NDVI-BASED VEGETATION DYNAMICS AND ITS RESPONSE TO PRECIPITATION CHANGES IN THE HEXI CORRIDOR OF CHINA FROM 2000 TO 2019

To explore the response relationship of vegetation dynamic change characteristics, clearness vegetation and precipitation changes in the Hexi Corridor, China. This paper analyzed the NDVI between 2000-2019 using linear regression slope method based on long time series MODIS data. The annual NDVI values of the Hexi Corridor range from 0.15 to 0.22. The vegetation overall showed an upward trend in the last 20 years, with an average slope from 0.0125/10a. But there was significant variability in the trend of inter annual changes, as compared from 2000 to 2009, the rate of exponential increases in vegetation in the Hexi Corridor slowed in 2010-2019, and the average slope of changes in vegetation cover decreased from 0.0139/10a to -0.006 8/10a. The variation trend of NDVI is basically consistent with precipitation. The positive and negative correlation between NDVI and precipitation account for 61.58% and 38.42% respectively. The positive correlation region is mainly located in the central and southwest regions with relatively rich vegetation. The regions with negative correlation are mainly in the northern and northeastern desert areas, where there is no vegetation cover. It shows that the relationship between vegetation index and precipitation in Hexi Corridor is relatively close in areas with abundant vegetation.