|MadSci Network: Environment/Ecology|
Before jumping into the answer to your question, letís define a rainforest: There are two main types: equatorial and tropical moist rainforests. Equatorial rainforest, of which two-thirds of the world's rainforest is composed, is found bordering the equator in Brazil, Zaire and Southeast Asia. The temperature (an average of 27 degrees Celsius) and the rainfall are the same year-round, with little if any seasonal fluctuations. Tropical moist forests are found north and south of equatorial rainforests, and have a noticeable dry and wet season.
Should we cut down rainforests? In doing so, we jeopardize many valuable functions that rainforests serve, not only to humankind, but also to global systems and millions of individual organisms. Although it makes up less than 5% of the earth's land, the rain forest contains one half of the world's animal population. The canopy alone houses more tree-dwelling animal species than any other habitat. Tropical rainforests are by far the richest habitat on Earth, housing as many as 30 million species of plants and animals - more than half of all life forms. At least two-thirds of the world's plant species plants, many with medicinal value, occur in the tropics and subtropics.
From this massive diversity of life, humans derive many useful products. For example, the diversity of insects in the rainforest means that rainforest plants have the ability to defend themselves with a variety of chemicals that act as natural insecticides. These chemicals can be adapted by humans for use in agriculture, where they are as potent as synthetic insecticides, but are often less toxic to humans and the environment.
Rainforest plants also contain valuable genetic information. For example, plant disease resistance from a rainforest plant can be genetically incorporated into our crop-plants. In the last fifty years, genes from wild rainforest plants have been used to prevent disease in hundreds of important crops, including coffee, sugar-cane, cacao, manioc, and bananas.
Approximately 25 percent of all prescription drugs come from rainforest plants. As the rainforest is destroyed, many potentially life saving medicines may be lost.
But rainforests are not simply sources of human products! They are part of the global weather system. Rainforests regulate rainfall which in turn affects global climate. They are a massive reservoir of carbon that, when burned or destroyed can contribute to the greenhouse effect. They are the single greatest terrestrial source of oxygen. The cutting of forests also changes the albedo or reflectivity of the earth's surface, which in turn alters wind and ocean current patterns, and can change rainfall distribution.
So, tropical rainforests are integral to a healthy planet and its ability to support life. They help regulate earth's climate, contain valuable genetic and food crop resources as well as medicines. They are home to millions of forms of life that have the potential to provide us with more information about life processes and our Earth. So why do we cut down rainforests?
Rainforests are located along the equator, predominantly within the borders of poor nations, many of which are in substantial debt. These governments lack the resources to respond to the rapid destruction of their forests. Poor farmers and their families depend on the forests to survive; They use the trees for firewood and the land for agricultural space. They lack the information and education on sustainable use of their resources. So the question of rainforest destruction is a delicate one. There is a clear urgency in preventing the devastation of these valuable, essential ecosystems. But there are many political and economic obstacles to surmount before a sustainable balance can be reached.
Caulfield, Catherine. In the Rainforest. London: Pan Books, 1986. Feldmann, Linda. "A Third World Debt-For-Nature Swap." Christian Science Monitor, (Jan 18, 1989, p.7.) SIRS, The Atmosphere Crisis, vol. 1, article #21. Meyer, Christian, ed. and Moosang, Faith, ed. Living With The Land. Gabriola Is, BC: New Society Publishers, 1992. Myers, Norman. The Primary Source: Tropical Forests and our Future. New York, NY: W.W.Norton & Co, 1984. Warburton, Lois. Rainforests. San Diego: Lucent Books, 1991.
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