Sabtu, 19 Februari 2011

Why are Rain Forests important?


Where would you go to find more kinds of plants and animals than anywhere else on Earth? You would go to a tropical rain forest.

Tropical rain forests are home to an amazing number of plants and animals. A patch of tropical rain forest no bigger than a school parking lot can have almost as many different species (kinds) of trees as there are in all the forests of Canada and the United States!

Biologists believe that more than half of the world’s plant and animal species live in tropical rain forests.

A rain forest is a place where there is lots of rain. One kind of rain forest is called a temperate rain forest. You can find temperate rain forests where the weather is cool and mild, and very wet.

A temperate rain forest grows near the Northwest coast of the United States. Just a few kinds of evergreen trees grow there. Most of the world’s rain forests are tropical rain forests with many kinds of trees.

Tropical rain forests grow in warm places near Earth’s equator. The equator is an imaginary line that goes around the middle of the planet. There are tropical rain forests in Central and South America, Africa, and Asia. The world’s largest rain forest is the Amazon rain forest in South America. It is always hot and wet in a tropical rain forest.

Different kinds of plants grow in different layers of a tropical rain forest. The ground in a rain forest is called the forest floor. The soil on the forest floor is very thin and poor. Some plants living there get their food from dead plants. Other plants on the ground eat insects. The pitcher plant is an insect-eating plant that grows in rain forests in Asia.

The plant layer just above the forest floor is called the understory. Not much sunlight gets down to this layer. Young trees and plants that like low levels of light grow in the shady understory.

The top layer of the rain forest is called the canopy. The tops of tall trees make up the canopy. They capture most of the sun and rainwater falling on the forest. The canopy is thick and green.

Between the understory and the canopy is a layer called the midstory. Medium-size trees grow in the midstory. Thick vines climb up, around, and between the trees. Mosses, orchids, and other air plants (plants without ground roots) grow on the midstory trees.

Most of the animals that live in a tropical rain forest are insects. The forest is alive with millions of beetles and ants. Bats and beautiful moths fly about at night. Snakes glide silently in and around the trees. Birds are everywhere.

In Africa, wild pigs, gorillas, and other large animals live on the forest floor. Elephants walk through the rain forests of Asia and Africa. Jaguars hide in South American forests and wait for prey, such as a wild pig, to go by.

Most of the rain forest animals live in the canopy. Monkeys swing from branch to branch in the rain forests of Central and South America.

Rain forests are home to huge numbers of plants and animals. Scientists are discovering new ones all the time. Some rain forest plants are used for medicine. Scientists believe there may be many other plants that could be used to treat cancer and other diseases.

Rain forests are like the “lungs” of planet Earth. The trees take up a gas called carbon dioxide. They give off a gas called oxygen. All animals must breathe oxygen in order to live. Too much carbon dioxide in the air could make Earth grow warmer.

For thousands of years, people have lived in the rain forests. People native to the forests hunt wild animals and collect plants for food. They use certain rain forest plants for medicines.

Today, rain forests all over Asia, Africa, and South America are being cut down. Loggers cut down hardwood trees for lumber. Teak, rosewood, and mahogany make beautiful furniture.

Farmers clear the rain forest to plant crops. But the poor rain forest soil soon washes away. Then the farmers must move and clear more rain forest.

People cut roads through the rain forest to reach mines and oil wells. Lumber companies build roads to haul logs. The amount of rain forest cut down every year would fill the state of Wisconsin!

Conservationists are looking for ways to save the rain forests. Some countries, such as Costa Rica in Central America, have set aside rain forests as national parks.

In other places, poor people need the rain forests for food and wood. Conservationists are looking for ways that people can use the forests without destroying them. People are learning how to grow nuts, seeds, and other crops in the rain forest. They are learning how to make butterfly farms and other places that people can visit on a vacation.

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