The world's forests, which cover one-third of Earth's land area, provide us with many essential services. They absorb carbon dioxide from the atmosphere and give us oxygen, limit soil erosion, aid in flood control and aquifer recharge, and host a wealth of biodiversity, points out Lester R. Brown, president of Earth Policy Institute, Washington, D.C. However, as human populations have grown, so, too, have the demands placed on these natural systems.
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机译：世界森林覆盖了地球三分之一的土地，为我们提供了许多基本服务。华盛顿特区地球政策研究所所长莱斯特·布朗（Lester R. Brown）指出，它们吸收了大气中的二氧化碳，并为我们提供氧气，限制土壤侵蚀，帮助防洪和含水层补给，并拥有丰富的生物多样性。人口也在增长，对这些自然系统的需求也随之增加。
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