Note: The following units are used in this document:   
1 hectare (ha) = 10,000 m²  =  2.47 acres
1 km² = 100 hectares (ha)
1 metric ton = 2000 kilograms
1 gigaton = 109 metric tons
1 petagram (pg) = 1015 grams (gm)

Unless otherwise stated, all units used in this document are metric.

"Man walks the earth and desert follows his steps." (von Storch and Stehr, 2000)

"The earth’s last great forests are being destroyed in this century, torn apart for trifling profits."     (NY Times)

Rainforests have always been subject to destructive natural forces -storms, landslides, floods, mud flows, volcanic eruptions, high winds, fire (mainly from lightning), drought, and climate change. These factors have recently been overwhelmed by anthropogenic (human) forces, however, as rainforests are being cut down everywhere at a very high rate. Approximately 50% of land which could support tropical rainforests now lacks it because of human activities. Deforestation is not a recent human activity only, as rainforests have been inhabited by humans for thousands of year. Charcoal deposits, indicative of human activity, have been found in the sediments of many tropical rainforests which we regard as virgin forests. Many patches of rainforest also show peculiar distributions of plant species some attribute to human "enrichment" of the forest with useful species. Granules of various starchy root vegetables have been detected on 5000 - 7000-year-old stone grinding tools found in Panama, indicating that people were raising crops in forests a very long time ago (Piperno, et al., 2000). However, at that time, human populations were low, and the forests regenerated.

Originally tropical rainforests covered 15-18 million km² of land surface, but by 1989 this area had been reduced by human activity to less than eight million km². The total area remaining as tropical rainforest is even smaller now, as rainforests are being removed at a rate of 100,000 to 200,000 km² per year, with approximately the same area being greatly disturbed (Skole and Tucker, 1993; Katzman and Cale, 1990); some say, several times as much (Pimm, et al., 2001). Sponsel, Bailey and Headland (1996) estimate the deforestation rate as 142,000 km² annually. Potter (1999) estimated that 13.7 million hectares are deforested annually in developing countries, equivalent to 137,000 square km, but down from 15.5 million hectares (155,000 km²) per year in the 1980's. Achard, et al., (2002) give figures of 5.8 million hectares (58,000 km²) annually, as well as 2.3 million hectares (23,000 km²) degraded in the humid tropics. Meadows, Meadows and Randers (1992) estimate that 17 million hectares (170,000 km²) per year of rainforest (2.1% of total area) were cut in 1990. The discrepancies and uncertainties are due to the fact that the main means of measuring deforestation - satellite imaging - is only approximate, and may underestimate the actual area cut. These rates, however approximate, indicate that about 1.8% (in Brazil, probably 2.6%) of the remaining tropical rain forest is disappearing annually, twice the rate of 1979. One Florida per year is being destroyed; one football field is cut per second. While the highest rate of deforestation is occurring in Southeast Asia, about 70% of the area deforested (approximately two million hectares per year) is in the Brazilian Amazon, followed by Indonesia and Zaire (Laurance, 2001; Skole and Tucker, 1993). The Amazon has lost about 14% of its rainforest, while 40% has been damaged by fragmentation. In the countries of Benin, Ivory Coast, Ghana, Nigeria, and Togo in Africa; western Ecuador, El Salvador, Atlantic Brazil, and Haiti in the Neotropics, the rainforests are virtually gone. In The Philippines, dipterocarp forests were reduced from 16 million hectares in 1960 to less than one million hectares twenty years later (Repetto, 1990). Thirty per cent of Ethiopia was forested in the 1960's; by the late 1980's, this had been reduced to perhaps 1% (MacNeill, 1989). In 1957, 57% of Myanmar (then Burma) was forested; by 1990, perhaps 25-40% of the country was still covered by forest. There is even less now, as Thai and Malaysian logging companies move in to exploit timber which is no longer available in their countries. If this rate were to continue, all rainforests will disappear in less than 50 years; if the rate were to increase exponentially, at the same rate that the human population is growing in tropical countries (about 2.3% annually), then the forests will disappear within 30 years. Projections of the rate of deforestation are complex because future demand is unknown, future human population size is unknown, and the remaining forest is in more remote areas and in terrain difficult for logging. Environmental groups are putting political pressure on governments to save rainforests, which may mitigate some of the pressures facilitating rainforest destruction.

Nevertheless, it is possible that by the year 2010 little will be left of this biome in a primary state, except in the central basin of Zaire and in the western Amazon, and a few other small areas, such as the Guyanas. Even these forests will not last beyond the mid-21^st century. Lowland forests, because of their accessibility and many useful products - timber, rattan, fruits - are the most threatened, since they are also prime terrain for cultivation of oil palm, rubber and other crops, and livestock, mainly cattle. Despite these dire predictions, relatively little rainforest is under government protection, (in the Amazon, about 3-4% is protected) and many of these protected areas exist only on paper. Many protected areas are small and fragmented, which is detrimental to their continued existence and to the preservation of biodiversity. The areas which will be preserved are those which are in inaccessible or inhospitable areas, such as mountainsides, rocky or steep terrain, areas which are too dry, too wet, have very poor soils or are otherwise incompatible with agriculture.

Some areas are being reforested (about 10%) but these hardly begin to compensate for losses, and they are nothing like the original forest. Rainforests are not as amenable to reforestation as temperate forests, partly due to the poverty of many tropical soils, the fertility of which is further reduced by logging, and to the extensive erosion which follows logging activity. In the tropics in general, one tree is planted for each ten which are cut; in Africa, this proportion is one to 29 (MacNeill, 1989). And the resulting "forests" are often simply tree plantations without any of the diversity or richness of the original forest. In 1982 Lanly estimated that 11.3 million hectares of mature forest were being deforested annually, of which 5.1 million hectares were left to reforest (become secondary forest) and about one million hectares were forested by human activities. However, the gains in forest area from regrowth cannot begin to compensate for the ongoing deforestation by logging and burning.

We do not know the exact relationship between deforestation rates and loss of biodiversity. Many factors are involved in this complex relationship, since even the removal of a few trees or a few species from a forest may cause a cascade of species losses due to changes in microenvironment, the removal of "keystone" species or disruption of the highly complex interrelationships among species. It has been estimated that on islands where 90% of the forests have been disrupted, 50% of species will be lost (For a discussion of biodiversity loss, see above, Part II, G.) Of course extinction rates depend on many factors - type of forest, soil type, intensity of disruption due to human activities, degree of endemism, extent of land degradation, and so forth. Some species will also survive deforestation - those which can adapt to disturbed forest or exist in human-dominated landscapes. Even in the areas of rainforest which survive, however, the plants and animals will be subject to "edge" effects - heat, light and predation (see above). As forests become ever more fragmented and isolated, the organisms in them are finding it increasingly difficult to survive. Small populations will be unlikely to persevere as their environments change and they are exposed to increasing hunting/gathering pressures and stress. As mentioned above, there is an enormous number of species in these forests, but most are composed of relatively few individuals, randomly distributed throughout the geographical range of that species, or located in one small area only (endemism). In addition, many rainforest species require large, contiguous areas of undisturbed forest; most cannot thrive in degraded habitats. Thus forests which have been fragmented do not contain the full range of forest species. Perhaps 50% of the world’s species are threatened with extinction because of deforestation, and some estimates of the current extinction rate place it at one thousand times the natural one (see Part II, G1).

It is becoming clear that rainforest ecosystems may collapse when a certain "critical mass" of forest has been cleared or damaged. That is, ecosystems cannot maintain themselves when too much forest has been removed, due to the loss of interrelationships among species. When a number of environmental factors act together (synergism), they may cause the demise of the forest ecosystem. For instance, in Borneo, where much of the forest has been cut, burned, or leased for logging, a number of factors - drought, deforestation, fragmentation - have combined synergistically to endanger the remaining rainforests. The past 20 years have been years of severe and prolonged drought and uncontrolled logging. Unusually dry conditions have led to innumerable forest fires, further damaging the forests.

1)Southeast Asian Dipterocarps: As mentioned above, dipterocarp species (the large canopy trees) of Southeast Asia fruit sporadically and synchronously, and only during El Niño years. Within six weeks of the onset of El Niño, the dipterocarps flower, fruit and disperse seeds, a bounty for fruit-feeding animals. Some of the seeds will sprout into seedlings, the next potential generation of dipterocarps. Synchronous reproduction requires large areas of intact forest; as this area is reduced, fewer viable seeds are produced. According to recent data, on the island of Borneo this intricate reproductive system is in trouble. Many species of dipterocarp in protected forests surrounded by logged areas have failed to produce viable seedlings over the last decade. This is in contrast with 1991, when the same area produced 155,000 seedlings per hectare after a mast fruiting. The loss of reproductive ability may be due to the synergistic impacts of El Niño droughts, logging activities, and the establishment of plantations on former forest land. Areas of intact forest surrounded by degraded ones can provide food and shelter for animals fleeing damaged areas, but they consume all of the fallen seeds, leaving none on the ground to sprout. Because there is not enough food for the additional wildlife, populations of seed- and fruit-eating species will crash (Curran, et al., 1999; Hartshorn, 1999). As an example, orangutan populations have declined by 50% in the past 10 years (Wuethrich, 2000).

2) Fires: Fires destroy seeds (as well as killing animals and trees), and smoke from fires kills seedlings, is unhealthy for animals, and can inhibit rainfall. Additionally, trees which are killed in fires provide fuel for future, more devastating fires. During the El Niño droughts of 1997-1998, 10 million acres of forest in Central and South America were consumed by fire; another 11.5 million acres burned in Southeast Asia. Some of this land had been logged; some was primary forest. Many of these fires were set deliberately to clear pasture or cropland, and then burned out of control because of the dry conditions. Forty per cent of the El Ocote Biosphere Reserve in Chiapas, southern Mexico, was destroyed in 1998 by fires set by hunters to drive prey and by farmers and ranchers in the vicinity. These fires burned for almost four months, as did fires in Chimalapas Biological Reserve, in Oaxaca state (Cochrane, 2001). More than two million acres of rainforest burned in southern Mexico in that year (Stolzenburg, 2001). Unsustainable logging in East Kalimantan (Indonesian Borneo) has exacerbated the risk of spontaneous fire, already severe due to dessication from El Niño and the small fires normally set by people for forest conversion, hunting, and animal collection, as well as disputes over land ownership. In 1997-1998, approximately 5.2 million hectares (52,000 km²) were affected by fires, 42% with "severe damage" and 34% with "total damage." Pulpwood plantations and recently-logged areas suffered the most, pristine forests the least, as the latter are naturally resistant to fire (Siegert, 2001).

The fragmentation of forests encourages fires; most fires begin near or at forest edges. Trees near the edges also suffer more from drought and many more of them die during dry periods than trees in the forest interior. These synergistic effects are being seen in many tropical areas, such as the Amazon, which is becoming increasingly drier. Many parts of the Amazon are now barely wet enough to support tropical rainforests and so are hard-hit by drought and are vulnerable to fire. Drought, even more than logging, may eventually doom many Amazonian tropical forests through changes in the hydrological environment.

According to Cochrane, et al., (1999), almost 50% of the remaining Amazon rainforest has been disturbed by accidental fires. Fires reduce the understory vegetation, increase temperatures and decrease humidity under the canopy, all of which conditions lead to greater risk of additional future fires. As Cochrane (2001) points out, the temperature in an intact forest usually remains below 28^oC, but where the canopy has been reduced by fire, temperatures may reach 38^oC, leaving the forest ripe for more fires. Similarly, reduction of canopy cover by 40%, such as occurs after a fire, reduces the humidity greatly, providing ideal conditions for more fires. Recurrent fires are much more destructive than are initial fires, because their intensity tends to be greater, and even large trees will be consumed. Thus, a destructive cycle begins.

It has been estimated that global net primary productivity (NPP), terrestrial, aquatic and marine, equals about 225 petagrams. Of this, humans divert or use 42.6 petagrams, of which 7.2 petagrams are utilized and 35.4 petagrams are diverted. Thus, 19% of the total NPP is consumed or diverted by humans: 31% of the terrestrial and 2% of the marine NPP. But this is not all. Humans, by altering surface and atmospheric conditions, diminish the potential NPP of the planet. We cover potential productive land with asphalt and concrete; we make agricultural land from forests and savannahs; we desertify many formerly productive areas of the earth’s surface; we lower or destroy the productivity of many waterways and lakes. If we add the amount of NPP lost by these activities to the amount of NPP usurped by humans, we approximate 60.1 Pg, or 39% of total potential NPP. Whether or not these figures are accurate, we know that humans appropriate a huge amount of global NPP for their purposes. Ehrlich and Wilson (1991) and Vitousek, et al., (1986), among others, estimate that 40% of global NPP is co-opted by humans (the same amount as is consumed by animals and decomposers combined). A new paper (Rojstaczer, Sterling and Moore, 2001) estimates that human use of global terrestrial NPP amounts to between 10% and 55% (the great variability occurs because of the uncertainty in the important parameters).

1) Agriculture:  Nearly 15% of the land surface of the earth is being used for crop agriculture, and another 6-8 % for pastureland. By converting forests to agricultural land (and by other means - pollution, sedimentation, etc.), we are reducing the primary productivity of the land. Agricultural land, pastures and other converted areas are much less productive than are forests, because of lower plant biomass and lower biodiversity. Additionally, only about 10% of the organic material produced on agricultural land is usable as food. If we include these losses, we can estimate that humans utilize almost 40% of the potential net primary productivity (NPP) of all of the terrestrial plant life on earth for their purposes (Vitousek, et al., 1986; Diamond, 1987). In addition to our direct usage of NPP, we affect the remaining 60% as well. Thus, we are shifting from ecosystems with very high NPP to those with low NPP.

According to one calculation, by converting seven million km² of forest to pasture (a figure from about 15 years ago), we have lost 1.4 petagrams of net primary productivity, about equal to the amount of organic material that humans use directly per year (or 3% of the biosphere’s total net primary productivity). This is out of an estimated total of 149.6 petagrams of NPP per annum for the terrestrial areas of the planet (Vitousek, et al., 1986).

2. Timber:  The conversion of land from forest to other purposes also reduces the NPP of the land, as less than 50% of the NPP of forest land is being utilized as timber.

3. Habitations, recreation:  When land is converted for purposes of lawns, golf courses, etc., the organic matter produced on the converted land is not used, for the most part.

Countries which contain large areas of rainforest have regarded their forests mainly as an exploitable economic resource. These forests are often regarded as useless unless "developed" by conversion for agriculture or exploited as sources of mineral wealth, rubber, and wood. They are expected to "carry their own weight" by providing land and materials for development and export commodities for the export market (and thereby the enrichment of the public and private sectors). Rainforests are also seen as vast sources of land for the relief of social pressures - land for the landless peasant or urban slum dweller as well as incomes for the poverty-stricken. Thus forests become political commodities as well as economic ones, useful as places to send unemployed or marginal social groups. The costs of such deforestation are disregarded or seen as tolerable in comparison to "nonutilization." This is so because the consequences of environmental degradation will occur in the future, whereas the economic benefits from rainforest destruction are immediate, and governments in general are interested mainly in the short term. Also, the costs of land degradation often descend upon people other than those making policy and/or reaping the financial rewards of rainforest exploitation. The poor who descend upon the forests after roads have been constructed or logging has occurred remain impoverished and driven by the same economic forces which pushed them to the forests in the first place. They are forced by the intractable facts of the rainforest environment - poor soils, erosion, loss of soil nutrients, distance from markets - to move frequently and to sell cheaply. Often, also, those living in countries outside of the tropics suffer from the effects of rainforest destruction - increased greenhouse gases in the atmosphere, changes in weather and rainfall patterns, and loss of rainforest products. This is well summarized by Amelung, Torsten and Diehl (1992): "The tropical rainforest is an economic resource providing a multitude of products and input factors for a number of economic activities and industries. From the viewpoint of the respective tropical countries these resources should be exploited in order to enhance the development process, even if the exploitation of these resources incurs serious environmental problems in the long run."

For many years, until approximately 1940, most land cleared in tropical areas was from land which had lain in fallow; relatively little was cleared from undisturbed forest. However, after 1940, mature fallow land could not meet demand, and land which had lain fallow for only short periods of time was increasingly utilized. Such lands, when cleared, rapidly became degraded woodlands or grasslands, and more primary forest was cut to meet the demand. This has continued at an accelerating rate to the present. Soares-Filho, Assunção and Pantuzzo (2001) modeled factors which are conducive to deforestation in northern Mata Grosso, Brazil. They found that risk factors for deforestation included proximity to roads, urban areas and to land already deforested. Lowland forests are also much more susceptible to cutting, because of their accessibility and, sometimes, soil fertility compared to areas at higher elevations. What are the factors which have produced this situation?

1) Human population growth:  The human population continues to grow explosively, although the rate at which it is increasing has been slowed in the past few decades. Nevertheless, the last billion human beings have been added during the past 12 years! Population pressures, particularly acute in tropical areas, force the acquisition of ever more agricultural and habitable land, and, as suitable lowland fertile areas have already been brought under the plow, more and more marginal and fragile lands with poor soil, hills and mountains are being cultivated. Also, as human numbers increase, mankind appropriates more and more of the total solar energy and primary productivity of the earth. At present humans use almost 40% of the solar energy captured in organic matter. Many, if not all, of the following causes of rainforest destruction are closely linked to the exponential growth in human population during this century. The disappearance of rainforests and biodiversity is proportional to the rate of expansion of the human population.

2) Land ownership patterns:  In many tropical countries, land ownership is highly skewed. Huge tracts of land are owned by the wealthy, leaving large numbers of landless peasants, who are forced to farm marginal lands and to cut forest for farmland.

3) Conversion for agriculture:  By 1993, the land area converted to agriculture amounted to 4,810,000,000 hectares (48,100,000 km²), or 36% of global terrestrial area, although recently the rate of land conversion has not kept pace with population growth due to technological improvements in agriculture (Goklany, 1998). (While these technological changes have reduced the rate of land conversion, they have caused significant environmental damage, and have permitted increased rates of human population growth, which in itself has necessitated increased land conversion.) Approximately 3.1 million hectares of tropical rainforest per year are cut to provide agricultural land (Achard, et al., 2002). Of the agricultural land in tropical countries, 38% in Africa, 38% in South America, and 67% in Asia has been converted from areas of tropical rain forest. The area of land converted from forest to agricultural purposes in the past 140 years is more than twice that converted between the origin of agriculture, about 10,000 years ago, until the mid nineteenth century. Almost 80% of tropical deforestation is the result of conversion of forest land for agricultural purposes, but surprisingly only about 5% of this loss between 1980 and 1990 was due to the establishment of large plantations and farms. Most was the result of population growth and the consequent search for small plots of arable land to feed the additional people. Tilman, et al. (2001b) estimate that by 2050, 18% more land will have been converted from natural ecosystems for agricultural purposes, or a net loss of 10 billion hectares, an area larger than the United States, and half of all potentially arable land remaining. As they stated, "Land use and habitat conversion are, in essence, a zero-sum game: land converted to agriculture to meet global food demand comes from forests, grasslands and other natural habitats."

a. Conversion for large plantations and ranches: In the second half of the 20^th century, the business of agriculture has shifted from small, independent farms to huge commercial operations, which require large tracts of land. This shift has been driven by the rise of the global agricultural economy and the consolidation of land into a few hands, and also by the growth in affluence of a number of countries. This has substantially increased the international demand for meat, coffee and other luxury goods, many of which are produced in tropical countries and exported. If everyone in the world were to consume meat and animal products at the level of North Americans (approximately 25% of calories), only about 2.8 billion people could be supported by our ecosystems. Presently, only about 20% of deforested land is used to increase local food production, and even much of that food is exported (beef, coffee, etc.). The impact of ranching and large-scale agriculture on forest systems are also exaggerated by government policies which encourage the clearance of land (see Section C7).

b. Swidden agriculture: Shifting cultivation, or swidden farming, is thought to be a major - if not the major - cause of deforestation in Southeast Asia. More than two million km² of closed forest land may be included within these cultivation systems (Amelung, Torsten and Diehl, 1992). This is especially true in Africa. Up to 80% of deforestation in Southeast Asia has been attributed to this type of agriculture (Palm, et al., 1986). This is true for some types of traditional farming, and so-called "slash-and-burn" agricultural method produces huge amounts of greenhouse gases annually - as much as 1.6 metric tons (Kaiser, 1997). However, if properly practiced, it is the only type of agriculture which can be sustained in tropical forests. With this system, it is possible to farm in a sustainable manner, taking into account the ecology of the forest. In shifting cultivation (and there are many variants), vegetation is cut in small patches of forest (primary or secondary); generally, some trees are allowed to stand. This practice forms openings which allow the sunlight to penetrate, and the burning of the remaining vegetation enhances the fertility of the soil by providing organic material. The open area is planted with a variety of crop species. In Amazonia, for instance, the major crops are numerous varieties of cassava (as many as 48, according to Dufour, 1990), plantains, bananas and other fruits, medicinal plants, and sometimes poisonous plants. Valuable species of trees, such as timber and fruit trees, may also be planted in the swiddens. The crops are staggered, so that they provide harvests for several years. Trees are harvested after maturity and until forest regrowth reclaims the plot. Trees are harvested after maturity and until forest regrowth reclaims the plot. The diversity of species provides protection against plant pests, and also some insurance against the failure of any one crop. After a few years (two to three crops), soil fertility decreases, and the forest is allowed to regenerate for a number of years (the "fallow"). The crop and fallow ratios vary according to the soil and crop, but the fallow time must be lengthy. Fifteen to thirty years, in most places, is needed in fallow after one to three years of cultivation. During the fallow period, the farmers remove fruit, wood, and other items from the forest, and harvest staples from other swidden plots. Animals, too, share in the vegetables and fruits in the gardens. Since many trees are retained and others planted, natural regeneration is encouraged. However, the composition of the forest changes, since many crop plants, especially trees, remain in the regenerating forest, and it becomes a mosaic of swidden patches at various stages of forest regeneration or cultivation. This system retains the genetic pool of primary species, and is not very destructive if the area cut is small and allowed to reforest. In fact there is some evidence that trees in swidden plots may grow as rapidly as natural forest. However, biomass and species diversity remain lower than in primary forest, and it may take more than 100 years for a swidden area to revert to primary forest (Dufour, 1990). As population pressures mount near rainforests, less and less time is being allowed for fallow and forest (and, therefore, soil) regeneration. Now, too often, the soil becomes degraded because the fallow is too brief, leaving the seed bank depleted, shoots disrupted and allowing weeds to invade. Then the plot is abandoned, as it is no longer productive. Even more damaging, permanent agriculture is now replacing the traditional shifting agricultural systems.

c. Land degradation: The recent expansion of agricultural land and pastureland accounts for less than half of the deforestation currently occurring. The remainder is due to the degradation of abandoned farms and ranches, leading to demand for additional pristine forest land to be converted for agriculture (Hoffman and Carroll, 1995). Land conversion of most tropical rainforests is unsustainable; the land soon becomes infertile and less productive due to erosion, reduction in rainfall, salinization of soil and reduction in soil water retention, and consequent increased danger of flooding. Much agricultural land is soon abandoned because of soil impoverishment. Approximately one-third of the area of land deforested annually in the Brazilian Amazon, for instance, is abandoned every year (Houghton, et al., 2000). Not all of this land is capable of reforestation, however, and large areas of previously-forested land which had been used for agriculture have been replaced with grasslands rather than forest.

d. Coca cultivation: Some mention should be made of the contribution of the drug trade to deforestation. In South America, coca has been planted for centuries, but in small quantities and carefully. Peru had only 18,000 hectares of coca in 1972. Fifteen years later that figure had increased to 200,000 hectares, much of it in the forest interior and on slopes with bare soil, without regard for erosion. But the profit was more than US$1 billion (Amelung, Torsten and Diehl, 1992; Salati, et al., 1993). The same process is occurring elsewhere in many tropical forest regions of Southeast Asia (Laos, Myanmar) as well as in the Neotropics.

4) Housing and urbanization:  As towns and cities enlarge, their demands for space and goods increase continuously. To provide land for housing and cities in tropical areas, forests must be removed. In addition to the demand for space, urban areas require great amounts of wood for construction and fuel. The demands of New Delhi for wood, for example, have extended 700 kilometers from the city perimeter. Cities also require many other forest products, from food to roofing materials to medicines. Many of these cannot or are not harvested sustainably, and the excess consumption leads to forest degradation or destruction.

5) Commercial logging and the demand for wood:  The shift from traditional logging methods to modern international methods has been disastrous for forests. Traditionally only large trees only were removed, and few species were desired. Forests were permitted to regenerate naturally for long periods of time before reharvesting. But modern timbering involves the extraction of high yields per unit area, the removal of smaller trees and of trees of many species (some of which may be "keystone" species, and/or the source of food for many animals). In addition, cutting cycles are much shorter than traditional long fallow periods, and cut-over areas are often not permitted (or cannot) reforest naturally. Even if reforested, these areas are usually impoverished, since they are basically converted into single-species tree plantations. Large-scale logging operations require large roads, with consequences discussed under "Timber trade" (see Part VII). Additionally, the huge modern markets for timber have skewed the economic picture, and the development of modern logging machinery has made it possible to cut vast quantities of timber at rates previously impossible. The forestry sector has greatly distorted the forest products industry. For example, in 1938 in Indonesia, the relative value of timber to non-timber forest products was 55% to 45%, but since then the timber trade has become inflated, and revenues for minor forest products have declined precipitously. In truth, many of these products have been superseded by other, synthetic substances, and so there is less incentive to conserve forests for their products.

Much of the logging occurring in tropical rainforests is illegal, accounting for perhaps as much as 65% of the world supply of timber (Haugen, 2002). Illegal logging occurs even in national parks and reserves, and includes the cutting of protected species, underreporting and overcutting, smuggling, and logging without permits, among other violations. This type of activity is rampant especially in Southeast Asia, some African countries and parts of Brazil. The loss of revenue to the government of Cambodia from illegal logging is equivalent to the entire national budget of that country, but the high government officials control this trade (along with the remnants of the Khmer Rouge). And Cameroon lost 50% of its potential tax revenues because of illegal logging during the decade of the 1990's (Abramovitz, 1998). Much of the wood imported into the United States and the European Union is derived from illegal sources, yet it is not mandatory to confiscate these imports. Such official complaisance - indeed, complicity - with illegal activities to satisfy domestic markets is driving much tropical deforestation today.

6) Use as a fuel source: Forests serve as sources of fuel when no alternative energy source is available. This is a substantial cause of deforestation. In parts of Africa and in India, 60% - 90% of energy needs are supplied by wood (Robinson, 1988; Sponsel, Bailey and Headland, 1996). It is no surprise, given the burgeoning populations of these areas, that little forest remains. In many places, great swathes of trees have been cut to provide charcoal, as in Brazil. The volume usage of wood for fuel has been estimated as 1.12 m³ per capita per year in the former Indochina and 0.53 m³ in the Philippines (Palm, et al., 1986).

7) Government policies:  Governments in tropical countries often feel that exploitation of natural resources is an opportunity for economic development and a solution to socioeconomic problems. In this they are usually mistaken. Foreign companies reap many of the profits, pay low taxes, and let the country clean up the mess. Thus, forests or other natural resources pay the price for ignorance, corruption, exploitation, and inadequate protection. But it is much more complicated than that. Government policies - in both developed and developing countries - virtually mandate unsustainable development. Economic policies are made without regard for the environmental consequences. Tax and fiscal incentives, marketing policies, resettlement schemes, trade policies - all exacerbate resource depletion. Policymakers frequently disregard environmental issues or assume that the resources are infinite, replenishable, or replaceable by new technologies. Some feel that the environment should be freely available for exploitation to support the market. Others are simply unaware of the consequences of the incentive systems which they are constructing

Governments in countries under land pressure may sponsor "development" projects, in which they offer forest land to the impoverished. Indonesia in the past sponsored a transmigration scheme (transmigrasi) of moving people from overcrowded places such as Bali and Java to Sumatra, Borneo (Kalimantan) and New Guinea. These people were given little assistance, so they cut down rainforest for agricultural land. Although governments think that policies such as this are a cheap way of dealing with land shortages, overpopulation, and poverty, in fact they have been quite disastrous. The poor soils in rainforests can usually support agriculture for only three to five years; then the fields became infertile, forcing people to move into and cut down more primary forest (or to leave). Such schemes are ultimately futile, and do not contribute to anyone’s long-term benefit. Rice production in Malaysia has been reduced by more than 25% because of erosion, a decrease in rainfall, and other consequences of deforestation (Sponsel, Bailey and Headland, 1996). Similarly, governments (Brazil’s, for example) often encourage landless peasants to move into and colonize "unowned" forest land, which may have been opened up by logging roads. This relieves some of the economic and political pressures on the government. (For additional examples, see the case studies of Malaysia, Brazil, and others, (see Part IV).

Governments frequently build roads into wilderness areas to encourage forest exploitation for logging or for small-scale agriculture, and offer subsidies and tax breaks as well as imposing legal requirements that land must be logged to be registered. Logging concessions are usually short-term, and although these agreements may contain certain minimal requirements relating to permissible tree diameter and harvesting volumes, there are few incentives for timber companies to log carefully or to reforest (or to adhere to the conditions of the contract, for that matter). On the contrary, since the fees for logging concessions are based on land area, there is definite advantage to the company to remove as much timber as possible, so as to recoup investments in equipment and, especially, roads. The government often stipulates that logging roads be durable so that they may be used in the national road system, which leads to permanent inroads into the forest.

Even where some effort is made to control timbering, the government usually has very weak enforcement capabilities. Moreover, governments obtain revenue from logging, and they are highly subject to pressures from the wealthy and the well connected. Threats of violence are quite frequent as well. So there are many incentives to establish government policies favoring special interests (often the officials’ friends and relatives). In actual fact, the timber concessionaires are often military or government leaders and politicians.

It is unlikely that governments in tropical countries will give up short-term gains for long-term conservation goals. Their populations are rising too rapidly, they lack resources, and there are powerful (and often corrupt) interests which are closely linked to the government or government officials.

8) Subsidies from governments and international lending agencies:  Many international agencies such as the World Bank have invested billions of dollars in tropical countries for various development purposes - expanding agriculture and building dams and roads, for example. Moreover, the lending and repayment policies of both the World Bank and the International Monetary Fund are such that countries must deplete resources to repay their loans to these agencies. Although the World Bank has environmental guidelines, of its several thousand employees, only three were conducting full-time environmental reviews in the 1980's (Holden, 1986). Government subsidies - direct or implicit - often operate to the detriment of many aspects of the environment, such as soil, fisheries and rainforests. Governments in tropical countries subsidize rainforest destruction in many ways - by promoting unsustainable agricultural activities, logging concessions, lumber finishing, and so forth. These subsidies, which Myers (1998) calls "perverse," are more expensive than the result warrants, and encourage unsustainable and inefficient activities. This does not cover the true costs of such subsidies, which must also include increased taxes, unemployment, the depletion of natural resources, the diversion of financial resources from better uses, the unequal distribution of benefits (mainly to the rich), and many others. But these consequential costs of subsidies are incalculable. As Roodman (1996) asks, "How does one...calculate the costs in dollar terms to indigenous Dayak people in the Malaysian state of Sarawak of the loss of forests on their homelands, which the government has brought about by sanctioning large-scale logging by outsiders?"

Brazilian government support for 12 million hectares of existing cattle ranches has cost it more than US$2.5 billion as of more than 10 years ago (Repetto, 1990). In all of these activities, the government fails to protect the public interest. Subsidies, selling logging concessions below market value, allowing environmental destruction - are all paid for by the taxpayer. Pimm, et al., (2001) estimate that subsidizing environmentally destructive policies costs US$2 trillion every year globally; a figure of US$1.45 trillion is given by Myers (1998); US$950 billion to $1,950 billion by Balmford, et al., (2002), almost the same as Pimm’s estimate. As the latter points out, this amount is two-and-a-half times as much money as the Rio de Janeiro summit’s budget for sustainable development, which the governments involved claimed they could not afford! The United States alone provides more than 20% of these perverse subsidies, so that U.S. taxpayers are bled of $2,000 per year to fund them, not to mention the $2,000 more through environmental degradation and increased costs for goods (Myers, 1998).

As an example, the World Bank has assisted the entry of Thailand into the global economy, but not without cost. Thailand has received many millions of dollars in World Bank funds, credits and loans. A key part of the Thai development program was a focus on expansion of rubber production. In 1961 the Rubber Replanting Project began under the auspices of the Thai Ministry of Agriculture, and it has been funded in part since 1976 by The World Bank. By 1991, 480,000 hectares of mature rubber forest had been converted to new varieties of rubber trees and rubber exports had increased by 5%. For a token sum, planters could obtain forestry department land and also substantial subsidies for fertilizer, new varieties of rubber trees, and herbicides. Much of the conversion activity was illegal, as legal logging roads cut into forests opened them up to incursions by illegal logging operations. As a consequence of this project, in 1988 Thai farmers received, not only more income, but also disastrous floods, caused by excessive logging and agricultural conversion, although The World Bank had estimated that the replanting would result in minimal ecological problems or erosion. The environmental impact statement in the 107-page document for the third replanting project was one paragraph long (Hamilton and Chatterjee, 1991). In this, as well as many other cases, large international agencies in collaboration with national governments have, until recently, given short shrift to the environmental consequences of their policies, instead focusing on economic returns, rapid economic growth, and increased export capacity.

9) Inadequate valuation of tropical rainforests as resources:  Historically, governments of countries with rainforests have not valued their forests sufficiently as resources, especially over the long term. If forests have value to them, it is as a short-term resource to be exploited, or as a source of land for agriculture or to relief of social pressures. They sell logging concessions and licenses very cheaply, give tax concessions to logging companies, and allow land speculators to make vast profits on forest land. Often "stumpage fees" (fees charged for logging concessions) are below the costs of management, let alone the cost of reforestation. Although in 1987 the Philippine government could have collected US$250 million from the timber harvested that year, it obtained less than one-sixth that amount because of low royalties and taxes, widespread smuggling of timber, and tax evasion. At the same time, timber companies walked away with huge profits. In Indonesia, over a period of five years in the early 1980's, the government collected royalties and taxes on only 86 million of the 125 million hectares actually harvested (Repetto, 1990).

Such policies cost the public a great deal in lost revenue (not to mention lost resources), but also provide a tempting scenario for fortune hunters, both local and foreign. Governments usually discount future value in favor of systems yielding faster returns, such as agriculture. This is especially true in societies where the human population is growing rapidly. This phenomenon pressures governments and forestry industries to "mine" forests as a quick-return resource. Thus, little effort is made for protective management or conservation. Balmford, et al., (2002) have calculated the total economic values (including goods and services) of several different tropical ecosystems under conditions of either exploitation (land conversion) or non-conversion (conservation), and found that the economic benefits of non-conversion were considerably higher than those obtained when land was converted for other uses. Among the cases considered were rainforests in Malaysia and Cameroon, and mangrove forest in Thailand. They concluded that "...conversion of remaining habitat for agriculture, aquaculture, or forestry often does not make sense from the perspective of global sustainability." Thus, current rapid land conversion for agriculture and other uses make no long-term economic sense. By this conversion, we decrease the biological base which provides us with services which are vital for our existence, or, as the above authors put it, we are causing the "erosion of natural services." They calculate that we lose US$250 billion per year worth of such services by land conversion.

Alternative - i.e., non-timber - uses of the forest are worth huge amounts of money every year. The rattan trade of Southeast Asia alone is worth about US$3 billion annually (Dobson, 1995; Ryan, 1992). But non-timber resources, if harvested at low, sustainable levels, can be rapidly replenished and their collection can disrupt the forest minimally. We can make a comparison of the economic value of timber versus non-timber products of tropical forests in the Amazon, for example. In some one-hectare plots of forest land near Iquitos, 842 trees of a diameter greater than 10 cm were located; these trees represented 275 species and 50 families. Of these 842 trees, 350 (72 species) provide marketable goods. Eleven species (including palms) produce edible fruits, sixty species are valuable as timber; one produces rubber, and many of the smaller plants and palms produce pharmaceuticals. After harvest, the net yields for non-timber products were, over a 20-year period, 90% of the value of the timber, a one-time crop (Dobson, 1995). And the forest remained. It has been found that 26% of species in the Peruvian Amazon near Iquitos yielded products of commercial value. Over time (here, 20 years) the renewable, non-timber products were worth almost thirteen times as much as the timber (Review in Alper, 1993). Timber is basically a one-time crop, or at least has a very long period between harvests, while non-timber products could be gathered frequently and indefinitely. However, Godoy, et al., (2000), working in Honduras, found that local people received only a relatively small amount of value (cash and/or consumption) for rainforest products, between US$49 and US$1089 (a mean of US$347) per hectare per year annually.

10) Inadequate protection of tropical rainforests:  Even where governments have set up reserves, wildlife areas, and parks, few resources are expended on protection and management. Most "protected" areas exist only on paper. Many forestry posts remain unfilled (for lack of funds or lack of trained/interested personnel), and many forestry department civil servants work in offices far from the forest and are not actively engaged in management. In Ghana, at least half of the forestry positions were left vacant and the departments involved with forest management are seriously underfunded (Repetto, 1990). In Peru, the state of Loreto has set aside a large "community reserve," the Reserva Comunal Tamshiyacu-Tahuayo, but few funds have been allocated for it, and virtually no government personnel are working in or near it (See RCF website.). The same is true for many parks in Africa. Moreover, destructive activities may be encouraged if they are profitable. Logging is carried out in parks in Indonesia with government approval, for instance. In other cases, parks have been established by evicting local people or curtailing their activities within the park without compensation. Thus, although the integrity of tropical parks depends on the goodwill of local people, in their establishment the government disrupts traditional management and forces local people into destitution. Not surprisingly, they will use the forest destructively in an attempt to survive. Thus, the establishment of parks has sometimes led to a worsening of the situation and may increase forest destruction.

11) Establishment of transportation networks:  Wherever roads or railroads are constructed to facilitate communication among parts of the country, forests are removed. Approximately 70% of deforestation occurs within 50 km of large roads. Eight to 18 million hectares of the Brazilian Amazon is in danger of deforestation within a quarter-century by the proposed construction of only four major roads (Bonnie, et al., 2000). Accessibility to interior and hitherto inaccessible portions of the forest are provided by roads, and people will follow them for mining, homesteading, and extraction. In Costa Rica, a large road building effort was made in the late 1970's and now no forests are left anywhere near the roads (Sader and Joyce, 1988). When Brazil built the Trans-Amazon highway, vast areas of the Amazon basin were opened to logging and farming, and the government has since continued to build roads into primary forests. Economists often assume that access to markets will increase the profit to farmers and will reduce the incentive to cut forests. However, it turns out that obtaining a profit from land encourages farmers to open more land to agriculture in order to increase their profit still more. In Nicaragua, cattle grazing is profitable. Roads built to increase accessibility to these ranches have indeed increased profitability, but the profits have been used to convert more forest land to ranches.

12) Mining and other extractive activities:  Mining and other extractive industries are attracted to rainforests where mineral resources are found. Gold-prospecting, for example, sends people into the forests, where the prospectors utilize toxic chemicals (mercury), cut down trees for fuel, and empty the surrounding forest of animals by hunting. Moreover, many of these industries, particularly gold mining, release toxic wastes. More than 100 tons of mercury have been dumped into tributaries of the Amazon by gold miners (Salati, et al., 1993). These extractive industries also spawn ancillary industries which may demand charcoal, for example, which can be supplied only by removal of more timber, generally in the vicinity of the factory. Interestingly, in Brazil, where there are around 500,000 miners, it is said that most of the gold and gemstones are smuggled abroad, and thus little benefit accrues to the region or to the Brazilian government from this most destructive activity. From 1975 through 1988, the value of these smuggled commodities has been estimated at US$18 billion (Salati, et al., 1993) Oil drilling has destroyed forests in Nigeria and Pacayu-Samiria Reserve in Peru, for examples, and has contaminated large tracts of land.

13) Inappropriate interventions:  Sometimes measures intended to reduce rainforest exploitation boomerang. For example, trade bans to discourage unsustainable harvesting of forests may reduce their value to the country, and increase their exploitation in order to recoup lost revenue. A government ban on logging in Thailand led to a race to cut down all marketable timber prior to the date of institution of the ban. Thailand now has almost no virgin forest left.

14) Dam construction/use of rainforests as hydropower sources:  Dams are becoming ubiquitous on the large rivers of the tropics. They are popular development projects for international aid agencies such as The World Bank. However, they are devastating to rainforests, as they flood large areas of forest, fragment populations of plants and animals, block animal migrations, and inhibit reproduction of both plants and animals. While in 1950, there were only 5700 large dams in the world, now there are 41,000, and they disrupt almost 60% of large river basins (Johnson, Revenga and Echeverria, 2001). Dams are relatively recent innovations in tropical America, being constructed in large numbers only after 1970 when international agencies began to favor and pay for this type of large development project. Dam construction continues apace because of the demand for power in this region. Brazil intends to deliver 50% of its power needs from dams in the Amazon, despite the fact that they produce very limited amounts of electricity (in the range of 250 MW or less). Many dams are ostensibly for flood control, although inundation is a normal state of affairs in areas with monsoons and seasonal forests, and is often essential to maintaining soil fertility, providing food for fish and other animals, and aiding in reproductive migrations of aquatic species.

a. Barriers: Dams affect the aquatic communities of rivers by reducing current flow and by separating the upper and lower parts of rivers with impenetrable barriers. Fish migration is affected, since many neotropical fish migrate long distances, often in complex patterns involving flood plains. Consequently certain species have become locally extinct upstream of dams, such as the dorada, picuda, bagre and patalo above the Betania Dam in Colombia. Similar effects have been seen in fish and shrimp populations on Caribbean islands. Migratory fish have become extinct in the upper Parana River (a tributary of the Plata River) in Brazil/Paraguay, where numerous dams have been built over the past half century. In the Lower Plata basin, catfish are almost extinct, and other fish are declining in population. The population of Chinese paddlefish, endemic to the Chang Jiang River in China, has declined greatly since the Gezhouba Dam was built, as the dam impedes the fishes’ access to breeding sites upstream. This species will doubtless become extinct since it can no longer reproduce. Chinese sturgeon were similarly affected by this dam; they can no longer migrate and the fish is extinct below the dam. Asian river dolphins are endangered by the alteration of rivers. The Indus dolphin population consists of fewer than one thousand animals, the Yangtze dolphin of China, fewer than 200. These are not sustainable population numbers. The Irrawaddy dolphin, an estuary dweller which enters rivers, is gone in many parts of its former habitat, such as the Chao Phya River in Thailand. This dolphin will suffer even more when additional large-scale dams planned for Southeast Asian rivers prevent migration and block access to upstream habitats.

b. Flooding: Dams, by reducing flooding, also adversely affect many fish which depend on flood plains for much of their food supply. These fish may achieve as much as 75% of their growth during the flood season, and juveniles of many species are dependent upon feeding in flood plains. (See the case of the tambaqui, discussed above in Part II, Section F3b). Physical and chemical conditions are also altered in the river waters and reservoirs.

c. Build-ups of organic materials: Organic matter decays slowly in tropical waters, consuming much oxygen. When dams inundate forest areas, the dead plants may not decay for centuries, resulting in oxygen-deprived water and high acidity. During the construction of the Tucurui dam in Brazil, 1750 km² of forest were flooded to produce 7.6 megawatts of electricity (Wolfe and Prance, 1998). This led to oxygen depletion of the water, and the death of many fish. The water below the Balbina Dam in Brazil, which has a reservoir of the same size, is almost completely deoxygenated (Salati, et al., 1993). It produces only 3% (250 megawatts) of the energy of the Tucurui Dam, and has not produced sufficient energy for the city of Manaus, for which this massive rainforest destruction was planned (Wolfe and Prance, 1998; Salati, et al., 1993). In Surinam, 1% of the total land mass of the country was flooded in building the Brokopondo Dam, producing 30 megawatts. The deoxygenation of the water and release of hydrogen sulfide from decomposing vegetation damaged the dam’s turbines and affected animal and plant life as far as 110 kilometers below the dam site. The same is true for many dams in tropical areas.

d. Alteration of water flow patterns: Dams alter water flow patterns by preventing dry- and wet-season variations, which is disastrous for many organisms that are adapted to these natural cycles. Some fish, for example, will migrate and breed only when water levels reach a certain threshold. Reduced discharge below dams also concentrates pollutants.

e. Water retention: Dams affect the retention of water on land. The natural flow of rivers is replaced by substantial evaporation from reservoirs, changes in the drainage systems of large areas and modification of runoff to the oceans (essential for estuaries and continental shelf fertility) and the timing and volume of these discharges.

f. Introduction of exotic species: Exotic species of fish and crustaceans have been introduced into reservoirs, where they have no natural predators, and where they often drive endemic species to near extinction.

15) Poverty and wealth:  It has long been assumed that poverty is a driving force in deforestation. Certainly environmental problems due at least partly to human population growth are aggravated by poverty, particularly in developing and tropical countries. Habitat destruction is occurring most rapidly in the tropics where there are the highest population growth rates, the greatest proportion of poverty, and the least economic opportunity. In poorer countries, people are searching for basic necessities. While people in tropical countries contribute heavily to deforestation in their search for food, fuel, and shelter, in developed countries it is the well-to-do who do so, with their insatiable demand for consumer goods. Here, prosperity is the driving force in deforestation. The global market for tropical hardwoods, for instance, continues unabated, and there is increasing interest in other rainforest products, such as rattan. In a less direct way, human demand for tropical products (coffee, rubber, meat etc.) leads to the destruction of rainforests for agricultural or ranch land. As Soulé (1991) put it, "Habitat destruction and extinction, however, will occur most rapidly in the tropics..., where lack of economic opportunity, demographic momentum, and restrictions on reproductive choice are the engines that power the destruction of life. It is probable that the price of raising human economic welfare to a standard similar to that in the wealthier countries will be biotic devastation in the tropics on a scale inconsistent with the persistence of wildlands...the loss of most tropical wildlands in the next 50 years or so, an epochal catastrophe for earthly life, appears a virtual inevitability."

When, in approximately 35 years or so, the world population doubles, the consumption of food and fiber is expected to rise threefold, the demand for energy, fourfold, and economic activity, fivefold. If people being added to the world’s population (not to mention the current poor) should become more prosperous, few of the world’s ecosystems - particularly rainforests - would survive the onslaught of demand. At present there are great inequities in consumption. The average American uses twenty times as much energy as a person in Bangladesh or Ethiopia or Bolivia, and consumes very great quantities of tropical products - wood, coffee, tea, sugar, soy beans, palm oil. Even assuming no change in current patterns of living standards, most rainforest land is expected to be co-opted for agriculture, mining, housing, and pasture within the next half-century because of human population growth.

16) Excessive extraction of forest resources:  Extraction by local people of resources from rain forests has been touted as a means to save forests by providing economic alternatives to logging and conversion for agriculture. However, we know little about the quantity of resources which can be extracted without affecting forest ecosystems and structure. Much damage has been done to forests by excessive tapping for latex (rubber) or resins and gums (gutta percha and similar products), and by inexpert extractors drawn by the desire for profit. In Southeast Asia, rattan (a more than US$3 billion international business) is being depleted by the great demand. In South America many forests lack Brazil nut seedlings and saplings - perhaps due to the removal of seeds in such great quantities that not enough remain for reproduction of this species.

In many places, animal populations have been severely depleted by unsustainable hunting, in some cases so much so that the forests in which they lived are termed "empty forests." Since large mammals, especially primates, reproduce relatively slowly, the situation is especially grave for them. Unsustainable hunting occurs because human populations in the tropics are burgeoning and, to a lesser extent, because of increasing urbanization, increasing affluence among some groups and desperate poverty among others. More than one million tons of bushmeat are harvested annually from Central Africa, clearly an unsustainable amount (McGraw, 2001; Whitfield, 2003). In many parts of West Africa, the forests have been denuded of wildlife. In Vietnam, twelve species of forest mammals are no longer seen because of excessive demand for meat. The demand for bushmeat is greatest in the vicinity of urban areas, where commercial hunters ply the forests for almost any animal of reasonable size, but villages and towns in or near forests also depend upon hunting for food. Such people must go farther and farther into the forest to find game, since the forests near inhabited areas have already been depleted. Miners, loggers and other who work in forests are expected to provide their own food, and so naturally they hunt. But the instrument for excessive hunting is the demand for timber. Intensive hunting is enabled by logging practices as logging roads open up the forest interior. "The roads into these forests would not be there if it weren’t for the timber industries that build them. And timber trucks are one of the primary means for transporting bushmeat. The global bushmeat crisis is a direct effect of western and Asian commercial interests" (Ebersole, 2001).

17) Philosophical and ethical attitudes:  Underpinning all the causes of rainforest loss listed above are the cultural values which permeate most societies today - an anthropocentrism which centers values on humans. The corollary of this is the absence of an ethical system which considers other organisms as significant or important, or which assumes that human beings are responsible for the well-being of the earth and its other inhabitants. Thus, most ethical and religious systems approve or condone exploitation by humans of nonhuman organisms, and/or the primacy of human concerns over all others. Consequently, only 1.5% of all charitable donations in the United States go to environmental or animal welfare charities, while approximately half goes to religious organizations (Soulé, 1991).

Since the 18^th century, the idea of "progress" (equivalent to development, in many cases) has been prevalent in Europe and other developed areas and has led to destructive uses of natural resources. Human activities - urbanization, industrialization, expansion of agriculture - were and are seen as "progressive," and were (and are) thought to lead to the "advance of civilization." In many countries, one cannot take title to land until it is "improved," i.e., deforested.

18) Economic attitudes:  It’s the short-term! Associated with the philosophical and ethical ideas mentioned in #17 has been an indifference about the future consequences of actions, an interest in short-term gain over long-term sustainability, a preference for free markets, and the idea that everything can be valued in terms of economics (dollars). Over time, as economic systems have become global and surpluses the norm in affluent countries, more and more goods have become available, and, as populations surge, there are more and more people to consume. Population growth, as well as the increasing desire of each individual to have more goods (and an increased ability to pay, in some countries) has led to an increase in consumer demand which shows no signs of peaking. The demand for more goods has fueled destructive activities in tropical countries, which provide many of these goods (exotic woods like mahogany and ebony, beverages such as coffee and tea, pharmaceuticals, precious metals, foods such as chocolate, cheap meat, and bananas). Many of these products are raised not only at the expense of rainforests, which are cut down to provide land or timber, but at the expense of local foodstuffs. Land which had been or could be used for local subsistence purposes is converted for raising export goods - cocoa, coffee, palm oil, soybeans and the like.

Coffee is an interesting example. Globally, there are approximately 11.8 million hectares of coffee plantations, almost all of which have been established in former rainforests. For a long time, coffee trees, which require shade, have been raised on plantations in which many forest trees are retained to provide shade for the light-intolerant coffee trees. These plantations, while not undisturbed rainforest any longer, still provide excellent habitat for a number of species, particularly birds, insects, rodents, reptiles and amphibians. More than 150 species of birds have been reported from coffee farms in Central America. These "canopy farms" provide an income for local farmers as well as retaining the integrity of the forest to some extent. More recently, new varieties of coffee which tolerate direct sunlight have been introduced, obviating the need for a shady tree cover. This coffee is raised on plantations which have been razed of their tree cover, and, because they are so open (coffee trees are rather small and spindly), do not provide a good environment for wildlife. Halweil (2002) states that there are fewer than half as many bird species in "sun" coffee plantations as in "shade" plantations. Trees in sun plantations require huge amounts of fertilizer, herbicides and pesticides, which contaminate the local waterways and soils. Additionally, because all of the forest trees have been removed, there is no chance that the forest can ever grow back when the plantations are abandoned. Half of the coffee now produced in Central America comes from these "full-sun" plantations. Likewise, cocoa is grown on eight million hectares worldwide. Coffee and cocoa plantations occupy 80% of the original rainforest land in Ivory Coast. Oil palms have taken the place of three million hectares of lowland rainforests in Malaysia, which produces half of the global supply of palm oil, and Indonesia, with 2.5 million hectares of oil palm planted, has designated 15 million additional hectares for cultivation of this tree (Hardner and Rice, 2002).

The interest in short-term profits is incompatible with conservation because the benefits of conservation activities will not necessarily be seen for a long time, perhaps for centuries. There is a substantial difference in time scale between economic development projects and conservation projects. Economic development forecloses options; conservation is dedicated to keeping options open. However, as Goodland (1995) maintains, "The south will gain more from a preventive approach than from emulating the short-sighted and expensive curative approach and similar mistakes of the north."

a. Free market economics and the profit motive: In elaborating economic theories, economists have often made the assumption that natural resources exist to be exploited by humans, and that the value of everything - including our environment - can be expressed in terms of money. If, then, everything on earth has to justify itself in terms of its value in the world economy, plants and animals (and other natural resources) are simply exploitable objects, only to be kept if they turn a profit for someone. As expressed by Amelung, Torsten and Diehl (1992), "The tropical rainforest is an economic resource providing a multitude of products and input factors for a number of economic activities and industries. From the viewpoint of the respective tropical countries these resources should be exploited in order to enhance the development process, even if the exploitation of these resources incurs serious environmental problems in the long run." This attitude toward rainforests, not to mention other resources, is widespread and pervasive. In part it is due to the philosophical attitudes mentioned above, in part to greed or unconcern on the part of governments and individuals, and in part to desperation.

b. The international economic order and powerful business interests: The purpose of the current global economic order is to make profits, and, as the components of this system are not tied to any particular social or cultural system (except the capitalistic economic system), their concerns are almost entirely economic. The marketplace rules these global organizations, and it gives high value to wood and wood products, as well as to agricultural and pastoral uses of land. It has little regard for the "ecosystem services" provided by rainforests, and which are essential for the health of the earth. Consequently, species which are popular in international trade (such as rattan and mahogany) usually suffer depletion, and the forests in which they reside are damaged or destroyed. In Papua New Guinea, where local people control most of the forest land, international logging interests override weak and corrupt government controls and persuade inhabitants to sell them logging concessions (usually at very cheap rates). This happens over and over again in tropical countries, in which the forest sector becomes a fief of the multinational logging operations.

c. Local economic benefits: Obviously, local ranchers, farmers and loggers benefit in the short run, in obtaining (at least briefly) some profits from the removal of rainforest. For some, these benefits are very large, especially in comparison with using the forest for other purposes, although their activities may result in losses for others. Consumers elsewhere may obtain cheap goods - foodstuffs, construction materials and fibers, although generally these goods do not substantially alter their standard of living. These sorts of marginal benefits are known as "diffuse gains." For instance, in the 1980's, Malaysia, Indonesia and The Philippines exported 85 million cubic meters of wood (4% of the global wood supply), worth about $3 billion (Katzman and Cale, 1990). While the benefits to the logging companies were great, loss of this supply would have simply shifted the global market toward nontropical woods and increased consumption of wood substitutes. Thus in these cases, the tremendous deforestation occurring in tropical countries (almost complete in The Philippines, and well on the way in the others) has not had a crucial effect on the global economy. Certain groups have indeed been enriched, however.

The same is true of meat derived from tropical cattle ranching. Amazonian meat production yields only 3% of meat imports into industrial countries, although the vast areas of forest converted for ranching are irremediably degraded. In the process of producing wealth for the few, many poor and indigenous peoples - those without political power - are dislocated and marginalized, and people in developed countries lose many values. "In economic terms, tropical deforestation imposes external diseconomies [a cost borne by those not involved in the activity providing the economic benefits] on the remaining inhabitants of the globe. If the polluter always paid [for these diseconomies], the parties responsible for deforestation would compensate the rest of the world for the lost aesthetic, scientific, climatological and economic option values." (Katzman and Cale, 1990, p. 828)

19) A tolerance for greed and corruption:  Corruption in both private and public sectors in many places has led to unbridled deforestation for various purposes, but all in the name of profit. Frequently this involves collusion between the exploiters and government or the bribery of officials responsible for enforcement of conservation regulations or for the protection of reserves. Corruption often begins at high levels and continues all the way down the government hierarchy. Logging companies may bribe government officials for logging concessions, or legislators to keep fees and taxes low, or low-level officials not to enforce regulations. At a local level, village officials can be tempted to ignore violations or to allow logging or extraction to occur where it is not permitted. Ill-paid guards at parks and reserves may be bribed by poachers to close their eyes when animals are killed within the confines of protected areas. Many people in tropical countries depend upon "fees" of this sort for survival because wages are low or agricultural profits limited. These practices are so pervasive that - even should the will exist - eradicating them appears almost impossible.

20) Social structures:  In some countries the social system displaces populations. For instance, poor farmers may lose their land to large agricultural interests, mining concerns, road building, and other ventures over which they have no control. Many of them are thus forced to go into the forest to survive. Uncertain land tenure and property rights systems also lead to the displacement of small farmers, as they may not be able to establish ownership of their land. In many tropical countries, also, societies are changing rapidly and traditional cultures are being homogenized into the global mainstream. Traditional or indigenous cultures have low populations and often have evolved life styles amenable with resource conservation. Although they use the resources of their environment, they generally do so sustainably and not destructively. As they are uprooted and incorporated into more urban environments, they lose the connection with nature and the intimate knowledge of the forest which previously had permitted their survival (and the survival of the forest). The most rapidly-changing or colonizing cultures tend to be the most destructive, since they are moving into uncharted territory (literally and figuratively) and have no intimate connection with their new landscape. They have not developed mechanisms for living comfortably and sustainably in their new environments. Poor, transitional cultures place little value on protection of nature, and wealthier, rapidly-changing societies also frequently seem to be uninterested in it, particularly if the "nature" is far distant.

21) Wars and disruptive social change:  The many civil wars in tropical countries bleed them of resources which might otherwise be used to improve the standard of living or for conservation. Wars also frequently result in a breakdown of civil authority and even governments. The last thing of interest in a country involved in a foreign or civil war is environmental protection. In many countries, wars have been disastrous for reserves and other protected areas; habitat is destroyed and species (particularly large animals) become extinct in battle and refugee areas because of hunting pressures. This has occurred particularly in Africa, where many civil wars have raged in rainforest areas - in Zimbabwe, Uganda, Mozambique, Rwanda, Burundi and the Democratic Republic of the Congo. Similar wars have occurred in East Timor and parts of the Philippines, and another has been simmering for years in the province of Aceh in northern Sumatra. And the drug wars in South America - Colombia, Ecuador, Peru - often involve forested areas. Frequently guerrilla fighting occurs in forests, or anti-government forces establish camps in the forest, using it for survival, and often hunting animals to local extinction. Skirmishes between rival groups disrupt agriculture and animal husbandry, leading people to exploit the jungle for survival. Civilians in contested areas will often leave their villages and hide in the forest, where to survive they must hunt for plants and animals. The recent involvement of civilians in wars has thus been very destructive of forest well-being in unsettled countries.

22) Ecotourism:  Ecotourism is already a very lucrative industry and is often mentioned as an activity which can help save rainforests (see below), but this is not always the case. In Kenya, national parks generate $40 per hectare per year from tourism (as opposed to $0.80 per hectare for agriculture). Each lion is worth about $20,000 annually (Dobson, 1995)! Yet, ecotourism can be problematic, since the profits from it often go to a few wealthy individuals and not to local people; thus the incentive to the latter to preserve the park or resource is absent. The incursion of agriculture and pastures and illegal logging, fishing and hunting are often the result. In addition, ecotourism is not an unmixed blessing, as a large number of tourists is not entirely benign. Overuse of roads and waterways, disturbance of animals, disruption of migration patterns, littering, and pollution coincident upon the use of motorized vehicles (including boats) are frequent. Moreover, ecotourism can have unexpected consequences. In Nepal, rapid growth in the tourist industry has promoted deforestation. Since tourists arrived in large numbers, there has been an increased demand for dairy products. The result - forests cut to provide cattle pasture to meet this demand. Tourists also require a great deal of water, which can stress local supplies. About 15,000 m³ of water are required to irrigate one hectare of high-yield rice for a year, or to supply 100 nomads and 450 cattle for three years, and 100 urban families for two years, but this amount of water will supply 100 guests at a luxury hotel for only 55 days (Dobson, 1995)! Food supply - type of food and quantity - can be another problem. And the capriciousness of tourism creates "boom and bust" cycles for local inhabitants.

In general, park entry fees (if any) are too low to cover the costs of damages tourists do and to provide incentives for local inhabitants to preserve rainforests (or other ecosystems). Often, the revenues from ecotourism are not reflected back to the resource. A non-forest example of this is in Kenya, which receives $40 million annually from tourism, but gives only $13 million to the wildlife service. Only $20 of the thousands of dollars spent by a tourist on a "safari" goes for conservation (Dobson, 1995).

23) Distrust of government:  Many people in tropical countries have little confidence in their governments, or in their policies. Government agents are often corrupt. In some cases the government establishes protected areas without consulting local communities and is thereby seen as arrogant and dictatorial. The military is sometimes used to guard these reserves, and, generally, is not viewed favorably by the community or seen as protecting their interests. They are frequently correct in this assumption, unfortunately.

We have artificially separated the many causes of rainforest destruction, but of course many of them are interrelated. The driving force for most deforestation is the rapidly increasing human population in all of the countries which encompass rainforests within their boundaries, as well as in other countries which provide the consumer demand for tropical products. In the past, exploitative activities were at least sometimes compatible with rainforest regeneration because demand was relatively low; now, however, the demands upon rainforests are far beyond their carrying and regeneration capacities.

Goklany (1998) summarizes the major causes of rainforest destruction as follows: "...changes in forest cover seem due to population pressure for agricultural land (particularly in Africa and Asia), poor government policies (e.g., subsidies, resettlement schemes, and creation of water reservoirs), domestic demand, uncertain land tenure and property rights systems, social structures that displace various populations who then have to resort to deforestation, and corrupt political structures."

Rainforests have a measure of control over many aspects of our environment, and are responsible for much of the terrestrial productivity. These we can call the "essential services" of natural forests.

1) Preservation of biodiversity, which is invaluable to forest productivity (see Part II).

2) Renewable source of forest products, such as timber, medicines, fruits -not to mention chocolate! There is the potential to discover many new foods, domestic animals, industrial products, and medicines in rainforests. Most obviously, rainforests are a source of valuable timber - mahogany, ebony, hard wood dipterocarps from Southeast Asia, and many others less well known. Wood has many properties desirable to humans and animals. It is hard, durable, resistant to many organisms such as fungi, resistant to water, useful as fuel (including charcoal) and as construction material. But in addition, many rainforest plants produce insecticides, herbicides and fungicides which could be useful to humans. For example, leaf-cutter ants will not remove leaves from the tree species Hymenaea courbaril because its leaves produce a fungicide which will kill the fungus the ants cultivate in their gardens (Robinson, 1988) Capuchin monkeys in Venezuela rub themselves with millipedes (Orthotomus dorsovittatus) which secrete benzoquinones, noxious compounds which repel mosquitoes (Angier, 2000). (The massaging may even become a social ritual, with monkeys mutually massaging each other.). A number of plants and trees in the rainforest have proved useful as producers of medicines, and many drugs have been found in the pharmaceuticals of tropical medicine men. Quinine, the first known antimalarial, comes from a neotropical tree, and curare, used as a poison for arrow tips by indigenous peoples in the Neotropics, is also useful for heart conditions. One quarter of our medications come from natural sources; additionally, about 70% of the drugs used today are models of natural chemicals. Most of the medicines from forests have been derived from plants, but many others come from fungi, bacteria and reptiles (snakes). Others remain to be discovered, since less than 0.1% (about 1100) of known plant species has been examined for potential medicinal use. The search for potential medicines and drugs ("chemical prospecting") is a strong argument for rainforest preservation. It is difficult, however, for a tropical country to receive benefits from the development of pharmaceuticals from their rainforests.

3) Reservoirs for genetic resources and centers for evolution: As we continue to deplete the organisms on earth and homogenize our genetic resources, we increasingly need sources of genetic variability. Since rainforests are so amazingly diverse, they can provide a vast reservoir of genetic potential. Without such genetic resources, we will have no way of improving breeding stocks of plants and animals. All of our domestic plants and animals came from wild antecedents which have been altered by interbreeding and selected for traits which are favorable for human use. As we reduce or eradicate our gene pools, our sources of variability decline dangerously.

4) Regulation of hydrological functions: This is both local and global. Rainforests stabilize water flow, maintain water quality, provide watersheds, and regulate runoff of water from soil. In doing so, they prevent flooding, erosion, landslides, and desertification. Erosion is one hundred times greater on deforested than on forested slopes, for example.

5) Regulation of air quality: Rainforests modify atmospheric chemistry (e.g., they can act as "carbon sinks" and absorb CO₂ from the air (see Part I, Section K).

6) Climate stabilization: Rainforests have an influence on rainfall patterns. The humidity and cloud cover over them affect the climate in many other parts of the world. Rainforests create their own moist environment by recycling rainfall. If they are removed, entire regions become drier, and the rainforests remaining may not be able to maintain conditions sufficiently humid for their own survival. Thus, a destructive cycle ensues. Dessication will not simply be local, but regional and global (see Part I, Section K).

7) Soil fertility and retention: Without plant roots, particularly tree roots, to hold them, thin tropical soils are washed away by heavy tropical rains. Soils in deforested areas cannot retain fertility, since most of the organic matter in a forest is in the vegetation, not in the soil, as is the case in temperate forests. Once some of the vegetation is removed, soil humus levels drop precipitously, with a concomitant loss of fertility. And with little vegetation, the complex soil communities of animals, fungi and bacteria are disrupted, severely impeding the possibility of restoring fertility (see Part I, Section L).

8) Control of pests/parasites: Forests are filled with animals (and even plants) which prey upon pests or potential pests (mainly insect) of crops or domestic animals. Complex forest ecosystems are much less subject to outbreaks of infestation or infection than are tree plantations or farms.

9) Pollination services: Many of the animals in forests are the sole pollinators of many forest plants, and they are often highly specific to the plant(s) they pollinate. Loss of forest cover and thus, of animal habitat, has caused and is causing serious problems with the reproduction of forest trees (see Part II, Section F1).

10) Sources of education and knowledge: This includes biological and medical research of all kinds, as well as education for people about natural systems, climate, biodiversity, and soils.

11) Sources of housing for people and animals

12) Aesthetic factors and sources of recreation

13) A potential source of insight into the relationship between human groups and forests. Not all human societies have had destructive relationships with rainforests, and we need to know about these harmonious relationships as a source of information about agriculture, husbandry, etc.

14) As wilderness, for its own sake

15) Ethical reasons: Humans, at the moment the dominant species, have a responsibility to protect the earth.

The "services" which forests provide are incomparable; nothing can be substituted for them. Most human efforts to make such substitutions have ultimately been unsatisfactory. These efforts have amounted to serious interventions into natural systems, and add to the human impact on ecosystems and the environment. Among these interventions have been the replacing of natural controls with synthetic pesticides and natural soil maintenance by inorganic fertilizers. Rainforest services are invaluable (although estimates have been made of their monetary worth (see Part II, G8) and it is not an overstatement to say that their economic worth is incalculable or infinite, since we are totally dependent upon other living organisms for our existence.

F. Consequences of deforestation: What happens when tropical forests are logged?

1) Damage to remaining trees and other vegetation and increased fire susceptibility:  Even when timber extraction is carefully done, with only selected trees being removed, much damage is done to the remaining forest. Roads must be cut, trees dragged out with bulldozers, and "landings" constructed to hold the logs. There is much subsidiary damage; many other nearby trees and vegetation are damaged or killed (uprooted, trunks broken, bark lost). Alper (1993) reports on studies in which it was found that extraction of 10% of trees can destroy up to 50% of the canopy, with skid roads and roads damaging another 10% to 20% of the area. This does not leave much of the forest unscathed. Similar results were found in Malaysia. For the 10% of the trees harvested, 55% of the remaining ones were damaged or destroyed. And in Sarawak, only 21% of the trees remained intact after logging (Jacobs, 1988). After the desired trees are removed, a great deal of debris ("slash") remains - broken branches, trunks, uprooted underbrush. Because the canopy has been opened, more sunlight strikes the ground, heating it and reducing humidity. These alterations in microclimate lead to changes in the understory vegetation, which is no longer shaded and protected from high temperatures by the canopy. Under these conditions the slash and surrounding forest become highly vulnerable to fire.

2) Impoverishment of soils and erosion:  Soils, as complex ecosystems in themselves, are essential to any future use of rainforest lands. Logging and/or burning remove soil-stabilizing elements - the roots of trees and soil microorganisms. Heavy tropical rains then wash away topsoil and litter, removing nutrients and silting rivers and reservoirs. The nutrients eventually wash into the ocean, causing eutrophication of tropical estuaries.

When forests are cut and burned, the ash and decomposed vegetation release nutrients into the soil. The soil, thus enriched, can support two to three years of growth of shrubby and herbaceous plants, after which nutrient levels fall below that necessary for agriculture. Because of this, cropping in tropical areas is transient, necessitating the abandonment of fields within a few years. Why is this so?

a. Alterations in soil nutrients: Tropical forest soils are often (but not always) very poor and thin. There is generally very little external input of nutrients, so soil fertility depends on an extremely complex system of nutrient cycling based on the decomposition of leaves, dead plants and animals due to the activities of soil flora and fauna (see Part I, G5). This provides most of the nutrients in the soil, but they are rapidly taken up again by the plants, leaving little organic material in the soil. This elegant and fragile system, which permits rainforests to exist on poor soils, is seriously disturbed by logging. When the vegetation cover is removed, nutrients are leached out by rainfall, which also washes away the delicate layer of topsoil because of high water flow rates. The worst offenders are the areas (skid trails, log landings) where the vegetation, litter and topsoil have been scraped away. The remaining soil is left with high levels of quite insoluble compounds of iron and aluminum oxides, but little organic matter (carbon compounds). Since most organic matter is in the vegetation, removing trees reduces many nutrients (and potential organic matter), while burning volatilizes carbon, nitrogen and sulphur. Soil fertility does not return for decades, and if logging is done on a short rotation cycle, so many nutrients are lost that the forest may not be able to recover.

Tropical forests contain twenty to fifty times more carbon in their vegetation than do agricultural lands which replace them. Closed forest is estimated to contain at least 116 metric tons of carbon per hectare in the soil and vegetation (Houghton, 1995), whereas carbon levels in the soil after cultivation are reduced by as much as 50% within five years of forest cutting (Matson, 1997), from between 36%-70%, according to Lodge, et al., (1996). In areas of the Amazon rainforest which were converted to sugar cane plantations, soil carbon levels fell 83-93% within 12 years (Lodge, et al., 1996). Other estimates indicate that the conversion of forests to agricultural land can cause a 40% reduction in soil carbon levels, conversion to pastureland, a 20% reduction. Shifting cultivation causes declines in soil carbon of 18-27%, and fallow periods of at least 35 years are required to for soils to regain their original carbon content (Detwiler and Hall, 1988). Erosion, topsoil removal by machinery, and soil oxidation further reduce carbon content and soil fertility. Loss of forest area also generates ancillary damage. A study done in Malaysia found that an 18% decrease in forested land reduced biomass by 28% (Brown, Gillespie & Lugo, 1991). For every ton of carbon released by deforestation, 0.6 tons more of carbon were released by the reduction in biomass of the forest surrounding the cleared area due to degradation, mostly from "selective" logging and other exploitative activities. The 38% of forest area lost in Southeast Asia between 1880 and 1980 has led to a 50% loss in biomass (Houghton, 1995).

b. Irreversible changes in soil structure: The clearing of forests also exposes the soil to sun and oxygen. In some soils, chemical changes occur in the soil under these conditions, resulting in the formation of a rocklike material, laterite. This has occurred in many places, and is not only a modern phenomenon. The temples at Angkor Wat, in Cambodia, were built 600 - 1000 years ago of sandstone and laterite. Some have speculated that the downfall of the Khmer civilization was due to forest clear-cutting with resulting laterization of the soil, rendering it unfit for agriculture or, indeed, any productive use. The same has happened in many places in the Amazon, producing "pavements of rock." Only certain tropical soils are suitable for agriculture or ranching. In addition, the use of heavy machinery compacts tropic soils, reduces the ability of seedlings to root, and diminishes soil aeration and water absorption.

c. Loss of soil seed banks and seedlings on the forest floor, and damage to the shallow roots of trees remaining after cutting. Seeds in the soil and seedlings on the forest floor are lost during logging procedures. Plants other than trees are very important in forest ecology and are trampled, damaged or removed.

d. Loss of microbial flora and invertebrates in soils: Microbial decomposition of organic matter is the major source of soil carbon. Many fungi and bacteria which are vital in decomposition and nutrient cycling are vulnerable to disruption by the removal of trees because they are sensitive to the moisture fluctuations and increased forest floor temperatures caused by the opening of the canopy by logging. Among these organisms are nitrogen-fixing bacteria without which plants cannot survive, as soil nitrogen stores need to be replenished. Recolonization by bacteria of disturbed areas may not occur because they cannot normally be disseminated over large gaps. Mycorrhizal associations with tree roots are also disrupted.

e. Erosion: Land under forest suffers erosion rates of about 0.2 - 10 tons per year per hectare. The densest man-made forests (plantations) have erosion rates of from 20 - 160 tons per hectare per annum; grassland, about 200 or more tons; and primitive agricultural systems, 1000 tons per year (Jacobs, 1988). Removal of forest cover in Ghana increased the soil erosion rate from one ton per hectare per year to more than 100 tons (Repetto, 1990). In many places, removal of forest cover has led to desertification. In 1882, 9.4% of the land area of the earth was desert and wasteland, but by 1952, 23.3% of land surface had been classified as such. This correlates with the great decrease in global forest cover, from 43.9% of total land surface in 1882 to 21.1% in 1982. The Sahara Desert is largely manmade. The forest cover was removed, the land was overgrazed, and poor irrigation methods were used. Unfortunately, we have not improved our record since, as the Sahara continues to expand southward by several miles per year. The Thar Desert in India was forested 2000 years ago, but is now extremely dry as a consequence of logging and overgrazing. It is spreading outward by five kilometers per decade and has increased in size by 60,000 square miles in the past 100 years. The same is true of the central plain of the Irrawaddy River in Myanmar (formerly Burma), which not so long ago was forested, and is now arid and barren.

f. Reductions in agricultural yields: As deforestation alters climatic conditions, reducing rainfall, and causes erosion and floods, agricultural production has fallen in many areas. Rice production in some places in Southeast Asia has declined by more than a quarter since deforestation has become rampant.

3) Loss of biodiversity (including genetic diversity):  Extinction is not new. It has occurred continuously since life began, and there have been a number of extinction crises in the past. However, the current paroxysm is the first great extinction brought about by human activity (although we suspect that prehistoric humans were involved in the extinction of a number of large mammal species, and perhaps some species of fish and shellfish) (See Part I, D1.) The "natural" rate (i.e., the rate not affected by human activity) is about one species per year. The current rate is much higher, but since we do not know how many species there are, it is impossible to know with exactitude how many are lost annually.

Tropical rainforests are, with coral reefs, the most endangered ecosystems in the world, and are vulnerable to a substantial loss of biodiversity. Deforestation depletes biodiversity by destroying habitat, by separating contiguous areas of rainforest from each other, by interfering with plant reproduction, and by exposing organisms of deep forest to "edge" effects (Part II, G5). Logging does not simply remove a few trees from the forest. When canopy trees are cut, many smaller forest trees and plants dependent upon them for shade or support or moisture vanish. Animals dependent upon trees or other vegetation for food, shelter, water, and breeding sites also disappear. Only those animals (generally the larger ones) which can migrate to contiguous forest areas survive. Plants in cut-over areas often cannot be pollinated, or if they are, their seeds fall upon unsuitable open areas where they cannot survive. In addition, many rainforest species are restricted to relatively small areas and are found no where else. When the areas in which these species reside are logged or burned, they will disappear.

Logging activities push roads into previously untouched forest. Even if logging is selective, the logging roads and tracks made to pick up the cut trees cause damage to soil and plant life. Erosion is common along these roads. And since roads create openings where none previously existed, the forest now has a long "edge," where conditions are very different from a normal forest interior (there is more light, temperatures are higher, humidity is lower). As we have seen, species adapted to the conditions within a forest interior cannot survive along the newly-formed edges. If areas are clear cut, the problems are exacerbated. (For a more detailed discussion of these issues, see Part VII; Part II G5f.) Additionally, the loggers hunt animal populations previously untouched. And the roads act as conduits into the forest where people can penetrate relatively easily. People follow the logging roads in search of agricultural or grazing lands, and they deforest more areas along these roads. And they, too, hunt, for subsistence and for sale of "bushmeat" to the burgeoning cities of the tropics. Modern tools make these colonists much more efficient than formerly, for they now have shotguns, chainsaws, and outboard motors.

Ancillary consequences of deforestation are common. Pollution, silting and other damage which results from logging lead to declines in biodiversity. In Malaysia, more than half of river fish species disappeared after logging activities, for example (Ryan, 1992). Amphibian populations in tropical areas have declined or disappeared under the multiple stresses of habitat loss, pollution and disease.

Many of the species being lost are vital to the preservation of our ecosystems, or to significant parts of them. Others may have potential value to humans in terms of food or medicine. It is shocking and surprising to learn that 85% of the food which humans eat comes from only 20 types of plants, and that two-thirds of it comes from just three: rice, maize and wheat. Humans must find new sources of food so that, should some pestilence strike one of these vital crops, famines would not occur. Some of these food sources might yet be found among the species which are thoughtlessly being extinguished in rainforests.

As has been pointed out, biodiversity losses of today are comparable to the great mass extinctions of eons past. After the Cretaceous extinction, 65 million years ago, it took between five and ten million years for mammals and coral reefs, and 25 million years for other marine organisms to regain species richness equivalent to previous eras. After the Permian extinction (250 million years ago), when half of the marine invertebrate families were lost, twenty million years were required for recovery (Myers, 1988a). Recovery from the current human-induced extinction will doubtless require even more time, since we are eliminating both animals and habitat. Where can new large species evolve? Most endangered now are large mammals, since they are the easiest to hunt, the lowest in numbers, and require the largest habitats and ranges. The organisms which will remain will be a more homogeneous lot, "generalists" like humans, organisms which can survive in contact with humans and in the chinks we have left for them. They need to be able to reproduce rapidly, disperse widely, and live under difficult conditions. They must be "weeds!" We are selecting for rats, cockroaches, invasive grasses - all of which are tough and can live in disturbed environments. These "weedy" species represent only a small fraction of the rich variety of organisms which exist today (but there are fewer every day). They will soon form a much higher proportion of existing organisms, as the gene pools which allow for evolution are rapidly shrinking.

Examples of biodiversity loss:

a. The case of mahogany(Swietenia macrophylla):

Mahogany historically has been logged unsustainably, with timber companies and loggers extracting all available trees and moving to new areas when the local supply becomes exhausted. By 1735, mahogany had become rare in Jamaica and loggers moved on to Central American countries for their supplies. Two species of mahogany (the Caribbean and Pacific coast mahoganies) are now virtually extinct; the supply of mahogany now comes from a third, South American species. This species will no doubt go the way of the others unless incentives for its preservation are provided, since logging in the tropics is done with little government oversight and few incentives to operate sustainably. CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora, an international agreement which regulates international trade in specified species of endangered plants and animals) and regulatory bodies have been of use in the protection of certain species of animals, but not of plants and trees. Involved countries (which profit from mahogany trade) have blocked the listing of mahogany by CITES several times, although mahogany regenerates slowly, logging of this species is virtually unregulated, and the mahogany supply is dwindling rapidly (Gullison, et al., 2000). Boycotts of mahogany products have been effective locally but not globally, and have not provided sufficient incentive for preservation. Very recently, CITES, bowing to great international pressure, has listed mahogany as an endangered species.

b. The case of Borneo:

Here are the results of research on the changes in biodiversity in a particular area of Malaysian Borneo (Bennett and Dahaban, 1995). One year after logging began in one area surveyed, there was no significant change in the total number of species, but some species, such as the Burmese brown tortoise, the rail babbler, and the four-striped ground squirrel, had disappeared from this area, and populations of ungulates, primates and hornbills (despite their protected status) were significantly lower. Hunting of many of these animals was far above sustainable levels. Squirrels thrived, since the removal of their larger food competitors left them greater food supplies (fruits, seeds). Some species - tree shrews, magpie robins, and bulbuls - species not previously found in the forest, but which are tolerant of disturbed areas, appeared to replace the species dependent upon undisturbed forest. Two to four years after selective logging, primate and mammalian species diversity was lower, except for ungulates. Hunting did not so much reduce the number of species present (although some species disappeared) as it did greatly diminish the abundance of animals. Generally, then, with the advent of selective logging and shifting cultivation, there were shifts in species, with edge-tolerant and colonizer species replacing primary forest species. There are frequently unintended and unanticipated consequences of forest removal. For instance, flying foxes are the only known pollinators of some forest trees in Borneo, but as they are heavily hunted, some tree species will disappear. Civet cats are major seed dispersers necessary for forest maintenance and regeneration, but as they are hunted to near extermination, the forests will be unable to sustain themselves. We know little of the eventual consequences of removing large animals from the forest ecosystem, and even less about forests’ needs for various smaller animals, or insects or plants.

4) Loss of genetic resources and evolutionary potential:  This is closely related to #3. Leakey and Lewin (1995) called the tropical rainforest a "cauldron of evolutionary innovation." As species are eliminated or their genetic variability is lessened by population depletion, we lose the potential for producing new varieties of food, fiber, medicines and other crops. Genes cannot be manufactured; we need the genetic resources of current species to provide new and improved varieties. This is especially critical as the size of the human population continues to climb. Since much of the suitable agricultural land is already being utilized, providing sufficient food and other materials for our burgeoning population must come from the manipulation of genetic resources - "manufacturing" new crops and animals by selection, and by the development of transgenic organisms.

5) Changes in the water cycle:  Trees recycle 50% or more of the precipitation striking rainforests through evaporation and evapotranspiration. These processes are extremely important in the hydrological cycle and in large-scale movements of water vapor, and, thus, climate stabilization. When trees are removed, there is a decrease in the amount of transpiration (the cycling of water from vegetation to soil or air and back). Since tree roots penetrate more deeply than those of grass or replacement vegetation, tree loss reduces water uptake, which still further reduces evapotranspiration. This causes a diminution of rainfall (because there is less moisture in the air), less cloud cover, and increased aridity. Temperatures become more extreme because of reduced cloud cover and because of the reduction in evapotranspiration, which has a cooling effect (similar to the cooling of one’s skin by evaporation of perspiration). In deforested areas in the Amazon, there may be an increase of as much as 40% in local annual temperatures. There is evidence that if a critical amount of rainforest is removed, such changes will be sufficient to reduce rainfall below the level required to support the remaining rainforest. It may all be reduced to arid scrub and grassland.

6) Changes in water levels and erosion:  Forests are storage mechanisms for water, both in the soil and in the organisms which live in them. Tree roots are essential to hold soils, which in turn are able to absorb vast amounts of rain water. With deforestation, surface runoff increases and flooding and silting of dams, rivers, and of river mouths often ensues. Another consequence of deforestation is that more water remains in the soil, as few deep roots remain to take it up, so that there is excess groundwater which enters streams, lakes and rivers, raising water levels. Serious flooding occurs regularly in areas where forests have been cut, in tropical as well as temperate areas. Deforestation in mountainous areas leads to swollen rivers, as water runs off the bare hillsides. These rivers overflow their banks, causing destruction to human habitation as well as to agriculture. Deforestation, coupled with the seasonal alternation of monsoon and dry season in Asia, has led to great changes in water flow from rivers, and, frequently, to flood or drought. This has encouraged the construction of more dams for flood control (which further alters the water flow). In Thailand, unrestrained logging had reached such levels by 1988 that the mountainous northern part of the country was engulfed in massive floods, with villages buried in mud slides and logs from clear-cut hills. In the Philippines, a similar disaster struck in 1991 when a typhoon triggered flash floods in areas which had been clear-cut by logging. Bangladesh is notorious for the recurrent floods which occur on lowlands cleared of trees by a growing population needy of fuelwood (Fornos, 1991; Sponsel, Bailey and Headland, 1996).

7) Changes in vegetation:  The removal of forest cover often leads to the invasion of weedy and undesirable plants, which have seeds more able to survive heat and dryness. Species which are best able to adapt to new extreme conditions will become the dominant plants. For example, the babassu palm, Orbignya phalerata, is highly tolerant of such conditions and has colonized deforested areas along the Transamazonian Highway, as well as swamp forests along the banks of small tributaries and upland plateaus in which gaps have been formed by deforestation. The invasion of this palm decreases the development of canopy trees by shading their seedlings and smothering them in leaf litter.

In the Neotropics, in general, there are many slow-growing, shade-tolerant trees which do not grow well in large gaps, and relatively few with light-tolerant seedlings, so that large gaps are often filled with woody climbers and fast-growing sun-loving trees such as Cecropia. In other cases, the drier and hotter conditions after deforestation have led to the invasion of cut-over areas by grasses and scrub trees and the conversion of the forest to savannah or grasslands. Natural reforestation occurs only where there are large "banks" of seeds remaining, particularly those of climax species. In Para State, Brazil, many cattle ranches were abandoned when they became unprofitable, but since no tree seeds or seedlings remained, the pastures became filled with low, woody vegetation rather than rainforest trees.

8) Climate change and increase in greenhouse gases:  "Greenhouse gases" are atmospheric gases which have been accumulating in an unprecedented fashion in recent years. They have been cited as major factors in the increase in mean global temperature which appears to be occurring at present. Most important among these gases are carbon dioxide (CO₂) and methane (CH₄). How is this related to tropical forests? Changes occurring during deforestation include the movement of carbon (as CO₂) to the atmosphere from vegetation which is burned to make agricultural fields, the release of carbon from decaying vegetation ("slash") remaining after logging, and the loss of carbon when wood products are removed from the site. On the other hand, if and when forests regrow, carbon is returned to terrestrial systems by the incorporation of CO₂ from the atmosphere into new plant material.

The data on the release of carbon to the atmosphere from deforestation is quite variable. According to recent studies in the Brazilian Amazon, during land conversion, 20% of forest biomass is burned, 70% remains on site as slash, 8% becomes wood products, and 2% is released as CO₂ by burning (Houghton, 1995; Houghton, et al., 2000). Approximately 0.18 - 2.0 petagrams (1 petagram [Pg] = 10¹⁵ g) of carbon are released annually by deforestation in this region, but the rapid regrowth of young forest on abandoned agricultural land absorbs about the same amount. (As a reference, the global aboveground plant biomass is estimated as between 568 and 651 Pg of carbon [Potter, 1999].) In this case, the absorption of carbon by the natural ecosystem is able to overcome the release of carbon to the atmosphere by respiration, fire, and logging. Other studies suggest that deforestation is a substantial source of atmospheric carbon, in fact, the second largest source of atmospheric CO₂ after fuel burning. Tropical deforestation has been estimated to add (net) from 0.4 - 4.2 Pg of carbon per year to the atmosphere (Palm, Houghton and Melillo, 1986), while Detwiler and Hall (1988) gave an estimate of the same order, 0.4 to 1.6 Pg per year. Scholes and Noble (2001) estimate 1.6 Pg annually. Potter (1999) estimated that 1.44 Pg of carbon is released to the atmosphere annually by deforestation, offset somewhat by 0.29 Pg/yr accumulated in vegetation and soil by regrowth and expansion of forests. The net release of carbon to the atmosphere by deforestation amounts to approximately 20-30% of global carbon emissions (Kremen, et al., 2000). Slash-and-burn agriculture also adds to the production of CO₂ released to the atmosphere because farmers burn fields every few years. Such methods add approximately 1.6 metric tons of carbon annually to the atmosphere, as well as other greenhouse gases such as nitrogen oxides and hydrocarbons (Kaiser, 1997). Nitric oxide is another greenhouse gas released during forest burning. It is not only the immediate effects of deforestation which provide a source of carbon dioxide; there are long-term effects as well. Since organic material below ground decomposes more slowly than surface biomass, disturbed soils will continue to release carbon for decades after the forest has been removed.

Recent calculations by Cox, et al., (2000) indicate that land temperatures may rise by as much as 8^oC because of increased CO₂ in the atmosphere (an additional 600 Pg by the year 2100, or 6 Pg annually) due to a reduction in the ability of the oceans to absorb this gas and because of the deforestation and collapse of the Amazon rainforest. Collapse would be a consequence of increased aridity (as discussed above) and an enhancement in the respiration of soil organic matter because of higher temperatures. In other words, the earth would be losing six Pg of "carbon sinks" per year directly by rainforest removal and indirectly by the effects of global warming (much caused by deforestation) on still-standing forest. Rainforests must suffer the double insult of being the cause of their own destruction! They also calculate that mitigating the loss of these sinks would cost about $200 per ton of potential carbon emissions, or US$1.2 trillion per year.

Thus, the removal of forests, at least partly through its effects on atmospheric gases, may lead to destabilization of the global climate. These climatic changes may reduce agricultural and natural productivity, and will certainly adversely affect tourism, transportation and forestry activities. There have already been shifts in boreal forests, which are retreating northward because of global warming. Many animals have already altered their migration times and reproductive seasons. This may have negative consequences when their life cycles are out of synchrony with their sources of food and shelter. Growing seasons for plants have increased by several days in some places. Increasing temperatures have allowed the invasion of nonnative species into some ecosystems, as well as alterations in the species composition of these ecosystems (Walther, et al., 2002). At the very least, the complex interrelationships which have evolved over millions of years are being and will be further disrupted by continued warming.

The enhancement of photosynthesis and growth (and, so, carbon uptake) which occurs with higher temperatures has been mentioned as a possible mitigating factor in climate change. However, there are limits to how much additional growth can be expected by warming. Most plants have either physiological or physical limits on growth, and, also, as plants age, they grow more slowly and consume less carbon dioxide.

9) Difficulty of reforestation:  Although tropical rainforests can regrow under natural conditions, where clearings are caused by floods, storms, or treefalls, they cannot regenerate under many current land-use practices. Forests regenerate poorly if at all when large areas are logged, the soil is damaged or removed, or erosion is severe. Rainforest ecosystems are vulnerable to disruption because of their internal complexity and interdependence. Because there are few individuals of any one species, removal of even small numbers of them has a substantial effect on species composition and interrelationships in the forest by depressing reproduction, and long periods of time will be required to reconstruct viable populations. Forests are also dependent upon their closed nutrient cycles; disruption of these cycles by exposure and extraction of trees can cause their destruction.

If the land has been cleared for a long period of time, reforestation occurs slowly or not at all, due to the lack of suitable seeds and seedlings, increased ground temperatures, decreased humidity, and the like. Near the temples at Angkor Wat in Cambodia, the forest, which has been regrowing since the destruction of the Khmer empire in 1431 A.D., is still not the same as the surrounding original forest. The same is true of the forest which has regrown in the aftermath of the collapse of the Mayan and Aztec civilizations more than 500 years ago. It may take one thousand years for a rainforest to recover its original level of biomass after clearing and burning, since few seeds and seedlings of rainforest plants can survive burning. This is in marked contrast to temperate forests, which may regenerate within 100 years. In areas where the soil is compacted, as occurs when heavy logging machinery is used, there is little recovery of rainforest trees, even after decades, since compacted soil inhibits root growth. In Malaysia, a field which had been abandoned in 1944 was not colonized by any dipterocarp (the huge hardwoods which dominate Southeast Asian tropical rainforests) until 1976. Also, in Brazil, abandoned cattle pastures in Para state reforested to some degree, but climax forest was not attained, since there were no seed trees remaining in the vicinity (Whitmore, 1998).

Southeast Asian forests are dominated by many species of dipterocarps. Dipterocarps are quite varied, but many species produce seeds synchronously every three to six years ("mast" fruiting). Since dipterocarps are highly desired for timber, logging of these forests has been intense and largely uncontrolled. Fragmentation has caused changes in tree density, distribution, seed production, and climate, and has greatly reduced the ability of the dipterocarps to reproduce. In a recent study in a national park in Borneo (a protected area surrounded by logged forest), fewer species than previously were able to produce viable seeds, and no new seedlings were found several months after fruiting. This is in comparison with 155,000 seedlings per hectare found in 1991 (Hartshorn & Bynum, 1999; Curran, et al., 1999). Obviously, reproductive failure of the major tree species in the forest will substantially alter the proportions of species and entire ecosystems dependent upon them.

10) Increase in physical disturbances:  Normally, rainforests rarely burn. In Amazonia, natural fires occur at an estimated rate of one fire every several hundred to several thousand years (Cochrane, et al., 1999). Primary forests are much more resistant to fire than are either secondary forest or selectively-logged forests. Human activities - leaving "slash" after logging and opening the forest by logging - reduce humidity, raise temperatures, and increase the probability of spontaneous fires. Such fires in themselves reduce the viability of the forest by removing most of the seeds and seedlings which could permit the area to reforest. A huge fire in Borneo in 1983 burned 3.5 million hectares of land after a drought, and similar extraordinary conflagrations occurred in Southeast Asia in 1997.

11) Loss of "ecosystem services" which rainforests provide:  Ecosystem services are worth many trillions of dollars per year to the planet but are in decreasing supply as the demand increases. Among these services are those mentioned above: provision of watersheds, regeneration of soils and maintenance of the organisms within them, prevention of erosion and siltation, decomposition of wastes (dead organisms and their products), nutrient cycling, maintenance of the water cycle and rainfall levels, control of pathogens (especially insects), provision of food, medicines and fibers, maintenance of local and regional climate, reduction of wind damage, prevention of desertification and flooding, maintenance of renewable natural resources, and many others. Attempts to replicate the ecosystem services of natural forests and other ecosystems have not been satisfactory. Among these attempts are the construction of dams for flood and drought control (rather than retaining forests and natural ecosystems), using pesticides rather than relying on natural pest control, using fertilizers rather than allowing natural soil maintenance, and so forth. These replacements, often deleterious, are also tremendously expensive and require large amounts of energy. (Costanza, et al., 1997) have estimated the annual values of tropical forest contributions to ecosystem services as follows: climate regulation, $223 per hectare; disturbance regulation, $5 per hectare; water regulation, $6; water supply, $8; erosion control, $245; soil formation, $10; nutritional cycling, $922; waste treatment, $87; food production, $32; raw materials, $315; genetic resources, $41; recreation, $112; cultural, $2; for a total value per hectare per year of $2007. Assuming an area of 1.9 billion hectares of tropical forest, this gives a total value for tropical forests of $3.815 trillion dollars per year.

12) Disturbance of adjacent unlogged areas:  Deforestation affects not only the logged portion of the forest, but affects habitats in proximity to logged areas. This is due partly to edge effects, partly to the necessity for large areas of undisturbed forest for migration and feeding activities (animals) and reproduction (animals and plants, especially trees). For instance, 15,000 km² per year were deforested in the Brazilian Amazon between 1978 and 1988, but the areas fragmented and degraded by this activity amounted to another 38,000 km² per year (Skole and Tucker, 1993). In Paragominas state of Brazil, for the harvest of one commercially-valuable tree, thirty other trees of a diameter greater than 10 cm were destroyed, and the normal 80% to 90% canopy cover was reduced to less than 50% (Uhl, et al., 1997). In another study in Brazil, 150 trees were damaged severely by the extraction of six or seven timber trees (Uhl, 1994). Fires arising from the drier environment and debris remaining from logging damage much more forest, as well.

13) Unintended consequences:  Related to #12 are the unintended consequences of forest conversion. For example, the loss of lowland rainforests to agriculture in Central America has been detrimental to the cloud forests of the upper mountain areas, which depend upon high levels of humidity for the preservation of their highly productive and biodiverse ecosystems. In Costa Rica, the removal of more than 80% of the lowland rainforest and the conversion of this land to crop-and pastureland, has had detrimental effects on the montane cloud forests nearby. The cloud layer now lies at higher elevations, because the reduced evapotranspiration from agricultural land (in comparison to forested land) lowers the amount of moisture in the air which flows from the lowlands up the mountainsides. This will lead to reduction and fragmentation, and ultimately, disappearance, of cloud forests (Lawton, et al., 2001).

14) Disruption of culture and livelihood of indigenous peoples:  Three to six million indigenous people lived in the Amazon basin at the time of Columbus, but fewer than 500,000 remain today. Worldwide, there are five to ten million such people, but their numbers are falling as they are driven out of forests by government decree, resettlement, or deforestation. As they disappear, we lose their extensive knowledge of the ecology of their areas. Many of these people practice subsistence shifting cultivation and hunting, and often represent the last bastions of traditional forest management systems. For their survival and the persistence of their way of life, large tracts of diverse forest are required. Population densities must be very low; otherwise resources will be overexploited and exhausted.

The Yanomami of Brazil are hunters, fishers, and collectors, and practice shifting cultivation of bananas, plantains, manioc and other tubers. The Kayapo, also of Brazil, live similarly, cultivating 250 varieties of fruits, numerous kinds of nuts and tubers, and many medicinal plants in forest openings and small fields. They grow 13 different types of bananas, 11 of cassava, and 17 of yams (a diversity unknown to countries like the United States, where agribusiness has reduced the varieties of corn raised commercially to six, for example). They raise bees, and have semi-domesticated some forest plants and animals. The government has carried out actions to force these people into more urban settings, and/or logged the forests they require for sustenance. In Borneo, the expansion of the logging industry into the interior of the island has similarly destroyed traditional life patterns. The indigenous groups receive very few of the proceeds of the timber industry (usually only a few percent), although many indigenous men now work at low-paying logging jobs. Because their salaries are so low, agriculture must provide a substantial portion of their livelihood. Therefore, many people have moved into locations where they can be employed, buy goods and market agricultural products. The new access to markets has encouraged many to expand their jungle swiddens for raising cash crops, with corresponding ecological damage. Many of these areas are unsuitable for the introduced crops. For example, many wetlands reclaimed for rice culture have become acidic. As many immigrants from other parts of Southeast Asia move into Borneo, attracted by jobs, they engage in environmentally destructive activities in the interior as shifting cultivators, timber concessionaires, unlicensed logging workers, and pepper farmers. Although some have been integrated into a cash economy, there are substantial areas of poverty; few farmers can make a good living, and hired labor is poorly paid.

15) Exacerbation of social imbalances:  In Brazil, most of the newly-opened land is owned by large ranchers and land speculators. The colonization of former rainforest land has enriched the wealthy by means of tax incentives and benefits, while leaving the poor small farmers on land which must be abandoned within a few years, in isolated areas with few medical or educational facilities. As seen in #14, although some people have been integrated into the cash economy, many remain very poor.

16) Economic losses:  The global market for rainforest goods and services is worth many billions of dollars. This includes forestry, fisheries, mining, pharmaceutical plants, and tourism.

a. Potential revenue loss: Even in forests where only a few trees per hectare are removed, many trees of other species are destroyed or damaged. Utilizing these less-valuable trees rather than destroying them would be economically beneficial, and would reduce the need for further deforestation to obtain the few individuals of the highest value species. Tropical timber prices have generally stayed high, and, as the more valuable tree species are being depleted, logging contracts are being obtained for less-popular ones. The incidental loss of previously less-desirable species and the loss of other forest products through clear cutting, ancillary damage and careless extraction has been an incalculable financial disaster, as well as an ecological one. For instance, if only one-sixth of forest fruit trees were damaged by logging activity, the net financial gain of logging (over the long run) would be zero. In Peru, the fruit of the aguaje palm of Amazonia is in great demand for eating, ice cream and other products, and gives considerable income to local people. Forest fruits and rubber are worth more per hectare in the long run than timber, but no one saves the forest for these products.

b. Loss of forest resources to local inhabitants, and for export: Export revenues for forest products can be substantial. The value of non-timber forest products may be much greater than the value of the logs which could be obtained from a forest. In addition, local people stand to benefit from these products, as opposed to the timber trade, which is so often controlled by the wealthy or by foreign companies. People near logged forests also lose fuelwood and other forest resources - meat, hides, fruits, oils, resins, fibers, construction materials and medicines.

c. Costs of environmental destruction: Flooding, erosion, soil nutrient loss, damage to fisheries by sedimentation, are all part of the costs of deforestation. In Ghana, the removal of forests increased soil erosion rates by 100-fold, leading to a nutrient loss 40% greater than the nutrient levels of fertilizer later applied to the converted forest land. There are many similar examples throughout this document (Repetto, 1990).

d. Depletion of timber: Logging companies are putting themselves out of business. Many commercially-valuable species of timber trees are becoming extinct, either locally or globally. Teak, which once covered much of northern Thailand, is virtually gone there and logging companies are now harvesting the last teak forests in Burma and Laos as well (with the complicity, indeed, the collaboration of the governments). Mahogany, which is found scattered throughout the Amazon forests, is almost gone in many local areas, and logging companies are seeking pristine areas. The hardwood Virola surinamensis, the most valuable tree in the eastern part of the Amazon, is nearly extinct because of logging. Cutting rainforests has not provided tropical countries with a panacea to poverty, or a certain road to prosperity; rather, deforestation has led to depletion of an invaluable natural resource.

17) Increase in pathogens:  Pathogens are relatively benign in undisturbed forest because trees of any one species are generally widely-spaced. When the forest is disrupted (and especially when monocultures are established), reducing diversity, pathogens and parasites can spread more easily and epidemics occur. Logging and road construction provide opportunities for the entry of pathogens into healthy trees through cut stumps or wounds, which may also attract insect pests. Many diseases become rampant in tree plantations or secondary forests which contain many trees of one species (as has happened in tea, rubber, and cocoa plantations). The witches broom fungus, a natural pathogen of cacao in the Amazon, has spread rapidly in the cacao plantations established under rainforest canopy in Brazilian Atlantic rainforest (Bright, 2001). A fungus, Botryodiiplodia theobromae, is normally present in pines, but when trees are stressed, as in a plantation setting, where all trees are of one species and close together, infections can be lethal. This has occurred in Venezuelan Caribbean pine plantations. Epidemics of another fungus, Ceratocystis, have been reported from acacia plantations in Costa Rica (Gilbert and Hubbell, 1996) and in Eucalyptus plantations in Republic of the Congo and Brazil (Wingfield, et al., 2001). Oil palm plantations in Southeast Asia carved out of forests are apparently responsible for the spread of a root-rot fungus, Ganoderma. In Australia, the incidence of and mortality from Armillaria, a pathogen of Eucalyptus trees, was greatly increased by selective logging, because of the exposure of living trees to freshly-cut (infected) stumps (Gilbert and Hubbell, 1996). Here, too, logging and other stresses incident upon logging increased the severity of infection of another root-rot fungus, Phytophthora cinnamoni, by increasing soil temperatures and moisture. This pathogen has reduced tree density in diseased areas by as much as 43% within 10 years, while at the same time, tree density increased 10% in uninfected areas. In diseased areas, the forest has become filled with large gaps and grassy areas. Healthy areas still retain an open canopy/woody understory structure. Forests may not recover from these insults for centuries, and epidemics may substantially alter the species composition of forests by removing many individuals of the susceptible species from the area of infestation (above data from Lodge, et al., 1996; for a discussion of plant diseases in tropical forests, see also Gilbert and Hubbell, 1996).

Logging also disturbs mosquitoes in the canopy, particularly malarial mosquitoes, and forces them to migrate from their normal forest environment - often to inhabited areas. Brazil now has the highest number of new cases of malaria in the world every year. In addition, new migrants into forests often introduce diseases to indigenous populations, and may carry local diseases back to urban areas. Many monkeys in the Cameroon rainforest are infected with immunodeficiency viruses similar to HIV and it is possible that these viruses may be transferred to humans when the monkeys are killed for food (Stephenson, 2002).

18) Loss of productivity:  The loss and degradation of forest lead to a diminution of primary productivity - that is, a loss of the productive capacity of that area. The deforested or damaged area loses its ability to retain nutrients, has reduced capacity to adapt (due to loss of gene pools), loses gene flow (because of fragmentation), and has reduced capacity to store water. Carbon stores in converted areas are much lower than in forests. For instance, pastureland in Amazonia stores only 3% as much carbon in its plants as does an intact rainforest (Perry, 1994). If an area is not allowed to reforest, carbon stocks will not be replenished, especially since converted forest lands are usually subjected to abusive land-use practices.

19) Loss of evolutionary potential:  Rainforests, like other highly diverse ecosystems such as coral reefs, wetlands, and estuaries, have always been centers for the evolution of new species. Most major groups of vertebrates, and probably insects and others, originated in warm climates, especially in rainforests, which have the highest rate of evolutionary diversification. When rainforests are gone, we will have lost a vital source of future biodiversity. We are rapidly eliminating refuges for species. With increasing human disturbance and encroachment on formerly pristine areas, plants and animals have nowhere to go to escape human activity. Species depletion will probably be wholesale across taxonomic categories because such extensive areas of the environment have been eliminated, and virtually all have been modified - if not directly, then by pollution, acid rain, modifications of rainfall patterns, and more. In the past, recovery from massive extinction events (as in the Permian age) has taken millions of years; there is a now a question whether recovery can occur at all for many groups of organisms. Humans have altered or destroyed so many habitats and ecosystems that many groups will disappear. In the past, rainforests and other tropical areas have "powered" evolution because of their high diversity and relatively benign climates. These forests being removed, few areas of great biodiversity remain as centers of future evolutionary expansions.

20) The creation of "environmental refugees":  Many millions of people have been and are being forced to leave their land and homes because of environmental degradation. Deforestation, mining and other activities in the tropics lead to loss of soil fertility, erosion, flooding, depletion of animal life and many other features which make living in these areas marginal and eventually impossible. As people establish farms on tropical forest land, they are forced to move onward as the land rapidly becomes unsuitable for agriculture, an endless cycle of destruction and desertion. The World Watch Institute (Ryan, 1992) has estimated that, by 1989, at least ten million people had been forced to abandon land because of environmental factors. Eight million of these had left their land in Africa, Asia and Latin America due to land degradation. The other two million had relocated because of "natural" disasters, most of which were of human origin.