A climatically significant abiotic mechanism driving carbon loss and nitrogen limitation in peat bogs

Sphagnum-dominated bogs are climatically impactful systems that exhibit two puzzling characteristics: CO₂:CH₄ ratios are greater than those predicted by electron balance models and C decomposition rates are enigmatically slow. We hypothesized that Maillard reactions partially explain both phenomena by increasing apparent CO₂ production via eliminative decarboxylation and sequestering bioavailable nitrogen (N). We tested this hypothesis using incubations of sterilized Maillard reactants, and live and sterilized bog peat. Consistent with our hypotheses, CO₂ production in the sterilized peat was equivalent to 8–13% of CO₂ production in unsterilized peat, and the increased formation of aromatic N compounds decreased N-availability. Numerous sterility assessments rule out biological contamination or extracellular enzyme activity as significant sources of this CO₂. These findings suggest a need for a reevaluation of the fixed CO₂:CH₄ production ratios commonly used in wetland biogeochemical models, which could be improved by incorporating abiotic sources of CO₂ production and N sequestration.