrace, color, national origin, sex, religion, age, disability, politicalbeliefs, and marital or familial status. (Not all prohibited basesapply to all programs.) Persons with disabilities who requirealternative means for communication of program information(braille, large print, audiotape, etc.) should contact the USDA’sTARGET 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 equalemployment opportunity employer.

Mastrantononio, J. Louise; Francis, John K. 1997. A student guide to tropi-cal 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, rang-ing from rain forests to savannas. Tropical forests are disappearing atan alarming rate as they are converted to farmland and other uses.Modern forest management practices can help stem the tide by provid-ing income and valuable products while maintaining forest cover. PuertoRico has already gone through deforestation and partial reforestation.The Luquillo Experimental Forest is an interesting example of a pro-tected and managed tropical forest.

Keywords: Deforestation, forest management, Luquillo Experimen-tal Forest, tropical forest.