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托福阅读背景知识:沙漠化

发布时间:2013-04-11 13:45:16 来源:杭州朗阁培训中心 编辑:杭州朗阁小编
  为帮助广大的考生更好地备考迎考,杭州新托福为各位考生整理了托福阅读背景知识:沙漠化,考生们可以参考一下。  大多数区域的沙漠化...
  为帮助广大的考生更好地备考迎考,杭州新托福为各位考生整理了托福阅读背景知识:沙漠化,考生们可以参考一下。
  大多数区域的沙漠化是由于人类活动而不是自然进程所致。沙漠周围的半干旱区域存在一个微妙的生态平衡并且被她们的潜能限制去适应增长的环境压力。持续增加的人口使土地承受更大的拉力来为他们提供食物和燃料。在潮湿地带,土地可能能够承受这些压力。在沙漠边缘的干旱地区,土壤所承受的压力远远超过了它减退的能力和沙漠化的结果。
  Desert, about already accounts for 1/4 of the Earth's surface in recent decades in order to increase faster. The expansion of desert conditions in the area not previously desert-like changes called desertification. Presumably, the earth's surface 1/4 is also being used by this trend threat.
  The formation of desertification is mainly due to the reduction of the natural vegetation and thus caused due to wind and water due to soil erosion. In some cases, loosening the soil is scraped away, leaving the surface of the stone. In some other cases, good particle is removed, the sandy particles aggregate to form a movable hills or sand.
  Even in areas retain the soil surface, vegetation reduction lead to a reduced ability of the soil to absorb water. Raindrops on the loose soil allows the The good texture particles transfer to the tiny soil voids, making the soil almost can not be water infiltration, absorb the sharp decline in the amount of water, the results of water and soil water increased soil erosion rate increased. Makes the vegetation gradually drying caused the soil absorb moisture decreased ability to further reduce soil progressive deterioration circulation.
  In some areas, the increase in the desert area trend caused by the dry weather conditions. Continued global warming in the past thousands of years to make the drought worse. If atmospheric pollution caused by global warming continued to increase, this process can also exacerbate.
  四个特定的活动被认为是沙漠化进程的主要因素:过度耕种、过度放牧、过度的采伐和过度的灌溉。随着人口密度增加,作物耕种已经扩展到了干旱地区,所以农作物失收很正常。由于粮食作物的增加使得自然植被被移出,农作物失收使大片的土地没有植被覆盖并且容易受到风雨的侵蚀。
  以上就是杭州新托福培训为大家整理的托福阅读背景知识:沙漠化。想了解更多相关信息和学习技巧,欢迎您访问我们的网站。祝烤鸭们考试顺利,大家加油!
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