The rainforest is one of several types of forest found throughout the tropics, and each type has different characteristics. The closed forests account for about half of the total area of tropical forest (around 62 per cent of the natural tropical forest) and comprise two types of continuous tree cover (Table 1.1). Eleven-twelfths of the closed forests, by area, are tropical moist forests and the rest are deciduous and semi-deciduous forests of various types. About two-thirds of the moist forests are tropical rainforests, composed of evergreen broadleaved trees which flourish in the high temperature and humidity of the low latitudes. The tropical moist deciduous forests (or monsoon forests) grow on the fringes of the tropical rainforests, and lose their leaves in the dry season (Ehrlich & Ehrlich, 2002).
Thesis Statement: Rainforests can never be replaced once we have lost them.
Table 1.1 Distribution of tropical forest types
Total area (million km2)
Tropical moist forests
Tropical moist deciduous forests
Deciduous and semi-deciduous forests
Tropical forest plantations
Source: World Resources Institute (2008).
Most of the remaining tropical forests are open woodland, including shrublands and types of savanna, pasture and grassland which are partly wooded. Almost all (97 per cent) of the tropical forests which have been modified by human activity are fallow forests, areas which have recently been farmed and then abandoned or left to regenerate naturally. Only a very small area is covered by tropical forest plantations. The industrial plantations produce commercial timber, pulpwood or charcoal; the non-industrial plantations are mainly for fuel wood production or environmental protection.
The tropical rainforests provide a discontinuous belt of green around the globe, between the tropic of Cancer (23.5° north) and the tropic of Capricorn (23.5° south). Dense rainforest is the natural climax vegetation of the hot, humid tropical zone and it flourishes particularly in the lower latitudes (between 10° north and south of the equator). Just under half of the tropical zone (49 per cent according to the World Resources Institute) is covered by forests.
Most of the tropical countries with surviving rainforests are developing countries, for which the forests provide a valuable capital asset. The total area presently covered by tropical rainforests is estimated at 12 million km2, which accounts for nearly a third of the world's forests (covering roughly 30 million km2). The distribution of forests within the tropics is uneven, reflecting the distribution of land and sea and the impacts of this on climatic boundaries. The latitudinal boundaries of the rainforest are determined mainly by precipitation, while altitudinal limits are determined more by temperature (Ellis, 2008). Some rainforests thrive beyond the 10° north and south latitudes, where high rainfall encourages forest growth. Such patches occur in Central America, the north-east coast of Australia and the great valleys of southern China.
The main rainforests today are found in three areas Latin America, Western Equatorial Africa and South-East Asia. Latin America houses the American Formation which is dominated by the Amazon and Orinoco Basins. It has over half (56 per cent) of the world total, much of it (3.31 million km2, 48 per cent of the area's total) in Brazil and the rest in Peru, Ecuador, Colombia, Venezuela and French Guiana. Amazonia is the world's largest and most important surviving rainforest. The remaining rainforests are scattered in sixteen countries in West and Central Africa (18 per cent of the world total) and South-East Asia (25 per cent of the world total). The African Formation includes the Cameroons and the Congo Basin in countries such as Gabon, Zaire and Madagascar. The Indo-Malaysian Formation in South-East Asia includes parts of western and southern India, the Far East (especially in Indonesia (Eden, 2006) particularly Borneo and Papua New Guinea -- which now has about 10 per cent of the world's remaining tropical rainforest) and north Australia.
Destruction of the Rainforest: Rates of Loss
The rainforests are under attack. These rich and complex ecosystems, which have survived millions of years of natural environmental change (indeed they have flourished through it), are now facing a fight for survival. The hands of people are inflicting more damage on the rainforests in a matter of years than the entire forces of nature have done over geological time-scales. Norman Myers, an international expert on rainforests, pointed out early in 1990 that 'at issue is the most exuberant expressions of nature that has ever graced the face of the planet during four billion years of evolution (Aiken & Leigh, 2006). Within just another 40 years at most, we may see the last remnants fall to the chainsaw and the matchbox.' The timetable is open to debate; that the fight for survival is on is not.
We have already seen some evidence that today's rainforests are shrunken remnants of much larger forests from the ancient past. These survivors represent the outcome of long periods of climatic change; they are natural distributions, in equilibrium with today's climatic constraints in the tropics. But even that picture reflects a theoretical distribution rather than an actual pattern of vegetation on the ground. The maps of world vegetation distribution, for example, show climatic climax vegetation -- what should exist under prevailing climate, in the absence of damaging human activities, rather than what does exist. There is little doubt that many areas shown on the maps as rainforest no longer have natural forest cover, having been cleared for one reason or another. Disparities between theoretical and actual distributions of rainforest reflect human disturbance of the forest habitat. This comes in two forms. Degradation involves complete loss of the forest, which might be cut down and replaced by open woodland or agriculture. The loss is permanent. Depletion involves some change to the forest ecosystem, but not complete removal. Some plant and animal species are lost, but forest remains (albeit a much-modified forest). Natural regeneration can re-establish the forest ecosystem, given a long enough periods without further depletion. Both forms of disturbance of rainforests are widespread, but degradation poses the greatest threat.
What is more certain is that clearance of the rainforest has been going on for a long time. There is evidence of clearance for agriculture at least 3,000 years ago in Africa, 7,000 years ago in South and Central America and possibly 9,000 years ago in India and New Guinea (Flenley, 2005). Traditional forms of forest clearance by burning were small-scale and localized and they had relatively little impact on the overall extent, distribution and character of the rainforests. Indeed they may even have contributed to development of the diversity of species.
More recent exploration of the rainforests, prompted by the search for commercially useful resources as well as by land hunger, started the irreversible tide of forest destruction and clearance. Early episodes were small-scale and isolated. During the fifteenth century, for example, groups of English and Dutch migrants lured by a gold rush looked to the Brazilian Amazon to meet their need for food and charcoal. Forest species were exploited for food; trees were felled and burned for charcoal. In the eighteenth century parcels of rainforest were cleared from the hills of central Minas, in eastern Brazil, to create land for cattle ranching. Soil depletion and erosion quickly followed. More widespread exploitation of the rainforests began during the eighteenth and nineteenth centuries as demand started to grow in the western world for tropical plantation crops.
Losses and Losers
Some of what is lost when rainforests are cut down or burned reflects their intrinsic value. Most of us are never likely to be able to set foot in a real rainforest, but that is not the issue. What matters is that the rainforest is important quite simply because it is there. Whether or not it has some inalienable right to survive is a debating point in moral philosophy; the fact that we would miss it if it disappeared completely is a matter of human nature and sensitivity. The extrinsic values of rainforest are easier to quantify and thus they form the basis of any evaluation of the impacts of deforestation. Whatever utilitarian interest we might have in nature's richest ecological storehouse (including many interests we were probably totally unaware of, such as using drugs and medications derived directly from rainforest products), we are all losers as the remaining forest reserves dwindle and disappear (Bunker, 2000).
Inevitably the most direct losers are the people for whom the rainforest is a home. Traditionally an estimated 50 million people live in the world's rainforests. These are mainly tribal peoples whose lifestyles and cultures are tightly interwoven with the natural cycles and processes of the forest, and who have adapted over many generations to life in the forest. Here we concentrate on the main impacts of deforestation, which include the loss of biodiversity and natural resources, loss…