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Succession and Ecosystem Change

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After a forest fire, secondary succession occurs in an ecosystem.

Which of the following statements BEST explains why pioneer species are replaced by other “climax” trees?

A

The fast growing trees and other pioneer species absorb environmental pollutants more quickly than the "climax" trees and die off, leaving space available for the "climax" trees.

B

The "climax" trees eventually grow taller than the fast growing trees and other pioneer species and shade out the fast growing trees beneath them.

C

The pioneer species change the chemical composition of the soil in a way that favors the growth of grasses and perennials.

D

The roots of the woody pioneers spread through the soil and inhibit the fast growing trees ability to obtain essential nutrients.