Using data from satellite observations, it is estimated that between 16.4 and 20.4 million hectares of tropical forest are being destroyed each year (a hectare equals 107,639.1 square feet [10,000 square meters]). Only 50 percent of the world's mature tropical forests remain; 750 to 800 million hectares of the original 1.5 to 1.6 billion hectares of tropical forest have been destroyed.
There are two types of tropical forest: wet and dry. The greatest loss has occurred in wet forests, commonly called "rain forests." In Latin America 37 percent of tropical rain forests have been cleared; in Asia that figure is 42 percent, and in Africa, 52 percent. Most of the deforestation occurs as the result of logging, cutting trees for firewood, or the clearing of forests to create agricultural lands.
Attempts to grow crops on former rain forest land, however, are largely unsuccessful. This is because most of the nutrients in a tropical rain forest exist within the plants themselves; the soil is very nutrient-poor. When the plants are stripped away, the exposed soil is rapidly eroded by torrential rains. After the rain ceases, the sun bakes the ground into a hard crust, rendering the soil incapable of supporting vegetation.
Sources: Lean, Geoffrey, et al. WWF Atlas of the Environment, pp. 65-68; National Wildlife, vol. 30, no. 3 (April-May 1992), p. 16.