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| Titel |
Role of plant-mediated gas transport in CH4 emissions from Phragmites-dominated peatlands |
| VerfasserIn |
Merit van den Berg, Joachim Ingwersen, Eva van den Elzen, Leon P. M. Lamers, Thilo Streck |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131753
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| Publikation (Nr.) |
 EGU/EGU2016-12193.pdf |
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| Zusammenfassung |
| A large part of the methane (CH4) produced in peatlands is directly oxidized and the extent
of its oxidation depends on the gas transport pathway. In wetland ecosystems, CH4 can be
transported from the soil to the atmosphere via diffusion, ebullition and via aerenchyma of
roots and stems of vascular plants. Compared to other wetland plants, the very common
species Phragmites australis (Common reed) appears to have a high ability to transport
gases between the soil and atmosphere. The gas exchange within Phragmites plants
takes place via convective flow through the culm, which is believed to be achieved
by a humidity-induced pressure gradient and is more than 5-times as efficient as
diffusion. By this mechanism, CH4 surpasses the upper (oxic) soil layers and therefore
oxidation of CH4 may well be reduced. On the other hand, transport of oxygen in
Phragmites plants tends to enhance O2concentration in the rhizosphere, which will foster
CH4oxidation in deeper soil layers. It is therefore unknown whether humidity-induced
convection leads to higher or lower overall CH4 emission in Phragmites, which is
essential to understand their role in the emissions from these very common peatland
types.
To investigate whether this internal gas transport mechanism of reed promotes or reduces
CH4 fluxes to the atmosphere, we conducted manipulative field experiments in a large
Phragmites peatland in South-West Germany in October 2014 and July 2015. Using large
chambers, we compared CH4 fluxes from intact plots, plots with cut reed, and plots with cut
+ sealed reed to exclude gas transport through the plants. Additionally, pore water samples
from the plots were analyzed for possible changes in soil chemistry due to the change of
oxygen transport into the soil by the treatments. Based on our results, we will explain the
potential role of rhizosphere oxygenation and convective flow on CH4 emissions
from Phragmites-dominated peatlands in relation to other environmental condition. |
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