Carbon utilization of peat soils at low temperatures

Despite low temperatures and frozen conditions, low temperature biogeochemical processes in northern peatlands are crucial for the long-term net ecosystem carbon balance. We hypothesized that peat soil microorganisms have the capacity to utilize simple C substrates sustaining both catabolic and anabolic processes in frozen peat soils. To evaluate this hypothesis, we added 13C- glucose to laboratory incubations of boreal peat soil at -5, -3, 4, and 9°C. The microbial catabolic and anabolic utilization of the substrate was tracked by following the transformation rates of the 13C-glucose to 13C-CO2, 13C water-soluble compounds and the incorporation of 13C into phospholipid fatty acids (PLFAs). This allowed the evaluation of the impact of below zero temperatures/soil freezing on metabolic rates and the validation of the activity of the microbial community under typical winter peat soil temperatures.