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| Titel |
Environmental factors influencing trace house gas production in permafrost-affected soils |
| VerfasserIn |
Josefine Walz, Christian Knoblauch, Luisa Böhme, Eva-Maria Pfeiffer |
| 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 |
250135609
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| Publikation (Nr.) |
 EGU/EGU2016-16495.pdf |
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| Zusammenfassung |
| The permafrost-carbon feedback has been identified as a major feedback mechanism to
climate change. Soil organic matter (SOM) decomposition in the active layer and thawing
permafrost is an important source of atmospheric carbon dioxide (CO2) and methane (CH4).
Decomposability and potential CO2 and CH4 production are connected to the quality of
SOM. SOM quality varies with vegetation composition, soil type, and soil depth. The
regulating factors affecting SOM decomposition in permafrost landscapes are not well
understood. Here, we incubated permafrost-affected soils from a polygonal tundra landscape
in the Lena Delta, Northeast Siberia, to examine the influence of soil depth, oxygen
availability, incubation temperature, and fresh organic matter addition on trace gas
production.
CO2 production was always highest in topsoil (0 – 10 cm). Subsoil (10 – 50 cm) and
permafrost (50 – 90 cm) carbon did not differ significantly in their decomposability. Under
anaerobic conditions, less SOM was decomposed than under aerobic conditions. However, in
the absence of oxygen, CH4 can also be formed, which has a substantially higher warming
potential than CO2. But, within the four-month incubation period (approximate period of
thaw), methanogenesis played only a minor role with CH4 contributing 1-30% to the total
anaerobic carbon release.
Temperature and fresh organic matter addition had a positive effect on SOM decomposition.
Across a temperature gradient (1, 4, 8∘C) aerobic decomposition in topsoil was less
sensitive to temperature than in subsoil or permafrost. The addition of labile plant
organic matter (13C-labelled Carex aquatilis, a dominant species in the region)
significantly increased overall CO2 production across different depths and temperatures.
Partitioning the total amount of CO2 in samples amended with Carex material into
SOM-derived CO2 and Carex-derived CO2, however, revealed that most of the
additional CO2 could be assigned to the organic carbon from the amendment. A
significant increase in SOM-derived CO2 (positive priming) was only evident in
permafrost samples. Here, the relative priming effect was significantly stronger at lower
temperatures. |
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