Urban Campus Microbial Ecology from Homogenization to Differentiation: Evidence from Vegetation and Green Space Health Risk Gradients
Urbanization threatens ecosystem services by fragmenting habitats and increasing the number of impervious surfaces. However, the semi-managed and vegetatively diverse green spaces of university campuses provide a unique setting for studying their effects on soil microbial communities, which are foundational components of urban biodiversity. Our results indicated that grassland soils harbored significantly higher bacterial and archaeal a-diversity than shrub and tree soils, reflecting greater species richness and evenness. Beta diversity analysis further confirmed the distinct segregation of microbial communities among the vegetation types. Differential abundance analysis using ANCOM-BC2 revealed that both vegetation type and ecological health status strongly influenced the soil microbial composition at the genus level. Specifically, Cetobacterium and Symbiobacterium were enriched in tree soils, Uliginosibacterium and Lichenibacterium in shrub soils, and Variibacter, Siphonobacter, and Bathyarchaeia in grassland soils. Across the health risk groups, low-risk soils exhibited higher abundances of Cyanobacteriales, Leptolyngbyaceae, Chloroflexaceae, and Methanobacterium, whereas moderate- and high-risk soils were enriched with taxa such as Symbiobacterium, Thermobifida, Cetobacterium, Nitrolancea, and Nitrosotaleaceae. These patterns indicate predictable shifts in bacterial and archaeal communities driven by vegetation type and ecological health, reflecting compositional differentiation linked to habitat and environmental risks. Functional predictions using PICRUSt2 suggested possible increases in nitrogen metabolism and antibiotic-related pathways in grassland soils, whereas higher-risk plots exhibited trends toward pathways linked to greenhouse gas production and microbial stress. Collectively, these findings provide insights for optimizing campus ecological management and urban green-space planning, advancing our understanding of how fine-scale habitat attributes in urban environments shape diverse, functional, and resilient soil microbiomes in urban environments.