Artikkelit jotka sisältää sanan 'flooding'

Anna M. Laine, Kenneth A. Byrne, Gerard Kiely, Eeva-Stiina Tuittila. Vedenpinnan muutoksen lyhytaikaiset vaikutukset hiilidioksidi- ja metaanipäästöihin peittosuolla.
English title: The short-term effect of altered water level on carbon dioxide and methane fluxes in a blanket bog.
Avainsanat: Sphagnum; Drainage; peatland; methane; flooding; ecohydrology; photosynthesis; respiration; Racomitrium; Rhynchospora alba
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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.
  • 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 Sähköposti: ei.tietoa@nn.oo (sähköposti)
  • Byrne, Sähköposti: ei.tietoa@nn.oo
  • Kiely, Sähköposti: ei.tietoa@nn.oo
  • Tuittila, Sähköposti: ei.tietoa@nn.oo
Jari Huttunen, Hannu Nykänen, Jukka Turunen, Olli Nenonen, Pertti Martikainen. Typpioksiduulivirrat suunnitellun Vuotoksen tekojärven alueen soilta.
English title: Fluxes of nitrous oxide on natural peatlands in Vuotos, an area projected for a hydroelectric reservoir in northern Finland.
Avainsanat: global change; Northern boreal peatlands; climate warming; flooding; greenhouse gas emission; hydro dam
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Nitrous oxide (N2O) fluxes were measured on ten natural minerotrophic peatlands in an area planned for a hydroelectric reservoir (Vuotos) in northern Finland. The mean N2O fluxes from the sites with mean water tables from –25 to 3.4 cm (negative below the peat surface) ranged from –30 to 230 µg m–2 d–1 during summer 1994. At the driest site, the herb-grass spruce mire with the mean water table at –38 cm, the mean summertime N2O emission was 940 µg m-2 d-1 in 1994, attributable to the increased N2O release at low peat temperatures in autumn. A similar increase in the N2O emissions was not found in 1995, as the measurements were finished before the peat started to freeze. The mean N2O fluxes at the sites correlated negatively with the mean water table levels. The peatlands in the northern boreal zone are unlikely important sources of atmospheric N2O in their natural state. The planned reservoir would barely have large long-term N2O emissions from the pelagic zone, but the importance of temporally flooded areas in the postflood N2O release is uncertain similar to the short-term emissions following the flooding.
  • Huttunen, Research and Development Unit of Environmental Health, Department of Environmental Sciences, Bioteknia 2, University of Kuopio, PO Box 1627, FIN-70211 Kuopio, Finland Sähköposti: ei.tietoa@nn.oo (sähköposti)
  • Nykänen, Sähköposti: ei.tietoa@nn.oo
  • Turunen, Sähköposti: ei.tietoa@nn.oo
  • Nenonen, Sähköposti: ei.tietoa@nn.oo
  • Martikainen, Sähköposti: ei.tietoa@nn.oo

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