中文摘要：

通过逐象元回归和一致性检验构建1981-2010年间洮河流域NDVI序列,整编同期气温、降水等资料,采用Sen斜率、主成分、相关性及回归残差分析等方法,就洮河流域不同地理-生态区间植被动态的时空特征及所受气候变化和人类活动的影响进行研究。结果表明,1981-2010年期间,洮河流域植被动态总体增强且空间分异明显,甘南高原植被动态增强幅度高于黄土区。从植被季节变化的趋势和幅度来看,甘南高原主要表现为植被萌发期提前,黄土区表现为萌发期提前和枯萎期延迟。在气温和降水所代表的水热要素与NDVI之间构建植被动态预测模式,率定和校验期精度良好,能够反映不同生态-地理区间植被动态与气候变化之间的数量关系。总体来看,洮河流域植被变化由气候和人类活动共同驱动,气候模式输出和残差分析结果表明,洮河流域植被动态受气候因素的影响显著,气候变化对洮河流域植被活动增强的贡献率超过90%。

英文摘要：

Climate change and human activities have controlled and influenced all kinds of land surface processes.In order to investigate the impacts of climate change and human activities on regional vegetation dynamics,we combined AVHRR NDVI (1981-2006) and MODIS NDVI (2001-2010) to extract the full time series for vegetation dynamics from 1981-2010 across the Taohe River Basin (TRB).Air temperature and precipitation data from gauge stations during the same period were compiled to regress relationships between climate impacts and vegetation changes,and the Sen' s slope was adopted to analyze trend variations in vegetation index and climatic factors.Principal Component Analysis and correlation analysis were used to detect and select key factors with high sensitivity to vegetation dynamics and the regression residual method was used to assess the impacts of human activities on vegetation dynamics.The results suggests that vegetation activity was strengthened across the whole TRB,while the magnitude of increase on the Gannan Plateau (southern Gansu) was higher than on the Loess Plateau,with significant heterogeneity in both time and space.Climate change has led to the variations in the vegetation growing season.There was a very high probability that germination was shifted earlier in both regions,while the withering or dormant season was delayed on the Loess Plateau.On the whole,regional vegetation dynamics in the TRB were due to the combined effects of climate change and human activities.The regression expressions showed good performance with high Nash coefficients and correlation coefficients during calibration and validation.The increase in air temperature contributed more to vegetation change than other climatic factors.Human activities exerted trivial effects on vegetation dynamics,and more than 90％ was the result of climate change.