Comparisons of soil nitrogen mass balances for an ombrotrophic bog and a minerotrophic fen in northern Minnesota
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Science of The Total Environment. 550: 880-892.
Wecompared nitrogen (N) storage and flux in soils froman ombrotrophic bogwith that of a minerotrophic fen to quantify the differences in N cycling between these two peatlands types in northernMinnesota (USA). Precipitation, atmospheric deposition, and bog and fen outflowswere analyzed for nitrogen species. Upland and peatland soil sampleswere analyzed for N content, and for ambient (DN) and potential (DEA) denitrification rates. Annual atmospheric deposition was: 0.88-3.07 kg NH4+ ha-1 y-1; 1.37-1.42 kg NO3- ha-1 y-1; 2.79-4.69 kg TN ha-1 y-1. Annual N outflows were: bog—0.01-0.04 kg NH4+ ha-1 y-1, NO3- 0.01-0.06 kg ha-1 y-1, and TN 0.11-0.69 kg ha-1 y-1; fen—NH4+ 0.01-0.16 kg ha-1 y-1, NO3- 0.29-0.48 kg ha-1 y-1, and TN 1.14-1.61 kg ha-1 y-1. Soil N content depended on location within the bog or fen, and on soil depth. DN and DEA rates were low throughout the uplands and peatlands, and were correlated with atmospheric N deposition, soil N storage, and N outflow. DEA was significantly greater than DN indicating C or N limitation of the denitrification process. We highlight differences between the bog and fen, between the upland mineral soils and peat, and the importance of biogeochemical hotspots within the peatlands. We point out the importance of organic N storage, as a source of N for denitrification, and propose a plausible link between organic N storage, denitrification andNexport frompeatlands. Finally,we considered the interactions of microbial metabolismwith nutrient availability and stoichiometry, and how N dynamics might be affected by climate change in peatland ecosystems.
KeywordsBog, Denitrification, Fen, Peat, Soils, Watershed N budget
Hill, Brian H.; Jicha, Terri M.; Lehto, LaRae L.P.; Elonen, Colleen M.; Sebestyen, Stephen D.; Kolka, Randall K. 2016. Comparisons of soil nitrogen mass balances for an ombrotrophic bog and a minerotrophic fen in northern Minnesota. Science of The Total Environment. 550: 880-892. https://doi.org/10.1016/j.scitotenv.2016.01.178.