基于荒漠化差值指数的荒漠绿洲过渡带土地沙化研究

Study on Land Desertification in Desert-Oasis Ecotone Based on Desertification Difference Index

沙化过程对土地质量影响很大,沙化过程动态监测是了解沙化过程的有效途径之一。以1991年、2001年和2011年LandSat TM遥感影像为数据来源,通过荒漠化差值指数法对腾格里沙漠东南缘格林滩绿洲20年间沙化土地进行动态监测及分析。结果表明:Albedo-NDVI特征空间荒漠化监测模型对于沙化土地分级便捷可行;1991年至2011年间格林滩绿洲重度沙化土地和中度沙化土地面积呈减少趋势,轻度沙化土地和非沙化土地有所增加;中度沙化土地和重度沙化土地之间相互转化,且与其他类型土地之间也存在相互转移,主要转出为轻度沙化土地。研究区东部林地面积明显增加,南部和北部中度沙化土地逐渐转为轻度沙化土地,研究结果对当地生态恢复具有一定的实践指导意义。

Dynamic monitoring of desertification process not only has theoretical importance for understanding of it,but also has certain practical value for ecological restoration planning.Taking the Gelintan oasis in the southeastern margin of the Tengger Desert as the study area,the LandSat TM remote sensing images in 1991,2001 and 2011 were used to dynamically monitor and analyze the changes of the desertified land in the region over the past 20 years based on the desertification difference index.The results showed that the Albedo-NDVI space desertification monitoring model was convenient and feasible for the classification of land desertification degree.Analysis of the images from 1991 to 2011 revealed that the area of severely desertified land and moderately desertified land in the Gelintan oasis took a decreasing trend,accompanied by the slightly desertified land and non-sandified land increasing.We also found that transformation happened often between moderately desertified lands and severely desertified lands.Actually,similar change was seen for every types of land,which were mainly changed into lightly desertified land.Meanwhile,the research indicated that the area of forest land in the eastern part of the study area increased significantly,and the moderately sandy land in the south and north of the study area turned into slightly desertified land gradually.