基于MODIS的川西北江河源区草地退化状况时空分析

摘要

川西北江河源区位于四川西北部,其境内的草地有着十分高的生态服务和社会服务价值.以其作为研究区域,利用2001年-2010年MODIS植被指数数据,通过GIS的空间分析和地统计分析功能,得到10年内江河源区植被覆盖度.同时,使用四川省高寒草甸草地生物量模型在MODIS植被指数的基础上反演了2001年-2010年川西北江河源区草地生物量.综合草地植被覆盖度和草地生物量指标,建立了川西北草地退化状况分级评价体系.结合研究区DEM数据对草地退化状况的空间分布进行了分析,结果表明:①草地退化率与海拔高度呈反比关系,海拔越高,退化率越低,反之,退化率越高;②草地退化率随着坡度的增大呈缓慢升高状态,在32.28°退化率达到最大,之后退化率开始出现降低趋势;③草地在各坡向上的分布面积虽有高有低,但退化率变化不大.%The source regions of Yangtze and Yellow rivers,located in the northwest of Sichuan,has a very high value in ecological services and social services.Now,serious grassland degradation is endangering the environment of the SRYYR. There is an urgent requirement to analyze and review the grassland resources,status of grassland degradation so as to ensure sustainable development in the SRYYR.So it is necessary to establish an evaluation system of grassland degradation based on vegetation coverage and grassland biomass,and then,analyses the spatial distribution of degraded grassland,combining with DEM data in the study area.The result shows that:(1)the rate of degradation and the altitude have an opposite relationship, higher the altitude is,lower the rate of degradation is.On the contrary,higher the rate of degradation is;(2)the degradation rate of grassland increases slowly with the increase of slope gradient.The degradation rate reaches the maximum at 32.28 de-gree.Then,the degradation rate begins to appear to reduce;and(3)even though the area of grassland distributes more or less in the upward slope,the deterioration rate changes unobtrusively.