Robert, an American scientist, has shown that when native grassland areas are invaded by trees, carbon is lost from the soil.“We are studying why the soil carbon disappears, but one theory is that trees do a lot more of their growing above ground compared to grass, so less carbon goes directly into the soil from trees.” said Robert.
In wet areas of the world, the gain from trees absorbing carbon dioxide above ground seems to be outweighed by the loss of carbon from the soil below ground.
Countries that plan to fight against global warming by planting trees may have to think again.Solutions to environmental problems are often more complex than they first appear, and understanding the Earth's climate is a very great challenge.
36.People usually hold the opinion that________.
A.huge dust storms can destroy carbon dioxide
B.planting trees could reduce global warming
C.huge dust storms can destroy the oceans on the Earth
D.planting trees is the only way to control huge dust storms
37.Andy, an environmental scientist, believes that________.
A.environmental problems are more complex than
expected
B.trees shouldn't have been planted in dry places
C.dust plays a more important part than trees
D.carbon dioxide is harmful to everything
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