Coupled effects of grazing exclusion and surface energy balance on grassland runoff dynamics

Study region The study area is located in the Xilingol League of Inner Mongolia, China, a representative temperate semi-arid steppe region with a mean annual precipitation of approximately 280–350 mm. This watershed functions as a critical ecological security barrier for pastoral communities in northern China and represents one of the most extensive temperate grasslands in the world. Study focus Based on paired grazing exclusion and free-grazing field experiments, this study constructed a coupled modeling framework integrating the Distributed Hydrology Soil Vegetation Model (DHSVM) with the land use dynamics model (intPLUS). The framework was designed to quantify how grazing exclusion regulates grassland runoff through changes in vegetation cover, soil physical properties, and surface energy balance acting as a key mediating pathway, and to project future runoff dynamics under CMIP6 climate scenarios. New hydrological insights for the region Structural equation modeling indicated that upward longwave radiation was negatively associated with runoff, with a standardized total association of β = −0.291, highlighting an important linkage between surface-energy conditions and runoff variability in the semi-arid grassland system. Under SSP5–8.5, the grazing-exclusion configuration produced lower simulated daily high-flow indicators than the grazing configuration under the same climate forcing. These findings highlight coordinated associations among grazing management, vegetation–soil conditions, surface-energy processes, and runoff dynamics, providing new evidence for understanding ecohydrological responses in semi-arid grasslands.