Logging operation affected rainforest ecosystem

The emphasis on – indeed, obsession with – the extraction of timber from forests is fairly recent. Previously forests were considered valuable for their “minor” products such as resins, incenses, fibers, and the like. The situation of late has been reversed. In Southeast Asia, for example, timber now represents as much as 95% of foreign trade. This shift has occurred because of several factors: (i) governmental desire to maximize revenues, which favors exploitation of timber resources, with the potential for large profits; (ii) dissatisfaction with the modest revenues available from minor product extraction; (iii) the desire to attract large-scale investment capital; and (iv) the desire to extend governmental control over remote areas. All these have contributed to the rise of the global timber trade.
Tropical countries produce about 35% of the world production of “roundwood” (total wood removals), which amounted to about 3.4 billion m3 (cubic meters) in 1988, and about one-fifth of the world’s wood products (Amelung, Torsten and Diehl, 1992). Most international tropical hardwood now comes from Southeast Asia – Malaysia, Indonesia and The Philippines – although the industry has shifted from The Philippines to Indonesian and Malaysian Borneo (Kalimantan, Sabah and Sarawak) as the forests in The Philippines are now seriously depleted. Southeast Asia has become dominant in this trade because its forests are very rich in commercial timber species and contain a large proportion of light hardwood trees, which are most in demand in the international market. In 1988, Malaysia provided 62% of legal timber product exports, worth $1.5 billion, most of which went to Japan; while Indonesia provided 22% (Dobson, 1995). At current rates of cutting, commercially-valuable trees will be gone from Malaysian and Indonesian Borneo early in this century. As these forests are becoming depleted of hardwoods, many of the Southeast Asian timber companies have headed for South America. South American logging mainly supplies internal demands, although there is a substantial export business in hardwoods, especially mahogany. Africa also produces much wood for export, although the percentage of foreign exchange earned by timber products is much lower than in Southeast Asia. In Cameroon and Liberia, 12% of exports consist of timber and wood products (Dobson, 1995). Forty-five percent of the global demand for tropical timber comes from Japan, for which wood is the second most valuable import; Japan is followed by Korea and Taiwan (Amelung, Torsten and Diehl, 1992). Tropical wood is made into plywood, veneer, and forms for concrete for construction purposes. The plywood and veneer are exported as finished products and are important in the Japanese economy. The wood construction forms for concrete are used once or a few times and then discarded. The United States is the second largest importer of tropical hardwoods, with demand continuing to grow. Tropical woods are still only a small part of the US market for wood, however, and are used for paper pulp and chip wood, as well as for furniture and construction. Although the US could be self-sufficient in hardwood production, tropical hardwoods are cheap (and of course the destruction cannot be seen).
Those obtaining timber concessions in tropical countries are almost uniformly politically connected or are contributors to political campaigns or to the politicians themselves. The concessionaires are frequently politicians themselves, desiring large profits. For example, in Indonesia, most of the timber concessionaires are government officials or retired military men. One can readily see that monitoring logging operations or investigating violations is almost impossible under these conditions.
The timber industry generally pays relatively little for the concessions to log forests. Usually the companies pay low taxes, or obtain tax “holidays” from the government. These favors are considered by governments as an inducement to business, but in fact they are often payoffs for friends, relatives or other powerful interests. The terms of the concessions, at best, do nothing to encourage logging companies to log sustainably or non-destructively.
Generally, a particular area should not be logged more often than 25-40 years, but timber concessions are usually granted for less than 20 years; thus, there is no incentive to the timber companies to cut selectively. They take what can be sold, as rapidly as possible, without caring whether or not the forest will be able to maintain its productivity. Additionally, the fees imposed on logging are usually based only on volume, not on timber value or type. Not surprisingly, logging companies engage in “high-grading” – extracting trees of the highest value over large areas, in the process damaging less-valuable trees at will. This results in the loss of or severe damage to as much as 75% of the uncut trees (not to mention other vegetation) (Repetto, 1990). Timber companies also often obtain concessions which are larger than they can manage, often absurdly large. In the Ivory Coast, timber companies, within seven years, obtained concessions for two-thirds of the country’s production forests. In 1990, in Thailand, Indonesia and the Philippines, logging concessions granted covered more than the total area under forest (Repetto, 1990). Few concessionaires log their holdings; they resell the logging rights to other companies, thereby acting as middlemen. This can be highly lucrative.
Logging activities begin with the construction of roads to gain access to the timber. This itself consumes huge areas of forest – as much as 15% of the logging area may be cleared for roads. The intrusion of roads into forests can be devastating, as has been discussed elsewhere in this document. Roads open up forest interiors to pests and diseases, increase erosion and waterway sedimentation, and, most destructively, begin the chain reaction of incursions by farmers, ranchers, hunters, miners and land speculators.
Recently, many countries have developed wood-processing industries, and seek to export sawn wood, rather than raw logs. This is intended to provide employment opportunities and to add value to forest products. However, many developed countries have high tariffs on processed wood, and thus many of these industries are not economically sound. The government must prop them up by banning the export of raw timber or setting export quotas based on domestic production.
The global demand for timber is rising, albeit at a slower rate than previously. Why? Firstly, temperate wood production is rising (mainly from tree plantations) and thus the demand for tropical woods is not growing as rapidly as previously. Although the world population is growing, it is not growing substantially in countries in which consumption is high – the developed countries of Europe and North America. Consumption is rising more in developing countries, in which most demand for wood is for fiber (paper and pulp). The overall decline in population growth rates also is depressing the growth rate of wood consumption. Unfortunately, if the returns from timber harvesting do not increase, there is more pressure to “cash in” on primary forests and to “liquidate” one’s capital. The value of the forest is not seen to be increasing and thus countries can maximize the financial returns from the forest by harvesting it as rapidly as possible. Thus, logging may appear to be financially optimal. Over the longer term, however, it will not be so. One must take into consideration other uses of the forest, as well as the services it supplies, and not simply the return from removal of timber
Regulation of the timber industry can be difficult. When regulations are imposed by a country, the logging companies simply move elsewhere where restrictions are fewer. When Thailand banned logging, Thai timber companies moved to Burma and Laos; when Malaysian timber became scarcer, Malaysian companies moved to other places in Asia and into South America. Malaysian companies are now important in Brazil, and are negotiating to open one of the largest remaining intact forest areas – Surinam – to logging.
Tropical countries have undergone a “boom and bust” development of their forests. At first, when they had plenty of forest filled with valuable, old-growth species of trees, they cut down timber for export or processed wood products. Then, when the accessible forest was depleted, they turned to second-growth forests, or forests more difficult of access (such as forests on steep slopes or at higher altitudes), but as these forests cannot sustain harvests as high as primary forests, inevitably there was a dwindling of profits. This has led to the ruthless exploitation of less valuable species, and the re-logging of previously-cut areas.
It has become clear that tropical countries are cutting down their forests but obtaining relatively little benefit from it. Rather than tropical timber being an extraordinarily valuable source of foreign exchange, in fact the prices of tropical woods are quite low, lower than for good temperate hardwoods. Only about one-third of the production of timber is exported to developed countries overall; the remainder is used internally or goes to other developing countries. In fact, much of the consumption of wood and wood products is occurring in developing countries, with their rapidly-increasing populations and lower tariffs (although tariffs have become lower in many developed countries because of GATT). Tropical woods are not used for high-end products, but for items which could be made with fast-growing plantation softwoods.
Again we turn briefly to Brazil, the country with one-third of the world’s tropical rain forests. In Brazil, all land which is not privately owned belongs to the states, although some supra-state agencies regulate forest exploitation. Both states and the federal government are able to issue land titles and engage in land sales, however, a situation which quite naturally leads to confusion and impotent regulation. The central government is also the sponsor of colonization. Neither states nor central governments have shown much mercy to or understanding of Brazil’s amazing assets, which are regarded mainly as sources of immediate wealth.
The Brazilian Amazon contains a billion cubic meters of wood with a value (as timber) of several trillion dollars. As in other places, timber extraction has been destructive and has had a significant impact on the standing forest. Little logging activity here even pretends to be sustainable. At present, forest destruction is occurring at about two million hectares per year (Laurance, 2001a), the world’s highest absolute rate. The causes of deforestation are the rapid increase (by tenfold) of the non-indigenous population in the Amazon, a substantial increase in industrial logging and mining, encouraged by road construction, and the movement of deforestation deep into the core of the Amazon rather than more localized deforestation along the margins.
In Para State, for example, large-scale logging began in the 1960’s in the usual way – a road built, a few areas colonized for slash-and-burn farms, logging, then ranching and land speculation when the road was paved. At first, only high-value hardwoods such as mahogany were logged, and, as these trees are dispersed throughout the forest, logging was selective. Such trees are now rapidly being exhausted in accessible areas, and they often must be hauled as far as 300 miles to mills. However, new systems have been introduced which are much more intensive, and are intended to supply the many local sawmills and mills in the Amazon estuary (more than 1000). Under this system many species of trees, and often fairly small ones, are utilized. Only a few species and trees per hectare are taken at first; then logging becomes more intensive as roads and market access improve. Along the Belem-Brasilia highway, logging has become mechanized, and as many as 100 tree species are utilized. Where high-value species are absent, settlers often log areas themselves near government roads and send the logs to local mills. Mechanized, intensive timber extraction requires capital, creates vertically-integrated timber companies, and provides export timber. It has a severe impact on the forest; as many as 30 trees of substantial size are destroyed for every one harvested, and the canopy cover is reduced from 80-90% to less than 50% (Uhl, 1997).
In Para state alone, 4000 km2 of forest are logged every year, and the pace is accelerating as the Brazilian population grows and the economy expands, increasing demand (Uhl, 1997). The amount of timber removed is beginning to exceed natural regrowth, which inflates the price of wood and thereby enhances the attractiveness of timber extraction to large companies. Harvestable timber is beginning to disappear near government roads, which will lead to the construction of roads by logging companies deep into virgin forest.
Any number of examples of rampant deforestation could be given; almost every country which has tropical rain forest can offer a tale similar to that of Brazil, if not on the same scale. In most places, trees are first cut for timber and wood pulp; then the logging roads are used to provide access for a transient population of farmers, who clear what vegetation remains by burning.
Much tropical forest may not be primary forest, as mentioned earlier in this document. As much as 12% of the Amazon forest (and probably a great deal in Africa and Southeast Asia as well) may have been altered by past agricultural systems of indigenous peoples. Therefore many rainforest ecocommunities are probably the result of centuries of swidden agriculture, which has left forests composed of many stages of regeneration and succession, although we view them today as “pristine” or “virgin” forests. However, modern agriculture does not leave forests relatively intact, as did these earlier agricultural systems. As the human population has grown and the standard of living has improved for some, the demand for the products of agriculture has soared. In addition, improvements in agricultural technology have allowed ever greater areas to be cultivated by relatively few individuals.
The greatest alterations of the global environment have been a consequence of the expansion of agriculture into former grasslands, forests and even mountainous enclaves. The total area of cultivated land has increased more than 450% in the past three centuries, although the rate of expansion has slowed lately due to intensified agricultural management, improved technologies, and the decline in arable land which has not been already utilized for agriculture (Matson, et al., 1997). Thus, while the human population increased from three to five billion (an 80% increase) in the three decades between 1960 and 1993, the global area devoted to cropland increased only 8% (Goklany, 1998). (Since then more than one billion people have been added to the human population.)
Much of the new agricultural land has come from former forest land, particularly rainforests. Over the past century and a half, approximately 40% of the agricultural land in Africa, 40% in Latin American and 70% in Asia has been derived from former tropical forest land. Even so, it has provided only two million km2 of the 15 million km2 of farmland globally (Pimm, et al., 2001). During this time period, the amount of land converted from forest to agriculture was more than double all of the land converted from the earliest origins of agriculture to about 1850. And the trend continues. Already 23% (4,700,000,000 hectares) of the earth’s land area has been converted to agricultural and pastoral use. This represents 45- 60% of the land potentially suitable for agriculture (Dobson, 1995). Some predict that pastureland may increase by more than five hundred million hectares, and cropland by more than three hundred million hectares in the next half century. In that case there will be 18% more agricultural land in 2050 than at present, with a loss of one billion hectares of natural ecosystems (larger than the land area of the United States), mainly in the Neotropics and sub-Saharan Africa (Tilman, et al., 2001b). This represents one-third of the remaining forests, savannas, and grasslands. Lost will be their ecosystem services and many of their species and products. However, most of this presently uncultivated land is little suited to agriculture. This marginal land might produce crops for a few years and then become scrub land or desert, as has happened already in many places where such areas have been co-opted for agriculture. In Africa, the Sahara Desert is expanding rapidly because of overgrazing and overuse of arid lands for agriculture. Declines in agricultural productivity because of land degradation could increase these impacts, driving a demand for yet more land and intensification of pesticide and fertilizer use. These effects could be mitigated by lower per capita consumption of meat, or if global population were stabilized at lower levels than projected (and, conversely, these effects could be exacerbated if the human population continues to increase)
Modern technologies which have allowed agricultural expansion have an ugly face, in that they have contributed heavily to habitat degradation by the excessive use of water for irrigation, the release of excess nutrients which causes eutrophication, pollution from pesticides and herbicides, salinization, and other problems with water resources (see below). It can also be argued that these technological advances, in addition to increasing productivity, have permitted more population growth than would otherwise have been possible, and thus have increased land conversion. Against this one can say that smaller populations lacking the new technologies would still have required much more agricultural land and would not have saved any land for conservation when it could have been utilized for food production.
Humans now appropriate almost 40% of the primary production of terrestrial ecosystems, much of it for agriculture and pastureland (Vitousek, et al., 1986; Rojstaczer, Sterling and Moore, 2001; Field, 2001). As the human population continues to increase (to perhaps nine billion by 2050) and as per capita wealth increases, what can we expect for agriculture in this next century? Will we continue the trajectory of the twentieth century, when global food production doubled between the 1960’s and 2000, and during which there were great increases in global nitrogen and phosphorus fertilization, as well as in irrigation? Tilman, et al., (2001) have made a series of projections based on past trends. Their mean projection was for global fertilization to be 2.7 times present values by 2050, with annual additions of 236 million metric tons of nitrogen to the terrestrial environment, and with phosphorus fertilization rising to 2.4 times present values. Irrigated land would be 1.9 times as great in area as at present. This may be put in perspective if we realize that humans already add as much nitrogen and phosphorus to the land as is supplied by all natural sources of these minerals; thus, the addition of yet higher proportions of them to the soil would be staggering, and would have serious environmental consequences.

It is fascinating to consider the effects which agriculture has had on this planet over the thousands of years since it originated. The conversion of forest to agricultural land has had numerous repercussions on the physical and biological environment. Conversion increases albedo levels (the proportion of light energy which is reflected from the land surface), increases heat transfer to the atmosphere, reduces evapotranspiration from plants and trees, compacts soil (which increases rainfall runoff), increases erosion, and affects air turbulence (and therefore air movements and winds). From a biological point of view, conversion has led to a loss of biodiversity, movements of species around the world, shifts in local plant and animal populations, the destruction of ecosystems, and the invasion of exotic organisms and diseases into areas where they are not endemic.
Agricultural land differs in almost every respect from the original forested land. The removal of the vegetation cover and its alteration during the conversion of forested land to agricultural land lead to:
a. Chemical, physical and biological alterations in soil: After forest conversion, the soil environment is seriously perturbed. The soil structure often becomes compacted, chemical processes in the soil are disrupted, and the diversity and quantity of soil microbes declines.
i) Erosion: the removal of the vegetational cover for agricultural purposes reduces the proportion of rainfall absorbed by the soil, leading to runoff and erosion. The silting of streams, rivers, lakes and estuaries results, reducing water supplies, lowering fish survival, and inhibiting photosynthesis in water plants. Erosion additionally depletes the nutrients in the soil, which means that it cannot sustain as much plant growth as formerly. In Malaysian rainforests, erosion removes approximately 24.5 m3 of soil per square kilometer per year; in tea plantations which have replaced rainforest, the erosion rate is 488 m3 per kilometer per year (Jacobs, 1988).
ii) Alterations in soil microorganisms: Soil microorganisms are closely adapted to their environments and the plants that inhabit it, and they regulate decomposition and nutrient availability in the soil. They are vital also for the cycling of organic compounds from soil to vegetation and back again. Studies have shown that the variety of species and the abundance of organisms in the soil in tropical agricultural lands is less than 50% of that of the primary forest originally on that land (Matson, et al., 1997).
iii) Loss of organic material in soil: During land conversion to agriculture, organic matter is lost from the soil. Much of the vegetation which provides organic material to the soil is removed, so there is less humus, the loss of which leads to alterations in soil structure, lessened water retention, and lowered fertility. In tropical soils converted to agricultural purposes, soil carbon can drop more than 50% within five years (Matson, et al., 1997).
iv) Soil compaction: When tropical soils are cultivated, they become substantially compacted. This is due to the use of heavy machinery, trampling by livestock and so on. The porosity of the upper layers is reduced, particularly when the land is used for pasturage. When porosity declines, drainage is poor and gas diffusion reduced, which profoundly alters the composition of the soil flora and fauna by reducing their abundance and biodiversity by more than two-thirds. These changes may act to compact the soil even further because compacting and decompacting forces become unbalanced after deforestation. Many South American pastures have been invaded by exotic grasses and by a type of earthworm which can constitute more than 90% of the soil invertebrates. The “casts” from these earthworms cover the soil surface and lead to substantial compaction, and they impede gas exchange and encourage methane production (Chauvel, 1999).
b. Reductions in biodiversity: One of the more obvious effects of the conversion of forest land to agricultural uses is the loss of animal and plant diversity. In many cases, the very complex ecosystems of the forest are reduced to a simple system of only one or a few crops – cattle, oil palm, or rubber. Many, if not most, rainforest animals require either undisturbed forest or well-grown secondary forest. Many cannot survive in small fragments, as their ranges are too large, or their distribution (especially in the case of trees) is too sparse for adequate reproduction. Again, the presence of large open areas discourages the growth of shade-loving seedlings, and encourages only those tolerant of high temperatures and hot sun. Many animals cannot cross even moderate-sized open spaces and thus are trapped in forests fragmented by agricultural plots. Uhl and Parker (communication to Dobson, 1995, p. 234) have calculated that a hectare (1 ha = 10,000 m2) of rainforest can support about 800,000 kilograms of animal and plant mass. Used for pasture, 6 m2 of land (1/1666 of a hectare) can provide the meat for a quarter pound hamburger, (and, by extrapolation, one hectare of land could theoretically provide 1666 small hamburgers, weighing approximately 189 kilograms, compared to the abovementioned 800,000 kilograms of biomass). Even the tiny area of 6 m2, however, as forest, could support one sixty-foot tree, 50 saplings, the seedlings of twenty to thirty species, which vegetation could sustain many birds, thousands of arthropods, and many transient amphibia, reptiles, and mammals (Dobson, 1995). Or, as Prance put it, a “cow lives on an area [1 1/2 ha] that could have had over 700 individual trees of about 200 species, and many other plants and animals as well – an enormous natural biomass with much greater productivity and value than that offered by the skinny, malnourished cow that now wanders around the weed-infested pastures that have replaced the forest.” (Prance, 1986, p. 84)
c. Depletion of forest ecosystems because of the spread of pathogens and the incursion of exotic species: Because of the prevalence of monocultures and the importation of exotics, agriculture is an inviting feast for pathogens, because there are large stands of uniform hosts. Epidemics in agricultural areas can spread to nearby forests, particularly when they are fragmented. An unexpected effect is that forests may be cut in an attempt to find areas which are not contaminated with the pathogen. This happens particularly in large-scale agricultural operations, such as occurred in Central America when banana plantations were ravaged by the fungus Fusarium oxysporum. New plantations then had to be cultivated by cutting virgin forest. Banana companies now own great tracts of land so that, if this scenario should be repeated, they will have pristine land in which to make new plantations. Recently it has been suggested that the malaria parasite evolved from a common ancestral population around the time of the development of agriculture. Agriculture, by enabling a great increase in human population, and with its large areas of standing water promoting the breeding of mosquitoes, apparently provides an excellent milieu for the spread of the malarial parasite Plasmodium (Pennisi, 2001).
d. Chemical contamination of soil and water and alterations of natural mineral cycles (carbon, nitrogen, phosphorus): In a natural tropical rainforest system, the input of gases and chemicals from the environment is approximately equal to the outgo, but these connections to the outside environment are small compared to the internal cycling of chemicals from vegetation/animals to soil and back again. This cycling is severely altered in agricultural systems since the quantity of vegetation is much reduced and the crop is removed from the system, thus depleting it of essential organic matter. Because of this, nutrients must be added in the form of fertilizer (mainly nitrogenous). The use of fertilizer adds another dimension to this equation, as it substantially alters the global nitrogen cycle. Only half of the nitrogen and phosphorus from fertilizer is utilized by the crops; the other half remains in the ground and enters the groundwater. Both phosphorus and nitrogen cause eutrophication of waterways – nitrogen of estuaries and coastal waters, phosphorus of lakes and streams. Eutrophication frequently leads to toxic blooms, the loss of biodiversity, and changes in species composition in aquatic ecosystems. Nitrous oxides and ammonia (a nitrogen compound, NH3) enter the air and change atmospheric chemistry; they contribute to the greenhouse gas load, they contribute to acid rain and are important components of smog. All in all, increases in nitrogen and phosphorus levels can cause great losses in biodiversity and radical alterations of both aquatic and terrestrial ecosystems. Pesticides used in agriculture are toxic, and can damage adjacent forests. Some of them mimic natural animal and plant hormones and others are immunosuppressants, further damaging the survival of plants and animals. Tilman, et al.(2001b), estimate that pesticide production will increase to 2.7 times present levels by 2050 (mean projection), with the expected consequences of declining human (and animal) health and continued environmental degradation.
e. Detrimental alterations in water supplies and in waterways: Irrigation of converted lands leads to salinization (salt deposits), water logging of soil, high nutrient levels in waterways in the vicinity of agricultural areas and water depletion in streams, rivers and other waterways. Meanwhile, agriculture consumes approximately 70% of the fresh water used by humans – 35% of the total available fresh water (Vitousek, et al., 1997; Johnson, Revenga, & Echeverria, 2001).
f. Displacement of native species and disruption of ecosystems by the introduction of exotic species: Many forest species are threatened by the invasion of exotic species introduced either deliberately as crops and livestock or inadvertently. Many of these have no natural enemies in forest systems and are able to invade the habitats of native species, driving them to population declines or to local extinction. Others act as pathogens, parasites and predators of local species. These biological “invasions” are very extensive and many are irreversible. They at the least disrupt local ecosystems and drive losses in the biodiversity of native species and populations.
g. Soil depletion and loss of productivity: Many farms are established by small-scale cultivators who follow logging roads into the forest. Once roads have penetrated the forest, access becomes easy, and people who are fleeing the poverty of cities or worn-out farms (often rain forest land which has been degraded by agricultural activities) follow and establish small agricultural or ranching operations. When the nutrient level of the land decreases sufficiently, they abandon these farms and penetrate farther into the virgin forest, leaving degraded fields behind. Often this deserted land is unable to regenerate forest and becomes scrub or wasteland. This has occurred in northern Vietnam (among many other places) where Hmong farmers kept cleared areas under cultivation to the point of soil exhaustion. These areas have become permanent grasslands, no longer able to sustain a forest (Fox, et al., 2000). In Malesia, huge areas of “lalang” (Imperata cylindrica), a tough, aggressive, and virtually inedible large grass, have replaced former forests converted to farms. In Indonesia 8.6 million hectares [86,000 km2] are already covered with Imperata, and 2000 km2 more are lost to this grass yearly (Jacobs, 1988). It forms a monoculture with little diversity and supports few animal species, particularly in comparison with the original tropical forest. Imperata is extremely difficult to eradicate because herbicides are prohibitively expensive, as is manual removal. Farmers who burn the grass find that this activity reduces soil nutrients and only enhances the regeneration of the grass – a “double negative” score.
h. Increase in surface albedo and decrease in surface roughness, both leading to temperature increases and decreases in precipitation.
All of these consequences are related. As mentioned above in numerous places, most tropical soils are not very suitable for agriculture and their fertility is transient when the vegetation is removed. The ecosystems which replace rainforests are less productive than they are and are not as valuable economically. Often, agricultural practices and crops planted on deforested land are unsuitable for local conditions. Also, when many tropical soils are farmed or grazed, they rapidly become infertile. If the forest is not allowed to regenerate, the soil will be permanently damaged. Then, yet more forest needs to be cut. Despite the patent unsuitability of many tropical forest areas to support agriculture, governments in tropical countries frequently encourage and subsidize the migration of people into forests. The government often stipulates that one can take title to land only by “improving” it, i.e., by cutting down the forest and cultivating the land or by building a house on it.

In many places now, settlers simply cut and burn the forest to establish permanent cultivated fields or pasture. This type of “slash-and-burn” agriculture has converted huge areas of upland Vietnam into wastelands within the past 30 years. Repetitive burning in the current practice of slash-and-burn agriculture produces many greenhouse gases (carbon dioxide, nitrous oxide, hydrocarbons). More than 1½ million metric tons of carbon per year are released into the atmosphere by these agricultural methods, approximately 23% of the total released by human activities (Kaiser, 1997). In 10 years, almost as much plant material will have been burned in pastureland to clear weeds and stimulate the growth of grass as had been burned initially to create the farm or ranch. Previously, traditional agriculture used small fields and less intensive cultivation, and fields were permitted long fallow periods. Now fields are being reused on very short rotation schedules, so that the forests do not have time to recover, nor is there time for fertility to be re-established. In Vietnam some groups are still using traditional swidden systems, in which the landscape is a mosaic of swidden fields, secondary forest, and older forest. About 84% of the area in Ban Tat (village) is still under secondary regenerating forest or successional vegetation (down from 92% in 1952). However, over the past 50 years, the area covered by closed or open canopy forest has decreased considerably, and the area of scrub and grassland has more than doubled in size. The change has been from primary forest to heterogeneous secondary vegetation, with concomitant fragmentation. Nevertheless, most of the land (except for rice fields in the valley floor) has not been permanently converted to agriculture, nor permanently deforested, but it is on its way (Fox, et al., 2000).
Cattle ranching often follows farming on converted rainforest land in the Neotropics. When cultivated land becomes depleted within a few years of conversion, ranchers and land speculators frequently purchase it for cattle ranches. This process is encouraged by government land policies and by the construction of paved roads, which allow easy access to markets. These operations are often subsidized by the government (see above), and financed by the sale of logging rights, so that ranching even on poor soils can be profitable if the rancher has large holdings. However, pastures, like agricultural land, will become degraded if not treated properly, and will become weedy fields unless they are cleared of debris and burned, fertilized, tilled, and planted with forage species. The capital for this kind of pasture regeneration usually comes from the sale of timber or timber concessions. In this way forests act as capital or a subsidy for pasture renewal and maintenance.
Agriculture has become a global economic factor more than a subsistence issue. Those countries with the most productive land and technologies gain the greatest market share. The disappearance of traditional swidden systems as local agriculture becomes subsumed into the global trade in commodities is a major cause of rainforest destruction. As roads are built into forests, farmers are encouraged to convert from subsistence farming (small quantities of a number of crops) to cash cropping of a few species. Under global pressures, large companies and interests purchase land from small farmers, and use this land for monocropping of marketable species for export. In this competitive atmosphere, modern agricultural techniques are used – fertilizers, pesticides, and new crop varieties, often genetically-engineered. Thus, the landscape not only becomes deforested but homogeneous. An ancillary – if unintended – consequence of the reduction of crop species is the loss of “support” species – mycorrhizae, nitrogen-fixing bacteria, pest predators, and pollinators. Modern agricultural conversion of rainforests not only removes forests, but it endangers biodiversity too, by utilizing only a few species at the expense of all the others, and by disrupting the ecological webs among organisms.

What crops are being raised on converted land? Many countries, in an effort to boost exports, have switched from subsistence food crops to export crops. Among these are coffee, cocoa, nuts, oil palm, and tobacco. Some of these require a great deal of land such as peanuts, maize, rice, cotton and, of course, livestock. Other crops like coffee and cocoa need shade and must be surrounded by other trees or forest. Until recently, coffee trees were raised among other forest trees. However, new types of sun-tolerant coffee trees have been developed and large swathes of rainforest are being cut for new-style coffee plantations, which are edging out traditional forest-based coffee agriculture. The drug trade is also a guilty party. A great deal of rainforest in South America has been cut for coca plantations. In Peru, in the 1980’s and early 1990’s, this crop had a value of approximately $1.2 billion, or 50% of export earning (Amelung, Torsten and Diehl, 1992). This industry is not being subsidized! But it has cost governments many millions of dollars in “search and destroy” missions, criminal activity, policing costs – and lost forest resources.
Since many crops cannot tolerate the declining ground water levels caused by excessive deforestation, much tropical agriculture is not ultimately sustainable. In addition, many tropical agricultural activities are not profitable, and must be subsidized by governments. Among these are cattle ranching in the Amazon and sugar cultivation in Central America.
What might be done to mitigate the effects of continual pressure for agricultural expansion? It is a horrifying fact that the area of badly-degraded former forest land which can no longer be cultivated is equal to that which is currently under cultivation. Something is seriously wrong with our land-use policies if we are willing to throw away millions of square kilometers of formerly extremely productive land for a very short-term gain (if any). It is difficult to feel optimistic about the prospects for either forests or the farms which take their place in the tropics, for reasons given above. Although a lengthy discussion of agriculture is not within the purview of this document, a few changes which could improve the depressing situation are mentioned below.
a. Institute sustainable agriculture: Some scientists feel that sustainable agriculture can be practiced on former forest land, thus obviating the need for further incursions into virgin rainforests for new agricultural land to replace worn-out fields. However, most soils in the tropics are highly weathered and of poor to variable fertility, which makes a great deal of tropical forest land marginal for agriculture. Agriculture on these lands is limited by acidity, nutrient deficiencies, low phosphorus levels, and the poor physical structure and condition of the soils. Because of these factors, the land is farmed for a few years, after which the soil becomes eroded and exhausted, and the farmers move on to fresh forest land. This is a most destructive cycle. Since during cultivation of former forest land essential soil organic matter is rapidly lost by leaching, the key factor in making agriculture sustainable lies in preserving soil fertility. Soil organic matter consists mainly of dead parts of plants and animals, microbes, substances released from plant roots, and fungi. The combination of organic material and microbial mats gives stability and porosity to the soil, and the microbes decompose the organic materials to chemical compounds which can be absorbed by plants. The organic content of soils also enhances its water-maintaining capabilities. Thus the preservation or restoration of all these elements is essential to sustaining agriculture in tropical regions, although maintaining organic matter is more difficult in tropical regions because soils are often easily compacted and easily depleted. Vegetal cover must be maintained, fallows must be sufficiently lengthy, and crops must be carefully managed. Even so, with such a regime, in many of these infertile soils moderate yields can be obtained only with the use of fertilizers. In addition, soil structure must be improved, microbes replaced, and crops suitable to the local environment, mycorrhizae, and soil type chosen. Agriculture must be adapted to take advantage of natural processes rather than relying on great quantities of fertilizers and pesticides.
b. Modern high-tech agriculture: In some places new technology appears to be destructive of forest; elsewhere, protective. As one example, highly mechanized agricultural systems use relatively little labor. In Brazil, much previous rainforest land has been cut for soybean plantations, which are mechanized, and which have displaced small farmers. These farmers are forced to move into the rainforests, where they remove tree cover to make new farms. In the Philippines, in contrast, an irrigation project on Palawan Island was sufficiently labor-intensive to occupy farmers, thus reducing pressure on the forests (Helmuth, 1999). Modern technology can be a mixed blessing, although new irrigation techniques, plant breeding and genetic engineering can raise productivity in some places.
c. A reduction in consumption of meat and animal products: Growing feed for cattle and other domestic meat animals consumes a huge proportion of the world’s agricultural output. It is much more efficient to eat plants directly, rather than to consume them via animal flesh. In this transfer, most of the energy in the plant is lost.
d. Comprehensive land-use planning: This could involve restoring agricultural land to forest or other ecosystems for the ecosystem services which it could provide (watersheds, for example), and by planning agricultural lands so as to minimize fragmentation of ecosystems, to preserve biodiversity, and to preserve wetlands and other types of essential habitat from agricultural conversion.
e. Improvement in agricultural productivity (preferably without resorting to pesticides, herbicides and mineral-laden fertilizers): New equivalents to the “Green Revolution” for rice are needed.
f. Investment in research: This element is essential to design agricultural systems which are more efficient and less destructive to ecosystems and global ecology, to control pathogens and pests and to maintain fertility.
One could sum up the situation as Manners (1978) did some time ago, “The rapid conversion of tropical rain forests into cultivated fields and pastures may appear to offer a solution to immediate problems of a growing population and its demand for space, food and jobs; in the long run, however, present land-use practices risk permanent degradation of the resource base.” And he didn’t know the half of it.
How much would it cost to save some of our natural ecosystems? Perhaps only US$8-10 billion would be needed to provide adequate finances for reserve protection worldwide. To expand reserves to a minimum of 10% of land area (a generally agreed-upon conservation goal) would be economically feasible; even strict protection of this 10% and the maintenance of the “multiple use” reserves now existing (4.7% of land area) is not unmanageable. This might cost an additional sum of $16.6 billion per year over 30 years (including the cost of land purchase and reserve management). Additionally, compensation must be paid to those – local communities, mainly – who would suffer economically by loss of available resources from the assumption of land into reserves. These “opportunity costs” might reach $5 billion per year. Biodiversity also must be protected beyond the limits of the reserves, in agricultural lands, aquatic and marine environments and forests. Because so much effort would be required to make agriculture environmentally sound, $290 billion might be necessary for this protection. (Figures are from James, Gaston and Balmford, 1999). Pimm, et al., (2001) suggest that establishing a network of reserves of 15% of terrain in tropical countries (about two million hectares) would be relatively inexpensive, since the desirable areas are sparsely populated and land values are low. They estimate about $10 per hectare for purchase and management; adding another two million km2 of land and providing adequate management for this land and the two million km2 already protected might cost US$4 billion. Where biodiversity hotspots are heavily populated, the cost will be higher.
Although the sums required for conservation of land and biodiversity appear high, it is considerably less than the amount of money being spent by governments on projects detrimental to the environment. There are subsidies to agriculture, fisheries, energy production, road transportation and other industries, all of which cost governments between US$950 billion and $1.45 trillion a year (US$2 trillion, according to Pimm, et al., 2001, and almost that according to Balmford, et al., 2002). Since these maintain the prices of resources at less than market levels, exploitation is assured. In the European Union, $82,500 is spent per square kilometer on agricultural subsidies and, in the U.S.A., $16,100, while governments can spare, on average, only $2000 per square kilometer on parks and reserves. And this sum is considerably less in tropical countries. Zimbabwe spends US$132, Tanzania, $27, and Cameroon, $20 (Inamdar, et al., 1999). Supporting nature reserves would cost about 2% as much as these harmful subsidies, and a global conservation program would consume only about 20% as much as the subsidies. The problem is not “affording” to protect our essential ecosystems, the problem is to engender the political will to do so. The obstacles to sustainability are social, institutional, and political. Environment as well as economics must be combined in the making of public policy. As Pimm, et al., (2001) point out, his figures for reserve protection fall well within the range of the worth of some of the wealthiest individuals, and amount to approximately 1/1000th of the value of the ecosystem services which we obtain from the biodiversity of the planet. (The recent tax rebate given to the American taxpayer by the US government cost almost US$40 billion.) Is it worth to spend less than US$30 billion a year for the purchase and maintenance of reserves, in order to receive goods worth more than US$30 trillion (Costanza, et al., 1997)?
But the developing countries, with most of the world’s rainforests, cannot afford the costs of preservation. A transfer of capital from developing countries to developed countries is now occurring, which results in a transfer of the environmental costs of global development and growth to the developing countries. In 1989 this cost was estimated at $14 billion. This figure did not include resource depletion costs, only environmental pollution costs (MacNeill, 1989). Although it is essential for developing countries to maintain their resources for future use, they have instead been depleting them at a rapid pace. The result is that they bear the environmental costs of the use (pollution and loss of watersheds, for example) as well as the depletion of the resource, for the advantage of people in developed countries.
But economics alone cannot establish value for our rainforests and other natural ecosystems. As Krutilla (1973) put it: “There may be substantial commercial value in preserving wild species and natural environments, but the market cannot communicate [this value]. The conventional market operation does not provide adequate information or rewards to ensure the preservation of rare and irreproducible natural phenomena.” And Goodland (1995) says, “For natural life-support systems no practical substitutes are possible, and degradation may be irreversible. In such cases . . . compensation cannot be meaningfully specified.” The wealthier countries must now make the commitment to invest in resource preservation, rather than depletion, for the benefit of everyone and for the future well-being of the planet.
The value in the 1980’s of the timber trade for Malaysia, Indonesia and the Philippines was about US $3 billion, for about 85 million m3 of wood, only about 4% of the total world supply Katzman & Cale, 1990). These forests are being cut for wood which could easily be supplied elsewhere – from nontropical forests or from wood substitutes. The same is true for other products from converted forests. Beef from ranches in Brazil (and only some of this meat comes from Amazonia) amounts to just 3% of meat imported into developed countries. This meat is worth about $450 million, a minuscule amount compared to the value of the standing forest (Katzman and Cale, 1990). Sadly, tropical rainforests are being destroyed for relatively little gain, particularly in comparison with their value as forests and ecosystems (see above). Much of the destruction is waste – forests burned without extraction of timber and other forest products, forests converted to farmland and then abandoned within a few years, forests being cut for wood and wood products which could come from other sources, including wood substitutes.
“It is hard in this age of near-universal selfishness, materialism, and unease to read book after book of practical reasons for saving wilderness without feeling a twinge of regret for the passing of the priceless, uncorrupted wilderness . . . Now, as with everything else, wilderness has its price. It is . . . difficult to imagine wilderness remaining wilderness after the drug companies, hydrocarbon refiners, gold miners, manatee catchers, and rubber planters have finished with it.” (Ehrenfeld, 1986)
“We are rapidly acquiring a new picture of Earth, and it is crammed with millions upon millions of nature’s species on the verge of being replaced by billions upon billions of hungry people, asphalt, brick, glass, and useless eroded red clay baked by a harsh tropical sun . . . Isaac Asimov may have been particularly visionary when he described the planet Trantor, a sphere of steel and concrete; a hollow joke of its former self. Could Trantor be future Earth?” (Erwin, 1988)
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