Fungal energy channeling sustains soil animal communities across forest types and regions

Emerging evidence suggests that microbivory prevails in soil animal communities, yet the relative importance of bacteria, fungi, and plants as basal resource energy channels across taxa and forest types remains unstudied. We developed a novel framework combining stable isotope analysis of essential amino acids (eAAs) and energy fluxes to quantify basal resource contributions and trophic positions of meso- and macrofauna detritivores (Collembola, Oribatida, Diplopoda, Isopoda, Lumbricidae) and predators (Mesostigmata, Chilopoda) in 48 forest sites of different management intensity across Germany. Fungal energy channeling dominated, with the highest energy fluxes and 73 % fungal eAAs across forests and regions. Chilopoda, however, acquired more energy from bacteria and plants. Energy fluxes to Lumbricidae were highest, but decreased, alongside those to other macrofauna, in acidic forests. Trophic positions varied between regions, reflecting changes in community structure linked to regional factors. Our findings highlight the stability and pivotal role of fungal energy channeling for forest soil animal communities.