科尔沁地区现代沙漠化过程的驱动因素分析

Analyses on Driving Factors to Sandy Desertification Process in Horqin Region, China

基于近50a科尔沁地区沙漠化土地发展—再发展—逆转的时空变化的研究结果,以气候波动和人类活动变化作为主驱动因子,探讨现代沙漠化过程的驱动因素的作用。近40多年气候的波动在一定程度上直接地通过不同时期的降水-温度组合影响着沙漠化的进程,间接地通过人类对气候波动的响应而产生的经济活动来加速沙漠化的进程。尽管科尔沁地区的气候驱动因子呈现出有利于沙漠化发展过程的趋势,但在近10多年来,这种驱动力的作用被有利于沙漠化逆转过程的驱动力所抵消。人类活动是研究区沙漠化过程中更加活跃的驱动因子,体现在土地利用方式的转变和强度的增加,以及由此而产生的对自然植被群落毁灭性的破坏而加速了沙漠化的进程。以土壤风蚀为例,这种加速可以是自然条件下的4～10倍;随着沙漠化程度的加剧,所产生的在土壤养分、生物多样性和生物生产量等方面退化的加速也与自然条件下的情况相差3～10倍以上。同样是人类活动,在合理的土地利用、采取各种沙漠化防治措施的情况下,又可使沙漠化过程逆转。从这一点上来说,人为驱动因素应是起绝对主导作用的。

Based on the changes of temporal-spatial distribution of sandy desertified lands for the last 50 years, which had been in a process of expanded and reversed in the Horqin Region of China, the climatic variation and human activity have been taken as the major driving factors to discussed their impact on the process of sandy desertification. The climatic variations for last 40 years have affected directly the process of sandy desertification by different compounding model of temperature and precipitation in different decades, and affected indirectly the process by the human economic activities responded its variations. The climatic driving factor has presented the trend in favor of the desertification development in the region, but for last 10 years such function had been counteracted by the other function that was propitious to desertification reversion.The human activity is the much more active factor to the process of sandy desertification which mainly incarnates on the changes of the landuse fashion (from rangeland to farmland) and enhance of landuse intensity (over-cultivation, over-grazing and over-fuel collection). The fatal destruction to natural vegetation by human activities had accelerated the development of desertification. Take soil wind erosion as example, such human impact can increase wind erosion by 4 to 10 times contrasted with natural one. Along with the aggravation of desertification degree, the acceleration of degradation on soil nutrient, bio-diversity and bio-production can be 3 to 10 times or more contrasted with natural process. The human activities can reverse the sandy desertification depend on the reasonable landuse and adopting varied prevention and cure measure for combating desertification. From this point, one can say that the human driving factor play absolutely role on the process of desertification. So we would like to define the sandy desertification is that a land degradation characterized by wind erosion mainly resulted from the excessive human activities in arid, semiarid and part of sub-humid regions in North China.