A soil food web approach to integrate soil fauna into multitrophic biogeochemistry

Soil fauna is essential in mediating the formation and turnover of soil organic matter, the largest terrestrial pool of organic carbon, yet remains absent from nearly all existing biogeochemical conceptual frameworks. Soil fauna impacts element cycling via trophic (microbivory, herbivory, detritivory, predation) and non-trophic (bioturbation, dispersal, waste products) pathways. These effects should be integrated into multitrophic biogeochemistry by considering the environmental context (abiotic constraints, quality and quantity of carbon inputs), by including soil food web structure, and by accounting for the role of soil fauna as agents of connectivity. We highlight the need for better quantification of soil fauna and consideration of carcasses and feces as substantial carbon flows. Based on a soil food web approach, these concepts will improve the quantification of the impact of soil fauna on carbon cycling and help to predict how soil fauna will affect carbon cycling under future global change scenarios.