Trade-off relationships of ecosystem services for soil retention carbon sinks in the Loess Plateau of China

Although soil retention (SR) is crucial to reaching carbon neutrality, soil erosion has become more complex due to climate change and increased human activity, and its function of retaining soil is closely related to regional nitrogen and phosphorus nutrient purification, it is still unclear how these ecosystem services (ESs) are changing and interacting. This work used the InVEST model to evaluate the spatial and temporal evolution of carbon storage (CS), SR, and water purification (WP) from 2000 to 2020 in Yaozhou District, Tongchuan City (YDT), a typical county on the Loess Plateau. The three main ecosystem services (ESs) are connected through Bayesian modeling, and the drivers and trade-offs are altered. Multi-scenario scenarios are also established to offer recommendations for regional sustainable development and ecological restoration. The findings demonstrated that (1) whereas CS exhibited a declining trend (-0.607 t/ha) between 2000 and 2020, both SR (+51.02 t/ha) and WP (total nitrogen (TN) export reduced by 0.06 kg/ha and total phosphorus (TP) export decreased by 0.003 kg/ha) were greatly enhanced in YDT. (2) While CS-WP has a synergistic relationship primarily related to topography and land use/cover types, SR-WP and CS-SR exhibit trade-offs. (3) Land use/cover type was the main determinant of the three ESs, while the largest impact on WP was caused by population density. Precipitation and slope have the biggest effects on SR. The two factors that affect CS the most are temperature and the Normalized Difference Vegetation Index (NDVI). These findings provide a theoretical basis for the county's sustainable ecological and economic development while also helping scholars better comprehend the connections and processes underlying SR, CS, and WP.