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Below ground carbon turnover and greenhouse gas exchanges in a sub-arctic wetland.

Author:
  • Lena Ström
  • Torben Christensen
Publishing year: 2007
Language: English
Pages: 1689-1698
Publication/Series: Soil Biology & Biochemistry
Volume: 39
Issue: 7
Document type: Journal article
Publisher: Elsevier

Abstract english

Here we present results from a field experiment in a sub-arctic wetland near Abisko, northern Sweden, where the permafrost is currently disintegrating with significant vegetation changes as a result. During one growing season we investigated the fluxes of CO2 and CH4 and how they were affected by ecosystem properties, i.e., composition of species that are currently expanding in the area (Carex

rotundata, Eriophorum vaginatum and Eriophorum angustifolium), dissolved CH4 in the pore water, substrate availability for methane producing bacteria, water table depth, active layer, temperature, etc. We found that the measured gas fluxes over the season ranged

between: CH4 0.2 and 36.1 mgCH4m-2 h-1, Net Ecosystem Exchange (NEE) -1000 and 1250 mgCO2m-2 h-1 (negative values meaning a sink of atmospheric CO2) and dark respiration 110 and 1700 mgCO2m-2 h-1. We found that NEE, photosynthetic rate and CH4 emission were affected by the species composition. Multiple stepwise regressions indicated that the primary explanatory variables for

NEE was photosynthetic rate and for respiration and photosynthesis biomass of green leaves. The primary explanatory variables for CH4 emissions were depth of the water table, concentration of organic acid carbon and biomass of green leaves. The negative correlations between pore water concentration and emission of CH4 and the concentrations of organic acid, amino acid and

carbohydrate carbon indicated that these compounds or their fermentation by-products were substrates for CH4 formation. Furthermore, calculation of the radiative forcing of the species expanding in the area as a direct result of permafrost degradation and a change in hydrology indicate that the studied mire may act as an increasing source of radiative forcing in future.

Keywords

  • Physical Geography

Other

Published
  • ISSN: 0038-0717
E-mail: lena [dot] strom [at] nateko [dot] lu [dot] se

Professor

Dept of Physical Geography and Ecosystem Science

+46 46 222 37 46

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Department of Physical Geography and Ecosystem Science
Lund University
Sölvegatan 12
S-223 62 Lund
Sweden

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