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| This
beautiful Amazon rain forest is thick with plants,
trees, and animals.
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What is a rain forest?
The tropical rain forest is a forest of tall trees in a region of year-round warmth and plentiful
rainfall. Almost all such forests lie near the equator. They occupy large regions in Africa,
Asia, and Central and South America, and on Pacific islands. The largest tropical rain forest
is the Amazon rain forest, also called the selva. It covers about a third of South America.
Tropical rain forests stay green throughout the year.
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A tropical rain forest has more kinds of trees than any other area in the world. Scientists
have counted about 280 species in one 2 1/2-acre (1-hectare) area in South America. Most
forests of this size in the United States have fewer than seven species. More than half of the
world's species of plants and animals may live in tropical rain forests. More species of
amphibians, birds, insects, mammals, and reptiles live in tropical rain forests than anywhere else.
The tallest trees of a rain forest may grow as tall as 200 feet (61 meters). The crowns (tops)
of other trees form a covering of leaves about 100 to 150 feet (30 to 45 meters) above the
ground. This covering is called the upper canopy. The crowns of smaller trees form one or
two lower canopies. All the canopies shade the forest floor so that it receives less than 1
percent as much sunlight as does the upper canopy.
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| This South
American parrot lives in the rain forest, along with
thousands of other birds and animals. To save them we need to save
the rain forest. Photo copyright © 1998, World Book.
|
The forest beneath the
canopy
Most areas of the forest floor receive so little light that few bushes or herbs can grow there.
As a result, a person can easily walk through most parts of a tropical rain forest. Areas of
dense growth called jungles occur within a tropical rain forest in areas where much sunlight
reaches the ground. Most jungles grow near broad rivers or in former clearings.
The temperature in a rain forest rarely rises above 93 �F (34 �C) or drops below 68 �F
(20 �C). In many cases, the average temperature of the hottest month is only 2 �F to 5 �F
(1 �C to 3 �C) higher than the average temperature of the coldest month. An average of 50
to 260 inches (125 to 660 centimeters) of rain falls yearly in a tropical rain forest. Thundershowers
may occur more than 200 days a year.
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The air beneath the lower canopy is almost always
humid. The trees themselves give off water through the pores of their leaves. This process,
called transpiration, may account for as much as half of the rain in the Amazon rain forest.
