Tropical Rain Forest, a forest of mainly evergreen broad-leaved trees found in continually moist, warm climates in areas of the world near the Equator. Tropical rain forests are found in the basin of the Amazon River in South America; in parts of western and central Africa, including the basin of the Congo River; on Madagascar; and in parts of Central America, northern Australia, and Southeast Asia. These forests are sources of many economically important products, including mahogany, teak, rosewood, and other hardwoods used in furniture making; rubber; fruits and nuts; and plants from which many medicines are derived.
Tropical rain forests support an abundance of life; they contain up to two-thirds of the world's species of living things. The lush vegetation has depleted the soil of most of its nutrients, but decaying plant and animal matter supply nutrients necessary for plant growth. Most trees grow to a height of 100 to 150 feet (30 to 45 m); some reach 200 feet (60 m). Many rain forest trees are characterized by buttressing (the development of wide-spreading, flange-like buttresses at the base of trunks for support) and cauliflory (the production of flowers directly on trunks and inner branches instead of on stem tips). Most trees have tall, slender trunks and mushroom-shaped tops. A dense canopy is formed by the upper branches of trees and by woody vines and epiphytes (air plants, such as orchids and bromeliads) that cling to these branches. Shade-tolerating plants of various heights grow beneath the canopy.
Many tropical rain forests have been destroyed or are in danger of being destroyed by extensive logging and clearing of land for farming and cattle ranching. In a practice called slash-and-burn, farmers cut and burn trees to clear the land. Heavy rains soon wash away the few nutrients that are in the soil and only a few crops can be raised on the cleared land. After one or two years, the farmer abandons the cleared land and repeats the process on another part of the forest. Once the land is cleared, trees and other plants native to the rain forest cannot grow, or can do so only with great difficulty.
The destruction of tropical rain forests causes ecological changes both locally and worldwide. As trees are destroyed, the natural water cycle is disrupted—there is less vegetation to give off water (through the process of transpiration) to form clouds, and rainfall is reduced. In some cleared areas, desert-like conditions occur.
Many scientists believe that the destruction of tropical rain forests is responsible for increased amounts of carbon dioxide in the atmosphere. The cause, as they see it, is twofold—the burning of trees releases carbon dioxide into the air and, with the depletion of the forests, there are fewer plants to absorb (through the process of photosynthesis) the carbon dioxide that is already there. Carbon dioxide has the potential of warming the earth through a phenomenon called the greenhouse effect. The warming of the earth could create worldwide disturbances of weather systems.
With the destruction of tropical rain forests, many species of living things are becoming extinct. The potential to study these species is lost and with that loss, any benefits that humans might have derived from these species.
National and international organizations are making efforts to conserve tropical rain forests. Some governments are forming national parks and reserves and passing strict laws regulating the use of their forests. Most rain forest destruction is in countries that are poor and have rapidly expanding populations. Conflicts arise between groups trying to save the forests and those that see the rain forests as a means of providing food and homes for people, products for trade with other countries, and opportunities for foreign investment.