Resource: Amazon Rainforest

Tropical rainforests are the richest of all the world's biomes. Although these forests cover only about six percent of the earth's surface, they contain more than half of all living species of plants and animals, including hundreds of species of trees and thousands of species of insects. Perhaps more important, scientific research suggests that the ecological health of the planet as a whole hinges on the continued existence of tropical rainforests. For example, scientists estimate that tropical rainforest plants generate about 40 percent of the oxygen in the earth's atmosphere, and that, through evaporation, rainforests contribute water vapor that is essential for maintaining global weather patters.

Yet every minute of every day, dozens of acres of tropical rainforest are cut down for the lumber they contain and to create farms and ranches. Somewhat surprisingly, efforts to turn rainforests into agricultural land have met with dismal failure. After two or three meager years, farmers and ranchers typically abandon their fields in search of new land and richer soil. Then they cut and burn more trees, converting another piece of productive rainforest into unproductive farmland.

The reason rainforest land is unsuitable for farming has to do with the soil -- or, more precisely, what's not in the soil after the trees are removed. Unlike an intact rainforest, the soil that is left behind when a rainforest is cleared is horribly devoid of nutrients. This is because the majority of nutrients in this biome are locked up in the tissues of rainforest plants and animals. When these organisms are removed, the nutrients they contain are removed too. Even when trees are burned, a process that breaks down the wood and returns some nutrients to the soil, heavy rains often wash away huge amounts of unprotected soil, leaving behind land that is more depleted than ever.

Today, conservation efforts are aimed at educating local people about ways they can reclaim land that has already been cleared and use it in a more sustainable way to grow crops, raise cattle, and produce timber. Without such efforts, the world's tropical rainforests -- and life on earth as we know it -- may not survive.

What are the climatic conditions in the Amazon rain forest biome?

Where are the world's rain forests located?

What are some animals that live in the rain forest, and how are they adapted to their environment?

What are some plants that grow in the rain forest, and how are they adapted to their environment?