Spatiotemporal patterns and carbon balance zoning optimization of county-level carbon budget in Fujian Province.

The terrestrial ecosystem carbon budget is critical for mitigating global climate change and advancing regional low-carbon development. This study analyzes county-level carbon budgets in Fujian Province, China's first ecological civilization pilot zone, from 2000 to 2023. Spatiotemporal dynamics of carbon emissions and sequestration were investigated, and a carbon balance zoning framework was developed. County-level carbon emissions exhibited a coastal-high, inland-low pattern, in contrast to the spatial distribution of sequestration. The carbon compensation rate displayed temporal stability, whereas the economic contribution coefficient showed pronounced spatial heterogeneity and the ecological support coefficient conformed to a low-coastal, high-inland structure. By integrating the evolutionary characteristics of carbon balance zones from 2000 to 2023 with major function-oriented zoning, nine sub-regions were identified and targeted optimization strategies were proposed. These findings elucidate the mechanisms of county-level carbon balance, thereby contributing to regional low-carbon transitions and informing carbon reduction strategies.