On how ecosystem pattern changes can affect water-related ecosystem services, a case study in the Huolin River Basin, China

Global ecosystem degradation has emerged as a pressing issue profoundly influencing various hydrological processes and the provision of ecosystem services. Yet, the mechanisms through which ecosystem pattern changes affect water-related ecosystem services (WESs) remain insufficiently understood, particularly in ecologically fragile regions. Accordingly, this study investigated the Huolin River Basin, a critical ecological barrier in Northeast China, and quantified the hydrological effects of its ecosystem pattern changes. The Soil and Water Assessment Tool (SWAT) model was employed to systematically evaluate the effects of ecosystem degradation and conservation scenarios on four key WESs: water conservation, water yield, flood regulation, and drought mitigation. The scenarios encompassed individual and combined changes in forest, grassland, and wetland across four gradients (±25 %, ±50 %, ±75 %, and ± 100 %). The results revealed that under the baseline condition (current ecosystem pattern), the basin retains an average annual water conservation capacity of 8.98 × 10 8 m 3 and a water yield of 21.79 × 10 8 m 3 , with average numbers of months with floods and droughts reaching 114.34 and 152.83, respectively, across 56 sub-basins. Ecosystem degradation generally reduced the water conservation capacity while increasing water yield and the frequency of floods and droughts, whereas conservation measures produced opposite effects. Complete degradation scenarios amplified flood and drought frequencies by up to 17.55 % and 11.51 %, respectively, while comprehensive conservation scenarios reduced these risks by up to 2.84 % and 6.45 %. Thus, ecosystem protection and restoration can effectively enhance WESs and improve hydrological resilience. These findings provide critical scientific evidence to support ecosystem management and landscape optimization in the Huolin River Basin and are transferable to other ecologically vulnerable regions worldwide.