Greater trophic diversity of soil animal communities under land use and warmer climate

More than half of all life on Earth lives belowground and regulates a wide range of ecosystem functions via their diverse trophic interactions. However, information on how trophic diversity of soil animals varies across functional groups and major environmental gradients is lacking. Here, we use stable isotope analysis (13C/12C and 15N/14N ratios) of 28 high-rank taxa of soil animals from 343 sites across 15 countries to inspect the variability in trophic diversity across climate regions and land-use types. We found that trophic diversity of soil-animals communities is higher for microbial than for detritus feeders and predators, and increases in agricultural ecosystems compared to woodlands (+38%) and in tropical compared to temperate climates (+53%). The larger trophic diversity was related to both exploration of more diverse basal resources and longer trophic chains, possibly because of greater niche partitioning in resource-limited environments. Overall, this first comprehensive assessment of soil animal trophic diversity highlights that soil animals may broaden their trophic niches under global change, which potentially buffers global-change impacts on ecosystem functions and stability in the short term, while the increased flexibility in foraging may pose risks with long-term biodiversity and ecosystem health implications.