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Short-term effects of changing water table on N2O fluxes from peat monoliths from natural and drained boreal peatlands

Authors

  • Kristiina Regina,

    1. Laboratory of Environmental Microbiology, National Public Health Institute, POB 95, FIN-70701 Kuopio, Finland,
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  • Jouko Silvola,

    1. Department of Biology, University of Joensuu, POB 111, FIN-80101 Joensuu, Finland,
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  • Pertti J. Martikainen

    1. Laboratory of Environmental Microbiology, National Public Health Institute, POB 95, FIN-70701 Kuopio, Finland,
    2. Department of Environmental Sciences, University of Kuopio, POB 1627, FIN-70211 Kuopio, Finland
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Pertti Martikainen, fax + 358/17 201155,
e-mail pertti.martikainen@ktl.fi

Abstract

The effect of the water table on nitrous oxide (N2O) fluxes from peat profiles representing boreal peatlands of differing nutrient status was studied in the laboratory. Lowering of the water table in peat monoliths taken from two natural waterlogged peatlands for 14 weeks in a greenhouse at 20 °C increased the fluxes of N2O, an effect that was enhanced further by incubation in the dark. Raising of the water table in monoliths from two drained and forested peatlands caused cessation of the N2O fluxes from the drained peats, which had previously been sources of N2O. It is known that N2O fluxes have increased in peatlands drained several decades ago. The results suggest that it is not necessary for the water table to be lowered for several years to change a boreal peatland from a N2O sink to a source of the gas. In addition to the draining of peatlands, climate change can be expected to lower ground water levels during the summertime in the boreal zone, and this could cause marked changes in N2O fluxes from boreal peatlands by enhancing the microbial processes involved in nitrogen transformations.

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