Above- and belowground community linkages in boreal peatlands

In boreal peatlands, the aboveground (plant) and belowground (microbial) communities are acutely linked because the whole soil profile is partially decomposed plant matter (peat), and dictates the nutrients available to the belowground system. We characterized the aboveground and belowground communities in two boreal peatlands: a Sphagnum-dominated fen and a Carex-dominated fen. We link the plant and microbial communities by observing plant, litter and peat carbon and nitrogen values. The Sphagnum-dominated fen had greater plant diversity but provided low quality litter inputs (high carbon:nitrogen) that formed peat and that corresponded with greater fungi:bacteria and Gram-positive:Gram-negative bacteria microbial community compared to the Carex-dominated fen. The higher quality plant inputs in the Carex-dominated fen supported a 5 × greater microbial biomass that was also 2 × more active (as measure by CO2 production). In this approach we highlight that peatlands and their component plant and microbial communities play-out along a common resource-spectrum that dictates ‘fast’ vs ‘slow’ carbon and nutrient cycling (i.e., a plant–soil interaction spectrum) that can, in turn, affect carbon storage potential. As peatland plant community composition is predicted to shift and decomposition rates are expected to increase under climate change, our work highlights the importance of understanding plant–soil microbial interactions.