Trade-Off and Synergy Relationships and Driving Factor Analysis of Ecosystem Services in the Hexi Region

The Hexi region, located in a sensitive and fragile ecological zone in northwest China, requires a scientific assessment of ecosystem services and their interactions. Identifying the main factors influencing spatial distribution is crucial for the sustainable development and effective management of the region. This study evaluates key ecosystem services, including regulating services (water conservation, soil conservation, carbon storage) and provisioning services (NPP), using Spearman’s correlation and pixel-by-pixel spatial analysis to calculate spatial trade-offs and synergies. Geographic detectors were used to uncover the underlying driving mechanisms. The results show that: (1) From 2000 to 2020, soil conservation, NPP, and carbon storage showed fluctuating growth, while water conservation declined. Spatially, high-value areas of water conservation, carbon storage, and NPP were concentrated in the central and southern areas, while high values of soil conservation services were mainly in the northwest and southeast regions. (2) The trade-offs and synergies among various ecosystem services exhibit temporal shifts, along with spatial scale effects and heterogeneity. In the study area, the proportion of pixels showing a trade-off relationship between water conservation and soil conservation, and between water conservation and NPP, accounts for 48.21% and 21.42%, respectively. These trade-offs are mainly concentrated in the central and southeastern regions, while the northwestern counties predominantly exhibit synergies. (3) Precipitation was the dominant factor for water conservation, carbon storage, and NPP, as well as for the trade-offs among these services. Among natural factors, climatic factors were significantly more influential than socio-economic factors, and the interaction between two factors had a greater explanatory power than single factors.