Vegetation type mediates how urbanization reshapes the structure, function, and spatial variation of soil food webs

Abstract Urbanization represents one of the major anthropogenic alterations of the Earth's surface, with significant impacts on biodiversity and its functions. Soil animals are essential components of biodiversity, and their trophic interactions play integral roles in the functioning of terrestrial ecosystems. However, how urbanization reshapes soil food webs is largely unknown. We assessed the structure and function of soil food webs using stable isotope analysis and the energy flux approach in urban grasslands and woodlands in a subtropical city in China, using natural ecosystems in the city surroundings with the same vegetation type as the reference. In urban woodlands, total biomass was six times higher and energy flux was two times higher than in the reference natural forests, resulting in a 50% lower energy turnover (energy flux‐to‐biomass ratio) and supporting longer food chains. By contrast, urban grasslands had similar total biomass, total energy flux and energy turnover to wild grasslands, but both the bacterial‐to‐fungal ratio and soil consumption‐to‐faeces production ratio increased, suggesting accelerated soil carbon cycling. Further, we found that urbanization increases spatial variability of trophic interaction strengths, especially in woodlands, which was attributed to the strong specific predator–prey interactions and higher environmental heterogeneity of urban green spaces. Overall, contrary to the generally assumed negative impacts of land‐use changes on soil communities, our study demonstrates that urbanization enhances the total energy flux in soil food webs but changes the balance between different energy channels and increases the variability of trophic interactions. In addition, the divergent responses to urbanization observed in woodlands and grasslands emphasize the importance of vegetation‐specific management to improve soil ecosystem functioning, such as C sequestration in urban areas. Read the free Plain Language Summary for this article on the Journal blog.