Wetting-warming climate increases ecosystem carbon use efficiency of Chinese arid and semi-arid ecosystem

Co-limited by environmental constraints, ecosystems in arid and semi-arid regions (ASARs) are extremely sensitive to climate change. A warmer and wetter climate trend has been observed extensively in ASARs of China, but whether and how the changing climate has influenced ecosystem carbon allocation and balance remains largely unclear. To bridge this knowledge gap, we conducted a comprehensive study integrating manipulative experiments, flux observations, and model simulations and our research findings reveal that the changing climate exerts a significant influence on ecosystem carbon use efficiency (CUEe) in ASARs. Specifically, the effect of increased precipitation has outweighed the warming effect, resulting in a widespread rise in CUEe across most parts of ASARs. In regions with alpine vegetation, the stimulated effects of increased temperature and precipitation play a dominant role in shaping the pattern of CUEe changes. However, with intensified warming, its stimulated effect on CUEe gradually diminishes or even reverses in ASARs. These findings can improve our understanding of ecosystem carbon sequestration regarding the response of resource-constrained ecosystems to climate change, thereby guiding ecosystem management.