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  3. Studies of deforestation(采伐森林，毁坏森林) in Amazon rainforest have underestimated the actual extent of forest loss by half or more, a

Studies of deforestation(采伐森林，毁坏森林) in Amazon rainforest have underestimated the actual extent of forest loss by half or more, a

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问题     Studies of deforestation(采伐森林，毁坏森林) in Amazon rainforest have underestimated the actual extent of forest loss by half or more, according to a study published in the April 8, 1999, issue of the journal Nature.
    Past efforts to estimate deforestation in the Amazon have relied on satellite images to calculate forest loss. The new analysis found that satellite images were useful for estimating deforestation by logging(伐木)and fires on an extent of land, but failed to capture numerous smaller pockets of damage, including damages caused by selective logging(a harvesting technique in which only selected trees are removed) and surface fires, which is often hard to detect from satellite images, as new growth quickly masks it.
    The new study focused on Brazil’s Amazon region, where most of the rainforest is located. The researchers interviewed 1,500 wood mill operators and 200 landowners about logging practices, harvest records and fire damages on their lands. The researchers verified the information collected by measuring the actual wood harvest in selected parts of forest, and by surveying fire damages from an airplane at over 1,100 sample points.
    The research team found that damage from the fires varied significantly from year to year due to larger environmental factors, but roughly similar damage caused by logging. They determined that actual deforestation in the Brazilian Amazon was at least double the damage estimates derived from satellite images.
    Damages caused by logging and fires threatened the Amazon rainforest. Sunlight can penetrate holes in the forest shelter and reach the floor, drying plants and increasing the risk of fire. At the global level, many scientists worry that continued burning and logging in the forest will further raise levels of carbon dioxide in the atmosphere. Rising levels of carbon dioxide—a so-called greenhouse gas because it traps heat in the lower atmosphere— has been linked to global warming.
    Strict limits on logging, stronger efforts preventing fire, and controls on development could all help slow deforestation, the researchers said.
选项 A、past efforts to estimate deforestation in the Amazon have completely failed
B、that damages caused by logging and fires threaten the Amazon rain forest
C、Amazon rainforest disappears faster than thought
D、that satellite images are made use of for estimating deforestation
答案C
解析 本题为主旨归纳题。作者根据《自然》上的一篇文章指出亚马孙河流域的森林被毁坏程度被低估了。
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