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  3. A rare piece of good news from the world of conservation: the global extinction crisis may have been overstated. The world is un

A rare piece of good news from the world of conservation: the global extinction crisis may have been overstated. The world is un

admin2021-02-21  93
问题    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.
   This new view of the prospects for biodiversity emerged from a seminar held this week at the Smithsonian Institution in Washington, DC, but the controversy over how bad things really are has been developing since 2006. That was when Joseph Wright of the Smithsonian Tropical Research Institute in Panama suggested that the damage might not be as grim as some feared. He 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.
   This re-grown "secondary" forest is crucial to Dr. Wright’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.
   Helene Muller-Landau of the University of Minnesota therefore reckons 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 she suggests 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.
   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 seminar 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.
   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 food or profit.
   [A] results from excessive hunting for large birds and mammals in forests.
   [B] reckons that tropical-forest species will start to increase after 2030.
   [C] suggests that the global extinction crisis might have been overstated.
   [D] indicated that birds and mammals were still under severe pressures.
   [E] was put forward at a seminar held at the Smithsonian Institution.
   [F] pointed out that many large animals were disappearing from forests.
   [G] believes there is a hope of woodland recovery in Latin America and Asia.
William Laurance
选项
答案D
解析 William Laurance出现在第五段。该段最后一句说到，William Laurance的数据显示：即使在世界上保护得最好的一些原始森林，鸟类和哺乳动物也面临着严峻的生存压力。D中的birds and mammals是文中these species指代的含义，而severe pressures是文中的原词复现，故确定D为本题答案。
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