Integrating ecosystem service assessment and zoning management for transboundary environmental protection: A case study of the China–Vietnam Beilun river basin

Study region The China–Vietnam Beilun River Cross-Border Basin (BRCB). Study focus Transboundary basins are ecologically sensitive areas with major management challenges between countries, yet assessments of asymmetric ecological conditions and transboundary zoning remain limited. Taking the BRCB as the study area, this study developed an integrated ecosystem service assessment framework by combining InVEST,GWR, OPGD, hotspot analysis, and SOM. It systematically evaluated the dynamics of five ecosystem services (ESs), their trade-offs and synergies, and explored optimization schemes for transboundary zoning. New hydrological insights Over the past two decades, only water yield (WY) and soil conservation (SC) improved in the BRCB, with better performance on the Chinese side. ES hotspots were concentrated in northwestern forestlands on the Chinese side, while coldspots mainly occurred in southeastern transboundary built-up areas; multifunctional hotspots declined over time. OPGD results showed that ESs were mainly controlled by natural geographical factors, while socioeconomic influences strengthened, highlighting human impacts. Ecosystem service bundles (ESBs) differed markedly across the border: SC bundles and core ES bundles expanded on the Chinese side, whereas the Vietnamese side remained relatively stable. The study reveals country-level ecological imbalance in the BRCB and stresses the need for transnational monitoring and zoning management to support ecological sustainability in transboundary basins.