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| Titel |
Partitioning of soil CO2 efflux in un-manipulated and experimentally flooded plots of a temperate fen |
| VerfasserIn |
S. Wunderlich, W. Borken |
| 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 ; 9, no. 8 ; Nr. 9, no. 8 (2012-08-31), S.3477-3489 |
| Datensatznummer |
250007260
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| Publikation (Nr.) |
 copernicus.org/bg-9-3477-2012.pdf |
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| Zusammenfassung |
Peatlands store large amounts of organic carbon, but the carbon stock is
sensitive to changes in precipitation or water table manipulations.
Restoration of drained peatlands by drain blocking and flooding is a common
measure to conserve and augment the carbon stock of peatland soils. Here, we
report to what extent flooding affected the contribution of heterotrophic
and rhizosphere respiration to soil CO2 efflux in a grass-dominated
mountain fen in Germany. Soil CO2 efflux was measured in three
un-manipulated control plots and three flooded plots in two consecutive
years. Flooding was achieved by permanent irrigation during the growing
seasons. Radiocarbon signatures of CO2 from different sources including
soil CO2 efflux, incubated peat cores and live grass roots were
repeatedly analyzed for partitioning of soil CO2 efflux. Additionally,
heterotrophic respiration and its radiocarbon signature were determined by
eliminating rhizosphere respiration in trenched subplots (only control). In
the control plots, rhizosphere respiration determined by 14C signatures
contributed between 47 and 61% during the growing season, but was small
(4 ± 8%) immediately before budding. Trenching revealed a smaller
rhizosphere contribution of 33 ± 8% (2009) and 22 ± 9%
(2010) during growing seasons.
Flooding reduced annual soil CO2 efflux of the fen by 42% in 2009
and by 30% in 2010. The reduction was smaller in 2010 mainly through
naturally elevated water level in the control plots. A one-week interruption
of irrigation caused a strong short-lived increase in soil CO2 efflux,
demonstrating the sensitivity of the fen to water table drawdown near the
peat surface. The reduction in soil CO2 efflux in the flooded plots
diminished the relative proportion of rhizosphere respiration from 56 to
46%, suggesting that rhizosphere respiration was slightly more sensitive
to flooding than heterotrophic respiration. |
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