Amazon rain forest is the world’s largest tropical rain forest. It covers approximately 2 million square miles (5.2 million square kilometers) in South America’s Amazon River Basin. About two-thirds of the forest lies in Brazil. The forest also occupies parts of eight other countries, with the largest areas in Bolivia, Colombia, Peru, and Venezuela. The Amazon rain forest receives an average annual rainfall of 60 to 175 inches (152 to 445 centimeters). Temperatures average about 80 °F (27 °C).
Trees in most of the Amazon rain forest grow in several distinct layers. Some trees, called emergents, tower above the rest of the forest and may reach heights of more than 130 feet (40 meters). The upper canopy generally grows 80 to 130 feet (24 to 40 meters) high. Plants called epiphytes, or air plants, thrive in this layer. Aroids, bromeliads, ferns, liverworts, mosses, and orchids grow on high branches and tree trunks in the upper canopy. One or two lower canopies consist of saplings of the trees in the upper canopy, plus smaller trees and shrubs. Lianas (woody vines) wind around tree trunks and branches, extending from the ground to the upper canopy. The canopies get sunlight, but they prevent much light from reaching the forest floor. Most of the Amazon rain forest has soil with low fertility.
The Amazon rain forest contains a wider variety of plant and animal life than any other place in the world. Tens of thousands of different plant species live there. A 21/2-acre (1-hectare) area of the rain forest may contain up to 280 or more species of trees. Many economically important plants live in the rain forest. They yield such products as Brazil nuts, cocoa, curare (an important drug), dyes, pineapples, and rubber. More than 1,300 species of birds make their homes in the rain forest. The region’s rivers contain up to 3,000 species of fish. Millions of different insect species live in the forest.
Increasing demands for land and natural resources have seriously threatened the Amazon rain forest. Loggers cut down trees for wood products. Ranchers and farmers clear land to graze beef cattle and to grow such crops as soybeans.
Areas of the rain forest that have been cleared can regenerate. However, regenerated areas are much less diverse than the original forest. Large areas of the Amazon rain forest have been destroyed. Development, deforestation (the destruction of forests), disease, and gold mining also threaten the cultures of the few remaining native peoples of the Amazon rain forest. Many of these people depend on the forest to support themselves.
