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Effects of a transient oxic period on mineralization of organic matter to CH4 and CO2 in anoxic peat incubations
Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Department of Microbiology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
1998 (English)In: Geomicrobiology Journal, ISSN 0149-0451, E-ISSN 1521-0529, Vol. 15, no 4, 325-333 p.Article in journal (Refereed) Published
Abstract [en]

Rates of organic matter mineralization in peatlands, and hence production of the greenhouse gases CH4 and CO2, are highly dependent on the distribution of oxygen in the peat. Using laboratory incubations of peat, we investigated the sensitivity of the anoxic production of CH4 and CO2 to a transient oxic period of a few weeks’ duration. Production rates during 3 successive anoxic periods were compared with rates in samples incubated in the presence of oxygen during the second period. In surface peat (5–10‐cm depth), with an initially high level of CH4 production, oxic conditions during period 2 did not result in a lower potential CH4 production rate during period 3, although production was delayed 1 week. In permanently anoxic, deep peat (50–55‐cm depth) with a comparatively low initial production of CH4, oxic conditions during period 2 resulted in zero production of CH4 during period 3. Thus, the methanogens in surface peal—but not in deep peat—remained viable after several weeks of oxic conditions. In contrast to CH4 production, the oxic period had a negligible effect on anoxic CO2 production during period 3, in surface as well as deep peat. In both surface and deep peat, CO2 production was several times higher under oxic than under anoxic conditions. However, for the first 2 weeks of oxic conditions, CO2 production in the deep peat was very low. Still, deep peat obviously contained facultative microorganisms that, after a relatively short period, were able to maintain a considerably higher rate of organic matter mineralization under oxic than under anoxic conditions.

Place, publisher, year, edition, pages
1998. Vol. 15, no 4, 325-333 p.
Keyword [en]
carbon dioxide production, methane production, mineralization, oxygen tolerance, peatland, Sphagnum peat
National Category
Social Sciences Interdisciplinary
Identifiers
URN: urn:nbn:se:liu:diva-79154DOI: 10.1080/01490459809378086OAI: oai:DiVA.org:liu-79154DiVA: diva2:538484
Available from: 2012-06-29 Created: 2012-06-29 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Northern peatland carbon biogeochemistry: the influence of vascular plants and edaphic factors on carbon dioxide and methane exchange
Open this publication in new window or tab >>Northern peatland carbon biogeochemistry: the influence of vascular plants and edaphic factors on carbon dioxide and methane exchange
2001 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The interest in carbon dynamics and the interactions between ecosystems and the atmosphere has increased during the last decade due to the postulated threat of anthropgenically induced global and climate change. Northern peatlands, with their large stores of organic carbon and long-term net accumulation of atmospheric carbon dioxide are key ecosystems in these interactions. Furthermore, peatlands transform organic carbon to methane, which also is an important greenhouse gas.

The findings reported in this thesis and in the accompanying papers are based on both laboratory and field investigations of carbon transformation dynamics on the process scale and at the resolution of individual peatland plant communities. The data from one of the studies also is extrapolated in an attempt to identify environmental controls on regional scales in order to predict the response of northern pcatlands to climate warming.

The laboratory experiments focus on how climate variations, inducing fluctuations in groundwater level and also soil freeze-thaw cycles, influences organic matter mineralisation to carbon dioxide and methane. The field studies investigate year-to-year variations and interdecadal differences in carbon gas exchange at a subarctic peatland, and also how the physiological activities of vascular plants control methane emission rates.

The main conclusions presented include:

Soil freeze-thaw events may be very important for the annual carbon balance in northern peatlands, because they have the potential to increase mineralisation rates and alter biogeochemical degradation pathways.

Vascular plants exert a strong influence on methane flux dynamics during the growing season, both by mediating methane transport and through substrate-based interactions with the soil microbial community. However, there are important species-related factors that govern the nature and extent of this influence.

Caution has to be taken when extrapolating field data to estimate regional carbon exchange because the relevance of the specific environmental parameters that control this exchange varies depending on resolution. On broad spatial and temporal scales the best predictor of peatland methane emissions is mean soil temperature, but also microbial substrate availability (expressed as the organic acid concentration in peat water) is of importance. This temperature sensitivity represents a strong potential feedback mechanism on climate change.

Place, publisher, year, edition, pages
Linköping: Linköpings Universitet, 2001. 44 p.
Series
Linköping Studies in Arts and Science, ISSN 0282-9800 ; 245Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 729
Keyword
Biogeokemi, Biologi, Autekologi, Klimatologi
National Category
Social Sciences Interdisciplinary
Identifiers
urn:nbn:se:liu:diva-29578 (URN)14954 (Local ID)91-7373-233-8 (ISBN)14954 (Archive number)14954 (OAI)
Public defence
2001-12-14, Sal Elysion, Hus-T, Universitetsområdet Valla, Linköping, 10:00 (English)
Opponent
Supervisors
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2014-08-28Bibliographically approved

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