[单项选择]Conventional wisdom says trees are good for the environment. They absorb carbon dioxide -- a greenhouse gas -- from the atmosphere and store it as carbon while releasing oxygen. The roots of trees have been thought to trap sediments and nutrients in the soil, keeping nearby rivers free flowing . Trees have also been credited with steadying the flow of these rivers, keeping it relatively constant through wet and dry seasons, thus preventing both drought and flooding. Pernicious nonsense, conclude two pieces of research published this week.
The first, a four-year international study led by researchers at the University of Newcastle, in Britain, and the Free University of Amsterdam, identifies several myths about the link between forests and water. For example, in arid and semi-arid areas, trees consume far more water than they trap. And it is not the trees that catch sediment and nutrients, and steady the flow of the rivers, but the fact that the soil has not been compressed.
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A. The roots of trees can save nutrients in the soil.
B. The trees can steady the flow of the rivers.
C. In the next 30 years, the water demand will add by around 50%.
D. Trees trap much less water than they consume in arid areas.