Effects of elevated CO₂ on fen peat biogeochemistry

Effects of elevated atmospheric CO₂ concentration on northern peatland biogeochemistry was studied in a short-term experiment. Eight intact soil cores (11-cm diameter × 40-cm depth) with Juncus and Festuca spp. were collected from a calcareous fen in north Wales. Half of the cores were incubated under 350 ppm CO₂ concentration, whilst the other four cores were maintained at 700 ppm CO₂. After a 4-month incubation, significantly higher biomass (root + shoot + algal mat) was determined under elevated CO₂ conditions. Higher emissions of N₂O and CO₂, and higher concentration of pore-water DOC (dissolved organic carbon) were also observed under elevated CO₂. However, no significant differences were found in CH₄ emission or soil enzyme activities (β-glucosidase, phosphatase, and N-acetylglucosaminidase) in the bulk soil. Overall, the results suggest that elevated CO₂ would increase the primary productivity of the fen vegetation, and stimulate N₂O and CO₂ emissions as a consequence of an enhanced DOC supply from the vegetation to the soil microbes.