Effects of warming and drought on the microbial communities of a northern peatland

Northern peatlands store carbon as thick layers of peat comprised largely of decomposing Sphagnum moss biomass. The rate of decomposition in these cold, anoxic environments is regulated by heterotrophic microbial networks adapted to extreme conditions. The enzyme latch hypothesis posits that oxygen limitation suppresses phenol oxidases, allowing phenolic compounds to accumulate and inhibit decomposition, but recent evidence suggests these plant-derived compounds fuel microbial growth under anoxia. Therefore, changes in water table elevation that increase oxygen availability in peat may have important interacting effects with warming-driven shifts in plant inputs on microbial mediation of belowground carbon turnover. To determine how climate change drivers influence carbon turnover we leveraged the infrastructure of the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment: 5 warming treatments in a regression design with duplicates exposed to ambient CO2 and elevated CO2. A drought in 2021 caused an average water table recession of 30.05 cm, allowing us to test the interaction of warming and water table drawdown on microbial activity.