近20年来科尔沁南部沙地的动态变化

Changes of Desertification from 1985 to 2000 in South of Korqin Sandy Land

根据从1985年和2000年的TM影像上提取的土地沙漠化数据,运用ARC/INFO软件和Access统计软件,分析科尔沁南部沙地两个时段的沙漠化土地构成、空间分布及其在面积、程度和空间上的变化特点。主要结论如下:科尔沁南部沙地沙漠化土地面积大,占总面积的44%～50%;在沙漠化程度构成上,中度沙化土地面积最多、比例最大;受地貌和风向等因素的控制,沙漠化土地的空间分布特点具有一定的规律,西部是片状的重度和极重度类型;东部是东西向延伸、多类型复杂交错的分布区;北部是轻度和中度类型分布区。自1985年以来,沙漠化土地面积扩大,程度减轻。稳定以极重度和中度为主,发展以弱发展和中发展型为主,逆转以弱逆转为主。沙漠化程度转变的主要类型是潜在发展为轻度和中度沙化土地,重度和极重度逆转为中度沙化土地,这与人们对各种程度沙漠化土地的重视程度、投资治理重点的确定有很大关系。今后,应对沙化程度较轻的沙漠化土地和潜在沙漠化土地给予足够重视,避免沙漠化程度的加重和新的沙漠化土地的产生。

Based on the desertification data obtaining from TM image from 1985 to 2000, with the software of ARC/INFO and Access, desertification land composition and its distribution are studied, and also, changes character in area, degree and spatial from 1985 to 2000 are analyzed. The conclusions as follows: The desertification land area in the south of Korqin sandy land is large with the ratio between 44% and 50%. The main desertification type is moderate. With the effecting of topography and the main wind directions, there are some features in the distribution of desertification land. The serious and severe desertification land mainly distributed in the patches in the west region, several desertification degrees interlaced in the east with the extension from east to west, and the north region is the region with the light and moderate desertification lands. From 1985, the area of desertification land enlarged and the degree of it mitigated. The main degrees of desertification land of stable are the severe and moderate, the main degrees of desertification land of upgrading are light upgrading and middle upgrading, and on the other hand, the main degree of desertification land of degrading is light degrading. The changing trend among desertification degrees is that the potential desertification land developed into light and moderate desertification land, and the serious and severe developed into moderate desertification land, which with great relationship to the people's attitude to all kinds of desertification degrees and the selection of controlling area. The desertification land of light degree and the potential desertification land should be give much more attention in order to avoiding its upgrading and the new desertification land coming into being.