Temporal and Spatial Vegetation Index Variability and Response to Temperature and Precipitation in the Qinghai-Tibet Plateau Using GIMMS NDVI

The vegetation of the Qinghai-Tibet Plateau (QTP) is fragile and vulnerable to global and regional climate change. This paper analyzed the temporal and spatial variability of NDVI and response to temperature and precipitation in the QTP from 1982 to 2015. The results showed that: (1) there was a nonsignificant increase temporally, while there was a significant spatial increase that accounted for 63.26% of the total area and was distributed in the north, west, and south of the QTP. A significant decrease was concentrated southeast of the QTP. (2) Average NDVI values for the main vegetation types in the QTP were broadleaf forest>coniferous forest>shrub>meadow>alpine vegetation>grassland>desert. NDVI values of grassland, alpine vegetation, and desert vegetation had a significant linear increase, while NDVI for shrub, coniferous, and broadleaf forest decreased non-significantly. (3) The correlation coefficients between NDVI and temperature were spatially distributed in a north-south direction with latitudinal zonal characteristics. The correlation coefficients between NDVI and precipitation were distributed in an east-west direction with dry-humidity zonal characteristics. The study concluded that with the lack of hydrothermal conditions in the northern part of the QTP, NDVI increased significantly, while there was a significant decrease in areas with sufficient hydrothermal conditions.