Fungivorous nematodes drive microbial diversity and carbon cycling in soil

Soil bacteria and fungi mediate terrestrial biogeochemical cycling, but weknow relatively little about how trophic interactions influence theircommunity composition, diversity, and function. Specifically, it is unclearhow predator populations affect their microbial prey, and also thespecies with which their prey interacts. Owing to its extreme diversity,studying trophic dynamics in soil is a complex feat. To overcome thesechallenges, we performed a microcosm-based predator manipulationexperiment to determine the impact of a common fungal-feedingnematode (Aphelenchus avenae) on soil microbial communitycomposition, diversity, and activity (e.g., C-cycling parameters).Fungivory decreased fungal and bacterial alpha diversity and stimulated Cand N cycling, possibly via cascading impacts of fungivory on bacterialcommunities. Our results present experimental evidence that soil trophicdynamics are intimately linked with microbial diversity and function,factors that are key in understanding global patterns in biogeochemicalcycling.