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| Titel |
Long-term CO2 flux dynamics and soil C stock changes of a drained fen mire under different grassland management practices in Northeast Germany |
| VerfasserIn |
Jürgen Augustin, Michael Giebels, Elisa Albiac Borraz, Mathias Hoffmann, Michael Sommer |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089063
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| Publikation (Nr.) |
 EGU/EGU2014-3251.pdf |
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| Zusammenfassung |
| Fen mires, widely distributed in Germany and Northern Europe, contain extreme
high amounts of carbon (up to 5000 t C per hectare). For this reason, they play an
important role in the global cycle of the greenhouse gases carbon dioxide (CO2) and
methane (CH4). Currently more than 95% of all fen mires in central Europe are
drained. Therefore, they are assumed to represent extremely strong sources for
CO2,accompanied by a fast reduction of the peat carbon stocks. For a number of
reasons it is not possible to overcome this problem by restoration measures like
flooding at the most drained fen sites. Moreover, there are till now just few and
contradictory information about the contribution of alternative land use forms like
grassland extensification on the reduction of the CO2 source function of these organic
soils.
As a contribution to clearing this deficit, we have ongoingly measured the CO2 and CH4
exchange as well as the changes in C stock on a deeply drained fen mire near the village of
Paulinenaue from 2007 till 2012. The measurement sites is located within the so-called
Rhin-Havelluch, an 80000 ha shallow paludification mire complex in the northwest of Berlin.
The investigation included extensively and intensively used meadows (one cut vs. three cuts)
on two soil types with different C stocks (Hemic Rheic Histosol vs. Mollic Gleysol). We used
transparent chambers for measuring the CO2 flux net ecosystem exchange (difference
between gross primary production and ecosystem respiration) and non-transparent chambers
for measuring the CO2 flux ecosystem respiration and the CH4 exchange. Determined
soil stock changes based on a C budget approach, including cumulated annual net
ecosystem exchange, cumulated CH4 exchange, C export by harvest, and C import by
fertilization.
All current C fluxes were influenced in a complex way by ground-water level, plant
development, land use intensity (cut frequency) and current weather conditions. Averaged
over the whole investigation time all combinations of land use intensity and soil types
acted as strong CO2 sources and showed high soil C losses (up to 1070 g C m-2
yr-1). There was a tendency of lower soil C losses in case of extensive grassland
compared to intensive grassland use (820 vs. 1070 g C m-2 yr-1) and grassland at the
Gleysol site compared to the Histosol site (538 vs. 946 g C m-2 yr-1). However, the
cumulated C fluxes and the soil C losses are subject to a very strong interannual
variability. The actual range varied from 245 to 2092 g C m-2 yr-1 in case of the soil C
losses.
It can be therefore concluded that only long-term measurements (> 3 years) provides
reliable information about the C dynamics of drained fen mires. Due to the high interannual
variability, there is a high risk to get largely biased results if only short-term measurements
will be done. |
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