Artikkelit kirjoittajalta Eeva-Stiina Tuittila
Talviaikainen hiilivuo boreaaliselta suosukkessiogradientilta seuraa kesäaikaisen hiilidynamiikan vaihtelua.
English title: Winter carbon losses from a boreal mire succession sequence follow summertime patterns in carbon dynamics.
Original keywords:
sukkessio;
suon kehitys;
primaarisoistuminen;
hiilidioksidi;
metaani;
lumikerros;
Siikajoki;
maankohoamisrannikko
English keywords:
Carbon dioxide;
methane;
Mire development;
land uplift coast;
mire succession;
primary paludification;
snow pack;
Siikajoki
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Tekijät
Although carbon (C) gas exchange during the summer largely determines the annual C balance of mires, the wintertime fluxes cannot be ignored. Decomposition continues as long as the soil is not frozen and a proportion of the gases produced during summer are also released during winter. We measured carbon dioxide (CO2) and methane (CH4) fluxes along a successional mire sequence during two winters following growing seasons with divergent weather conditions. We studied the successional trends in wintertime C release in boreal mires, and quantified the contribution of wintertime C fluxes to annual fluxes. Wintertime CO2 and CH4 fluxes from the successional mire sequence were related to the flux rates during the previous summer. Average winter CO2 release along the successional sequence varied between 19.5 and 44.9 g CO2-C m–2 winter–1(6-months), and accounted for 8–14% of the annual CO2 release. There was no clear successional trend in CO2 fluxes. Average winter CH4 release along the successional sequence varied between 0.20 and 7.29 CH4-C g m–2 winter–1(6-months).The winter CH4 fluxes accounted for up to 38% of the annual CH4 emissions. Occasional CH4 uptake was detected at the younger successional stages during winter following the dry summer, while after the wet summer all sites emitted CH4. In general, most of the winter C losses were composed of CO2.
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Leppälä,
Mirva Leppälä, Finnish Forest Research Institute, FIN-91500 Muhos, Finland. Current address: Metsähallitus, Natural Heritage Services Ostrobothnia, BOX 81, FI-90101 Oulu, Finland, email: mirva.leppala@metsa.fi
Sähköposti:
ei.tietoa@nn.oo
- Laine, Sähköposti: ei.tietoa@nn.oo
- Tuittila, Sähköposti: ei.tietoa@nn.oo
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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Tekijät
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
Sähköposti:
ei.tietoa@nn.oo
- Byrne, Sähköposti: ei.tietoa@nn.oo
- Kiely, Sähköposti: ei.tietoa@nn.oo
- Tuittila, Sähköposti: ei.tietoa@nn.oo
Kasvillisuus ja C02-tase käytöstä vapautuneella turvetuotantoalueella Kihniön Aitonevalla.
English title: Vegetation and CO2 balance in an abandoned harvested peatland in Aitoneva, southern Finland.
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The vegetation and CO2 balance (difference between C02 fixation rate and respiration rate) in an abandoned harvested peatland in Aitoneva, Kihnio (62° 12'N, 23° 18'E) were studied during the summer of 1994. The daytime CO2 fluxes from sample plots representing different kinds of vegetation were measured using two different static chamber techniques. To investigate the compositional variation of vegetation and its relationship with CO2 balance, data on the vegetation of the sample plots was analysed by global non-metric multidimensional scaling (GNMDS). A total number of 20 plant species was observed on the sample plots. The dominant plant species was Eriophorum vaginatum L. The main variation in GNMDS were connected with colonization stage (total cover of vegetation). The C02 fixation rate varied between -56 and 1869 mg m-2 h-1 and the respiration rate varied between 34 and 1168 mg CO2 m-2 h-1. The CO2 fixation and respiration rate increased with increasing total vegetation cover. The highest respiration and the highest CO2 fixation rates were found in sample plots dominated by mature Eriophorum vaginatum tussocks. Those sample plots were the only ones having positive CO2 balance. Regression analysis indicated that the respiration rate depended on soil temperature. Variation in the water table had no influence on the respiration or the C02 fixation rate.
Key words: CO2 balance, Eriophorum vaginatum, GNMDS, harvested peatland, plant colonization
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Tuittila,
Department of Forest Ecology, P.O. Box 24, FIN-00014 University of Helsinki, Finland
Sähköposti:
ei.tietoa@nn.oo
- Komulainen, Sähköposti: ei.tietoa@nn.oo
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