塔里木河下游土地沙漠化的人为驱动作用分析

沙漠化发展的人为驱动力包括人口增长的压力、牲畜增长的压力、土地利用结构变化等因素,文中以典型干旱区塔里木河下游为例,在实地考察基础上和前人研究的成果资料相结合,分析人口增长与塔里木河下游沙漠化发展之间的关系,探讨人口增长对沙漠化的驱动作用。自1949年至2001年间,塔里木河流域人口增加了568×104人,年平均递增速度为2.01%,在较高的人口增长压力下,一方面导致了对粮食需求的增加,为了满足粮食需求,必然导致大量开垦,当地自然条件恶劣,土壤含沙量大,开垦后的旱作农业,在强劲的风力下,风蚀严重,土地很快发生退化。另一方面导致燃料需求的增加,该地区广大农村牧区仍以砍伐天然植被为燃料来源,伐木作柴,掘草为薪,燃秸取火现象非常普遍,广泛分布于沙漠边缘的柽柳、胡杨,它们庞大的根系和枝干起着防风固沙,屏蔽绿洲作用,经挖掘和砍伐,自然条件下难以恢复,结果导致沙丘活化。因此,控制人口增长、减轻土地压力、退耕还草、还林和保护植被是促进当地沙漠化土地逆转所必须的。

The human-driven reasons of desertification on the lower reaches of Tarim River

Human-driven factors for desertification include the pressure of population growth,increasing livestocks,land use changes and other factors.In this paper,based on field investigation and the results of previous research data,we analyzed the relationship between population growth and the development of desertification.From 1949 to 2001,population increased by 568×104,on an annual average rate of 2.01%.The pressure of population growth not only led to increasing demand for food,the demand for food will inevitably lead to a large number of reclamation.But the deterioration of local natural conditions will lead to severe wind erosion,and land degradation will occur very quickly.Population growth led to the increase in fuel demand.In vast rural and pastoral areas in the region farmers are still cutting the natural vegetation as a fuel source,logging for firewood,digging grass salary,Tamarix and Populus widely distributed in the desert edge,their roots and branches play a huge anti-wind and sand effects and shielding oasis.Mining and logging make it difficult to restore natural conditions,and result in activation of sand dunes.Therefore,controlling population growth,reducing pressure on land,returning farmland to animal husbandry,forestation and protection of vegetation are the methods to promote local desertification and land necessary for reversal.