Shift in the trend of browning in Southwestern Tibetan Plateau in the past two decades

Abstract

Within the context of climate change (e.g., climate warming and changes in atmospheric circulation) the temporal dynamics of vegetation growth on the Tibetan Plateau (TP) have remained unclear, especially over the most recent decade. Using a normalized difference vegetation index (NDVI), we investigated vegetation dynamics on TP from 2000 to 2018, with a special focus on the northeastern part controlled by the westerlies and the southwestern part controlled by the Indian monsoon. Results indicate that the northeastern part had a consistent greening trend, but the southwestern part was browning in the 2000s and turned to greening in the 2010s. Precipitation was the key factor controlling NDVI dynamics in both parts. Differences in seasonality and trends in the strength of the atmospheric circulation might contributed to the distinct NDVI dynamics in these two parts. Our findings, in combination with previous reports on changes in the westerlies and Indian monsoon, highlight the importance of linking vegetation dynamics and atmospheric circulation for predicting the trend of plant growth on TP in the future.