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| Titel |
Changes of the CO2 and CH4 production potential of rewetted fens in the perspective of temporal vegetation shifts |
| VerfasserIn |
D. Zak, H. Reuter, J. Augustin, T. Shatwell, M. Barth, J. Gelbrecht, R. J. McInnes |
| 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. 8 ; Nr. 12, no. 8 (2015-04-24), S.2455-2468 |
| Datensatznummer |
250117912
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| Publikation (Nr.) |
 copernicus.org/bg-12-2455-2015.pdf |
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| Zusammenfassung |
| Rewetting of long-term drained fens often results in the formation of
eutrophic shallow lakes with an average water depth of less than 1 m. This
is accompanied by a fast vegetation shift from cultivated grasses via
submerged hydrophytes to helophytes. As a result of rapid plant dying and
decomposition, these systems are highly dynamic wetlands characterised by a
high mobilisation of nutrients and elevated emissions of CO2 and
CH4. However, the impact of specific plant species on these phenomena is
not clear. Therefore we investigated the CO2 and CH4 production due
to the subaqueous decomposition of shoot biomass of five selected plant
species which represent different rewetting stages (Phalaris
arundinacea, Ceratophyllum demersum, Typha latifolia,
Phragmites australis and Carex riparia) during a 154 day
mesocosm study. Beside continuous gas flux measurements, we performed bulk
chemical analysis of plant tissue, including carbon, nitrogen, phosphorus
and plant polymer dynamics. Plant-specific mass losses after 154 days ranged
from 25% (P. australis) to 64% (C. demersum).
Substantial differences were found for the CH4 production with highest
values from decomposing C. demersum (0.4 g CH4 kg−1 dry mass
day) that were about 70 times higher than CH4 production from C.
riparia. Thus, we found a strong divergence between mass loss of the litter
and methane production during decomposition. If C. demersum as a
hydrophyte is included in the statistical analysis solely nutrient contents
(nitrogen and phosphorus) explain varying greenhouse gas production of the different
plant species while lignin and polyphenols demonstrate no significant impact
at all. Taking data of annual biomass production as important carbon source
for methanogens into account, high CH4 emissions can be expected to last
several decades as long as inundated and nutrient-rich conditions prevail.
Different restoration measures like water level control, biomass extraction
and top soil removal are discussed in the context of mitigation of CH4
emissions from rewetted fens. |
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