Destruction of Amazonian Rainforest and its effect on the environment

Destruction of Amazonian Rainforest

This area of the Amazon rain forest has been cleared by burning, following which a ground cover of small plants grew quickly, but could not prevent the rapid erosion of the soil by rain water, the signs of which can be seen in the channels leading down to the central gully. The fast erosion of already nutrient-poor soil makes regeneration of the forest an even more precarious prospect.

Anne LaBastille/Bruce Coleman Inc

Deforestation, the large-scale removal of forest, prior to its replacement by other land uses. It is proceeding at about 17 million hectares each year (170,000 sq km or 65,000 sq mi, an area larger than England, Wales, and Northern Ireland combined). Between 1980 and 1990, annual deforestation rates were 1.2 per cent in Asia and the Pacific, 0.8 per cent in Latin America, and 0.7 per cent in Africa. Forest area is generally stable in Europe and North America, although the rate of transition from old-growth forest to other forms in North America is controversially high.

Deforestation may be distinguished from forest degradation, which is a reduction in forest quality. The two are linked, and result in several problems. They cause soil erosion and watershed destabilization, resulting in flooding or drought. They reduce biodiversity (the range of habitat, species, and genetic types), particularly significant in tropical forests which are home to much of the world's biodiversity. The culture and knowledge of many forest peoples have evolved through centuries of nurturing the forest; they are diminishing as forest area reduces, access to forest is increasingly restricted, and traditional rights are eroded by governments. Deforestation affects the livelihoods of between 200 and 500 million people who depend on forests for their food, shelter, and fuel. Deforestation and degradation may contribute to regional and global climate imbalances. Forests play a major role in carbon storage; with their removal, excessive carbon dioxide in the atmosphere may lead to global warming, with many problematic side-effects.

While deforestation is now viewed as a problem, historically it was considered to assist national development. Natural forest “capital” was liquidated and replaced by other forms of capital to produce food, raw materials, energy, or infrastructure.

Agriculture in temperate regions has depended upon forest removal, capitalizing upon forest soil fertility. Most of England's woodlands were deforested by 1350. In continental Europe and North America, deforestation accelerated in the 18th and 19th centuries to clear land to grow food for industrial cities, and to meet fuel and construction needs. Rising agricultural productivity has since allowed much temperate farmland to revert to forest. From a low of 5 per cent in 1900, the United Kingdom's forest and woodland area is now 10 per cent.

Deforestation processes are, in general, more destructive in the tropics. Most forest soils in the tropics are far less fertile than temperate soils, and are erodible. This is because high rainfall leaches out nutrients from the soil, preventing them from building up. However, colonial policies were based on the mistaken assumption that lush forests were on fertile soils. They aimed to “conquer” the forests, principally for cash crop plantations and agriculture; and have left a legacy of exhausted soils.

Tropical deforestation increased rapidly after 1950, helped by the availability of heavy machinery. Since then, rising human populations have also cleared ...

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Tropical deforestation increased rapidly after 1950, helped by the availability of heavy machinery. Since then, rising human populations have also cleared forests the hard way—by hand. Annual rates of deforestation in 52 tropical countries nearly doubled from 1981 to 1990.

Modes of Deforestation

Slash-and-burn cultivation by small-scale farmers accounted for 45 per cent of tropical deforestation in Africa and South-East Asia in 1980. After a few years' cropping, many soils support only grassland and scrub, and farmers move to other forests.

Timber harvesting is a significant cause of deforestation in South-East Asia, Central Africa, and—until about 1990—West Africa. Logging frequently damages more trees than it removes. Timber production in the Pacific Northwest of North America, and in Siberia, often replaces tree cover through plantations (see below), or leaves the area to regenerate naturally through the process of succession (See Ecology), although soil degradation and erosion take place while the plant community is being re-established.

Clearance for settled agriculture, on infertile soils, results in short-term gains only. However, well-planned clearance has led to sustainable benefits, such as some rubber and oil palm plantations, which retain a forest-type structure aiding soil and water conservation.

Clearance for forest plantations has been significant in South-East Asia and South America. Foresters worldwide have removed natural forests to make way for plantations that are higher-yielding in timber production. However, there is now more awareness among foresters of the social and environmental losses arising from this. Forest plantations, since they often contain single species of tree all of the same age, do not reproduce the ecosystem of the original forest, which is generally characterized by a wide variety of flora and fauna at all stages of development. In the northern coniferous forests and temperate rain forests of British Columbia, where about 2,200 sq km (850 sq mi) of timber is harvested annually (approaching 1 per cent of the total commercially viable forest in the province), logging companies have been required since 1987 to replant all cleared land within five years; efforts are also made to retain the original diversity of tree species, although the animal and secondary plant ecosystems are necessarily affected. As replanting in British Columbia has only been undertaken on a serious scale since the mid-1960s, it is claimed by the provincial government that the cutting of old-growth forest will continue to be necessary for at least another 50 years, until second-growth plantings are sufficiently mature to replace them. This situation, broadly reproduced elsewhere in North America and Europe, means that the area of forest remains largely stable, although the proportion represented by old-growth is continually diminishing. Widespread concern at the loss of old-growth forests has led to many confrontations, such as at Clayoquot Sound on Vancouver Island in 1993, when more than 700 demonstrators were arrested while trying to prevent the cutting of timber in virgin stands of temperate rain forest.

Clearance for grazing was a major cause of deforestation in the 1970s and 1980s in Brazilian and Central American forests, with government-sponsored schemes to create large ranches. Regular woodland burning to maintain pasture is common in dryland Africa.

Clearance for fuelwood is a problem in the drier areas of Africa, the Himalayas, and the Andes.

Clearance for settlement, mining, and oil exploitation are locally significant, notably the organized transmigration schemes operated, until recently, in Indonesia and Brazil, where people from overcrowded areas were settled by governments in forests.

Clearance for roads and dams has directly resulted in deforestation.

Often, several deforestation agents work sequentially. Road development encourages timber exploitation, which opens the forest for agricultural settlement and fuelwood salvaging. About half of all logged tropical forests are eventually used for farming.

The Root Causes of Deforestation

Deforestation and forest degradation occur in response to policy, market, and institutional “signals”. These tend to either “push” people into the forest, through difficult economic or social conditions outside it; or to “pull” people into the forest, through the attraction of profits (from logging or forest clearance). Many policies effectively undervalue forests, such as low fees for logging, or they overvalue the benefits of removing forest for other uses, which can be seen in the subsidization of food prices. In contrast, they do not provide long-term incentives to look after forests. The lack of security of forest ownership and forest-use rights encourages exploitative behaviour. Some policies even require deforestation in order to show the owner has “improved” the land. Commercial and official debt, owed by many developing nations to industrialized countries, forces developing countries into deforestation to generate foreign exchange.

Whilst these are the root causes of deforestation, they are exacerbated by increasing population, increasing demands for forest products, and inappropriate technology.

Efforts to Control Deforestation

Traditional approaches to forest problems have emphasized laws and regulations. But these are often weakly enforced, and stronger groups are able to evade them. In poor countries, focus has been on aid-funded programmes, notably the international Tropical Forests Action Programme. These have proved insufficient to reduce deforestation. They have not tackled the root causes. Market-based, voluntary approaches are now appearing—such as forest certification and timber labelling—to favour the products of sustainable forest management.

There is now general agreement that, as deforestation is the result of many direct actions triggered by various root causes, action on only one front rarely solves the problem. Many efforts are required to encourage sustainable forest management, balancing environmental, social, and economic objectives. Critical are certain national procedures and policies. Since deforestation can produce both benefits and costs, it is important to estimate the gains and losses for each possible forest removal. The United Nations has recommended that every nation preserve at least 12 per cent of its representative ecosystems. Several countries are valuing forest benefits, and defining a Permanent Forest Estate (PFE) and standards for its use. The PFE is the amount and location of forest a nation decides it needs, now and for the future, for both protection and production purposes. Remaining forests are planned for eventual conversion to other land uses.

Contributed By:

Steven Bass

Slash and Burn Deforestation

The deforestation technique of slash and burn, utilized extensively to clear large areas of forest for agricultural and other purposes, causes an enormous amount of environmental damage. The removal of all trees and groundcover destroys animal habitats and greatly accelerates erosion, adding to the sediment loads of rivers and making seasonal flooding much more severe.

Sean Morris/Oxford Scientific Films

Deforestation for Timber Harvesting

This Costa Rican stream valley has been deforested for its timber, much of which is logged commercially for export. Since there is no longer a good root system to anchor the topsoil, it begins to erode. If the cycle continues, the area may eventually resemble a desert.

S.E. Cornelius/Photo Researchers, Inc.

Clearance for Settled Agriculture

This plantation of rubber trees in Ghana has been established on land that was formerly occupied by virgin forest. Although these are healthy trees which preserve the integrity of the soil, the diversity of animal and plant species that the area previously supported is inevitably reduced.

Robert Harding Picture Library

Clearance for Forest Plantations

Clear-cutting is a forestry technique in which all the trees in a given area are removed. The advantages of this technique (providing the clear-cut area is replanted) include the eventual production of trees of approximately the same age and height, which are easy to harvest using mechanized equipment. The disadvantages include the elimination of old growth forest and animal habitat, excessive erosion, and an unattractive landscape.

Mike Birkhead/Oxford Scientific Films