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  3. [A] This re-grown "secondary" forest is crucial to the pair’s analysis. Within a few decades of land being abandoned, half of t

[A] This re-grown "secondary" forest is crucial to the pair’s analysis. Within a few decades of land being abandoned, half of t

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问题     [A]  This re-grown "secondary" forest is crucial to the pair’s analysis. Within a few decades of land being abandoned, half of the original biomass has returned. Depending on what else is nearby, these new forests may then be colonized by animals and additional plants, and thus support many of the species found in the original forest.
    [B]   Elizabeth Bennett, of the Wildlife Conservation Society, an American conservation group, agreed and mentioned that for large birds and mammals, uncontrolled hunting for food and for trade is causing a phenomenon known as "empty-forest syndrome". She said that although many forests look healthy when viewed from a satellite, they are actually falling silent because many of their large animals have been removed for subsistence or profit.
    [C]  What everyone agreed, though, was that climate change is a threat. Even the optimistic Dr. Wright is worried because many tropical species evolved in an environment that has very little temperature variation, they are not equipped to cope with an increase of as little as 3°C, which is the sort of change that many climate scientists predict. He said that by the end of the century, 75% of tropical forests will be warmer than today, and what will remain in these hot, wet places is unknown.
    [D]   A rare piece of good news from the world of conservation: the global extinction crisis may have been overstated. The world is unlikely to lose 100 species a day, or half of all species in the lifetime of people now alive, as some have claimed. The bad news, though, is that the lucky survivors are tiny tropical insects that few people care about. The species that are being lost rapidly are the large vertebrates that conservationists were worried about in the first place.
    [E]   Dr. Wright and Dr. Muller-Landau therefore reckon that in 2030 reasonably unbroken tropical forest will still cover more than a third of its natural range, and after that date its area—at least in Latin America and Asia—could increase. Much of this woodland will be secondary forest, but even so they suggest that in Africa only 16-35% of tropical-forest species will become extinct by 2030, in Asia, 21-24% and, in Latin America, fewer still. Once forest cover does start increasing, the rate of extinction should diminish gradually.
    [F]   This new view of the prospects for biodiversity emerged from a symposium held this week at the Smithsonian Institution in Washington, DC, but the controversy over how bad things really are has been brewing since 2006. That was when Joseph Wright of the Smithsonian Tropical Research Institute in Panama and Helene Muller-Landau of the University of Minnesota first suggested that the damage might not be as grim as some feared. They reasoned that because population growth is slowing in many tropical countries, and people are moving to cities, the pressure to cut down primary rainforest is falling and agriculturally marginal land is being abandoned, allowing trees to grow.
    [G]   There are, however, two criticisms of this analysis. The first questions whether the raw data about forest cover are a good indicator of biodiversity, at least for big animals. William Laurance, a colleague of Dr. Wright’s, pointed out to the symposium that birds and mammals are more vulnerable to alterations in their habitat than are insects and other small animals. His data suggest that even in some of the world’s best-protected primary forests, these species face severe pressures.
    【D6】 → 【D7】 → 【D8】 → 【D9】 → G → 【D10】
【D8】
选项
答案A
解析 上一段(即F)末句提到砍伐原生热带雨林(primary rainforest)的需求减少，相对贫瘠的耕地逐渐荒废，树木由此获得生长空间(allowing trees to grow)、选项中，A、B、E的首句都提到森林。A中说到的regrown “secondary” forest与F最后的allowing trees to grow相一致，且A的第二句提到land being abandoned，正是指上段末提到的agriculturally marginal land is being abandoned这种情况，故A与F衔接紧密，应为本题答案。B讲述的观点与F的乐观看法相反，B中的Elizabeth Bennett不可能对上段观点持赞同意见，B首句的agreed显然逻辑不通，故B不可能接在F之后。E颇具干扰，therefore说明that从句所讲的推论是基于上段末的内容得出的。该推论包括“热带森林覆盖面积仍保有1／3以上”和“热带森林覆盖面积会增加”，第一点可以是砍伐减少的结果，但第二点则无法由砍伐减少和退耕还林直接得出。因为即使退耕还林能使树水增加，增加树木的地方不一定就能重新形成热带森林。只有通过A末句讲的support many of the species found in the original forest，这些增加的树木才会重新成为热带森林。因此不能选E。
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