Temporal and spatial changes in response to climate in grasslands of the Qilian Mountain National Nature Reserve

Understanding the growth and evolution of grasslands in the Qilian Mountains, China, and their relationship with climate is necessary for scientific evaluation of this complex regional ecosystem. In this study, MOD13Q1 and Landsat data and the normalized difference vegetation index (NDVI) were used to examine spatial and temporal changes in different grassland types in response to climate in the Qilian Mountain National Nature Reserve from 2000 to 2018. We found that 1) the grassland area decreased from 2000 to 2015, and the area mainly transitioned to forest land, farmland, or waterbodies; 2) the NDVI of summer grassland vegetation in the Qilian Mountain National Nature Reserve improved significantly from 2000 to 2018, and slight improvements were seen in other seasons; 3) the NDVI of different grassland vegetation types showed increasing trends, with the highest increase in desert grassland, followed by typical grassland and alpine grassland; 4) the effect of precipitation on the NDVI of different grassland vegetation types was higher than that of temperature.