中文摘要：

植被动态监测以及与气候变化的耦合关系是陆地生态系统研究的热点,而草地NDVI时空动态以及影响其变化的关键气候因子分析,对于草地覆盖变化的动态机理研究具有重要意义。基于遥感和GIS技术,利用黑河流域1999-2007年SPOT-NDVI数据和气象站点数据,分析了黑河中上游草地植被NDVI的时空变化特征以及与气候因子的相关性。结果表明,黑河中上游草地植被NDVI在1999-2007年间呈明显增加趋势;草地植被NDVI增加和减少的面积分别占草地总面积的71.53%和19.43%;增加的区域主要分布在托来山、走廊南山、冷龙岭和河西走廊中段的典型草原和高寒草甸草地,减少的区域主要分布在托勒南山、走廊南山和冷龙岭的荒漠草地向非草地过渡区域;黑河中上游不同草地植被NDVI的年内变化均呈单峰型,7月份达最大值;草地NDVI与气温呈极显著正相关（r=0.942,P〈0.01）,与降水量呈显著正相关（r=0.922,P〈0.05）,NDVI与相对湿度呈不显著正相关,与日照时数呈负相关性,并且不同草地类型牧草生长的限制因子不同。近年来伴随西北地区气候向暖湿转型,黑河中上游草地植被覆盖明显增加,气温是影响研究区牧草生长的关键气候因子。

英文摘要：

Vegetation dynamics and its coupled relation with the climate is a hot spot in the study of how terrestrial ecosystems respond to climate systems.Analysis of grassland NDVI（normalized difference vegetation index） spatiotemporal dynamics and exploration of key climate factors has important significance for research of grassland cover change.Based on the RS,GIS and SPOT NDVI data and monthly meteorological data from 1999 to 2007,the spatiotemporal variation characteristics of grassland vegetation NDVI in the middle and upper reaches of the Hei River and the correlation between NDVI and four climate factors were analyzed.1） The annual average NDVI and growing season NDVI increased in the middle and upper reaches of the Hei River.The area of grassland NDVI that increased accounted for 71.53% of the total grassland area,while that which decreased accounted for 19.43%.The grassland vegetation NDVI in typical steppe,alpine steppe and meadow of the Tuolai Mountain,Southern Mountain of Hexi corridor,Lenglong Ridge and the middle of the Hexi corridor increased,while the decreased regions were located in the zone between desert grassland and non-grassland of the Tuolai Mountain,Southern Mountain of the Hexi corridor and Lenglong Ridge.2） The grassland vegetation NDVI of the Hei River shows a single peak curve within the yearly changes of different grassland types,and the value of NDVI reached a peak in July.3） There was an extremely significant positive correlation between grassland NDVI and average temperature（R=0.942,P〈0.01）,and a significant correlation with average precipitation（R=0.922,P〈0.05）.The coefficient of correlation between grassland NDVI and relative humidity was positive but not significant,while the correlation with sunshine hours was negative.The limiting factor was different in the four grassland types.In recent years,with the shift from warm-dry to warm-humid climate in Northwest China,grassland vegetation coverage in the middle and upper reaches of the Hei River significantly increa