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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

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.