半干旱地区沙地景观破碎化趋势分析——以科尔沁沙地为例

Analysis on the Fragmentation Trend of Sandy Landscapes in the Semi-arid Areas ——A Case Study in Horqin Sandland

采用RS和GIS手段 ,对科尔沁沙地典型地区不同时期的农田和固定沙丘景观数量和形状破碎化的趋势进行分析 ,结果表明 :农业生产活动对农田景观的影响主要表现在对斑块数量破碎化的影响 ,而对斑块形状破碎化的影响不大。放牧过程对固定沙丘景观破碎化的影响非常显著 ,这一过程不仅影响到斑块数量破碎化 ,而且也影响到斑块形状破碎化。回归分析结果 ,二者为较复杂的抛物线型关系。此外 ,沙漠化过程对农田和固定沙丘景观破碎化影响的关联分析表明 ,沙漠化过程与所有的破碎化指数呈负关联。其中 ,除农田形状破碎化指数外 ,其他破碎化指数与沙漠化过程无显著的关联 ,说明随着沙漠化程度的增大 ,农田斑块的形状简单化的趋势也加强。

In this paper, the spatial distribution information of the croplands and the fixed dunes in the typical regions over Horqin Sandland is derived by means of RS and GIS, and the quantity and fragmentation trend of the croplands and fixed dunes are analyzed. The results show that the impacts of farming activities on the fragmentation of patch quantity are more obvious than that on the fragmentation of patch shape. The impacts of farming activities on the cropland landscapes are characterized by the stages and the complexity. There is a positive correlation between the fragmentation index of patch quantity and the cropland index when the cropland index varies in a range of 5.71～6.11, a negative correlation between them when the cropland index varies in a range of 6.12～7.64, and a positive correlation again when the cropland index is higher than 7.64. The impacts of grazing on the fragmentation of the fixed dune landscapes are significant, and the grazing not only affects the fragmentation of patch quantity but also the fragmentation of patch shape. Viewing from the results of regressive analysis, there is a complicated parabola linear relationship between them. Moreover, the correlative analysis on the impacts of desertification on the fragmentation of the cropland and fixed dune landscapes reveals that there is a negative correlation between the desertification and all the fragmentation indexes. In which there is no significant correlation between the desertification and other fragmentation indexes except the fragmentation index of cropland shape, which reveals that the simplification trend of the cropland patch shape increases with the increase of desertification.