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| Titel |
Land-atmosphere fluxes of methane and carbon dioxide at Siberian polygonal tundra - new data from 2009 in comparison to data from 2003/04 and 2006. |
| VerfasserIn |
Peter Schreiber, Christian Wille, Torsten Sachs, Eva-Maria Pfeiffer, Lars Kutzbach |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250043774
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| Zusammenfassung |
| The fluxes of carbon dioxide (CO2) and methane (CH4) between wet arctic polygonal tundra
and the atmosphere were investigated by the eddy covariance method and empirical
modeling. The study site is situated in the Lena River Delta in Northern Siberia (72Ë 22’ N,
126Ë 30’ E) and is characterized by a polar and distinctly continental climate, very cold and
ice-rich permafrost, and its position at the interface between the Eurasian continent and the
Arctic Ocean. The soils at the site are characterized by high organic matter content, low
nutrient availability and pronounced water logging. The vegetation is dominated by sedges
and mosses. Flux measurements were performed during one “synthetic” growing
season consisting of the periods July - October 2003 and May - July 2004, one full
growing season in 2006 (June - September), and during July - August in 2009. The
main carbon exchange processes - gross photosynthesis, ecosystem respiration, and
CH4 emissions - were generally found to be of low intensity. Over the 2004/2003
growing season (June - September), these gas fluxes accumulated to -0.43 kg m-2,
+0.33 kg m-2, and +2 g m-2, respectively. CH4 emissions from June - September
2006 were 1.96 g m-2 with highest emissions in July (+0.57 g m-2) and August
(+0.64 g m-2). Day-to-day variations of photosynthesis were mainly controlled by
radiation and hence by the synoptic weather conditions. Variations of ecosystem
respiration were best explained by an exponential function of surface temperature, which
indicates that plant respiration plays a major role within the tundra carbon balance. The
factors controlling CH4 emissions were found to be soil temperature and near-surface
atmospheric turbulence. The influence of atmospheric turbulence was attributed to the high
coverage of open water surfaces in the tundra. For the 2003- 2004 period, winter
fluxes were modeled based on functional relationships found in the measured data.
On an annual basis, CH4 emissions accounted for 14 % of the annual ecosystem
carbon balance. Considering the global warming potential of CH4, the tundra was an
effective greenhouse gas source. Comparison of data from 2003-2004 and 2006
showed a difference of only a few percent between the CH4 fluxes measured. In this
work, we present new analyses of CO2 and CH4 flux data from 2009 in order to
assess interannual variability in the greenhouse gas balance of the polygonal tundra. |
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