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This page presents some information on tropical forests, some reasons for deforestation and its implications.

Tropical Forests

Tropical forests may be rainforests with year-round rainfall, drier forest with seasonal rainfall and drier, open woodlands. Tropical forests are rich sources of biodiversity in that they cover only around 7% of the Earth's land surface but contain around 50% of all species (Earth Observatory, 2007). Forests have little financial value when standing but both the trees and the land on which they stand can be highly profitable when deforestation has taken place. Since 1850, there has been a 20% decrease in total global forest area (Houghton, 1999).

The majority of primate species are restricted to tropical forests so the state of the world's forests has a direct bearing on the ability on primate populations to thrive and survive (Eeley and Lawes, 1999).

Many people may be using rainforest products without being aware of it. Here is a quick list:

(Rainforest Alliance, 2008).

Why does deforestation occur?

The most obvious reason is to harvest timber. However, the chief cause of deforestation is to convert the land for agricultural use. This accounts for around 13 million hectares per year. Reforestation offsets some of the loss but the net change in the 2000-2005 period was a total loss of 7.3 million hectares per year (FAO UN, 2006: xii). In 2005, there were 4 billion hectares of forest worldwide (ibid.: xii).

Other causes include space and raw materials for infrastructure, including "roads, ports, housing and tourism development." (ibid.: 8).

Effects of deforestation

Loss of biodiversity

Rainforests are complete ecosystems and all plants and animals within them are inter-dependent. When the forest is disturbed, these inter-dependencies can be upset, sometime irrevocably. For example, primates are seed dispersers.  They collect food that they may eat elsewhere, passing or dropping the seeds away from the original plant.  This allows the plant to maintain its genetic diversity and avoid inbreeding. In forests where primates have been hunted to extinction, or where deforestation has occurred to such an extent that they can no longer survive there, these plants may become inbred and eventually die out, effectively killing the forest from within (Redford, 1992). In Indonesia, because of illegal logging, fires and the expansion of palm oil plantations, it is estimated that 98% of the forest will be gone by 2022 (UNEP, 2007: 6).  This will result in a huge loss of biodiversity within the next fifteen years. Between 1970 and 2003, 55% of all tropical species were lost as a direct result of human activities (WWF, 2006: 6).

Soil erosion

Despite the lushness of the vegetation, rainforest soil is very thin. Unlike European soils, the nutrients are mostly in the plants, not the soils. Without the trees and plants to hold the soil in place, the heavy rains wash it away (Myers and Kent, 1995).

Social impacts

Many indigenous peoples are dependent on rainforests. Hunting and gathering, and harvesting of natural resources such as rubber or nuts allow people living in or adjacent to rainforests to survive. Programmes to relocate communities so that forested land can be developed are likely to have devastating consequences for those people who know of no other lifestyle. However, they may find it difficult to challenge governments who are focused on economic development. Even where no centrally-forced relocation is implemented, such an environmental change may create environmental refugees of people who leave their homes for better lives elsewhere (Myers and Kent, 1995).

Climate change

Amazonia alone contains around two-thirds of the world's 'free' fresh water and most of its water is recirculated back into its own ecosystem. When deforestation occurs, the remaining forest has less capacity for evapotranspiring the same amount of moisture. The forest starts to dry out and there is also less rainfall for surrounding areas (Myers, 1984).

As well as local climatic effects, there are also global effects to deforestation. The Albedo Effect is the proportion of sunlight reflected back into space.  Being white, snow and ice are highly reflective with an albedo of 85-90%. Croplands have an albedo of 12-20%. At the other end of the scale, evergreen tropical rainforests have an albedo of 7-15%. Clearly, a change of land use from forest to cropland alters the amount of sunlight reflected from the Earth and this is why albedo is a fundamental factor in climate control, resulting in changes of airflow and precipitation (Myers, 1984: 282).

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