Nitrogen dynamics in two peatland-pond complexes in the mid-boreal plain, Alberta

Major nitrogen flux rates and pool sizes were measured in two peatland-pond complexes (one floating and one non-floating) in the Western Boreal Plain of Alberta, both consisting of a marsh and fen vegetation zone. Denitrification rates were substantial in both peatland sites (up to 24 g N·m -2·yr-1); the predominant product was N 2. In contrast N2O production was less than 2% of the denitrification product in the floating peatland while the non-floating peatland was a sink for N2O. Internal N fluxes and pools were significantly higher in the floating peatland, presumably due to increased moisture and carbon content in the peat supporting greater microbial biomass and activity. Plant biomass was lower in this site, possibly due to competition by microbes for available inorganic N. Monthly measurements of N fluxes and pools were combined to provide an estimate of internal N cycling within marshes and fens surrounding shallow ponds in the boreal plain.