Varied response of carbon dioxide emissions to warming in oxic, anoxic and transitional soil layers in a drained peatland

Peatlands are an important natural store of carbon. Here, we investigate how carbon dynamics in soils from three distinct layers from a drained peatland in the Qinghai-Tibet Plateau might respond to global warming. We incubated Zoige Plateau soil samples that represent oxic surface soil, permanently waterlogged anoxic deep soil, and a transitional interlayer, which varies between oxic and anoxic conditions with water table fluctuations, in the laboratory at 8 °C and 18 °C for 154 days. We find that carbon quality and microbial activity were highest in surface soils and lowest in interlayer soils. Carbon dioxide emissions were lowest in interlayer soils, where they were less sensitive to warming and more sensitive to nitrogen content than in the other layers. Conversely, carbon quality and microbial activity were the primary predictors of carbon dioxide emissions from the surface and deep soil, respectively. Our findings suggest a low vulnerability of soil carbon in interlayer soils of drained peatlands to warming.