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| Titel |
Organic sediment formed during inundation of a degraded fen grassland emits large fluxes of CH4 and CO2 |
| VerfasserIn |
M. Hahn-Schöfl, D. Zak, M. Minke, J. Gelbrecht, J. Augustin, A. Freibauer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 8, no. 6 ; Nr. 8, no. 6 (2011-06-16), S.1539-1550 |
| Datensatznummer |
250005955
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| Publikation (Nr.) |
 copernicus.org/bg-8-1539-2011.pdf |
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| Zusammenfassung |
Peatland restoration by inundation of drained areas can alter local
greenhouse gas emissions as CO2 and
CH4. Factors that can influence these emissions
include the quality and amount of substrates available for anaerobic
degradation processes and the sources and availability of electron
acceptors. In order to learn about possible sources of high
CO2 and CH4. emissions from a rewetted degraded fen
grassland, we performed incubation experiments that tested the effects
of fresh plant litter in the flooded peats on pore water chemistry and
CO2 and CH4. production and emission.
The position in the soil profile of the pre-existing drained peat
substrate affected initial rates of anaerobic CO2 production
subsequent to flooding, with the uppermost peat layer producing the
greatest specific rates of CO2 evolution. CH4
production rates depended on the availability of electron acceptors
and was significant only when sulfate concentrations were reduced in
the pore waters. Very high specific rates of both CO2
(maximum of 412 mg C d−1 kg−1 C) and
CH4 production (788 mg C d−1 kg−1 C)
were observed in a new sediment layer that accumulated over the 2.5 years
since the site was flooded. This new sediment layer was characterized
by overall low C content, but represented a mixture of sand and
relatively easily decomposable plant litter from reed canary grass
killed by flooding. Samples that excluded this new sediment layer but
included intact roots remaining from flooded grasses had specific
rates of CO2 (max. 28 mg C d−1 kg−1 C)
and CH4 (max. 34 mg C d−1 kg−1 C)
production that were 10–20 times lower than for the new sediment layer and were comparable to those
of a newly flooded upper peat layer. Lowest rates of anaerobic
CO2 and CH4 production (range of
4–8 mg C d−1 kg−1 C and
<1 mg C d−1 kg−1 C) were observed when all
fresh organic matter sources (plant litter and roots) were
excluded. In conclusion, the presence of fresh organic substrates such
as plant and root litter originating from plants killed by inundation
has a high potential for CH4 production, whereas peat
without any fresh plant-derived material is relatively
inert. Significant anaerobic CO2 and CH4 production in peat
only occurs when some labile organic matter is available, e.g. from
remaining roots or root exudates. |
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