Collaborative Mechanism of Soil and Water Ecological Governance Under Public–Private Partnership Model Considering Carbon Trading

In the current soil erosion control efforts, the lack of collaboration among multiple stakeholders is a major problem that restricts governance performance. Based on carbon trading and the Public–Private Partnership model, this paper constructs a tripartite differential game model involving the government, enterprises, and farmers, focusing on the government subsidy and the enterprise–farmer benefit-sharing mechanism. It systematically analyzes the dynamic evolution process of multi-stakeholder collaborative governance behavior under the collaborative mechanism. Through numerical simulation, the impacts of key variables such as benefit-sharing ratio, synergy effect of measures, and unit carbon sequestration on the optimization of enterprise governance measures, effort level, government fiscal expenditure, and tripartite benefits were analyzed. The results indicate that (1) the benefit-sharing ratio has a significant bidirectional regulatory effect on the system, with both excessively high and excessively low ratios weakening the collaborative governance effect; (2) the synergistic effect between governance measures significantly enhances the enthusiasm of enterprise governance and promotes the allocation of resources towards measure with better carbon sequestration benefits; and (3) the unit carbon sequestration significantly affects governance structure and government subsidy strategies, with the government being more sensitive to carbon sink responses of afforestation measures. The research results provide a theoretical basis for optimizing the ecological governance system under the “dual carbon” goal and also provide policy references for promoting the transformation of governance model from “government-led” to “multi-stakeholder collaboration”.