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close this book Diversity, globalization, and the ways of nature
close this folder 4. Forests under attack
View the document Deforestation in the 20th century
View the document Rain-forest environments
View the document Temperate forests

4. Forests under attack

Management of forest ecosystems has always been one of the most difficult challenges presented to humans. During the agricultural revolution, societies inhabiting forest areas in Europe, the Middle East, and other parts of the world started clearing trees to prepare land for crop production. In Roman times, hundreds of thousands of square kilometres of Mediterranean forests with their deep and fertile soils were eliminated to make way for cereal crops, such as wheat and barley. In Sudanese Africa, during the first centuries of the Christian era, a considerable portion of forest gave way to locally domesticated sorghum and millet crops and itinerant cattle-raising. In America, many of the forests surrounding the valley of Mexico were gradually removed to make room for corn and bean farms. In Asia, rice paddies replaced the extensive forests of China, Indochina, and some of the largest Indonesian islands.

Despite this worldwide reduction in area, at the time of the industrial revolution forests still occupied nearly 30% of the continental landmass, typically concentrated in humid and subhumid areas. In the 1600s, more than half of Europe and more than 90% of the humid regions of North and South America were covered by trees. In Africa, although long-term human habitation had significantly reduced forest areas (mainly through burning), resulting in "savannization," large tracts of land in humid and subhumid regions remained covered by forests.

In Europe, the industrial revolution brought about systematic and intense degradation of the forests. The main causes were the increase in population and the burning of firewood by industries and individuals. During the 18th and 19th centuries, new villages were established in less productive environments, such as steep and stony slopes in the cooler mountain highlands of the Alps, the Massif Central of France, and the Apennines in Italy; these areas were slowly converted to agricultural production, significantly reducing the forest cover.

In many areas of Europe, population growth outpaced the opening of new farmland. Often, this was simply because land was not available. In many cases, however, it was due to a concentration of land ownership in the hands of a few people. At the beginning of the industrial revolution, most of the surplus rural population had moved to cities to work in the new industries. However, European industries soon proved insufficient to absorb all the migrants. This prompted the migration to America, which by the end of the 19th century and the first half of the 20th century became intensive.

In North America, the arrival of millions of Europeans meant the opening of new forestlands for farming. New England was completely' covered by forests in 1620 and largely deforested 150 years later. In the 18th century, more than 4 million hectares of Arkansas marsh and swamp forests were converted to farmland (Reisner 1986). Between 1848 and 1858, Minnesota's population, next to the Canadian border, increased from 10 to 150 thousand (it was promoted from a territory to a state at this time). A similar situation occurred in the 1870s in the territory of Dakota (National Geographic 1986). By the late 1870s, more than half the temperate forests of North America had been eliminated, and the process continued for many decades. Because land had become scarce in the east, most new arrivals and many older settlers or their descendants moved west, clearing new land for agriculture.

In South America, most forested areas were in the tropics, particularly in the Amazon basin and the upper basins of the Parana and Orinoco rivers. Early deforestation of tropical ecosystems occurred during the colonization period along the northeastern coast of Brazil to make way for sugarcane plantations and, later, by the end of the 19th century, around Sao Paulo for coffee production.

The deforestation of mountain areas, which had begun in precolonial times, continued after European colonization, reducing forested areas to only the steeper or cooler slopes by the end of the 19th century. Well into the 20th century, however, a considerable portion of the continent's extensive tropical forests remained virtually untouched. This delay in deforestation was probably due to the abundance of grasslands in the more productive temperate areas (the pampas). The only forested areas in temperate climates were on the slopes and narrow plains along the Pacific coast in central and southern Chile and in the highlands of the Planalto of southern Brazil.

Deforestation in the 20th century

In this century, deforestation processes in Latin America have proceeded at a much faster rate. By the 1970s, most of the Araucaria forests of the Planalto in Brazil and the forests of the western foothills of the Amazon basin from Colombia to Bolivia had been partially or totally eliminated. More recently, new forest areas have been logged or burned in eastern Paraguay, Mato Grosso in Brazil, and Santa Cruz in Bolivia to make room for cattle and soybean and rice plantations. For the last decade, deforestation in the Brazilian Amazon region has been occurring at the rate of about 21 thousand square kilometres every year (Feamside et al. 1990), bringing the total area cleared to more than half a million square kilometres in the last two centuries.

In Africa, deforestation activity was widespread, particularly along the Guinean coast, to make way for peanut, cocoa, coconut, and banana plantations. Other areas affected included the central highlands (from Rwanda and Burundi to Uganda) and the tropical forests of south-central Africa from Angola to southern Tanzania. Today, African rain forests are greatly reduced to less than 1 million square kilometres, barely 4% of the total area of the continent and less than 20% of their original area.

In Mali, the use of wood for firewood, charcoal, and construction has resulted in deforestation. Annual wood use in this region is estimated at about 300 kilograms per person (360 kilograms in urban areas and 270 kilograms in rural areas) for a total of 1.7 million tonnes per year. Of this amount, more than 200 thousand tonnes per year are used in the Bamako metropolitan area, which has resulted in the forest retreating toward the southern part of the country. In the Mopti region, the burning of wood to smoke fish is also contributing to rapid deforestation and environmental degradation. Although some reforestation projects have been carried out (often giving priority to exotic instead of more appropriate indigenous trees), the general trend has clearly been toward deforestation. In Sudan, more than 48 million cubic metres of wood is cut every year for charcoal production or for use as fuel.

Deforestation has also been intense in southern and Southeast Asia. The trend has accelerated during the last few decades, particularly in Indonesia and Malaysia, where large, previously untouched areas of Sumatra, Borneo, New Guinea, and the Malaccan Peninsula have suffered extensive forest degradation.

The increasing demand for timber during the first half of the 20th century was met by a resource base mainly composed of natural or semi-natural forests (see Perez Arrarte 1993). During this period, the value of a forest was related to its logging potential. Over the last few decades, however, new potential values of forests have been emphasized: as ecotouristic resources, as sources of biodiversity, etc. This change in attitude has promoted a different approach to forest management and exploitation. Native people in Canada and the United States, who are reluctant to allow logging on their traditional lands, have found important allies in many environmental groups. Pro-logging lobbies are losing their influence, and exploitation of temperate forests in North America and Scandinavia is becoming more difficult.

Besides being "politically incorrect," logging in the North is also becoming uneconomic. In temperate climates, trees grow very slowly. In many areas downwind of industrial centres, wood stands are being affected by acid rain, further complicating things for forestry companies in the northern countries. Profitability among Canadian lumber companies decreased substantially from 1990 to 1993. The growth of a strong paper-recycling industry is also affecting the forest business, accelerating this trend. These tendencies have resulted in a decrease in the production of timber and paper pulp from northern forests and a substitution of material from more competitive artificial plantations in warmer latitudes, such as the southern United States, Brazil, Chile, and Argentina.

In many Third World countries, natural forests have also been beset by continuous logging, without allowing time for regeneration. As a result, the amount of material coming from natural tropical forests in these areas has also decreased. In some cases, new artificial forests were planted in place of the natural forests (southern Chile and Misiones in Argentina). In most cases, the newly planted areas are monospecific plantations of exotic trees. In some areas, cleared land has been converted to agriculture or animal production.

Globalization processes are promoting the gradual substitution of natural forests by artificial systems. The redistribution of economic roles is having an effect on the forestry industry at all levels. Some countries that were traditional producers are withdrawing from the international scene, while others that have not been producers are increasing their exports.

These trends are taking place at a time when the demand for timber and paper pulp is increasing worldwide. In spite of this, increased production - from 2.7 billion cubic metres in 1977 to 3.4 billion in 1988 - has been sufficient to meet the demand. Particularly important was the increase in paper pulp production (about 30% for the same period), which appears to be related to the increasing worldwide consumption of paper promoted by the information revolution. Wood and charcoal production increased 33% between 1977 and 1988 (Perez Arrarte 1993, p. 15).

Rain-forest environments

Tropical rain forests are located in areas where steady high temperatures and an abundance of water allow continuous growth of vegetation. Tropical rain forests grow year-round. Average daily temperatures remain between 20° and about 30°C and water shortages are infrequent. In addition, solar radiation is high, further favouring photosynthesis and associated biological processes.

These environments are characterized by multilayered vegetation reaching maximum heights of 40 to 60 metres. Nutrients are mainly stored in living biomass, rather than in the soil. Because of this, when vegetation is removed, the chances of the system recovering to its former state are limited. In addition, microclimatic changes - such as decreasing humidity, increasing temperature, and wind variations - can produce dramatic effects and make germination or regeneration of most native plant species difficult or impossible. Soil erosion, which is negligible under forest cover, increases radically when vegetation is removed. This further reduces the potential of the ecosystem to recover.

In brief, these modifications - loss of nutrients, deterioration of air and soil microclimates, and soil erosion - bring about a complete change of the whole ecosystem. When such a change occurs in a 1- or 2-hectare plot, the system may recover. However, when the deforested area measures tens or hundreds of square kilometres, the process may be irreversible.

African forests

In Africa, forests are mainly removed for two reasons: they are cleared for new farmlands and they are cut for lumber and firewood. When old-growth forests are eliminated, productivity of the soil decreases because of nutrient losses. In most cases, the decrease in fertility is so great that even applying fertilizers does not result in competitive agricultural activity. For poor farmers, fertilizers are unaffordable, except in rare cases where natural fertilizers or phosphate rock are available locally. Often, the only practical way to increase production is to clear more forest area for cultivation.

In earlier times, shifting cultivation from one small plot to another allowed the ecosystem to recuperate. With increasing population density and encroachment of commercial plantations, however, recuperation has become impossible, and the forest ecosystem disappears completely, with the consequent loss of bio- and cultural diversity and water resources. Such pressures are causing African forests to retreat at a sustained rate.

In the 20th century, the main culprits have been commercial crops, such as bananas, oil palms, rubber, and cocoa. In Nigeria, oil palm plantations have replaced forests over large areas, particularly in the eastern regions of the country. Coupled with the rapid growth and concentration of the population, this has left little forest remaining. In Cote d'Ivoire, about half a million hectares of forest are cleared annually to make room for cocoa, coffee, and other food products. From an area of 14 million hectares in 1956, the forest had been reduced to less than 5 million hectares 30 years later. The export of commercial crops and lumber explains the relative success of the country's economy in the short term; however, its unsustainability is evident.

Southeast Asian rain forests

In Southeast Asia, the originally extensive rain forests have been greatly reduced. In Burma, Indochina, and Thailand, forests have been replaced by farms and plantations. The forests of the more densely populated Indonesian islands (Java, Madura, Lombok, and Bali) have been logged or burned to the point where there are few remaining relics. As a result of deforestation on fragile soils, erosion has become a serious and widespread problem. In Java, annual erosion rates ranging from 10 to 40 tonnes per hectare have been reported. Recently, the drive toward deforestation has affected some areas that had remained untouched in Peninsular Malaysia, Sumatra, Mindanao (Philippines), and other less-populated islands of the region.

Large tracts of forest can still be found in Borneo (Kalimantan), New Guinea, and Celebes (Sulawesi). The Indonesian government attempted to promote settlement on these islands to alleviate the problems associated with the extremely high population density in Java (nearly 900 people per square kilometre). The initiative produced mixed results. To some degree, it relieved the population pressure in lava (although only temporarily). At the local level, however, the effect was disastrous. Large areas of rain forest were destroyed and the native people on the islands were displaced from their land. Javanese are alien to New Guinea and Borneo; the traditional cultures of these two large islands have been profoundly affected, and the process still continues.

The situation on Borneo is particularly complex. It belongs to three countries: unevenly populated Indonesia, a large multi-island country; oil-producing Brunei, which is small, rich, and densely populated; and the Malaysian states of Sarawak and Sabah. Deforestation and the annihilation of wildlife are still going on at a fast rate in the Indonesian part of Borneo, where settlement strategies have compiled a very poor record.

In Malaysia, until recently, authorities were not concerned with the preservation of the natural rain forests. In 1991, a Malaysian minister was quoted as saying: "It is not our business to supply the West with oxygen" (Economist 1993c). This attitude has changed somewhat. In October 1993, however, a major business deal was announced by a large company (owned by the Minister for Environment and Tourism) that involved a logging concession on 200 thousand hectares of rain forest, along with a coal mine and other components. Sarawak forests produce 80% of Malaysia's timber-related products, and Malaysian environmentalists predict that Borneo's rain forests will disappear in 20 years.

In other areas - for example, the Philippines, Thailand, and Sabah (on Borneo) - some tracts of rain forest are being conserved and the export of timber has been halted. Deforestation continues, but at a slower rate, mainly as a result of agricultural encroachment.

Until recently, the effects of deforestation were less pronounced in the eastern half of New Guinea (part of the republic of Papua New Guinea) and nearby islands (the Solomon Islands). In the last few years, however, the tropical hardwood timbers of these areas have been stripped beyond the level of sustainability. Francis Tilly, Prime Minister of the Solomon Islands, foresees the disappearance of all commercial timber from the islands in 15 years if this rate of deforestation continues. According to the Economist (1994a), landowners can get as little as $2.70 per cubic metre for their timber. The foreign buyer, however, can then sell this timber for as much as $350 per cubic metre! In the Solomon Islands and Papua New Guinea, most foreign logging companies are of Malaysian origin, escaping the increasingly tight controls on logging in their own country.

The Amazon rain forest

The quest for rubber, mainly after 1840, was one of the main factors in the settlement of the Amazon. In 1844, only 367 tonnes of rubber was exported from the region; in 1851, exports had increased to 1 391 tonnes and by 1910 to 42 000 tonnes. During this period, 600 to 700 thousand new settlers immigrated to the Amazon region as a direct or indirect result of the establishment of the plantations. The total population of the area, which was about 137 thousand in 1820, increased to 323 thousand in 1870 and to more than 1.2 million by 1910.

During this century, settlement of the Amazon has accelerated, mainly as a result of government policies promoting agriculture, cattle-raising, and logging in the region and bolstering a legal system that clearly favoured forest-clearing. A key element in this system was land allocation based on the concept of "squatter's rights"; title was awarded to whoever could demonstrate occupation of the land for a given period. Because occupation could be demonstrated by partial or total deforestation of the land to be claimed, systematic and widespread clearing of land for cultivation or speculation ensued.

Later, particularly after the discovery of the Serra Pelada gold deposits, mining activities developed, resulting in widespread degradation of the natural landscape and water resources. Gold was mined in open quarries, in mines, and in alluvial placers throughout the region, such as Mato Grosso and the Madeira River. Simultaneously, a number of other large-scale mining concerns, such as the iron and tin mines of Carajas, gradually spread throughout the region.

Another factor in the loss of forest habitat relates to the construction of large hydroelectric complexes, such as the Tucurui dam on the Tocantins River (with a flooded area of about 2 thousand square kilometres), the Samuel dam in Rondonia, and others.

Satellite images show that 410 thousand square kilometres of forest was cleared between 1978 and 1988 (Salati 1991). This amounts to almost 10% of the whole area, reducing total forest cover to slightly more than 4.5 million square kilometres. Of the approximately 425 thousand square kilometres of the Amazon that was cleared by the early 1990s, about three-quarters was eliminated in the last two decades (Preston 1991). At the same time, the Colombian Amazon forest (with a total area of about 280 thousand square kilometres) had been reduced by 1% to 260 thousand square kilometres, and the forests of the Peruvian Amazon had shrunk by about 60 thousand square kilometres (Salati 1991). Recent news from the Amazon region reveals a slowing of the deforestation process. In 1990, "only" 14 thousand square kilometres was cleared, compared with almost 20 thousand in 1989 and about 27 thousand square kilometres in 1988 (Preston 1991).

In Ecuador, the main problems resulted from petroleum exploitation. Frequent spills in the Ecuadorean oil fields have had a critical effect on the environment. One of the largest spills took place in the region of La Joya de los Sachas, affecting the Napo River basin (Varea 1992). Similar spills are frequent in Colombia, where the main oil pipelines are frequently attacked by guerrilla forces.

Significant effects of deforestation have been described by Salati and Nobre (1991) based on an empirical model developed by Shuttleworth (1988). From September 1983 to September 1985, about 10% of the rainfall in the study area of Salati and Nobre was intercepted by the forest canopy, accounting for 20 to 25% of the evaporation. The remainder of the water being returned to the air moved through the trees by transpiration. Over the same period, about half of the incoming precipitation resumed to the atmosphere as evaporation, a process requiring 90% of the energy input. Of net radiation, 75% went into evaporating water and the remaining 25% was used to heat the air (Salati and Nobre 1991). It is estimated that 50 to 60% of the rainfall in the region originates from the recirculated water vapour that arises through evapotranspiration. Thus, a reduction in the forest cover will decrease precipitation, perhaps up to one-half or more throughout the Amazon and in downwind regions, such as the Bolivian altiplano and the eastern slopes of the Andes.

Palaeogeographic studies show that less-humid periods were relatively common during the Quaternary period in the Amazon region. Colinvaux (1989) thinks that these changes were one of the causes of the high level of biodiversity in the area and that they coincided approximately with the glacial period:

The contemporary reality is that much of the Amazon basin will be turned into pasture as people clear the land for cattle grazing.... History does suggest that parts of the Amazon can be exploited productively without causing mass extinction, but wise use must he the overriding theme.

Despite the modifications that the area suffered in previous eras, for the last few thousand years the core of the great forest has remained largely unchanged despite demonstrated human occupation. The production systems developed during that time did not bring about the general degradation that is occurring now in newly settled areas. It is generally accepted that indigenous production systems are sustainable over the long term. Although we are not certain what the forest was like before human occupation, we do know that the current forest ecosystem is the result of indigenous management for several millennia. That management system was based on a careful slash-and-bum technique, where small patches of forest were cleared for planting, used for 3 or 4 years, and then abandoned, allowing the selective growth of new plants. Other areas were preserved as sources of medicinal plants, for example, or simply left alone. Under these management strategies, some areas of the forest were used without affecting their potential, and the rest of the ecosystem was protected, resulting in long-term conservation of local environments. In that way, people took advantage of the enormous diversity of the jungle; rather than attempting to obtain maximum immediate return, they ensured the optimum long-term benefits.

Temperate forests

Despite a long history of deforestation, temperate forests still occupy a vast area: 1 933 million hectares, compared with the 1 700 million hectares of tropical forests that remains today. More than 80% of the world's remaining temperate forest is found in North America and Eurasia (Table 2).

Most temperate forests are managed using interventionist strategies. Some are managed reasonably well, maintaining many components of the original ecosystems. In others, the indigenous ecosystem has been completely replaced with "artificial" (often exotic) plantations. Exploitation of temperate forests for lumber and other resources has led not only to a decrease in forested areas but also to a loss of biodiversity. In many cases, inappropriate management has produced negative effects on the living systems and on the supporting environment, such as substantial changes in the structure of the forest, a decrease in the number of species, and damage to wild fauna. In tree plantations, the negative effects are even greater because these "artificial ecosystems" are normally monospecific.

Table 2. World-wide distribution of temperate forests.

Region

Area

(million hectares)

Proportion of total (%)

Former

   

USSR

944

48.8

North America

620

32A

Europe

157

8.1

Temperate Asia

94

4.9

Temperate South America

68

3.5

Oceania

40

2.1

Africa

10

0.5

Total

1933

100.0

Source: FAO (1988, pp. 47-58).

In southern Chile, for example, the indigenous temperate forests were rich and diverse. Traditionally, they were used by the Mapuche and other local populations. Today, however, they are being supplanted by exotic monospecific plantations of trees grown for export (such as Pinus insigne). The negative environmental effects and the loss of diversity (both biological and cultural) that this practice is producing are becoming widely recognized.

Although temperate forests still cover large areas, their actual value has been reduced because of diminished diversity and other ecological changes. The continued use of forests in cool climates has recently become less economic because of their slow growth and increasing opposition from environmentalist groups (particularly in North America).

Soybeans and deforestation

Health-conscious people of the developed countries have discovered a food staple that is the "remedy to all ills" - soybeans. Rich in protein and low in cholesterol, they have become the diet supplement of the 1990s for those who want to decrease their risk of cancer and heart disease. The soybean plant is native to east Asia. It was domesticated by the Chinese about 4 thousand years ago and has become a component of the diet of people in most east Asian countries. Per-capita consumption has traditionally been high in China, Indonesia, Japan, Korea, Myanmar, and Thailand, probably one of the reasons for the low rates of heart disease and cancer in this region.

Western countries have known about and consumed soybeans since the time of Marco Polo, but only recently has this staple become important in the diet of their populations. In the 1980s, the increase in soybean use was particularly dramatic as a result of its growing popularity as an animal feed. In the United States, soybean use doubled, and similar trends were observed in Canada and several countries of the European Community (in the Netherlands, for example, soybeans are widely used as pig feed).

World production has followed the trend, growing substantially in the last few years. In the United States, production of soybeans increased from 1.1 to 1.9 million bushels between 1970 and 1907. Some increase in production also occurred in Europe and Asia; however, most of the increased demand has been met by clearing forestland for soybean production in South America. Argentina and Brazil are the largest producers of soybeans on the continent; Bolivia and Paraguay have also substantially increased production recently. Other South American countries are important suppliers, but produce smaller volumes.

The crop - For higher productivity, soybeans require well-drained, highly fertile soils; high temperatures; and abundant rainfall. The most appropriate soils for soybean production are sandy and silty tropical soils in humid areas that are not subject to regular flooding. The best results are obtained if soybeans are planted immediately after deforestation. For this reason, soybean producers have identified the large forest regions of South America as the best places for their farms.

Normally, trees are cut and sold and the stumps removed using heavy machinery. After other vegetation is cleared away, plots are prepared for soybean cultivation. Often, soybeans are planted in combination with other crops on a semiannual rotation. The crop normally associated with soybeans is wheat. The additional demand on the soil resulting from multicropping increases the rate at which some key nutrients (potassium and phosphorus) are depleted, although, because soybean is a leguminous vegetable, it replenishes nitrogen in the soil.

Tropical soils can sustain soybeans and associated crops for 3 or 4 years before their fertility is affected. Once the level of key nutrients decreases, productivity and yields also decrease and fertilizers must be applied. Because using fertilizer increases costs and reduces competitiveness and earnings, soybean farming companies and entrepreneurs often prefer to clear new, inexpensive forestland. This practice has resulted in systematic clearing of the tropical rain forest throughout the Mato Grosso-Santa Cruz-Paraguay region.

Tropical soybean production areas extend throughout central and southeastern Brazil, eastern Bolivia, and Paraguay, in addition to temperate regions in Argentina, Uruguay, and the Brazilian state of Rio Grande do Sul. As of the mid-1990s, soybeans are the most important item in the commercial agricultural economy of South America.

Effects on forest soils - Soybean farming in tropical soils causes much damage. Forest cover is eliminated, the soil remains bare or poorly protected for most of the year, erosion becomes widespread, rills and gullies develop, and gradually soil fertility is lost along with much of the soil itself. For this reason, the continued use of tropical soils requires heavy applications of fertilizer; when this is not possible, the land is used to raise cattle or is abandoned.

Soybean crops are affected by a large number of plagues. Among the insects that attack the plant are Auticassia gemmatalis, Rachiplusia mu, Pseudoplisia includens, Nezara viridula, Peizodums guildinii, Euschistus heros, and others at a more local level. In addition, soybeans are attacked by numerous nematodes, fungi, bacteria, and viruses. The crops are also frequently invaded by several local and exotic weeds, reducing productivity levels (Souza dos Santos 1988). To keep the crops healthy, farmers apply large volumes of agrochemicals to combat weeds, insects, and other pests. Some of these chemicals find their way into natural water systems, causing serious contamination not only in local streams but in swamplands as well.

As a result, soybean cultivation is degrading local ecosystems, and its expansion can only be explained by a lack of concern at political and local levels about the long-term integrity of these systems. The growth of soybean cultivation in South America has continued unabated for some time. Since the late 1970s, it has been the main crop in the upper Paraguay basin. In 1985, total production in Mato Grosso was 1.7 million tonnes and in Mato Grosso do Sul, 2.6 million tonnes. This represented over 20% of total Brazilian production or almost 5% of world production. If Bolivian and Paraguayan production are included, the total volume for the basin was about 6 million tonnes in 1985 (7% of world production).

During the last decade, expansion continued. In 1993-1994, annual production was 4.8 million tonnes for Mato Grosso (almost three times what it was 9 years earlier) and 2.3 million tonnes in Mato Grosso do Sul. Almost 10% of the current world supply of soybeans comes from the upper Paraguay basin, where the total area planted is about 3.5 million hectares and crop yields are about 2 tonnes per hectare.

Effects on rivers - The radical change in vegetation cover over such a vast region is influencing the hydrologic regime in rivers downstream. The principal rivers affected are the upper tributaries of the Paraguay (the Taquari and Cuaiaba rivers) and Parana (the Iguazu, Grande, Paranapanema, and Tiete rivers) and, to a lesser extent, some Amazon tributaries flowing from the south (such as the Xingu and Tapajoz rivers).

The main effects of deforestation have been increased runoff, higher flood peaks, soil erosion, larger amounts of suspended sediments in the water, rapid silting of dams, longer droughts, and generally more irregular flows in rivers throughout the year. However, a hydrologic feature of the region tends to even out these irregular flows - the Gran Pantanal wetland.

Gran Pantanal

Gran Pantanal (Figure 1) is a large region of swamps and marshland in southwestern Mato Grosso, Brazil. Extending for about 160 kilometres along the east bank of the upper Paraguay River, it resembles an interior delta formed as a result of Quaternary and pre-Quaternary sedimentation in a slowly sinking basin located to the west of the Gondwanic basalts and sandstones of Mesozoic and Cenozoic age (such as the Botucatu sandstones) and the Brazilian Shield.


Figure 1. The Paraguay River basin and the Gran Pantanal of Mato Grosso.

Rivers descending from the north and east arrive at the plain and produce enormous alluvial fans that obstruct the development of river valleys. This causes the formation of a characteristic meandering pattern as the riverbeds frequently change direction, leaving abandoned crescent-shaped lakes. The landscape is dotted with hundreds of lakes where aquatic organisms, waterfowl, and many other species flourish. Several well-defined rivers can also be identified, such as the Paraguay (the main river) and the Cuiaba, Taquari, Miranda, and Aquidabuana.

Before occupation by Europeans and criollos, the region mainly consisted of humid forest in the lowlands and cerrado in the neighbouring highlands. The ecosystems are intermediate between the Atlantic forest and the Amazon rain forest. Cerrado (the Spanish word for closed) is also a type of forest with a lower canopy and a bushier, grassier undergrowth. There is no sharp boundary between the cerrado and the humid forest; a gradual transition can be observed almost everywhere.

The level of biodiversity in the region was (and to a large extent still is) high; it includes tens of thousands of plant species, hundreds of thousands of invertebrates, and many fish, birds, and mammals. As a result of this natural richness, the area was densely populated during precolonial times. Conservative estimates put the population of the Gran Pantanal basin at no fewer than 1 million.

The arrival of the Europeans was traumatic. Spaniards came from the west (upper areas of Peru) and the south (Asuncion) and established religious missions in the Guaira region about 500 kilometres southeast of the Pantanal. Paulist slave traders (the Bandeirantes) reached the Guaira region by the end of the 17th century. They captured tens of thousands of indigenous people in the missions and villages and sold them to the owners of the sugarcane plantations of Pernambuco.

Despite the conquest and colonization efforts, however, both the regional ecosystem and portions of the local populations managed to survive until well into the 20th century. Most of the Pantanal remained in the Empire and later Republic of Brazil, some lies in Bolivia, and

Paraguay retained only the small area of wetlands in the Gran Chaco and Neembucu.

During the first half of the 20th century, activity centred around the Paraguay River, as quebracho wood was harvested for tannin and yerba mate plantations were established. In the 1960s and 1970s, criollo occupation increased following new Brazilian "development" policies that made new highways and roads a priority and encouraged uncontrolled colonization. Tens of thousands of migrants (from Rio Grande do Sul and other areas of Brazil) moved to Mato Grosso, establishing ranches throughout the region.

One common "style" of occupation was to clear the cerrado and forest, plant grasses, and introduce cattle. Deforestation was also carried out to prepare land for planting grains, mainly soybeans, rice, and corn. Rice plantations were established everywhere, mainly to obtain funding from the government. According to local agronomists, the rice plantations were a means to obtain easy credits. The forest was logged and removed or burned to make room for dry rice farming. After 3 or 4 years, grass seeds were included in the rice and, after 4 to 6 years, a new artificial grassy ecosystem was established.

On more fertile soils, the forest was cleared for soybean farming. In the early 1990s, soybean agriculture occupied 5 to 10% of the land in the Pantanal basin, and soybeans are the main agricultural export of the Brazilian states of Mato Grosso and Mato Grosso do Sul. Soybean production is also important in Santa Cruz (Bolivia) and eastern Paraguay.

Deforestation took place quickly; by the early 1990s, extensive areas had been cleared. In Mato Grosso do Sul, for example, 80% of the forest is gone. In the Gran Pantanal, deforestation was delayed somewhat because of the swampy conditions. Gradually, however, local ranchers have encroached on the natural ecosystem by burning trees or using "agrotoxic" substances. Many thousands of hectares of forest and swamp have been destroyed to make room for raising cattle.

The effects of this environmental degradation are being felt throughout the Pantanal region. The ancient, clear rivers have become brownish, muddy streams. Channels are being filled by sand, fishing is uncontrolled, and poaching of local animals is widespread (often organized by the ranchers themselves). The few remaining indigenous people have been dispossessed of their land and reduced to a situation of misery and desperation.

Impact of changes in the Gran Pantanal

The Pantanal is a huge natural-flow regulator. The plain covers 90 thousand square kilometres and receives water from rivers on the west, north, and east during the rainy season. Some of the water is lost to evaporation; the rest moves toward the southern outlet to form a free-flowing river (the Paraguay) several hundred kilometres to the south. The summer rainy season occurs in January and February, but the surplus flow of water in the Paraguay River is spread over the next 6 months because of the presence of the Pantanal.

Because of the Gran Pantanal, the peak flow period for the Alto Parana and the Paraguay rivers occurs at different times of the year: the Alto Parana reaches its maximum level in March and the Paraguay a few months later between June and August. Without the dampening effect of the Pantanal, flooding would occur at the same time in these rivers, causing disastrous flooding downstream of their confluence. During the rest of the year, river levels would be much lower, affecting navigation and the movement of merchandise to and from Rosario, Santa Fe, Parana, and all of Paraguay.

The sediment-loaded waters of the Bermejo and Pilcomayo rivers also affect the level of the Paraguay. These rivers arise in the highlands of Salta, Jujuy, and the Bolivian altiplano. Their peak flow period occurs in late summer or early fall. Without the Pantanal, this peak would coincide with a period of heavy flow in the Paraguay, with potentially catastrophic consequences up- and downstream from their confluence.

In brief, widespread deforestation in the Paraguay River basin combined with drainage of the Pantanal wetlands would significantly increase the flow in this river in summer and early fall. It would result in a much larger sediment load throughout the basin, and flood peaks in the river and its tributaries would be simultaneous. The volume that could be expected has not been calculated, but it would probably be at least twice the current highest flow in the Paraguay River and slightly less than twice the highest flow in the middle Parana.

Winter and spring flows, on the other hand, would be greatly reduced (probably several times lower throughout the basin), affecting navigation and the water supply of certain cities - this is already occurring in Cuiaba, Mato Grosso.

Several waterworks have been built in the Parana basin. The most important was the Itaipu dam, downstream of the largest falls (in terms of flow volume) in the world - Sete Quedas Falls. This dam, which cost over $10 billion, was completed around 1982, forming a 2 thousand square kilometre lake and producing a significant quantity of hydroelectric Dower. Although the energy produced is to be shared equally by Brazil and Paraguay, Paraguay uses only 5% of its share. The remaining 95% is sometimes purchased by Brazil or, lately, not used at all. Selling this energy to other countries is not permitted under the binational treaty.

Despite the huge amount of unused energy generated by the Itaipu dam, the governments of Argentina and Paraguay decided to construct a new mega-dam at Yacyreta Island (about 300 kilometres downstream of Itaipu). The cost of this dam may be over $5 billion and it will contribute a significant amount of energy to the already enormous surpluses existing in the region.

More recently, plans are under way to create a "hidrovia" or "hydro-way" to ensure river navigability through a complex array of dams, drainage and navigation canals, docks, piers, and other harbour structures (see box 1). The cost of the project might reach several billion dollars, adding to the considerable foreign debt of the countries along the Paraguay and Parana rivers. There is concern that these works may result in the virtual elimination of the Pantanal and that they will be useless, as canals remain dry for most of the year and flood catastrophically during peak flow periods.

The final result of these mega-plans may not be "development" or even "modernization," but the complete annihilation of some of the world's largest ecosystems, together with their associated traditional cultures. Some foresee a significant loss of opportunities, natural and human resources, and future financing possibilities for the countries and cities of the basin.

1. The Hidrovia Project

In the midst of ever-increasing damage to local ecosystems, a new regional integration project - Hidrovia - has been proposed. The aim of the project is to ensure that soybeans and beef, among other products, can be transported from the river ports of Mato Grosso and Bolivia (in Gran Pantanal and upstream) down to Buenos Aires in Argentina and Nueva Palmira in Uruguay for export. Today, the Pantanal can be navigated only by small boats and barges. Its river channels are already shallow and are filling with silt and sand. In fact, this situation created the swamp in the first place.

For commercial navigation to be feasible, deeper canals and complementary hydroworks may have to be built. Digging canals in the swamp, however, will have an impact on both the geo- and ecosystem. An immediate effect will be an increase in water velocity in the channels and erosion of the banks and riverbed. This process will occur first downstream, moving gradually upstream and resulting in widespread drainage of the swamp. The drier soils will then be available for use as rangeland. The aquatic ecosystem will be disturbed by noise, turbulence, and contamination from the expected heavy barge traffic.

The project may require the movement of millions of tonnes of earth and sediment and the use of heavy equipment and numerous labourers. One can only guess at the destructive effects of this work on wildlife and the ecological equilibrium. However, an independent investigation must be carried out to ensure that all factors are taken into account before a decision about the project can be made. This need is widely recognized by university researchers, local nongovernmental organizations (NGOs), and some political groups and authorities.

Indigenous people of the upper Paraguay basin

Despite aggressive occupation of their lands, attempts to eliminate or enslave them, migration, and acculturation, about 60 thousand indigenous people belonging to 15 nations have managed to survive in the Pantanal-upper Paraguay region. These people were evicted from their land in most of the cerrado regions of Mato Grosso, remaining only in isolated areas with less-fertile, stony soils or on steep hillsides and in the swamplands of Gran Pantanal. Several groups are in danger of extinction.

The Guarani people of Mato Grosso do Sul number about 30 thousand; they live on about 20 reserves, but the population is concentrated in small areas. During colonization, their religious leaders were ignored by the government and capitaos were appointed to govern them. The Guaranis resisted this move by continuing their rituals in secret and, later, by reviving some of their traditional systems of self-govemment (like communal assembly). The difficult situation in Guarani communities is reflected in the rate of suicides among the young people (31 cases in 1990, 21 in 1991, and 21 in 1992), which is among the highest in the world (see box 2).

The Guato people build canoes. They live by fishing and farming the islands of the Paraguay River. Only a few hundred Guatos still exist and only a few of these remember their own language.

The Guaycuru-Kadiweu belong to an ancient, large, seminomadic nation that became horseback riders in the 17th century. They lost some of their land in Mato Grosso in the 1950s and were left with a reserve of just over 500 thousand hectares. There are currently fewer than 1 500 Kadiweus living on their ancestral lands and a few hundred living elsewhere.

The Terena, who are descendants of the Arawak, are among the largest groups of indigenous people, numbering about 20 thousand. They farm (rice, beans, manioc, and corn) and display a high level of acculturation. Like other indigenous groups, they have had difficulty retaining enough land for survival. Today, they are virtually landless and depend largely on low-paying jobs on local ranches.

As in many other areas of the continent, the situation of the indigenous people of Mato Grosso is critical and, in many cases, desperate. A wealth of traditional knowledge is being lost every day, human rights are violated, and many indigenous people who are unable to visualize a future for themselves take their own lives. Along with nature's riches, Mato Grosso is losing its rich ethnic and cultural diversity and the knowledge necessary to ensure a more sustainable and just future.

2. The Guarani were right

Before "science," humans knew many things. Traditional knowledge was not supported by a theoretical framework, but it was rich and diverse. Tribes understood their environment: vegetation, insects, mammals, birds. They knew which plants could be used as medicines and which were poisonous. Knowledge was site-specific. In most cases, it was difficult to apply elsewhere; but locally, it allowed many groups to sustain a quality of life that should not be undervalued.

Scientific knowledge accumulated slowly. In many ways, it was nourished by the traditional or "empirical" knowledge of local groups. After many generations, scientists are still looking to traditional societies for elements of knowledge.

Some scientists, however, possessing the knowledge accumulated over generations, prefer to ignore the fact that traditional knowledge, in one way or another, provides the basic insights that allow continuing enrichment of the paths of science and technology. In the meantime, a huge body of knowledge about nature and its ways is being lost with the death of each shaman, wise man, and medicine woman.

Agronomists have failed in their attempt to increase production indefinitely with their "green revolution." Twenty years later, whole ecosystems have disappeared, taking with them species that were not even recorded. Hundreds of crop varieties have been wiped from the face of the Earth and erosion has become widespread. Although more food was produced for a period of time, our children and our children's children will not be able to grow crops in eroded soils. Monospecific, artificial ecosystems are vulnerable to plagues and require large quantities of pesticides that are contaminating water resources.

Dead fish, eroded soils, unique animals and plants eliminated - the technologists have failed. The Guarani knew how to clear a parcel of land; what, when, where, and how to plant; how to leave large areas untouched to conserve the medicines and to keep the spirits happy. The Guarani called them "spirits"; scientists call it "genetic biodiversity." Basically, it is the same thing. The Guarani were right.