Spatial variations and mechanisms for the stability of terrestrial carbon sink in China

Understanding the stability of terrestrial carbon sinks (S-TCS) contributes to more accurate prediction of the terrestrial carbon sink (TCS) in the context of future global change and helps inform climate change mitigation policies. Here, focusing on China, we analyzed the spatial distribution and driving mechanisms for the S-TCS, quantified by the interannual variability of the TCS, using three independent approaches (atmospheric inversions, ecosystem carbon cycle models, and machine learning models based on flux tower observations). We found that the interannual variability of the TCS in China is relatively small compared with the conterminous United States and geographic Europe, indicating a generally stable TCS in China. Spatially, the S-TCS is lower in the North China Plain, Northeast China Plain, and western Yunnan-Guizhou Plateau than in other regions, with varying underlying mechanisms. Large interannual variations in precipitation and high TCS sensitivities to precipitation fluctuations explain the low S-TCS in the North China Plain and Northeast China Plain, while high TCS sensitivities to temperature variations drive the low S-TCS in the western Yunnan-Guizhou Plateau. Our findings highlight the importance of considering local contexts for stabilizing and enhancing China's TCS in a changing environment.