基于RS和转移矩阵的泾河流域生态承载力时空动态评价

Spatio-temporal analysis of ecological carrying capacity in Jinghe Watershed based on Remote Sensing and Transfer Matrix

利用泾河流域1986、1995、2000、2008年4期遥感数据和转移矩阵分析方法,在G IS平台上,对该流域近23 a的生态承载力时空变化进行了定量评价和空间化表达,结果表明,泾河流域生态承载力空间分布极不均匀,整体呈南高北低,并由东南向西北递减,由上游向下游递增的空间变化趋势,表现出与流域地貌特征,土地利用/覆被和环境禀赋相关联的地理特性和空间异质性;随着时间的推移,全流域生态承载力呈逐年降低趋势,尤其以2000年以后下降趋势明显,但流域内部不同区域的生态承载力及其各类土地生态承载力的变化幅度与趋势各有不同;3个时段内(1986—1995年、1995—2000年、2000—2008年)流域各类土地生态承载力转换频繁,转向趋势明显,且以2000年为拐点,前两时段以林地和草地生态承载力向耕地和建筑用地生态承载力转移为主,后一时段以耕地和建筑用地生态承载力向林地和草地生态承载力转移为主,导致近23 a来泾河流域生态承载力及其内部组成变化均较大,说明土地利用/覆被的变化是流域生态承载力变化的主导因素,而1999年以后国家实施的退耕还林还草生态工程则是2000—2008年该流域生态承载力变化的主要驱动力。

The spatiotemporal dynamic and space pattern changes of Ecological carrying capacity（ECC） in a given watershed is an important topic in the field of watershed ecology and development sustainabiliby research on the basis of the remote sensing（RS） data and transfer matrix of land use with the help of geographic information system（GIS） techniques.The paper,for a case study of the Jinghe Watershed with Ecological Footprint method,estimated the ECC time series and analyzed the spatial distribution,spatiotemporal dynamic and transfer matrix of ECC using high resolution remote sensing data of 1986,1995,2000 and 2008 during 23 years.The results showed that the spatial distribution of ECC was significantly uneven in this region,in which the ECC in southern part of the watershed is greater than the northern part,tended to descend from southeastern to northeastern part and ascend from upstream and downstream gradually.As a whole,the differences between ECC were caused by different geography characteristics,environment conditions and land use/cover,and total ECC increased from 1986 to 1995 and decreased from 1995 to 2008,especially after 2000（a point of inflection）.The transfer matrix of ECC showed the transfer changes of ECC of 6 major categories land are frequent.The amount of total change for cropland was found largest,followed by forest,pasture,building-up land,water area and unused land.The change in ECC of cropland was nearly a pure swap-type of change to forest and pasture after 2000.The results provided a more extensive understanding on the spatiotemporal dynamic and space pattern of ECC in Jinghe Watershed and its changes really were caused by Land use/cover change after 2000 with the driving force came from the State campaign of Grain for Green Project introduced in 1999.