托福阅读30天备考之备考练习第七天

　　TPO3 PASSAGE 3 The Long-Term Stability of Ecosystems

　　1) Thefirst community in a succession is called a pioneer community, while the long-lived community at the end of succession is called a climax community. (对于专有名词的解释)

　　2) Individual fish maybe replaced, but the number of fish will tend to be the same from one year to the next. We can say that the properties of an ecosystem are more stable than the individual organisms that compose the ecosystem. ( attribute, properties and characteristic 的释义一致)

　　3) Support for thisidea came from the observation that long-lasting climax communities usually have more complex food webs and more species diversity than pioneer communities. (climax 和diversity的含义区分)

　　4) Alternatively, stability can be defined as the speed with which an ecosystem returns to aparticular form following a major disturbance, such as a fire. This kind of stability is also called resilience. ( stability 和resilience的区分)

　　5) Even the kind of stability defined as simple lack of change is not always associated with maximum diversity. At least in temperate zones, maximum diversity is often found in mid-successional stages, not in the climax community. (climax community和diversity的关系)

　　6) The destruction caused by the volcanic explosion of Mount St. Helens, in the northwestern United States, for example, pales in comparison to the destruction caused by humans. (举例常常最为考点)

　　7) Many ecologists now think that the relative long-term stability of climax communities comes not from diversity but from the “patchiness” of the environment, an environment that varies from place to place supports more kindsof organisms than an environment that is uniform. (对于patchiness抽象概念的解释)