Effects of habitat fragmentation on multiple ecosystem functions in urban remnant forests

Urbanization-driven habitat fragmentation threatens ecosystem multifunctionality (EMF) in remnant forests through biodiversity erosion. This study investigates the effects of habitat fragmentation on multiple ecosystem functions through analyses of fragmentation metrics, soil properties, and biodiversity across 30 remnant forest patches in Guiyang, China. Key findings reveal distinct drivers in edge and interior habitats. In edge habitats, the proportion and aggregation of impervious surfaces are key predictors of carbon dynamics and nutrient availability. In interior habitats, the contrast of the patch with the surrounding matrix is significantly correlated with carbon pools and phosphorus availability. The regulation of biodiversity involves distinct habitat differentiation, whereby microbial diversity governs pathogen control and carbon turnover at the edges, and plant diversity regulates enzyme activity and pathogen suppression trade-offs in the interior areas. Distinct interactions among ecosystem services are present and include pathogen defense synergies via shared microbial antagonistic networks alongside plant productivity (PP) that enhance microbial carbon pools through root exudates while concurrently boosting virulence control via antimicrobial traits. Conversely, trade-offs arise from resource allocation conflicts in which photosynthate competition occurs between plant growth and organic decomposition as well as opposing moisture requirements for pathogen suppression, which requires low humidity vs. water regulation (WR) demanding high retention. Crucially, habitat fragmentation metrics surpass soil properties and biodiversity in explaining overall EMF variation. Large patches with high core-to-edge ratios suppress edge-habitat EMF through extended disturbance interfaces. The scale-habitat differentiation effects identified in this study can inform conservation priorities focused on safeguarding clustered high-functioning small patches to leverage edge benefits and implementing dispersed development buffers with minimal impervious aggregation to protect interior habitat stability against landscape-scale stressors.