中文摘要：

标准化降水蒸散发指数（SPEI）是评估气候变暖背景下区域干旱的重要指标。基于生态功能分区,利用MODIS-NDVI数据和SPEI指数,探讨2000—2014年黄河源区植被指数和干旱指数的年际变化、空间分布规律以及两者之间的相关关系。结果表明：（1）2000—2014年黄河源区NDVI和SPEI总体上均呈波动上升趋势,植被覆盖状况略有好转,干旱程度有所降低;（2）NDVI与SPEI变化趋势的空间分布特征大致相同,东南部区域总体呈减少趋势,西北部区域总体呈增加趋势;（3）黄河源区降水量是影响植被生长的主要因子,也是影响SPEI变化的主要条件。当0.30.6时影响较小;（4）黄河源区大部分地区NDVI与SPEI呈正相关,其中呈显著正相关的区域分布在青根河生态区以及黄河源头生态区植被覆盖度较低区域;小部分地区由于受到人类活动的干扰,使NDVI与SPEI呈负相关或相关性较弱,其中呈显著负相关的区域在黄南草原生态区及周围草地退化、生物多样性敏感的区域。黄河源区干旱程度的下降对植被覆盖的增加有促进作用,为该区域的生态恢复提供了有利条件。

英文摘要：

Under the circumstances of global warming, standardized precipitation evapotranspiration index （SPEI） has become an important index in evaluating drought level. Based on eco-functional zoning, MODIS-NDVI and SPEI data collected in the source region of the Yellow River during 2000--2014, this study discussed the spatial-temporal change characteristics of NDVI and SPEI and their dependency relationship. Results showed： （ 1 ） the values of NDVI and SPEI demonstrated a rising trend in general in the period of 2000--2014, and the vegetation coverage turned better and the drought level decreased. （2） Both NDVI and SPEI had approximately similar pattern for spa- tial distribution,with a decrease in the southeast and an increase in the northwest. （3） Precipitation was acting as the main factor regulating vegetation growth and SPEI change. The effect of SPEI on NDVI was stronger in the case of O. 3 〈 NDVI 〈 0.6, whereas it was weaker if NDVI 〉 0.6. （4） NDVI presented a positive relationship with SPEI in most parts of the source region of the Yellow River, especially in the Qinggen river ecological zone and the source region of the Yellow River ecological region where were featured by relatively lower vegetation coverage. However, NDVI showed negatively relationships with SPEI in the Huangnan grassland ecological zone and its surroundings, especially at grassland degradation areas and biodiversity sensitive areas. enable vegetation coverage to increase in the study area and provide favorable the region. The decrease in drought level would conditions for ecological restoration in