HR: 1340h
AN: B23D-1601    [Abstracts]
TI: Landscape Controls of CH₄ Fluxes in a Catchment of the Forest Tundra in Northern Siberia
AU: * Flessa, H
EM: hflessa@gwdg.de
AF: Institute of Soil Science and Forest Nutrition, University of Goettingen, Goettingen, 37077, Germany
AU: Rodionov, A
AF: Soil Science, University of Halle, Halle, 06108, Germany
AU: Guggenberger, G
AF: Soil Science, University of Halle, Halle, 06108, Germany
AU: Fuchs, H
AF: Institute of Forest Management, University of Goettingen, Goettingen, 37077, Germany
AU: Magdon, P
AF: Institute of Forest Management, University of Goettingen, Goettingen, 37077, Germany
AU: Shibistova, O
AF: Sukachev Institute of Forest, Akademgorodok, Krasnoyarsk, 660036, Russian Federation
AU: Zrazhevskaya, G
AF: Sukachev Institute of Forest, Akademgorodok, Krasnoyarsk, 660036, Russian Federation
AU: Kasansky, O
AF: Field Station Igarka of the Permafrost Institute Yakutsk, Microrayon, Igarka, 663200, Russian Federation
AU: Blodau, C
AF: Institute of Hydrology, Univerity of Bayreuth, Bayreuth, 95440, Germany
AB: Soils have the capacity to both produce and consume atmospheric methane. The direction and the size of net- CH₄ exchange between soils and atmosphere is mainly controlled by the soil aeration, temperature and the amount of bioavailable organic matter. All these factors are strongly influenced by distribution and seasonal dynamics of permafrost. Thus, distribution of permafrost and the thickness of the active layer can exert strong influence on CH₄ dynamics in artic and northern boreal ecosystems. We analyzed the spatial and temporal variability of net-CH₄ exchange within a catchment located in the Siberian forest tundra at the eastern shore of the lower Yenissej River to constrain the current function of this region as a sink or source of atmospheric CH₄ and to gain insight into the potential for climatic change to alter the rate and form of carbon cycling and CH₄ fluxes in this region. Net-fluxes of CH₄ were measured from July to November 2003 and from August 2006 to July 2007 on representative soils of the catchment (mineral soils with different thawing depth, soils of bog plateaux) and on a thermokarst pond. In addition, dissolved CH₄ in the stream draining the catchment was determined. Field observations, classification of landscape structures from satellite images and flux measurements were combined to estimate total catchment CH₄ exchange. Nearly all soils of the catchment were net-sinks of atmospheric CH₄ with annual CH₄-C uptake rates ranging between 1.2 and 0.2 kg ha^-1 yr^-1. The active layer depth was the main factor determining the size of CH₄ uptake. Total net-exchange of CH₄ from the catchment was dominated by ponds that covered only about 2% of the catchment area. Due to high CH₄ emission from these aquatic systems, the catchment was a net source of atmospheric CH₄ with a mean annual emission of approximately 170 kg CH₄-C ha^-1. CH₄ concentration in streams draining the catchment can help to identify areas with high CH₄ production. The results suggest that CH₄ emission in this region is strongly influenced by permafrost degradation and thermokarst erosion in bog areas.
DE: 0475 Permafrost, cryosphere, and high-latitude processes (0702, 0716)
DE: 0490 Trace gases
DE: 0708 Thermokarst
SC: Biogeosciences [B]
MN: 2007 Fall Meeting