Changes in peatland soil fauna biomass alter food web structure and function under warming and hydrological changes

Boreal peatlands play an important role in terrestrial carbon storage. Soil fauna and their trophic interactions play a key role in regulating microbial communities and the flux of carbon (C) and nitrogen (N) belowground, thus controlling the storage/release of C and N in soil systems. At northern latitudes, soil temperature and moisture conditions under climate change are predicted to become more extreme and more variable, and these factors will play an important role in regulating decomposition and ecosystem functioning, like C and N dynamics, in boreal peatlands. The objective of this research is to quantify and model the effects of experimentally imposed temperature and moisture conditions that simulate potential future climate extremes on peatland soil fauna food webs and soil C and N fluxes. Results suggest that increases in temperature and soil saturation will alter total faunal biomasses with warming increasing and soil saturation decreasing biomasses. Shifts in fauna biomass drove changes in C flux, C mineralization, and N mineralization. However, under warming, increased population turnover rate alongside decreased feeding efficiencies increased the proportion of total C flux that is lost as respiration (i.e., C mineralization). Future research is needed to better resolve the opposing changes in potential future boreal peatland C and N dynamics threatened by potential future warming and climate-mediated changes in peatland hydrology.