4. According to paragraph 3, ecologists once believed that which of the following illustrated the most stable ecosystems?
○Pioneer communities
○Climax communities
○Single-crop farmlands
○Successional plant communities
Paragraph 4: The question of ecosystem stability is complicated, however. The first problem is that ecologists do not all agree what “stability” means. Stability can be defined as simply lack of change. In that case, the climax community would be considered the most stable, since, by definition, it changes the least over time. Alternatively, stability can be defined as the speed with which an ecosystem returns to a particular form following a major disturbance, such as a fire. This kind of stability is also called resilience. In that case, climax communities would be the most fragile and the least stable, since they can require hundreds of years to return to the climax state.
5. According to paragraph 4, why is the question of ecosystem stability complicated?
○The reasons for ecosystem change are not always clear.
○Ecologists often confuse the word “stability” with the word “resilience.”
○The exact meaning of the word “stability” is debated by ecologists.
○There are many different answers to ecological questions.
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2016-10-08
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