[Evaluation of Carbon Sequestration Service Flow in Minjiang River Basin for Supply and Demand Synergy]

Guided by the carbon peaking and carbon neutrality goals， clarifying the transmission mechanisms of carbon sequestration service flow （CSSF） in river basins is crucial for promoting sustainable development. To enhance the coordination between carbon sequestration service supply and demand in the Minjiang River Basin， this study quantified the current supply and demand status and proposed a comprehensive evaluation framework for carbon sequestration service flow. The framework incorporated the breakpoint formula， field strength model， and topographic distribution index to explore the spatial transmission characteristics of carbon sequestration service in both horizontal and vertical dimensions， ultimately proposing differentiated strategies for optimizing carbon sequestration service flow. The results are as follows： ① The supply of carbon sequestration service in the Minjiang River Basin exhibits a spatial distribution pattern of "low along the riverbanks and high in the mountainous areas，" while the demand shows a pattern of "high in coastal regions and low in inland areas." ② Overall， the basin is in a state of surplus supply， whereas urban development areas show a deficit. Notably， 45.4% of the regions in the basin show a mismatch between supply and demand， with areas of deficit exhibiting spatial aggregation. ③ Among the input areas in the Minjiang River Basin， 72.7% can receive effective carbon sequestration service supply from other counties， whereas Jinan District， Mawei District， and Changle District in the southeast are unaffected by carbon sequestration service flow. ④ From the high-terrain mountainous area to the low-terrain flat area， the V-level potential CSSF gradually loses its dominant position， with 86.5% of the CSSF in the Minjiang River Basin provided from higher-grade topographic counties to lower-grade topographic counties. The research findings provide scientific references for ecological protection， restoration， and compensation mechanisms in the Minjiang River Basin.