Precipitation regimes primarily drive the carbon uptake in the Tibetan Plateau

Warming and precipitation variations have significant impacts on carbon uptake in the Tibetan Plateau. However, which climatic variable or process primarily drives the inter-annual variations of carbon uptake is not clear. Using multiple gross primary productivity (GPP) estimates, we study the controlling factors of the previous-year lagged effect and evaluate the effects of climate variables on GPP in the Tibetan Plateau. Results show that the lagged ecosystems in which productivity is significantly associated with previous-year precipitation are more sensitive to biotic and environmental factors than unlagged ones. In addition, previous-year precipitation as a whole has a positive impact on GPP over the Tibetan Plateau. Furthermore, precipitation regimes including precipitation intensity and dry-days fraction, and current-year precipitation amount primarily drive the GPP variabilities instead of temperature, vapor pressure deficit (VPD), and radiation at the grid scale. Future projections suggest that precipitation amount and intensity will increase, and dry-days fraction will decrease, which indicates that precipitation might have a more complicated impact on carbon uptake via variations in intradistribution. Our study reveals the primary climatic factors that influence the variations of carbon uptake in the Tibetan Plateau, offering valuable insights for accurate carbon cycle modeling.