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黑河流域植被退化的主要原因分析 被引量:22

Analysis on the Main Causes Resulting in Vegetation Degeneration in the Heihe River Basin
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摘要 黑河流域地处我国西北内陆干旱区,生态与环境十分脆弱。据调查资料,自20世纪50年代以来,黑河中下游地区天然植被严重退化,植被覆盖度大于70%的林灌草甸草地减少了78.26%,覆盖度介于30%~70%之间的湖盆、洼地、沼泽草甸草地以及产量较高的草地减少了约40%,草地总面积也减少了将近50%。额济纳绿洲林地和沼泽地草匈植被面积与50年代相比,分布于河岸的胡杨、沙枣林面积减少54%,红柳林面积减少33%,成片的芨芨草甸、芦苇沼泽逐步消失,已被旱化的骆驼刺、花花柴、黑果枸杞群落取代;沿河乔灌木林严重退化,以疏林为主且林木生活力极差。植被退化的因素很多,近年来自然环境在缓慢地向干旱变化,但非主要因素,主要是进人下游的水量呈减少趋势,由此引起了区域地下水位持续下降,从而加大了包气带厚度,造成了包气带土壤的极度干旱化,使部分不适宜该水分和盐分生存的植物长势由密变稀、由好变坏、甚至死亡。 The Heihe River Basin is located in an arid area in northwest China, and its entironment is very frag- ile. According to the survey, the natural vegetation is seriously degenerated in the middle and lower reaches of the drainage basin. Since the 1950s, the area of the shrubbery meadow steppes with vegetation coverage higher than 70% has been reduced by 78.26%, the areas of the steppes with vegetation coverage varying in a range of 30%~70% in the lake basins and billabongs, marsh meadow grasslands and steppes with high forage yield have been reduced by about 40% , and the total area of steppes has been reduced by about 50%. The old-line Erjina Oasis has been in a deterioration trend, and the areas of woodlands and meadow vegetation have been seriously shrunk. The area of the riparian forests of Populus euphratica and Elaeagnus angustifolia has been reduced by 54% compare with that in the 1950s, and the area of riparian Tamarix ramosissima has been reduced by 33% ; the flaky Achnatherum splendens meadows and Phragmites australis marshes are in a gradual disappearance, and most of them have been replaced by the communities ofAlhagi sparsifilia, Karelinia caspica and Lycium ruthenicum; the riparian forests and shrubberies are seriously degenerated. There are many factors affecting vegetation degeneration, such as the arid trend of the natural environment in recent years, especially the decrease of inflow to the lower reaches of the drainage basin. Thus, a continuous drawdown of groundwater level and a seriously soil drought in va- dose zone occur because of the increase of the vadose zone thickness.
出处 《干旱区研究》 CSCD 北大核心 2008年第2期219-224,共6页 Arid Zone Research
基金 “十五”国土资源部重点科技计划项目(200010303)基金资助
关键词 植被退化 土壤旱化 河水量减少 黑河流域 vegetation degeneration soil drought inflow decrease the Heihe River Basin.
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