Spatial scale-dependence and controlling factors of ecosystem service supply-demand relationships in the Loess Plateau of China

• Mismatches between supply and demand of ecosystem services weakened from fine scale to coarse scale. • Trade-offs of supply-demand matches between the paired ESs mainly occurred at municipality and watershed scale. • Dominant influencing factors of supply-demand matches identified at fine scales are universal across scales. Integrating the supply and demand of ecosystem services (ESs) across various scales is crucial for regional sustainable development. However, the relationships between ESs supply and demand, along with their determinants, have not been thoroughly investigated from a multi-spatial perspective. In this study, we quantified four ESs (carbon sequestration, water yield, food supply, and soil conservation) at six spatial scales (pixel, 10 km, 50 km, county, municipality and watershed scale) in China’s Loess Plateau (LP), characterized by fragile ecological environment and high human activity. The ESs supply-demand matches and their trade-offs or synergies as well as the dominant influencing factors at different scales were identified. There was significant spatial heterogeneity in the distribution of ESs supply and demand across the LP. The balance between ESs supply and demand became obvious from pixel to watershed (municipality) scale, with the area proportion increased by 66.78 %, 57.85 %, and 17.89 % for carbon sequestration, water yield and food supply, respectively. The supply-demand match of paired ESs was dominated by synergistic effects at the grid scales and county scale, and their trade-offs mainly occurred in municipality and watershed scales. Population and GDP emerged as the primary factors influencing the supply-demand matches for carbon sequestration, water yield, and food supply, whereas soil conservation was primarily shaped by natural factors. Furthermore, the influence of dominant factors strengthened as the spatial scale increases. The load coefficient of GDP, land use degree and human activities index increased by 0.5057, 0.6985 and 0.6705 from pixel scale to watershed scale, respectively. Thus, implementation of specific management measures should consider both the overall situation of ESs at large scale and influencing factors at small scale. This multi-scale study sheds light on understanding the interactions between supply and demand in different ESs, and provides new insights for hierarchical ecosystem management.