Mechanisms of fine-scale landscape heterogeneity in shaping eco-hydrological processes in a typical subtropical forest of Southeast China: Insights from ground observations and a fine-scale terrestrial biosphere model

• Microtopography, vegetation, and micrometeorological factors exhibit spatiotemporal heterogeneities. • Microtopography and meteorology regulate vegetation distribution and eco-hydrological processes. • Ecohydrological processes respond consistently to meteorology and vegetation patterns. • Complex topography fosters strong topography-meteorology-vegetation interactions in humid areas. Topographic variation in complex terrains strongly influences meteorological conditions and vegetation patterns. This study explores the fine-scale landscape heterogeneity and its impacts on vegetation distribution and eco-hydrological processes at the Xin’anjiang Monitoring and Experimental Field Station in southeastern China through vegetation surveys, micrometeorological assessments, and Ecosystem Demography model (ED2.2) simulations. The results reveal significant spatiotemporal heterogeneities in meteorological factors, such as daily downwelling shortwave radiation (Rs ↓ ) (110.26–128.84 W/m 2 ), daily temperature (T a ) (15.69–16.97 °C), and annual precipitation (2069–2323 mm) and vegetation characteristics across 12 sites. ED2.2 simulations showed marked variation in evapotranspiration (ET), gross primary productivity (GPP), and soil water content (SWC) across different vegetation types. Moso bamboo had notably higher GPP (5.43 ± 0.31 g/m 2 /day) compared to cedar (2.69 ± 0.17 g/m 2 /day). Even among sites with similar vegetation, eco-hydrological processes varied due to differences in topography, soil, and meteorological conditions. Structural equation modeling revealed that GPP in Moso bamboo was strongly influenced by Rs ↓ (0.63) and T a (0.49), while GPP in cedar was less dependent on these variables (Rs ↓ : 0.38; Ta: 0.47), consistent with their habitat preferences and observed spatial distributions. These findings highlight the strong relationship between topography, meteorology, and vegetation in this humid hilly region, offering insights into future vegetation ecosystem changes under climate change.