Soil fauna impacts on carbon cycling in managed grasslands: A review

Grassland soil fauna impact the carbon cycle via their nesting behavior, consumption, and excretion. Management in grazed grasslands, such as grazing density, vegetation planting, and fertilizer application impact multiple aspects of grassland soil health and carbon storage, including soil fauna populations, which have a large and increasingly recognized role to play in grassland carbon dynamics. While prior work has focused on bacteria and fungi, soil fauna are now seen as a critical but understudied link in understanding carbon dynamics in soils. Grasslands represent 26 % of our global non-ice terrestrial land and support vital food resources worldwide. Grassland soils also currently hold vast amounts of carbon, but can hold more or less depending on management and soil functioning. Here we outline the ways that different groups of soil fauna, including ecosystem engineers, microbial predators, predators of other soil fauna, detritivores, and herbivores impact carbon and nutrient dynamics in the soil, and their related effects on the soil microbial communities. We also discuss how grassland management and land use affects different soil fauna populations with downstream effects on carbon dynamics in grasslands, and highlight where research is missing for different groups of soil fauna.