1975-2015年鄂尔多斯市沙漠化的时空演变过程

鄂尔多斯市地处温带草原向荒漠草原过渡的半干旱区，是中国沙漠化问题较为严重的区域之一，其土地沙漠化发展和逆转过程及影响因素在北方农牧交错带具有代表性。以7期Landsat卫星遥感数据为信息源提取沙漠化土地类型及程度的时空格局信息，分析了该地区自1975年以来的土地沙漠化过程，并结合气象及社会经济数据采用主成分分析法对驱动因子进行定量分析。结果表明：在脆弱生态环境背景下，鄂尔多斯市土地沙漠化受人口数量增加、过垦及过牧等人为因素的严重影响。不同时段土地沙漠化发展的方向与驱动力都有所不同，1975-2000年是土地沙漠化的急剧发展期，驱动力以人为因素为主导，自然因素为基础；2000-2015年是土地沙漠化的逆转期，驱动力以自然因素为主，人为因素为辅。

Spatial-temporal Evolution of Aeolian Desertification Process in Ordos City during 1975-2015

The Ordos City is located in the semi-arid region and also an ecotone from temperate steppe to desert steppe, and it suffers the serious aeolian desertification problems like the other parts of Northern China. Due to its representative and typical characteristics of the development and reversal process of aeolian desertification and its driving factors, Ordos City has become one of the hot areas of desertification research. We derives the spatial and temporal patterns change information of aeolian desertification from 1975 to 2015 based on the Landsat images, and analyzed the driving factors with the principal component analysis (PCA) and meteorological and social-economic data. The results showed that in the context of the fragile ecological environment, the development of aeolian desertification in Ordos City in the forty years was mainly influenced by human factors, such as population increase, reclamation and overgrazing. The trend of land desertification and the dominant driving factors are different at different periods:The land desertification tended to deteriorate from 1975 to 2000, and the main driving factors were human activities, followed by natural factors; The land desertification was reversed in 2000-2015, and the natural factors played more important role than human activity in this period.