Abstract: Based on the GIMMS NDVI and MODIS NDVI datasets, we constructed a long-term GIMMS-MODIS NDVI dataset of 1982-2020 in Hoh Xil with a simple linear regression model. We analyzed the temporal and spatial variations of NDVI by adopting trend analysis, significance test, and correlation analysis, and analyzed the responses of NDVI to temperature and precipitation based on pixel scale. The results showed that the average annual temperature and precipitation showed a significant rising trend in Hoh Xil from 1982 to 2020, with a rising rate of 0.06 ℃·a^-1 and 5.59 mm·a^-1, respectively. The NDVI increased gradually from northwest to southeast of Hoh Xil during 1982-2020. The NDVI value was the largest and varied most obviously in summer, while it was the smallest and tended to be stable in winter. The annual average NDVI showed a non-significant positive correlation with the average annual temperature. At the pixel scale, the correlations between NDVI and temperature were predominantly positively, surpassing that between NDVI and precipitation. The correlation was the strongest in autumn. The impact of temperature on NDVI outweighed that of precipitation.

Key words: Hoh Xil Natural Reserve, GIMMS NDVI, MOD13A3, temperature, precipitation