Landscape controls of CH₄ fluxes in a catchment of the forest tundra ecotone in northern Siberia

authored by

Heiner Flessa, Andrej Rodionov, Georg Guggenberger, Hans Fuchs, Paul Magdon, Olga Shibistova, Galina Zrazhevskaya, Natalia Mikheyeva, Olega Kasansky, Christian Blodau

Abstract

Terrestrial ecosystems in northern high latitudes exchange large amounts of methane (CH₄) with the atmosphere. Climate warming could have a great impact on CH₄ exchange, in particular in regions where degradation of permafrost is induced. In order to improve the understanding of the present and future methane dynamics in permafrost regions, we studied CH₄ fluxes of typical landscape structures in a small catchment in the forest tundra ecotone in northern Siberia. Gas fluxes were measured using a closed-chamber technique from August to November 2003 and from August 2006 to July 2007 on tree-covered mineral soils with and without permafrost, on a frozen bog plateau, and on a thermokarst pond. For areal integration of the CH₄ fluxes, we combined field observations and classification of functional landscape structures based on a high-resolution Quickbird satellite image. All mineral soils were net sinks of atmospheric CH₄. The magnitude of annual CH₄ uptake was higher for soils without permafrost (1.19 kg CH₄ha^-1 yr^-1) than for soils with permafrost (0.37 kg CH₄ ha^-1yr^-1). In well-drained soils, significant CH₄ uptake occurred even after the onset of ground frost. Bog plateaux, which stored large amounts of frozen organic carbon, were also a net sink of atmospheric CH₄ (0.38 kg CH₄ ha^-1yr^-1). Thermokarst ponds, which developed from permafrost collapse in bog plateaux, were hot spots of CH₄ emission (approximately 200 kg CH₄ ha^-1yr^-1). Despite the low area coverage of thermokarst ponds (only 2.1% of the total catchment area), emissions from these sites resulted in a mean catchment CH₄ emission of 3.8 kg CH₄ha^-1yr^-1. Export of dissolved CH₄ with stream water was insignificant. The results suggest that mineral soils and bog plateaux in this region will respond differently to increasing temperatures and associated permafrost degradation. Net uptake of atmospheric CH₄ in mineral soils is expected to gradually increase with increasing active layer depth and soil drainage. Changes in bog plateaux will probably be much more rapid and drastic. Permafrost collapse in frozen bog plateaux would result in high CH₄ emissions that act as positive feedback to climate warming.

External Organisation(s)

University of Göttingen
Brandenburg University of Technology
Martin Luther University Halle-Wittenberg
Russian Academy of Sciences (RAS)
University of Bayreuth

Type

Article

Journal

Global change biology

Volume

14

Pages

2040-2056

No. of pages

17

ISSN

1354-1013

Publication date

06.08.2008

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Global and Planetary Change, Environmental Chemistry, Ecology, General Environmental Science

Sustainable Development Goals

SDG 13 - Climate Action, SDG 15 - Life on Land

Electronic version(s)

https://doi.org/10.1111/j.1365-2486.2008.01633.x (Access: Closed)