Actual supply of soil conservation services limits their use: From an ecosystem service flow perspective

Soil conservation services (SCS) represent a vital subset of ecosystem regulating services, playing a critical role in mitigating regional land degradation and reducing flood disaster risks, a subject that has garnered considerable scholarly attention. Nevertheless, a significant mismatch persists between SCS supply and demand, highlighting the need for a deeper understanding of how SCS flows operate from supply areas to demand areas. Despite its importance, research on the dynamics of SCS flows remains underdeveloped, limiting its ability to provide robust support for informed and nuanced decision-making in sustainable ecosystem management. To address this research gap, this study conducted an investigation in the Jinghe River Basin (JRB), utilizing SWAT and GIS technologies to reproduce the spatiotemporal patterns of SCS. Additionally, this study quantitatively assessed and mapped the sediment reduction service flow volumes and pathways at four different spatial scales, aiming to elucidate the spatial transfer mechanisms of SCS flow within the JRB. Finally, based on the supply–demand-flow-use (SDFU) framework, this study quantifies the actual use of SCS flow by calculating its actual supply and potential demand, with a focus on analyzing the limitations to its actual use. The findings of this research yield several critical insights: (1) The spatial distribution patterns of high and low values in SCS supply and demand within the JRB exhibited significant congruence, while both components manifested a consistent temporal trajectory characterized by rapid initial escalation followed by subsequent stabilization. (2) The transport of SCS, facilitated by sediments in the water column, undergoes spatial displacement through slopes, rivers, and subbasins within the watershed network, with the flow volume of sediment reduction services reaching its nadir in 2000, increasing significantly in 2010, and slightly declining in 2020. (3) From 2000 to 2020, the actual use of SCS followed a similar trend to SCS flow, with the demand satisfaction rate steadily increasing (0.22, 0.34, 0.77), indicating that while the actual supply of SCS is meeting more demand, it still fails to fully satisfy the actual use. In summary, the attempt of this study not only enriches the research field of ecosystem service flow but also promises to provide theoretical guidance for the scientific management of land resources and sustainable regional development.