题目内容：

[单选题]［A］ New plants and animals then move into the area and begin to grow.

［B］ Just 2 percent of the sunlight goes through the many layers of leaves and branches above, so understory plant species have developed special traits to cope with low light levels.

［C］ On a smaller scale, large mammals, such as elephants, regularly destroy rain forest vegetation in the Congo River Basin in Africa.

［D］ An understory of shorter trees and a lacework of woody vines, or lianas, produce a forest of such complex internal architecture that many animals, including some sizable ones, rarely or never descend to the ground.

［E］ Less than one percent of the trees in the forest reside in the canopy and emergent layers.

［F］ Because more light penetrates the canopy, however, the vegetation of the understory and forest floor is better developed than in the tropics.

［G］ The rich, green canopy is teeming with life, and forest researchers have developed ingenious methods for accessing this mysterious ecosystem.