Supply-demand coordination and driving forces of soil conservation services in the middle and lower Jinsha River Basin, China

• A supply–demand–coordination–driving integrated framework for SCS was developed. • SCS supply increased by 11.8%, and demand decreased by 26.6% during from 2000 to 2020. • The threshold for achieving coordination has gradually declined, reflecting improved system resilience. • Zoning-based strategies were proposed for upstream protection, midstream regulation, and downstream optimization. The dynamic coordination of ecosystem service supply and demand is a critical pathway for achieving regional ecological governance and optimized resource allocation. This study focuses on the middle and lower Jinsha River Basin (MLJR) and develops an integrated analytical framework encompassing “supply-demand-coordination-drivers.” The RUSLE model was used to estimate the spatiotemporal patterns of soil conservation service (SCS) supply and demand from 2000 to 2020. The ecological supply–demand ratio (ESDR) and coupling coordination degree (CCD) were integrated to quantitatively assess the system’s coordination status. Additionally, machine learning algorithms and the multiscale geographically weighted regression (MGWR) were introduced to identify spatial heterogeneity and key driving factors. The results show that (1) from 2000 to 2020, the supply of SCS in the study area increased, while demand decreased. The ESDR rose from 0.13 to 0.19, indicating enhanced system service capacity. The regional coordination level exhibited a gradient pattern of “upstream imbalance – midstream transition – downstream coordination.” (2) During this period, the CCD increased from 0.25 to 0.28. Strengthened supply and reduced demand jointly improved coordination levels, and the threshold for achieving coordination gradually decreased over time. (3) Topography, vegetation, and soil conservation measures were the main driving factors, exhibiting significant nonlinear responses and spatial heterogeneity with respect to the ESDR. Human activities in the study area had a significant negative impact on supply–demand coordination, acting as a major disturbance to the system. This study constructs a multi-factor, multi-scale driver identification system, providing theoretical support for understanding the regulatory mechanisms of ecosystem services in typical mountainous regions and differentiated governance strategies. It also offers methodological references for optimizing watershed-scale soil conservation engineering and refined ecological spatial management.