题型：阅读理解 题类：常考题 难易度：普通
外研版英语必修五Module 6 Animals in Danger.同步练习
The largest land animal remaining on the earth, the African elephant, is of much importance to the African ecosystem. Unlike other animals, the African elephant is to a great extent the builder of its environment. As a giant planteater, it significantly shapes the forest－and－savanna surroundings in which it lives, therefore deciding the conditions of existence for millions of other animals that live in its habitat.
It is the elephant's great desire for food that makes it both a disturber of the environment and an important builder of habitat. In its continuous search for the 300 pounds of plants it must have every day, it kills small trees and bushes, as well as pulls branches off big trees. This results in numerous open spaces in not only deep tropical forests but also the woodlands that cover part of the African savannas. In these open spaces, there are numerous plants in various stages of growth, which attract a variety of other plant－eaters.
Take the rain forests for example. In their natural states, the spreading branches overhead shut out sunlight and prevent the growth of plants on the forest floor. By pulling down trees and eating plants, elephants create open spaces, allowing new plants to grow on the forest floor. In such situations, the forests become suitable for large－hoofed plant－eaters to move around and for small－sized plant－eaters to obtain their food as well.
Scientists are worried now that the African elephant has become an endangered species. If the elephant dies out, scientists say, many other animals will also disappear from vast areas of forests and savannas, greatly changing and worsening the whole ecosystem.
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