Soil conservation ecosystem service supply-demand and multi scenario simulation in the Loess Plateau, China

Ecosystem services are an essential foundation for sustainable human development. In view of the severe soil erosion on the Loess Plateau (LP), it is important to explore the spatial and temporal characteristics of the supply-demand balance of soil conservation services (SCSs). In this study, the soil conservation ecosystem service supply-demand ratio was innovatively proposed to quantitatively assess the supply and demand balance of soil conservation. First, the InVEST model was used to spatially quantify the supply (soil retention) and demand (soil erosion) of soil conservation services (SCS) in the LP from 2005 to 2020. Meanwhile, the spatial variation characteristics of supply-demand matching were analyzed. Second, to predict the soil conservation ecosystem service supply-demand in the future, the InVEST-PLUS model was used to simulate the supply-demand balance under multiple scenarios in 2030. The natural development (NDS), ecological protection (EPS) and economic development scenarios (EDS) were coupled with shared socioeconomic pathways (SSPs) and representative concentration pathways (RCPs). The results showed that: (1) from 2005 to 2020, the annual average soil erosion modulus of LP increased by 60.58 (t/(hm²·a)); soil retention per unit area increased by 12.89 t/hm2; both increased from northwest to southeast, and the spatial matching pattern of supply-demand was mainly low-low and shifted to low-high each year; and (2) based on the LULC of LP simulated by the PLUS model, the kappa coefficient and overall accuracy were 86.29% and 91.14%, respectively. A total of 19.8% and 22.97% of the built-up land was expanded under the NDS and EDS scenarios, respectively, and a total of 17,515.65 km2 of forestland and grassland was expanded under the EPS scenario; (3) 2030.NDS-SSP245, 2030.EPS-SSP126 and 2030.EDS-SSP585 scenarios, moderate and high surpluses accounted for 11.40%, 14.34% and 10.80% of the total surplus area, respectively; compared to 2020, the high deficit increased by 49.67%, 43.29% and 56.65% respectively. The study provided innovations for the coupling degree of future ecosystem services simulated by the InVEST-PLUS model.