Drought-Induced Variations in the Phenology of the Alpine Grasslands in the Qinghai Lake Basin

Quantifying the surface vegetation growth behavior is crucial to the understanding of the complex response of alpine ecosystems to climate variability. This study investigated the drought-induced phenological shifts of Qinghai Lake Basin (QLB). Phenological metrics including green-up and dormancy were retrieved from satellite vegetation index records from 1982 to 2022. Phenological metrics were characterized using simple linear regression method. The results showed that the long-term trends of QLB phenology were various. Meadow greenup and steppe dormancy were significantly advanced and the earlier trend of meadow dormancy and steppe greenup are insignificant. Drought conditions of the QLB were obtained using multiscale standardized precipitation evapotranspiration index (SPEI). The 6-month SPEI of April explains the most of the interannual shifts in greenup of meadow and steppe ranging from 11.56% to 19.36%. The 12-month SPEI of August and 6-month SPEI of April explains the most of variations in dormancy across QLB.