中文摘要：

植被NDVI对城市扩展及气候变化响应研究,对于科学评估区域生态环境变化及调整与约束人类活动具有重要理论和现实意义。以西安及其附近区域为例,基于区域土地利用、MODIS NDVI、气温和降水数据,分析了植被NDVI对城市扩展及气候变化的响应,结果表明：（1）2000-2014年研究区植被NDVI变化过程划分为2000-2007年的显著增加阶段和2007-2014年的显著减少阶段,前者主要分布于区域北部黄土高原、南部秦岭北坡,后者主要分布于区域中部关中平原尤其是西安及其附近区域。（2）2000-2015年研究区建设用地增加1 428.27 km^2,建设用地增加区域植被NDVI呈显著减少趋势。（3）研究区植被NDVI与年降水量的相关性高于年平均气温,同时西安及其以南区域植被NDVI与年平均气温、年降水量均呈负相关关系,反映出城市扩展等人类活动对植被NDVI变化的影响超过了气候变化的影响。研究结果表明植被NDVI总体受气候变化控制,但局部受人类活动影响更为严重,并且植被NDVI对气候变化的响应表现出波动性,而对城市扩展表现出线性减少趋势性,为通过植被NDVI变化区分自然因素与人为因素对环境影响提供了可能。

英文摘要：

Urban expansion reflecting human activities and climate change are the two main driving forces of global and regional ecological environmental change.As an important indicator of characterizing vegetation ecology in global land surface,vegetation NDVI provides a probability to study the impact of urban expansion and climate change on regional ecological environmental change.Compared with the previous independent analysis of the impact of urban expansion or climate change on vegetation NDVI,this paper will analyze the impact of urban expansion and climate change on vegetation NDVI together,and also analyze the difference of the two driving forces,which may provide a probability to quantitatively distinguish the effects of climate change and human activities.Taking Xi’an City and its nearby area for example,the impact of urban expansion and climate change on vegetation NDVI was analyzed based on the land use data,MODIS NDVI,yearly temperature and precipitation data in 12 meteorological stations,and the methods including linear trend analysis,correlation coefficient,partial correlation coefficient and t-test.Results show as follows：（1）The process of vegetation NDVI change was divided into 2 stages,2000-2007 and 2007-2014.The former stage showed significant linear increasing trend,which was mainly distributed in Loess Plateau area in northern study area and northern Qinling in southern study area.The latter stage showed significant linear decreasing trend,which was mainly distributed in Guanzhong plain,especially in Xi’an City and its nearby area.（2）Urban area had increased 1 428.27 km2,which was mainly from2010 to 2015 in the study area.Vegetation NDVI in the area of urban expansion showed a significant linear decreasing trend（P〈0.05）.（3）Overall,the correlation between vegetation NDVI and precipitation was higher than that between vegetation NDVI and temperature.At the same time,negative correlation between vegetation NDVI and temperature,precipitation was distributed in Xi’an City and its