托福阅读满分考试经验分享【文章分析】!在阅读文章资料的时候大家要学会对文章进行分析,这样说可能很多考生觉得比较抽象不好理解,小编通过举例的方式为大家详细讲解托福阅读文章分析的方法。

  托福阅读中的总结题是导致很多学生不能拿满分的原因,总结题考察考生抓取每个段落中心的能力。下面大象教育的汪娟老师给各位考生写出了TPO3 The Long-Term Stability of Ecosystems每个段落的中心,如果你们在课下能够每个段落抓成这样,那就意味着你抓住了这个段落的中心,进而说明你能够做对托福阅读中让很多考生云山雾罩的托福最后一题总结题也就是6选3题。

  The Long-Term Stability of Ecosystems

  Plant communities assemble themselves flexibly,

  and their particular structure depends on the specific history

托福阅读满分考试经验分享【文章分析】

  of the area. Ecologists use the term “succession” to refer

  to the changes that happen in plant communities and ecosystems over

  time. The first community in a succession is called a pioneer

  community, while the long-lived community at the end of

  succession is called a climax community. Pioneer and

  successional plant communities are said to change over periods from 1

  to 500 years. These changes—in plant numbers and the mix

  of species—are cumulative.

  Climax communities themselves change but over

  periods of time greater than about 500 years.

  第一段段落中心: 介绍了两个概念Pioneer community和Climax community。

  An ecologist who studies a pond today may well find it relatively

  unchanged in a year’s time. Individual fish may be 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.

  第二段段落中心:生态系统比组成它的单个生物体更稳定。

  At one time, ecologists believed that species diversity made

  ecosystems stable. They believed that the greater the

  diversity the more stable the ecosystem.

  Support for this idea came from the observation that

  long-lasting climax communities usually have

  more complex food webs and more species diversity than

  pioneer communities. Ecologists concluded that the

  apparent stability of climax ecosystems depended on their

  complexity. To take an extreme example, farmlands

  dominated by a single crop are so unstable that one

  year of bad weather or the invasion of a single pest can

  destroy the entire crop. In contrast, a complex

  climax community, such as a temperate forest,

  will tolerate considerable damage from weather to pests.

  第三段段落中心:生态学家曾经认为物种多样性使生态系统更稳定。

  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.

  第四段段落中心:根据稳定性的定义,climax community可以是最稳定也可以是最不稳定的。

  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. Once a redwood

  forest matures, for example, the kinds of species and the number

  of individuals growing on the forest floor are reduced. In general,

  diversity, by itself, does not ensure stability. Mathematical

  models of ecosystems likewise suggest that diversity does not

  guarantee ecosystem stabilityjust the opposite, in fact. A

  more complicated system is, in general, more likely than a

  simple system to break down. A fifteen speed racing bicycle is

  more likely to break down than a child’s tricycle.

  第五段段落中心:当稳定性被定义为缺乏变化的时候,也不总是与最大的多样性有关。

  Ecologists are especially interested to know what

  factors contribute to the resilience of communities

  because climax communities all over the world are

  being severely damaged or destroyed by human activities.

  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.

  We need to know what aspects of a community are most

  important to the community’s resistance to destruction,

  as well as its recovery.

  第六段段落中心:生态学家想知道什么对顶级群落的恢复力有帮助。

  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 kinds of organisms

  than an environment that is uniform. A local population that goes

  extinct is quickly replaced by immigrants from an adjacent

  community. Even if the new population is of a different species,

  it can approximately fill the niche vacated by the extinct

  population and keep the food web intact.

  第七段段落中心:生态学家现在认为顶级群落的长期稳定不是来自于多样性而是因为环境的斑块分布。

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