Plant community composition controls spatial variation in year-round methane fluxes in a boreal rich fen

Climate change is expected to impact the methane budget of boreal peatlands, highlighting the need to understand the factors that influence methane cycling, including plant community structure. In northern peatlands, the majority of methane is transported through plants, and the magnitude of this process is strongly linked to plant community composition. This presentation explores the causes of spatial variability in plot-scale methane fluxes in a northern boreal rich fen. Methane fluxes were measured using the manual chamber technique in a context of fine-scale biomass variations in plant community compositions from 36 study plots over 232 days throughout a full year. We found a significant correlation between methane fluxes and a vascular plant cluster statistically dominated by the sedge Carex rostrata in year-round, snow-free and snow season. The biomass of vascular plants, as well as the ratio of vascular plant to bryophyte biomass, also significantly correlated with methane fluxes in year-round and snow-free season. By identifying vegetation-driven emission hotspots, these results can enhance efforts to upscale emission predictions and improve ecosystem-scale methane modelling initiatives. Thus, our findings provide valuable insights for predicting realistic future changes in peatland methane emissions throughout the year.