锡林郭勒地区植被覆盖的空间分布及年代变化规律分析

Spatial distribution and temporal changing of vegetation cover in Xilinguole steppe region

以1981—2007年锡林郭勒盟归一化差异植被指数NDVI数据为基础,在Arcgis软件的支持下,通过图形代数、空间建模、图层叠加等方法,以植被指数的消长规律入手,分析锡林郭勒盟植被覆盖状况的总体分布状况及年代间的变化规律。结果表明：锡林郭勒盟植被覆盖状况总体上呈现图斑镶嵌交错、带状递变、自东向西依次递减的空间分布规律;总体来讲,20世纪80年代以来锡林郭勒草原植被的整体退化趋势一直在延续。荒漠草原区与典型草原区的生态地理界线都发生了明显的东移,21世纪初,相当于草原化荒漠状况的稀覆盖植被区的面积比20世纪80—90年代扩展了4~5倍,尽管低覆盖植被区的面积比例没有发生变化,但东部界线向东推移了1个经度的范围,密覆盖植被区面积极度萎缩,同时向东收缩了一个经度。

Based on the Normalized difference vegetation index（NDVI） data of Xilinguole League from 1981 to 2007, this paper analyzed the general distribution status and the changing rule of the vegetation cover between different decades with the methods of graphics algebra, lays overlying, spatial modeling and other statistical analysis by using Arcgis software. The results showed that the spatial distribution rule of average vegetation cover NDVI of Xilinguole League presented staggered mosaic pattern, successively zonal alteration, and declined from east to west. Generally, the degradation trend of whole Xilinguole steppe has been continued since1980＇s. At the beginning of the 21 st century, the ecological geographic borderlines of desert steppe and typical steppe moved eastward obviously. The area of the vegetation region with sparse cover corresponding to steppe desert expanded 4-5 times more than that in 1980＇s and 1990＇s. Despite the area proportion of the vegetation region with lower cover unchanged, but its eastern boundary shifted a longitude eastward, at the same time, the area of the vegetation region with dense cover shrunk extremely and its boundary also shifted a longitude eastward too.