Abstract:  

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.

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