liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Northern peatland carbon biogeochemistry: the influence of vascular plants and edaphic factors on carbon dioxide and methane exchange
Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
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 [sv]
Biogeokemi, Biologi, Autekologi, Klimatologi
National Category
Social Sciences Interdisciplinary
Identifiers
URN: urn:nbn:se:liu:diva-29578Local ID: 14954ISBN: 91-7373-233-8 (print)OAI: oai:DiVA.org:liu-29578DiVA: diva2:250395
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
List of papers
1. Effects of a transient oxic period on mineralization of organic matter to CH4 and CO2 in anoxic peat incubations
Open this publication in new window or tab >>Effects of a transient oxic period on mineralization of organic matter to CH4 and CO2 in anoxic peat incubations
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.

Keyword
carbon dioxide production, methane production, mineralization, oxygen tolerance, peatland, Sphagnum peat
National Category
Social Sciences Interdisciplinary
Identifiers
urn:nbn:se:liu:diva-79154 (URN)10.1080/01490459809378086 (DOI)
Available from: 2012-06-29 Created: 2012-06-29 Last updated: 2017-12-07Bibliographically approved
2. Effects of freeze-thaw cycles on low temperature carbon mineralisation in peat
Open this publication in new window or tab >>Effects of freeze-thaw cycles on low temperature carbon mineralisation in peat
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Recent investigations indicate that winter carbon emission from peatlands and low temperature carbon mineralisation processes conld have the potential to affect annual carbon budgets. Special emphasis has been put on periods of freeze-thaw events during spring and autumn. The aim of this study was to investigate the impact of freeze-thaw cycles on peat carbon mineralisation. This was addressed by following production rates and total amounts of CO,- and CH4-formation in surface (0-5 cm) and deep (45-50 cm) peat samples incubated at 4°C and comparing controls with replicate samples subjected to three consecutive freeze-thaw cyclesprior to incubation. Accumulation of fermentation products (H2, VF A and ethanol) were measured in order to gain further insight to the biogeochemical processes and transformation pathways involved. We conclude that freeze-thaw cycles affect both short and long term formation and exchange of C02 by altering the availability and amount of peat carbon substrates. Freeze-thaw events also resulted in an inhibition of methanogenesis with a concomitant accumulation in H2 and butyrate. We conclude that freezethaw cycling events can be of large importance for the carbon budgets of northern peatland ecosystems, although they are of a limited temporal duration.

National Category
Social Sciences Interdisciplinary
Identifiers
urn:nbn:se:liu:diva-79155 (URN)
Available from: 2012-06-29 Created: 2012-06-29 Last updated: 2012-06-29Bibliographically approved
3. Interdecadal changes in CO2 and CH4 fluxes of subarctic mire: Stordalen revisted after 20 years
Open this publication in new window or tab >>Interdecadal changes in CO2 and CH4 fluxes of subarctic mire: Stordalen revisted after 20 years
1999 (English)In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 85, no 1, 22-30 p.Article in journal (Refereed) Published
Abstract [en]

The first subarctic wetland CO2 and CH4 flux measurements were made at Stordalen in the beginning of the 1970s in connection with the IBP study. A return to this area in 1994-95 offered a unique opportunity to study possible interdecadal changes in northern wetland CO2 and CH4 emissions. Measurements of CO2 and CH4 fluxes were carried out in similar habitats as those investigated in 1974. The mire distribution of wet minerotrophic areas relative to the elevated ombrotrophic areas had changed dramatically over the twenty years. There were no significant differences between the CH4-flux in 1974, 1994, and 1995. However, the CO2 fluxes were significantly higher in 1995 than in 1974. Since differences in climatic conditions gave no cause for such a change it suggests a possible increase in decomposition rate to be due to other factors. We suggest changes in vegetation composition, altered mineralization pathways and disintegration of permafrost as causes for the interdecadal increase in decomposition rates.

National Category
Social Sciences Interdisciplinary
Identifiers
urn:nbn:se:liu:diva-33657 (URN)10.2307/3546788 (DOI)19692 (Local ID)19692 (Archive number)19692 (OAI)
Available from: 2009-10-09 Created: 2009-10-09 Last updated: 2017-12-13Bibliographically approved
4. Vascular plants as regulators of methane emissions from a subarctic mire ecosystem
Open this publication in new window or tab >>Vascular plants as regulators of methane emissions from a subarctic mire ecosystem
2002 (English)In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 107, no 21, 4580-4590 p.Article in journal (Refereed) Published
Abstract [en]

Vascular plant functions as controlling mechanisms of methane emissions were investigated at two contrasting habitat types at a subarctic peatland ecosystem in northern Sweden. One of the habitats was ombrotrophic (vegetation dominated by Eriophorum vaginatum and Carex rotundata), while the other was minerotrophic (vegetation dominated by Eriophorum angustifolium). Through shading manipulations we successfully reduced the gross photosynthetic rates of the vascular plant communities. At the ombrotrophic site a 25% reduction in gross photosynthesis lead to a concomitant 20% reduction in methane emission rates, indicating a strong substrate-based coupling between the vascular plant community and the methanogenic populations. At the minerotrophic site, methane emission rates were unaffected, although plant photosynthesis was reduced by almost 50%. However, the methane emission rates at the minerotrophic site were significantly correlated with the number of vascular plants. We conclude that at the minerotrophic site the vegetation influences methane emission rates by facilitating methane transportation between the soil and the atmosphere, while at the ombrotrophic site the relationship between the vascular plant community and methane emissions is mediated by substrate-based interactions regulated by plant photosynthetic activity. Copyright 2002 by the American Geophysical Union.

Keyword
Carbon exchange, Methane emission, Peatland biogeochemistry, Plant-microbe interactions, Vascular plants
National Category
Social Sciences
Identifiers
urn:nbn:se:liu:diva-46812 (URN)10.1029/2001JD001030 (DOI)
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13Bibliographically approved
5. Large scale variations in CH4 emissions from wetlands explained by temperature and substrate availability
Open this publication in new window or tab >>Large scale variations in CH4 emissions from wetlands explained by temperature and substrate availability
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Globally, wetlands are at estimates ranging 115-237 Tg C4/yr1 the largest single source of the greenhouse gas CH4 to the atmosphere. Important feedback mechanisms on climate change arising from changing exchanges of C02 between the terrestrial biosphere and the atmosphere have recently been identified2. A related question is how will possible changes in the CH4 emissions from wetlands affect the further development of the greenhouse effect? Here we show using comparable methods in a wide range of wetlands ranging from Greenland to Siberia that regardless the dependency on soil moisture, plant productivity and other factors, temperature is the strongest control and predictor of CH4 emissions across both temporal and large spatial scales. Furthermore, we show that CH4 flux variations not explained by temperature can beattributed to differences in microbial substrate availability (expressed as the organic acid concentration in peat water). Combined, soil temperature and organic acid concentrations explains 99% of the variation in CH4 fluxes between the different sites. The temperature sensitivity of the CH4 emissions shown suggests a strong feedback mechanism on climatechange that should valid incorporation in developments of global circulation models.

National Category
Social Sciences Interdisciplinary
Identifiers
urn:nbn:se:liu:diva-79157 (URN)
Available from: 2012-06-29 Created: 2012-06-29 Last updated: 2012-06-29Bibliographically approved

Open Access in DiVA

No full text

By organisation
Department of Water and Environmental StudiesFaculty of Arts and Sciences
Social Sciences Interdisciplinary

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 730 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf