关键词: RS/GIS, NOAA/AVHRR, 植被指数, 生态环境, 中国西北

Abstract: By combining the qualitative method with the quantitative method, with the support of Remote Sensing (RS) and Geographic Information System (GIS), the authors utilized the NDVI data during 1982-2000 whose resolution is 8km 8km and the ground meteorological data to analyze the changing process of ecological environment of different ecological type areas in Northwest China. We have got the average annual NDVI values and the yearly changing curves based on data of past years, and have showed the distribution of average annual NDVI in Northwest China and the distribution of NDVI difference change of decadal. From these results, we concluded that the ecological environment change in Northwest China showed obvious spatiotemporal characteristics: in the 1980s, the changes of ecological environment in Northwest China fluctuated mildly; in the 1990s, the changes fluctuated conspicuously; since 1998, the whole situation of ecological environment has been deteriorating. Different ecological type areas have different driving factors to inter-annual change of vegetation index: the inter-annual change of vegetation index in the Northwestern Loess Plateau Area(Area H) has close relation with precipitation, and that in the Northwestern Qinghai-Tibet Plateau Area(Area Q) has close relation with climate, but that in the Shaannan-Longnan Humid and Semi-humid Area(Area S) and the Northwestern Arid Area(Area G) has distant relation with precipitation or temperature. The changes of ecological environment showed noticeable regional differentiation. On the whole, the ecological environment in Northwest China ranks as: Area S better than Area H better than Area Q better than Area G. As for the decadal environmental changes, the whole ares had improvement from 1982 to 1990, only the Area G had larger degraded extent. The ecological environments of the four areas all had degraded at different degrees from 1990 to 2000, and the largest degradation was in Area S, the followed was Area H. The ecological environment situation in whole Northwest China is not so good, moreover, the degradation in recent years becoming more badly, which should be paid enough attention to.

Key words: RS/GIS, NOAA/AVHRR, Vegetation Index, ecological environment, Northwest China