中文摘要：

对草原植被长势变化的监测，及其与气候因子关系的分析，对生态环境治理及保护具有重要意义。本文利用250m的MODIS-NDVI数据，构建草原植被长势指数（MGI），分析了16天间隔的植被长势变化及其与降水、气温的相关性和对降水响应的滞后性。得到锡盟3种草原类型区2001—2010年草原长势变化情况，及降水、气温在草原生长不同阶段对草原长势的影响。研究结果表明：（1）在空间上长势东部变化好于中部与西部，北部好于南部；时间上2003年长势最好、2001年长势最差。（2）锡盟内3种草原类型区MGI均与降水关系明显，与气温相关性不显著，降水对温性草原区长势变化的影响最大。（3）在草原生长的不同阶段，影响因子不同，前期与后期主要受气温影响，中期主要受降水影响，草原生长对降水存在明显的滞后，一般在32—48天，同时指出草原植被在不同时间段对降水响应的滞后时间。

英文摘要：

Monitoring of grassland vegetation growth is an important part in grassland studies. It is helpful to acquire the grassland situation and has significance to environmental management and protection through analysis on the relationship between vegetation growth and meteorological factors. In this research, we obtained the spatial distribution of temperature and precipitation by using the ANUSPLIN spatial interpolation method and uses 16days, 250m MODIS-NDVI data to build grassland vegetation growth index MGI （modified growth index）, get the changes of Xilin Gol League grassland vegetation growth from 2001 to 2010, analyze the relationships between vegetation growth and temperature/precipitation, and reveal the hysteresis effect of precipitation. The resuits of this research showed： （1） spatially, the vegetation growth in east part is better than in central part and west part, in north part is better than in south part. Growth in 2003 is better than the other years, and 2001 is the worst year. （2） The correlation between MGI and precipitation of the three grasslands in Xilin Gol is significant, but the relation between MGI and temperature is week. Precipitation can explain 57.5% of desert grassland grow,75.2% of typical steppe grow and 63.7% of meadow prairie grow. So,we can say that vegetation growth performs better with the increase of precipitation. （3） Impact factor is different to grassland vegetation growth in different phrases, temperature limits the growth during early and late stage, precipitation is the main impact factor to growth during middle stage. Grassland vegetation grow has an obvious lag response, about 32-48 days. And we pointed out that lag response time is different in different grow stage, during early stage is 32days, during middle stage is 48days, and during late stage is 32days.