Chapter 4 Causes of Deforestation and Forest Resource

Chapter 4

Causes of Deforestation andForest Resource Degradation

PageHighlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Historical Context . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Soil: Its Relationship to Deforestation and Land Degradation . . . . . . . . . . . . . . . . . . 87Visible Agents of Forest Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Subsistence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Shifting Cultivators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Livestock Raisers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90Fuelwood Gatherers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91Fires, , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93Warfare, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

Commercial Resource Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95Commercial Agriculturalists and Cattle Ranchers . . . . . . . . . . . . . . . . . . . . . 95Loggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Underlying Causes of Forest Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98Property Rights and Control of Forest Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . 98Transformation of Forestry Administrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Chapter 4 References. . .

Table

Table No.7. The Main Soil Constra

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

Pagents in the Amazon Basin Under Native Vegetation 88

Chapter 4

Causes of Deforestation andForest Resource Degradation

HIGLIGHTS• Tropical deforestation and forest resource

degradation are caused by subsistenceagriculturalists, livestock raisers, firewoodcollectors, and loggers.

● The agents of tropical forest loss vary inprominence among the three major tropicalforest regions (American, Africa, and Asia),Many times, the combination of these activ-ities exacerbates forest resource problems.

In many tropical areas, political, ecocomic,and social forces lead to overexploitationand underinvestment in management oftropical forest resources.

Regardless of what activities are responsi-ble-for forest removal from tropical lands,the soil plays a large role in determiningwhether agriculture, new forest growth, orbarren wastelands will replace the forest inthe long run.

HISTORICAL CONTEXT

Deforestation of tropical lands is not solelya recent phenomenon, In fact, the main lossof forests in some places occurred in the 19thcentury, when forests were cleared to estab-lish plantations of export crops such as sugar,abaca, coffee, indigo, and tobacco (36).

Sugar plantations swept away the Caribbeanforests in turn: first Barbados, then the Lee-ward Islands, Jamaica, and Haiti. The slave re-bellion in Haiti left the country in ruins andmade possible the sugar boom in Cuba.

Cuba’s story is typical and better docu-mented than that of other parts of the Carib-bean (7). Upon reaching the northeast coast ofCuba in 1492, Christopher Columbus was im-pressed by the island’s rich forests. A few yearslater, priest Fray Bartolome wrote that it waspossible to walk from one end of the island tothe other without leaving the shade of trees.In 1812, forests still covered 89 percent ofCuba. But thereafter, fields of sugar cane began

to replace the forests. Fire and axe were usedto clear forests for ranching as well. Forestcover had shrunk to 53 percent by 1900. withthe declaration of the Republic in 1902, and thesubsequent heavy influx of foreign capital intothe Cuban economy, forests continued to shrink,Small farms were swallowed up by large plan-tations. The farmers were driven to eke out aliving in the hills where their struggle for sur-vival, together with the insatiable fuel demandsof the sugar mills, took a heavy toll on the up-land forests. By 1946, forest cover was downto 11 percent of the land area. The averageyearly deforestation had been 1.7 percent of theforest area that existed in 1900.

The history of Brazil, which was the world’slargest sugar producer until the middle of the17th century, illustrates the severe damage thatdeforestation can inflict. The northeastern re-gion of the country is notorious for its pover-ty. The densely populated coastal region re-ceives substantial rainfall and when the area

85

86 • Technologies to Sustain Tropical Forest Resources

was forest-covered, its soils were described asfertile and rich in humus. But the forests werecleared for sugar plantations, which were aban-doned as the soils wore out. Now the infertile,eroded soils only support savanna. Rainfall israpidly shed as runoff so that streams and stor-ages dry up during protracted droughts. As aconsequence, the region frequently gives riseto mass emigrations (50).

Similarly, little of South China’s tropical for-ests remain except in the extreme southwestand in the interior of Hainan Island. Fire andcultivation took a heavy toll as these forestscame under increased human pressure about1,000 years ago (45). Fire was used widely toclear forests for grazing lands and croplands.Overgrazing and poor agricultural practicesfurther reduced the likelihood that forestswould ever reestablish naturally. Timber wasused to build houses, temples, and ships, andwood was cut to supply fuel for cooking andheating. Forests probably were eliminated inpart to destroy the habitat of dangerous wildanimals or to minimize the hiding places forbandits. Today’s partly grass covered, eroded,

and depopulated hills and mountains in SouthChina attest to the severity of past land-usepractices and the inability of the forest toregenerate naturally (46).

In the African Sahel, resource degradationof dry forests has for centuries been caused bya combination of processes including dry anderratic climate, brush fires, trans-Saharantrade, gum arabic trade, agricultural expan-sion, and cattle. Herodotus and others, writingaround 450 B. C., described an active trans-Saharan trade based on precious stones called“carbuncles,” gold dust, and slaves. This tradehad great adverse impacts on the land. For in-stance, large areas were cleared of Acacia rad-diana to produce charcoal. In the late 18th cen-tury, huge caravans of 4,000 camels and 1,000men would stop at the desert margin and cutwood for charcoal to cook and trade. The char-coal even was used as emergency rations forthe camels (34).

The resulting encroachment of the desertmargin encouraged a southward shift ofdrysteppe vegetation. This, in turn, altered eco-

Ch. 4—Causes of Deforestation and Forest Resource Degradation • 87

logical relationships and amplified the impactof hazards such as drought (27). Even thoughthe human populations in the Sahel had suf-fered periodic droughts for centuries, fargreater harm was caused during the 1970’swhen drought was coupled with a seriously de-graded natural resource base. This is the ex-pected response of a resource system wherethere is self-perpetuating degradation. Theproblem increases gradually for a long time,but it is typically a logarithmic progression andcan lead to catastrophe (11).

For centuries, tropical deforestation has beenassociated with poverty (17). People displacedby development processes are often the directagent of deforestation. While peasant cultiva-tors and herders have done the actual tree cut-ting and burning, the causes lie in a chain ofevents that have left these people few optionsbut to destroy the forest or starve.

SOIL: ITS RELATIONSHIP TO DEFORESTATIONAND LAND DEGRADATION

Soils, by themselves, are not a direct causeof tropical deforestation. They do, however, setthe stage in many tropical regions for the prac-tice of shifting cultivation, which causes defor-estation. When it is cleared, forest land com-monly loses its fertility, produces decliningcrop yields, and ultimately is abandoned. Ifforest soils could sustain agriculture, continualrelocation of farm fields would be less likelyto occur and fewer forests would be cut down.But few tropical forest soils can sustain pro-ductive agriculture over the long term. Thepresence of large areas of either heavilyleached soils of low fertility, thin erosion-pronesoils, or dry soils makes the establishment ofpermanent farming sites extremely difficult.Therefore, regardless of what activities are re-sponsible for cutting tropical forests, the under-lying soil materials play a large role in de-termining whether agriculture, new forestgrowth, or barren wastelands will be the long-term results.

A simple but useful way of discussing tropi-cal forest soil is to divide the forest lands intothree categories:

1. hot, wetlands;2. arid/semiarid lands; and3. mountainous lands.

Although the soils on certain deltas, youngvolcanic materials, and flood plains may be fer-tile, most soils in hot, wetlands have signifi-cant fertility problems. These soils are formedby chemical weathering of rocks. Hightemperatures and high rainfall combine to ac-celerate leaching of nutrients from the rock andsoil mineral particles. The residual mineralstend to be composed mostly of aluminum, sili-con, iron, oxygen, and water, a chemical com-position so restricted that many food or treecrops planted on such soils will have stuntedgrowth or will not survive. In some of the soils,silicon and iron concentrations are so low, andaluminum so high, that the soil may approachor reach the composition of bauxite, an alumi-num ore. *

These soils have other problems when fer-tilized with certain essential plant nutrients.Phosphorus becomes so tightly held by certainclay minerals, aluminum, iron, and manganeseoxides that plants cannot extract enough fortheir own benefit (4,13). In the Amazon Basin,

*See Van Wambeke (47) and Fripiat and Herbillon (12) for moredetailed information. These are good references on soils of thehot, wet tropics that not only contain the commonly cited infor-mation on agriculture, soil names, etc., but also provide discus-sions of mineralogical and chemical processes.

88 ● Technologies to Sustain Tropical Forest Resources

for example, 16 percent of the soils suffer thisproblem. Overall, 90 percent of the Basin’s soils(table 7) have a phosphorus deficiency (37).Some 15 percent of the Amazon Basin soils ‘have a poor ability to hold potassium and othercommon plant nutrients (low cation exchangecapacity). If such nutrients are added to the soilas fertilizer, they can be expected to be leachedaway rapidly (4,13).

In addition, an estimated 2 percent of thesesoils will harden irreversibly upon drying (47),severely limiting reestablishment of vegetation(21). In some cases, soil hardening is so com-plete that the hardened material can be crushedand used as gravel for road building (24).

Undisturbed tropical forests have an efficientnutrient recycling system. As long as the forestis undisturbed, the nutrient supply remainsstable. Soil shaded by the closed forest canopyis cool enough for the abundant organic mate-rial to decay gradually. Thus, the forest soilstypically have a substantial humus content andcan hold the nutrients released by micro-organisms until they are absorbed back into theweb of tree roots to be recycled again. Slash-and-burn agriculture takes advantage of thehumus and of the rapid release of nutrientsthat occurs when the vegetation is burned. Butas soil temperatures rise, the humus is oxidizedrapidly, and as the forest is removed, the or-ganic inputs are reduced. Soil with less humusis less able to hold nutrients, and when rainfalls the soil fertility fades. If the land is re-turned to forest fallow soon enough, a newgrowth of trees can reestablish the soil’s hu-

mus, the web of roots, and the recycling sys-tem.

In hot, dry lands physical breakdown ofrocks and soil minerals plays a larger role insoil formation. In this process, the particles be-come smaller, but the chemical composition re-mains nearly the same and leaching of soil nu-trients is low. Physical disintegration can oc-cur in a number of ways; for instance, day andnight temperature variations cause rocks andminerals to expand and contract and, in time,crack. Salts and other substances collect incracks, expanding when wet and contractingwhen dry, further breaking the grains (3).Another mechanical way particles becomesmaller is through impact of other windblowngrains. And, of course, the growth of plantroots is a powerful agent in breaking up andholding rock and soil particles.

In arid/semiarid areas, nutrients needed bymany plants commonly are in the soil but be-come available to the plants only if sufficientwater is available (6). If most of the water evap-orates from the soil surface rather than perco-lating down into the soil, dissolved solids orsalts can accumulate as crusts at or near theland surface in concentrations that few plantscan tolerate (16).

Mountainous lands, though generally coolerthan the other two categories, exist in both wetand dry climates and, thus, either chemicalor physical processes may dominate. Ratherthan percolating into the ground to form thicksoils through chemical weathering, much of the

Table 7.—The Main Soil Constraints in the Amazon Basin Under Native Vegetation

Millions of Percentage ofSoil constraint hectares Amazon Basin

Phosphorus deficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 436 90Aluminum toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315 73Low potassium reserves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 56Poor drainage and flooding hazard . . . . . . . . . . . . . . . . . . . . . 116 24High phosphorus fixation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 16Low cation exchange capacity. . . . . . . . . . . . . . . . . . . . . . . . . 64 15High erodibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 8No major limitations . . . . . . . . . . . . . . . . . . . . ., . . . . . . . . . . . 32 6Steep slopes (>30 percent) . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 6Laterite hazard if subsoil exposed . . . . . . . . . . . . . . . . . . . . . 21 4SOURCE: P. A. Sanchez, D. E, Bandy, J. H. Villachica, and J, J. Nlcholaides, “Amazon Basin Soils Management for Continuous

Crop Production,” Science 216:821-827, 1982.

Ch. 4—Causes of Deforestation and Forest Resource Degradation . 89

rainfall runs off the land surface to streams.The soils that do form are easily eroded. Con-sequently, soils in mountainous lands, in gen-eral, are likely to be rocky and thin, except per-haps on the lower slopes (6). Deforestation inmountainous regions is one of today’s mostacute and serious ecological problems (10).

The presence of organic matter is an impor-tant factor in the soil’s productivity because it:

● contributes to the development of soil ag-gregates, which enhance root developmentand reduce the energy needed to work thesoil;

● increases the air- and water-holding ca-pacity of the soil, which is necessary for

●

●

●

plant growth as well as helping to reduceerosion;releases essential nutrients as it decays;holds nutrients from fertilizer in storageuntil the plants need them; andenhances the abundance and distributionof vital biota (3 I).

Therefore, deforestation, by reducing organicmatter, lowers the potential productivity oftropical lands. Thus, when tropical land isabandoned, natural regeneration of the forestmay not occur, and replanting the forest maybe difficult.

VISIBLE AGENTS OF FOREST CHANGE

Subsistence

Shifting Cultivators

Shifting cultivation is common in the Trop-ics. The techniques are basically similar every-where: farmers fell and burn the woody vegeta-tion; then cultivate the cleared ground for 1,2, or 3 years; and then abandon the site for along period to forest or brush cover (forest fal-low). There are four reasons for shifting to newfields: decreasing soil fertility, reduced soilmoisture, pest outbreaks, or excessive weedsthat raise labor requirements. Long fallow pe-riods generally allow the land to recuperateand become productive once more.

Shifting cultivators fall into two broad classes:indigenous groups and recent occupants. In-digenous groups have long experience with thelocal environment and use farming practicesthat tend to be resource conserving. Thesefarmers traditionally have practiced shiftingcultivation using methods particular to themand woven into their family and tribal customs,and sometimes into their religion. Usually thechoice of land to be cleared is based on knowl-edge of nature and soils. The timing of variousagricultural activities is determined by specificindications of nature, such as the blossomingof wild plants, the emergence of particular in-sects, and so on.

In contrast, recent occupants generally areless knowledgeable about local environmentsand apply farming systems that are more de-structive of resources (23). These people alsocut and burn part of the forest. But unlikenative populations, they may farm the sameplot until the fertility of the soil is exhaustedor shorten the fallow period so that the vegeta-tion cannot recover. This type of cultivator isoften a “colonist” who comes to the forests forland because ownership there is ill-defined orbadly protected.

Generally, the new lands are only marginal-ly productive for agriculture. In addition, re-cent occupants bring with them dietary pref-erences and agricultural technologies that aresuited to intensive culture of the more fertilelowlands. By applying inappropriate farmingsystems on fragile soils, they often destroy theland’s productivity.

A large part* of the agricultural populationof Latin America farms on steep slopes. Pop-ulation growth often leads to increased clear-ance of forested watersheds and forces manyfarmers to migrate down the slopes, clearing

*In most of the tropical countries of Latin America, over 30percent of the agricultural population is on steep slopes, includ-ing 50 percent in Peru and Colombia, 40 percent in Ecuador,65 percent in Guatemala and Haiti, and 45 percent in Mexico(33).

25-287 0 - 84 - 7

90 • Technologies to Sustain Tropical Forest Resources

Photo credit: H. Bollinger

Forested hillsides such as this one in Guatemala arebeing cleared for agriculture throughout the Tropics

in part because of population increases andinequitable land distribution

the forests as they go, even into the inhospitablehumid lowlands of the Amazon Basin. In re-cent decades, colonization by farmers whopractice shifting cultivation has taken placethroughout tropical Latin America. Coloniza-tion was primarily spontaneous in the 1940’sand l950’s, but became more systematicallyplanned by government agencies in the 1960’sand 1970’s.

Even traditional shifting cultivation practicesare breaking down under increasing popula-tion pressures. Commercial exploitation andsubsequent colonization leave less land for tra-ditional cultivators, With limited land and in-creasing populations, fallow periods have de-

creased. These shorter cycles do not allowenough time for forests to restore adequate soilfertility. The result is even more extensive for-est clearance and a gradual decline in humanliving conditions.

It is easy to attribute recent increases in shift-ing cultivation to population pressure and inad-equate land outside the forests. But other im-portant factors are involved as well. In manyplaces, good farmable land is reserved for theprivileged and not used intensively to produceneeded food crops for domestic consumption.Governments may build highways and pro-mote colonization projects as alternatives toland reform (as has happened in Latin Ameri-ca). Some colonization projects are viewed asan effective way to occupy empty territory.This is especially true near frontiers in Braziland Mexico (28). Still, indications are thatforest clearing by peasant farmers will con-tinue to expand with or without governmentencouragement and assistance.

Livestock Raisers

Nomadic herders in open forests are analo-gous to shifting agriculturalists in wetter trop-ical forests. In arid and semiarid areas, nomad-ic herding is a major land use (43). At one time,the nomadic way of life probably did not de-grade the limited resources of dry regions sig-nificantly because there was a long fallow pe-riod before an area was reused. It is likely thatan ecological balance among man, animals,and the surrounding natural vegetation existed.This has changed, however.

Livestock symbolize wealth and provide bar-ter materials and insurance against futuredisasters (44). Cattle herds have increased inthe Sahel in response to economic conditions.For example, the French-speaking Sahel hada fivefold increase in cattle during the 25 yearspreceding the 1968 drought (14). Cattle, how-ever, are poorly adapted to Sahelian condi-tions: their conversion efficiency of plants toanimal products is poor; they require substan-tial quantities of water; and they are highlyprone to stress, Further, their feeding habitsare incompatible with the Sahelian environ-

Ch. 4—Causes of Deforestation and Forest Resource Degradation • 91

ment. Since cattle are largely grazers, notbrowsers, they must be moved very frequent-ly or they may completely eliminate perennialgrasses. The reduction of dry-season grassestriggers a number of degradation processesonce the seasonal rains begin. Raindrops strik-ing the soil surface raise mud spatters that sealthe soil surface to water infiltration. Then over-land waterflow erodes the soil.

High-yielding wells have been built duringrecent droughts to alleviate chronic livestockwater shortages. This has led to a rapid in-crease in the number and size of herds of cat-tle and small ruminants, which in turn haveovergrazed the land in the vicinity of wells.Natural vegetation has disappeared in general-ly concentric circles around the wells until thegrazing resources are so distant from the wellthat animals nearly starve before they reach

forage sites. Meanwhile, parts of the remain-ing trees in the vicinity of the wells are loppedoff for animal feed, and goats overbrowseshrubs.

These effects accelerate desertification, aprocess that spreads desert-like patches aroundvillages or waterholes as a consequence of con-tinued excessive pressure on the natural envi-ronment. Desertification is serious in tropicalAfrica, Latin America, and Asia.

Fuelwood Gathers

Cutting trees and woody vegetation to meetthe growing demand for fuelwood has accel-erated the process of deforestation and nowseriously threatens the environmental stabili-ty of large areas. Such situations prevail in Af-rica (especially in the arid and semiarid areas


south of the Sahara, in the east and southeast,and in mountainous areas); in Asia (in the Hi-malayas and the hills of South Asia); and inLatin America (mostly in the Andean Plateau,the arid and semiarid areas of the Pacific coastin South America, and in the Caribbean).

Wood provides two-thirds of all fuel used inAfrica, nearly one-third in Asia, and one-fifthin Latin America (z). Among the poor in tropi-cal countries, it is often women and childrenwho collect subsistence firewood. When possi-ble, they avoid felling whole trees. Instead theylop off small branches, twigs, and roots andpick up dead wood from the ground. Men aremore likely to collect wood for commercial saleand are more to fell whole trees.

Demand for wood fuels is concentrated intowns, cities, and densely populated farmlands,so the impacts of fuelwood cutting and gather-ing are greatest around such areas. Eventual-ly, the intense pressures around urban placescan lead not only to destruction of the forestbut also to complete removal of tree and shrubcover.

It is the commercialization of fuelwood col-lection that most threatens forests. As townsgrow, markets develop for traditionally non-commercial firewood and charcoal. The rela-tively rich in small towns and fringes of cities,create the demand, while the poor, who areoften landless, take advantage of an opportu-nity to gain income (38). However, if the mar-

Ch. 4—Causes of Deforestation and Forest Resource Degradation ● 93

kets place a price on wood above the price ofcollecting and transporting it, the trees becomevaluable. In this case someone is likely to claimownership and to take over cutting from thelandless poor (l).

Fuelwood cutting and gathering often haveadverse effects on the land. Maintaining treeand bush cover in arid and semiarid areas isimportant to prevent desertification. Wherefuelwood is available, animal dung and cropresiduals are used as fertilizers and compost,but when wood becomes too scarce, these ma-terials are diverted to become fuels. For thevery poor, wood scarcity may mean the elim-ination of cooked food, boiled water, and anessential minimum level of warmth.

Firewood gathering is not the major causeof deforestation in Latin America, but the im-pacts are great on tropical mountain vegeta-tion. Large circles around mountain settle-ments have been denuded of woody vegetation.The use of wood and charcoal for industrialfueI is particularly important in Brazil, whereit provides 40 percent of the fuel used in thesteel industry (42).

Fuelwood gathering has had detrimental ef-fects in Africa and Asia. In the sparsely popu-lated Sahel, areas surrounding population cen-ters are largely deforested. The affected areascontinue to grow each year. Until recently,fuelwood was hauled as far as 50 kilometers(km) to large Sahelian towns; now, it is com-monly hauled 100 km. Within 40 km of Ouaga-dougou, the capital of Upper Volta, virtuallyall trees accessible to roads have been cut toprovide fuel for the city’s inhabitants. Only afew years ago, fuelwood could be collected inthe immediate vicinity of most households;now people must walk half a day to reach it.

Since collection and transport of fuelwoodin rural areas is mainly by human and animallabor, its free supply generally is limited toareas within walking distance of the consumer.Rural people will seek fuelwood from more dis-tant locations until travel time becomes toogreat; then consumption may drop. A surveyof India showed that most villages located in-

side or adjoining the forest meet their total fuelrequirements from the forest. At localities with-in 10 km of the forest boundaries, about 70 per-cent of the fuelwood used comes from the for-est; beyond 10 km, the use of fuelwood fromthe forests diminishes steadily until at about15 km it is almost nil (22). However, in nationssuch as Thailand, with developed road systemsand adequate trucks, urban consumers may usefuel or charcoal from much farther away.

Fires

Repeated burning has altered vast areas oftropical forest and woodland. Natural fires arecaused by lightning, volcanic activity, sponta-neous combustion, or sparks from rockfalls.The majority of manmade fires are set inten-tionally. Hunters use fire to drive game and toclear bush so that game can be seen more easi-ly. Gatherers use it to encourage the growth ofdesirable plants and to discourage the growthof others, and to smoke honey bees out of theirhives. Farmers use it to clear and fertilize landfor planting. Pastoral people use fire to kill in-sects and snakes and to discourage predators.Other people use fire to ease travel throughdensely vegetated areas, to make war on neigh-boring people, or for other reasons. The pri-mary reason, however, is to improve the qualityof grasses for grazing.

Repeated fires generally impoverish vegeta-tion and deplete soil through losses of organicmatter, reduced nutrient cycling, and reduc-tions in soil microbe populations. Regenerationmay be rapid, but plant succession depends ona host of factors including the frequency andintensity of fire. After frequent burnings, fast-growing, light-loving second growth trees andshrubs eventually are replaced by savannas(permanent grass-covered plains). Fires canconvert closed forests to savanna and can ex-tend conifer forests at the expense of the broad-leaved forests. Such degradation leads to theestablishment of plant communities adapted tophysiologically drier conditions.

Seasonally dry forests are being more severe-ly modified than wet forests. Many dry tropical

94 Ž Technologies to Sustain Tropical Forest Resources

forests were converted to savannas by humanactivities long ago. Some savannas are naturalgrasslands, but these have been expanded be-yond their natural boundaries by forest clear-ing for agriculture and by manmade fires. Inmany places, it is difficult to determine whatsavanna is natural and what is derived fromhuman activity, since all savanna vegetationis adapted to frequent fires and appears similarregardless of origin.

Warfare

Warfare has adverse effects on tropical for-ests. Bombing and shelling of some islands inthe Pacific during World War II nearly elim-inated the forest cover and the effects remained

visible years later (48). Forested areas of Cen-tral America, Vietnam, Laos, and Kampucheamore recently have suffered the effects of mil-itary conflicts. Dense patterns of bomb andshell craters can eliminate forests or severelydamage the trees. In some large areas, forestswere removed by plowing and bulldozing toeliminate protective cover for enemy troops.Attempts were made to burn large tracts ofdead, defoliated forests, but these largely wereunsuccessful (41).

Between 1961 and 1971, about 14 percent ofthe land surface of Vietnam was repeatedlysprayed with herbicides and defoliants, ad-versely affecting the forests and mangroves(29). A recent examination of Vietnam’s forests


some 12 years after the war shows that thelong-term effect of spraying on inland forestsdepended on the dosage (30). An obstacle to re-forestation of these damaged lands, which noware covered with coarse grasses, is uncon-trolled burning by village farmers even thoughthe land is more suitable for growing trees thanfarm crops.

The impact of defoliants has been most se-vere on mangrove forests, as much as 40 per-cent of which were sprayed. Natural regener-ation has brought the regrowth of some minor“weed” species, but commercial species havereturned naturally on only about 1 percent ofthe mangrove area (49). Some replanting hasoccurred, however, and commercial specieshave been reestablished

Commercial Resource Use

Commercial Agriculture andCattle Ranchers

Few data are available on the amount of de-forestation now caused by commercial farm-ing, which usually involves permanent fieldswith perennial bush and tree crops. This wasonce a major cause of tropical deforestation,but now it is a less significant cause than shift-ing cultivation and ranching.

Cattle raising plays a major role in the lossof tropical moist forests in the Brazilian Ama-zon and in Central America. In contrast, it isnot a major factor in moist regions of tropicalAsia and Africa, where shifting cultivation and

n some areas. logging are more important.

Photo credit: H. Bo//inger

Conversion of moist tropical forest to temporary grazingland in Panama, a common scene throughoutLatin America. Most of the beef is exported


Pastures commonly are abandoned after 10to 15 years of grazing because of declining soilfertility, erosion, soil compaction, invasion ofunpalatable weeds, and low productivity. Inparts of the Brazilian Amazon, ranches only5 years old fail because of pasture degradation(19). Pasture instability and degradation resultin greater pressure to clear new forests.

The area of pasture in Central America morethan doubled between 1950 and 1975, almostentirely at the expense of undisturbed forests.Between 1966 and 1978,8 million ha of Brazil’sAmazon forests were converted into 336 cat-tle ranches supporting 6 million head of cat-tle. In addition, some 20,000 other ranches ofvarying sizes have been established (25).

There are several ways that forests are con-verted to pasture in Latin America. On largeland holdings, forests are often leveled, burned,and seeded with native or introduced grasses.Owners of smaller holdings commonly cleartheir land by making arrangements with peas-ant shifting cultivators whereby the peasantsclear the land, farm it for 1 or 2 years, and thenseed it to pasture and move on (9,32). In south-eastern Panama and probably elsewhere, pro-fessional deforesters move into national forests,cut the forest, plant grass, and then sell plotsas “improved land” (28).

Land consolidation, however, is probably themost common means of converting forest topasture. Agricultural colonists leave their fieldsand move elsewhere when yields decline sig-nificantly or losses to pests or weeds becometoo severe. The land is abandoned or sold tomore successful neighbors, to a second waveof settlers with more capital, to speculators, orto cattle ranchers. Small plots may then becombined into larger, more efficient units thatsometimes are used for tree crops but morecommonly for pasture. This process is wide-spread in tropical Latin America (8).

A number of factors account for the accelera-tion of cattle ranch development. Cattle ranch-ing, having its roots in Spain and Portugal, al-ways has been a prestigious occupation inLatin America (32). Furthermore, a traditionexists in the Amazon and elsewhere in Latin

America that it is the act of deforestation, orother “improvement,” which gives one theright of possession of land. The capital costsof ranching are low compared with commer-cial crop production, and the market for beefis steady or expanding. Government incentivesminimize the costs of credit, land, taxes, andproduction for the conversion of rainforest topastureland. Finally, strong export marketshave encouraged expanded beef production inthis region of the world. U.S. companies an-nually import as much as 330 million lb of Cen-tral American beef. That is 25 percent of theregion’s annual beef production and 90 percentof its beef exports (39), though this importedbeef only amounts to about 2 percent of annualU.S. beef consumption.

Several researchers have recommended thatthe United States ban beef imports from LatinAmerican countries where cattle raising playsa major role in tropical forest destruction [28,39), or that the United States import no beeffrom Central America (26). A number of ques-tions would have to be answered before legisla-tion for the first suggestion could be seriouslyconsidered. How much time must pass betweenforest clearing and cattle grazing to avoid theproposed ban? How could it be proven thatbeef from a particular country is produced pri-marily at the expense of tropical forests? Whowould make the judgment that the beef is pro-duced primarily at the expense of tropicalforests? Who would monitor cattle grazingoperations day to day in each Latin Americancountry? Such questions need to be examinedcarefully and answered in detail to deal fairlywith other countries. The second suggestionis simpler than the first but the foreign policyimplications are equally complex.

A variety of inducements for cattle opera-tions come from international organizationsand development agencies. For instance, inter-national agencies and governments provideloans for cattle development, including creditfor individual ranchers. Between 1971 and1977, international and bilateral agencies pro-vided more than $3.5 billion in loans and tech-nical assistance to Latin America to improve


livestock production and meat processing (28).In sum, the growth of cattle ranching reflectsnot only markets but government and interna-tional assistance, low cost loans, and otherincentives.

Loggers

Commercial logging causes deforestation inmoist broadleaved and conifer forests, especial-ly in Asia, West and Central Africa, and partsof Latin America. It is expected that as theAsian wood supply is exhausted, the LatinAmerican share of international trade in trop-ical wood will increase accordingly, from 16percent today to about 40 percent by the year2000 (25). Most tropical American softwoods—and the more valuable hardwoods of tropicalMexico, the Caribbean, and Central America—

already are depleted. Most of the remainingtimber is in the Amazon, where most of it re-mains inaccessible and unsuitable for currentmethods of selective logging.

Logging practices in the tropical forests dif-fer from those in temperate woodlands. Log-ging companies have markets for only a fewtree species, and these are widely scattered inhighly diverse tropical forests. For example, inthe Ivory Coast only 25 species are regularlycut out of the hundreds available (25). Thus,extensive areas must be worked to get enoughlogs, and this can be quite destructive. Cuttingone tree commonly brings down other treesaround it. Additionally, species diversity de-creases with repeated selective cutting.

Logging practices frequently influence subse-quent natural regeneration and rarely are fol-

98 •Technologies to Sustain Tropical Forest Resources

lowed by assisted regeneration or intentionalreforestation. For timber concessionaires inAsia, tropical silviculture has been a rational-ization for cutting economically valuable treesrather than a technique for securing forest re-generation (35). National forestry departmentsusually exercise only weak control over loggingconcessionaires.

removal reinforce one another. Networks offorest roads designed to transport timber pro-vide entry for farmers. Through a sequence offelling, burning, and cultivation, forest landsare actively degraded to low productivityfarms, which in turn maybe converted to low-grade grasslands through further burning andgrazing. An adequately trained forestry staff

Even though loggers may gradually degrade rarely is available to police either the logging

forest quality, the relationship between loggers operations or the movement of cultivators intothe concession.and cultivators exacerbates the rapid depletion

of forest resources. These two agents of forest

UNDERLYING CAUSES OF FOREST DEGRADIATION

In most of the Tropics sustainable forestry Properety Rights and Control Ofand agriculture practices are not being devel-oped and applied. The underlying causes ofthis failure are institutional more than tech-nical (8,15).

Institutions include national, state, or provin-cial forestry departments as well as interna-tional donor and technical assistance agencies.Institutions also comprise the broad set of rulesand arrangements that assign rights to re-sources, define roles, and govern individualand collective ownerships. Institutions definewhat individuals can and cannot do, what theycan expect others to do or refrain from doing,and what they can expect the government todo on their behalf (15). Institutions set the rulesby which policies are applied to produce de-sired results; policies and actions correspondto the extent that institutions are effective.

Forest degradation represents a case ofchronic institutional failure. The two most im-portant factors are:

1. the pattern of property rights and the ab-sence of effective common property insti-tutions for forest-land management, and

Z. the ineffectiveness of State and nationalforestry agencies.

Forest Resources

Forests supply rural people with food, fuel-wood, and fodder. A large portion of bothmoist and dry tropical forests is governmentowned and people gather freely what theyneed. Sometimes the government allows suchgathering, but more often people take naturalforest products whether it is legal or not be-cause the forests are not well policed. Althoughsome forest land is owned by villages or tribes,the individual quest for wood and fodder oftenoverwhelms the collective need to sustainforests. The same principles hold true for otherresources. As pressures mount to fulfill humanneeds, overuse and mismanagement of re-sources lead to degradation and deforestation.

Growing population is a major force behindthis increasing demand, but property rightsstatus (or lack thereof) is an underlying causeof the failure to meet the demand with sustain-able production. Use without management ischaracteristic of natural resource systems thatlack clearly defined property rights. When anypotentially renewable resource is used in com-mon, no user will delay use or otherwise in-vest in efforts to sustain the renewability of the


resource unless some institution guaranteesthat he will benefit from the investment. Thus,tropical forests have been degraded because ofinstitutional problems related to control overaccess to forest land and forest products.

Uncertain institutional arrangements and in-adequate administering agencies are at the rootof many forest degradation problems. Whenforests become nationalized, as in parts of Asia,traditional tenure and institutions for commonproperty management of forest lands are aban-doned. National governments acquire formalcontrol, replacing local administrations and de-nying the validity of prior land-use arrange-ments. The rights of forest occupants to con-tinue using forest land, acquired over genera-tions, have been removed or reinterpreted inthe national effort to control people and terri-tory.

Unlike commercial agriculture, which gen-erally takes place on lands where propertyrights are understood, agreed on, and re-spected, forestry takes place on lands wherecomplex and often conflicting systems of landtenure apply. This difference creates the acutecontrast between investments in technologiesto increase agricultural productivity and thelack of such investments in forestry, The lackof clear land tenure will continue to constraindevelopment initiatives in forestry and effortsto reverse forest land degradation. Where com-munal or national tenure is clear, the lack ofcapable administration institutions is the ma-jor constraint.

The potential for forestry to support nationaleconomic development that brings benefits atthe village level is great, provided sustainableresource-use systems are applied. But such sys-tems depend on the establishment of institu-tions to administer forest lands as commonproperty. Developing these institutions will re-quire a better understanding of history, culture,and social organization than is now applied.

To be effective, forest administrations needlocal support and participation, and this con-trasts with how forestry bureaucracies typ-ically work. Unless the institutional componentof a forest management technology is under-

stood by villagers to support their goals, thattechnology will not be used. With respect tovillagers in or around public forests, effectivecommon property institutions would clearlydefine individual and group claims on the ben-efits that stem from the forest. However, whatgenerally prevails are claims on uses which,in the absence of control over rates of use, drivethe resource to depletion (5). Since privatiza-tion of forest lands may not be possible in manyparts of the Tropics, open access must be con-trolled through such means as issuing licensesfor users, setting quotas, taxing users, orstrengthening local social institutions (18).

Transformation of ForestryAdministrations

The second part of the issue of institutionalchange relates to changes in the forestry agen-cies themselves. Government forestry institu-tions typically have been designed to protectstate or private logging and ranching interests.In many countries, the forest has been a zoneof tension between the state and the people.The pattern has been exacerbated by govern-ment insecurity with respect to its citizens andborders.

Although agency attitudes and traditions aredeepseated, they seem to be changing as gov-ernment forestry institutions evolve from be-ing custodians of public land to functioning asmanagers of a development process. For exam-ple, in many Asian nations increasing strengthis being given to national forestry developmentcorporations charged with managing forestsaccording to sound economic principles. At thevillage level, small-scale forestry projects forlocal community development are beginningto be promoted by national agencies. These areintended to create new income for villagersfrom degraded public forest lands and to re-duce pressure on the remaining or regenerat-ing public forest. Some nations have begun toprovide forestry extension services for villagefarmers.

Many Asian nations also have begun to applypolicies to encourage investment in wood-proc-essing facilities and to use forest industries

100 ● Technologies to Sustain Tropical Forest Resources—

within broader strategies of regional develop-ment. Few African or tropical American na-tions have developed such policies, and veryfew nations in any region have developed feasi-ble long-term plans for forest land allocation.

Even where appropriate policies exist, for-est resource development is constrained bypoor implementation and reluctance to enforcethe policies. The effectiveness of governmentcontrol over logging concessionaires dependson the degree to which national leaders arecommitted to maintaining long-term forest pro-ductivity. The real value of hardwoods fromAsia and West Africa has made it difficult torestrain powerful individuals and firms fromenriching themselves by sponsoring illicit cut-ting, by misrepresenting volume and grade oflegally cut logs, or by conferring the rights toexploit the remaining forest to others. Severalnational governments have banned export ofunprocessed logs to encourage forest conser-vation and local employment. However, dataon tropical wood imports by industrializedcountries indicate that illicit logging and ex-porting continue despite the bans (15). The per-sistence of these problems is due to incentivesfor rapid economic gains by elite groups andthe lack of political commitments to conserva-tion and development of public resources forthe benefit of the general public.

Improving forest administration also de-pends on developing effective participatory ap-proaches to forest management. Through par-ticipatory approaches, forestry programs mayadapt techniques and institutions to local en-vironments to develop productive and protec-

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At the community level, common obstaclesto participation are the absence of appropriatelocal organizations and shortage of leadershipskills. Typically, even where community devel-opment is practiced, inadequate attention ispaid to building community problem-solvingcapacities and to dealing with social diversityin highly stratified village social structures (20).Effective community organization can providesome measure of control over corruption andcan restrict the opportunity for individuals inpositions of authority to take unfair advantageof their positions at the expense of others (15).

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Documents

Chapter 4 Causes of Deforestation and Forest Resource