Responses of vegetation growth to climate change over the Tibetan Plateau from 1982 to 2018

The Tibetan Plateau (TP) plays a critical role in Earth’s climate system and is highly sensitive to global warming. However, comprehensive analysis of the interaction between various climatic factors and vegetation growth across the TP is still limited. Using daily normalized difference vegetation index (NDVI) series interpolated from the 16-day satellite measurements and climatic data during 1982–2018, we investigated the spatiotemporal changes in growing season NDVI (NDVI GS ) and associated climatic drivers over the TP and analyzed the responses of NDVI GS to climatic drivers for different vegetation types. Our results show that NDVI GS of the TP as a whole exhibits a significant rising trend (0.0011 year −1 ; P < 0.01) from 1982 to 2018. However, trends in NDVI GS show apparent spatial heterogeneity over the TP with higher growth rates in forests (trend = 0.012 de −1 ; P < 0.01) and shrubs (trend = 0.009 de −1 ; P < 0.01) in the east and southeast than in alpine steppe (trend = 0.003 de −1 ; P < 0.01) and alpine meadow (trend = 0.006 de −1 ; P < 0.01) in the west and north. Air temperature, precipitation, and VPD serve as the dominant climatic factor affecting the NDVI GS trends in 62%, 19%, and 12% of the TP, respectively. Additionally, climatic factors show differential impacts on NDVI GS among different vegetation types. Air temperature has a predominantly positive correlation with NDVI GS for all vegetation types, while precipitation has a negative impact on plant growth in the eastern humid forest region but a generally positive impact in the other areas. Our results also highlight that the effect of VPD on NDVI GS varies among different vegetation types. These findings contribute to a systematic understanding of the possible mechanisms underlying the responses of vegetation growth to various climatic drivers across the TP.