Assessing cross-regional carbon responsibility through ecosystem service flows: A dual-factor ecological compensation framework for China

Abstract

Carbon sequestration services play a critical role in climate regulation and global carbon-cycle stability. However, the spatial mismatch between carbon sequestration supply and demand generates cross-regional ecological externalities and uneven environmental responsibilities, posing significant challenges for sustainable governance. Existing government-led vertical ecological compensation mechanisms often fail to capture interregional ecological linkages and differentiated responsibility relationships. Using Chinese counties as analytical units, this study develops an integrated framework that combines ecosystem service flow analysis with responsibility allocation and ecological compensation design. Specifically, a resistance-adjusted comparative ecological radiation force model (R-CERF) is employed to quantify ecological linkages between carbon-surplus and carbon-deficit regions under spatial heterogeneity, while SHAP-based explainable machine learning is used to identify the major drivers of carbon supply-demand patterns. Based on these analyses, a dual-factor ecological compensation framework incorporating ecological contribution and payment responsibility is established to differentiate theoretical compensation responsibilities across regions. Results indicate that from 2000 to 2020, China's carbon supply-demand mismatch intensified, with carbon supply concentrated mainly in Central and Western China and carbon demand clustered in Eastern urbanized regions. Demand was mainly associated with built-up land and socioeconomic activity, whereas supply was more closely related to forest-grassland resources and topography. Meanwhile, the ecological linkage network evolved from multi-centered diffusion toward structural convergence. Compensation relationships remained predominantly interprovincial, although intraprovincial compensation gradually increased over time. Compared with the traditional service-quantity-based approach, the proposed dual-factor framework further differentiated theoretical payment and compensation amounts by incorporating ecological contribution on the supply side and payment responsibility on the demand side, while largely preserving the overall structure of the compensation network. Based on these findings, this study proposes a multi-level ecological compensation pathway grounded in county-level responsibility identification, supported by cross-regional coordination, and safeguarded by diversified policy instruments. The proposed framework provides a novel perspective for integrating ecosystem service flows into regional environmental governance and offers methodological support for cross-regional carbon responsibility allocation and differentiated ecological compensation.