基于RS和GIS的中国西北不同生态类型区生态环境时空变化研究

采用定性与定量相结合的方法,在遥感（RS）和地理信息系统（GIS）支持下,利用1982-2000年的空间分辩率为8 km×8 km的NDVI数据（由NOAA-AVHRR提供）和地面气象资料,联合分析西北不同生态类型区生态环境的变化过程,得出中国西北地区NDVI的年平均值及其历年变化曲线、NDVI年平均值分布图和每隔10 a的差值变化图。由此可以看出,生态环境变化时空特点明显:20世纪80年代生态环境的变化波动不大,90年代以来波动变化明显,而且从1998年以后生态环境总体呈下降趋势；不同生态类型区植被指数年际变化的驱动因子不同,黄土高原区植被指数年际变化与降水量的相关性显著,而青藏高原高寒区与气温的相关性显著,其他分区与降水量和气温的相关性都不显著；生态环境变化的地域差异性明显,西北不同生态类型区中生态环境由好到差依次是陕南-陇南湿润半湿润区、黄土高原区、青藏高原高寒区、干旱区。四个分区1990年比1982年生态环境有所提高,但干旱区退化面积较大,2000年与1990年相比,生态环境都出现不同程度的退化,其中,陕南-陇南湿润半湿润区退化面积最大,其次是黄土高原区。整体生态环境状况不佳,而且近年的退化应该引起重视。

Study on Eco-environmental Spatio-temporal Change of Different Ecological Divisions in Northwest of China based on RS and GIS

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 Semihumid 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.