Spatial patterns and driving mechanisms of urban carbon sequestration service flows in China

Global climate governance increasingly relies on understanding the spatial mismatch between carbon emissions and ecosystem carbon sequestration capacity. As a critical regulating ecosystem service, carbon sequestration service flows exert substantial interregional spillover effects through spatial ecological interactions. However, existing research has largely focused on static supply–demand evaluations at regional scales, while the spatial flow processes and driving mechanisms of carbon sequestration service flows across cities remain insufficiently explored. This study quantified the supply, demand, and flows of carbon sequestration service flows across 333 prefecture-level administrative units in China from 2010 to 2024 using breakpoint–field strength models and spatial flow analysis. Furthermore, the XGBoost-SHAP model was adopted to detect the nonlinear driving mechanisms behind carbon sequestration service flows. The results showed that China’s carbon sequestration service flows presented a potential west-to-east linkage pattern, indicating a pronounced spatial mismatch between carbon sequestration supply areas and carbon emission demand areas. High-supply regions were predominantly distributed in western and northern China, whereas demand regions were concentrated in eastern coastal urban agglomerations. The total volume of carbon sequestration service flows first rose and then declined over the study period, while the radiation distance and spatial interaction of service flows continuously increased. The potential spatial linkage of carbon sequestration service flows were identified: Inner Mongolia-Beijing-Tianjin-Hebei, Yunnan–Guizhou–Pearl River Delta, and Northeast China/Sichuan-Xinjiang-eastern coastal urban agglomerations. XGBoost-SHAP analysis showed that PRE, DEM, TEMP, and GDP exhibited prominent main effects. PRE and TEMP had the strongest interaction, with DEM-TEMP and DEM-GDP showing relatively strong interactions compared with other variable pairs. The findings revealed the potential spatial linkage pattern of carbon sequestration service flows and offered scientific support for interregional ecological compensation and spatially coordinated carbon governance in China.