甘肃中东部植被生长季NDVI时空变化及其对气候因子的响应

为分析研究生态保护与修复工程实施背景下甘肃中东部植被生长季NDVI时空变化及其对气候因子的响应，采用MODIS数据产品MOD09Q1，运用最大值合成法、趋势分析法与相关分析法，对该区域2008—2016年NDVI的时空变化特征及其对气候因子的响应进行了分析研究。结果表明：（1） 时间层面上，2008—2016年植被生长季NDVI呈现出增加的趋势，增加速率为0.001 4 a^-1，2012年增幅最大；空间层面上，2008—2016年研究区内的低山丘陵区和平原区的植被生长季增加明显；部分中起伏山地植被活动减弱。（2） 生长季NDVI对不同气候因子的响应程度不同，在P<0.05的显著性水平下，生长季NDVI对气温的变化最敏感，区域内大部分面积上二者呈现出强相关与极强相关；降水次之，以中等相关与强相关为主；太阳辐射最小，以弱相关甚至不相关为主。研究结果可为针对区域差异性并有所侧重的生态工程的实施提供相应的参考与依据，从而加强区域生态安全，进而促进国家生态安全屏障的加快建设。

Spatiotemporal variation of NDVI in vegetation growing season and its responses to climatic factors in mid and eastern Gansu Province from 2008 to 2016

As a sensitive member of terrestrial ecosystem, vegetation can characterize the influence extent of natural and human factors on the regional ecological environment. In view of the scarcity of good ecological environment in the world, ecological engineering was used as a means to protect and restore the ecological environment. The quantitative index normalized difference vegetation index (NDVI) was widely used to study vegetation change and the relationship between vegetation and climate. Therefore, in order to analyze the NDVI variation in the vegetation growing season in mid and eastern Gansu Province, northwest China under the background of implementing the Ecological Engineering for Ecological Protection and Restoration, MOD09Q1 data was used to analyze the spatiotemporal variation of NDVI in the vegetation growing season and its responses to climatic factors by applying maximum value composite (MVC),trend and correlation analysis approach from 2008 to 2016.The results showed as follows: (1) On the time level, the NDVI of the vegetation growing season showed an increasing trend from 2008 to 2016,with an increasing rate of 0.001 4 a^-1,and the largest increase occurred in 2012.On the spatial level, the NDVI of the vegetation growing season in the study area, the low hilly areas and plains, increased significantly from 2008 to 2016.Furthermore,the vegetation activity in the rolling hills in some areas is weakened. (2) The response degree of NDVI to different climatic factors is different in vegetation growing season. At the significant level of P<0.05, NDVI variation in the growing season is the most sensitive to the change of temperature. Most of the areas in the region show strong and extremely strong correlation, and the precipitation is the second sensitive factor with moderate and strong correlation, and the solar radiation is the least, with weakly correlation or even without correlation. The research can provide the corresponding reference and basis for the implementation of the ecological engineering based on regional differences and the particular purposes, so as to strengthen the regional ecological security and accelerate the construction of the national ecological security barrier.