很多考生会抱怨托福阅读时间不够，还没完全理解文章就做题，正确率不高。其实这是我们对托福阅读素材不熟悉造成的，下面小编整理了一下托福阅读考试最新的素材，希望能帮助大家更加快速高效的备考托福。

　　托福阅读素材：热带雨林和温带森林的再生

　　内容回忆：

　　讲的是热带雨林和温带森林哪个在被 clear 之后更容易恢复。包括温带容易被恢复的原因：营养都在土里，种子在土里;热带不容易被恢复的原因：营养在 living trees 里面，种子很脆弱，水容易把土里的营养冲走。

　　参考阅读：

　　Our forests here in the Northeast are very resilient. When they are disturbed by cutting, fire, storm, infestation or disease, they bounce back rapidly. Existing seedlings (called advance regeneration) will take advantage of the increased light, water and nutrients. Others will grow from the damaged trees' stumps and roots. More seedlings will develop from seeds stored in the leaf duff on the forest floor, and from seed that blows in from nearby trees. Yet other seeds will be carried into disturbed areas by birds and animals.

　　Different tree species have developed different regeneration strategies over millions of years of evolution. Some trees produce many, small seeds and depend upon the wind for their dispersal. Other trees produce a few, large seeds and depend upon animals for their dispersal. Some tree seeds need little light or heat in order to germination; others need much heat and light. Some sprout from stumps and roots; others do not.

　　If there are seedlings of desirable species already established when a forest is cut or otherwise disturbed, a new, high quality forest can develop immediately. Many of our best timber stands developed in this way after heavy cutting in the past. For whatever reasons, conditions were right for germination and growth of those seedlings and sprouts before the overstories were harvested.

　　Unfortunately however, the opposite is more often the case. Desirable seedlings were not there before the last harvest; the right kinds of seeds didn't blow in or get carried in, and they didn't sprout from stumps and roots. The same usually happened when old pastures or fields were abandoned. Good quality seed sources weren't available, or if they were, the seeds didn't germinate and grow.

　　When forests are repeatedly high-graded, that is, when the best trees are cut and the rest are left to grow, the results are forests dominated by low-grade species, poor quality trees of grade species, and cull trees of all species. Such forests would probably have been better off if they had been clearcut because then at least the poor quality trees would have been removed.

　　In order to control and optimize regeneration, foresters have developed silvicultural systems to regenerate forests of different species mixes and ages. These systems are designed around the regeneration strategies of the desired species. They involve manipulation (cutting) of forest stands to influence the seed mix and light/heat conditions on the ground. Sometimes they also involve manipulation of existing (advance) regeneration and treatment of the seed bed (forest floor).

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