Social-ecological system sustainability in China from the perspective of supply-demand balance for ecosystem services

Ecosystem services supply-demand balance is the core of the human-earth coupling system and crucial for regional sustainability. However, comprehensive studies on large-scale, grid-based supply-demand relationships, inter-service trade-offs and synergies, and the impacts of land use are still limited. The study develops a socialecological analysis framework based on ecosystem services supply-demand balance, alongside a land use transition framework incorporating structure, conflict, and dynamics. The supply-demand balance of six services from 2000 to 2020, as well as the comprehensive supply-demand balance, were calculated. Additionally, the trade-offs/synergies between services were analyzed, service clusters were identified, and the spatial response of land use transition to the balance of each service was explored. The results show that carbon sequestration, grain production, habitat quality, and recreation and leisure services have maintained relative balance in past 20 years, while the balance index for water yield and soil conservation services have fluctuated. Notably, high-surplus areas are mainly concentrated in national nature protection ecological regions. The impact of land use conflict on the supply-demand balance exceeds that of land use structure and dynamics, with high-high cluster areas accounting for 26.8%. Spatial heterogeneity is observed in the trade-offs/synergies between different services within each watershed. Five clusters of ecosystem services supply, five of demand, and six of balance were identified. These findings can offer valuable insights into alleviating China's ecosystem services deficits, harmonizing regional human-earth relationships, and promoting the sustainability of socio-ecological systems.