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Peatlands play an important role in the global carbon (C) cycle, by acting as a large, long-term C sink. The C sink is sustained by a high water level that inhibits decomposition of organic matter. The C gas dynamics are therefore sensitive to changes in water level, and in climatically different years a peatland can vary from a sink to a source of C. We measured carbon dioxide (CO2) and methane (CH4) fluxes from vegetation communities ranging from hummocks to low lawns in a blanket bog. After a one-year calibration period the water level was both lowered and raised experimentally and the changes in vegetation composition and gas fluxes were monitored during a further year. In all vegetation communities the water level drawdown increased the respiration rate and decreased methane emission; rising water level decreased respiration and increased methane emissions. The effect of altered water level on photosynthesis depended on species composition. Water level drawdown decreased photosynthesis in most communities; rising water level decreased the photosynthesis of hummocks species, and increased the photosynthesis of Rhynchospora alba.
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Laine,
Anna M. Laine, Department of Civil and Environmental Engineering, University College Cork, Cork, Ireland; University of Oulu, Oulu, Finland, P.O. Box 3000, 90014 University of Oulu, telephone: +358 8 5531521, email: anna.laine@oulu.fi
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ei.tietoa@nn.oo
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Byrne,
Sähköposti:
ei.tietoa@nn.oo
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Kiely,
Sähköposti:
ei.tietoa@nn.oo
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Tuittila,
Sähköposti:
ei.tietoa@nn.oo