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论述荒漠化的危害。

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2022-06-15 22:43
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(1)土地退化
主要表现:
①生态环境破坏,植被覆盖率降低,表层土壤发生退化,由于水蚀、风蚀作用,使植被赖以生存的肥沃表层土壤荒漠化
②沙漠蔓延,吞噬绿洲、农田,直接造成农牧业减产
③洪涝灾害引起大量土体搬运、沉积
④土壤肥力降低
⑤土壤发生次生盐渍化、酸化(使用过多的某种化肥)
⑥土壤污染,这是由于工业、城市的废弃物堆放或过量使用化肥造成的
(2)生物群落退化:荒漠化引起植被退化,进而导致土地退化,反过来又影响动植物的生存和发展,这样形成恶性循环过程,使生物群落的密多样性等向着坏得方向演替。
(3)气候变化:植被的退化引起地面反射率、二氧化碳吸收率的变化,从而对气候的变化产生影响,现在全球气温回升,降雨量减少,蒸发量加大,沙尘暴发生次数增大。
(4)水文状况的恶化
主要表现:
①洪峰流量增大,形成洪涝灾害,枯水流量减少,断流时间增加
②地上径流增加,地下径流减少,水蚀作用加大,水质变化,甚至在一些地方,地下水位下降,为土地资源的退化创造了恶性循环的条件。
③一些地区地下水位提高,土壤发生次生盐渍化,有些河湖滩地天然绿
洲的沼泽土、草甸土逐渐向盐渍化土地演变。
(5)污染环境:土地在沙漠化过程中产生一系列沙尘物质,在风力作用下同时对
环境发生严重污染,不仅影响人类活动,还损害人类身体健康。
(6)毁坏生活设施和建设工程:环境破坏,生态环境失调,自然灾害频繁发生,常常危害人类的生命财产安全。


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