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| Titel |
Simultaneous high C fixation and high C emissions in Sphagnum mires |
| VerfasserIn |
S. F. Harpenslager, G. Dijk, S. Kosten, J. G. M. Roelofs, A. J. P. Smolders, L. P. M. Lamers |
| 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 ; 12, no. 15 ; Nr. 12, no. 15 (2015-08-06), S.4739-4749 |
| Datensatznummer |
250118056
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| Publikation (Nr.) |
 copernicus.org/bg-12-4739-2015.pdf |
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| Zusammenfassung |
Peatlands play an important role in the global carbon (C) cycle due to their
large C storage potential. Their C sequestration rates, however, highly vary
depending on climatic and geohydrological conditions. Transitional mires are
often characterised by floating peat with infiltration of buffered
groundwater or surface water. Sphagnum mosses grow on top, producing recalcitrant
organic matter and fuelling large C stocks. As Sphagnum species strongly differ
in their tolerance to the higher pH in these mires, their species
composition can be expected to influence C dynamics in transitional mires.
We therefore experimentally determined growth and net C sequestration rates
for four different Sphagnum species (Sphagnum squarrosum, S. palustre,
S. fallax and S. magellanicum) in aquaria, with floating peat influenced
by the infiltration of buffered water. Surprisingly, even though the first
three species increased their biomass, the moss-covered peat still showed a
net efflux of CO2 that was up to 3 times higher than that of bare
peat. This species-dependent C release could be explained by Sphagnum's active
lowering of the pH, which triggers the chemical release of CO2 from
bicarbonate.
Our results clearly illustrate that high Sphagnum biomass production may still
coincide with high C emission. These counterintuitive C dynamics in mire
succession seem to be the result of both species- and biomass-dependent
acidification and buffered water infiltration. Together, these processes can
explain part of the large variation in C fluxes (ranging from C
sequestration to C release) reported for pristine mires in the literature. |
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