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Below ground carbon turnover and greenhouse gas exchanges in a sub-arctic wetland subject to permafrost degradation.

Ström, Lena LU and Christensen, Torben LU (2007) European Geosciences Union general assembly, 2007
Abstract
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 mg CH4 m-2 h-1, Net Ecosystem Exchange (NEE) -1000 and 1250 mg... (More)
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 mg CH4 m-2 h-1, Net Ecosystem Exchange (NEE) -1000 and 1250 mg CO2 m-2 h-1 (negative values meaning a sink of atmospheric CO2) and dark respiration 110 and 1700 mg CO2 m-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. (Less)
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publishing date
type
Contribution to conference
publication status
published
subject
conference name
European Geosciences Union general assembly, 2007
conference location
Vienna, Austria
conference dates
2007-04-15 - 2007-04-20
language
English
LU publication?
yes
id
f0994f77-651e-4f77-9434-34b65dd89a1c (old id 715165)
date added to LUP
2016-04-04 13:52:05
date last changed
2018-11-21 21:16:50
@misc{f0994f77-651e-4f77-9434-34b65dd89a1c,
  abstract     = {{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 mg CH4 m-2 h-1, Net Ecosystem Exchange (NEE) -1000 and 1250 mg CO2 m-2 h-1 (negative values meaning a sink of atmospheric CO2) and dark respiration 110 and 1700 mg CO2 m-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.}},
  author       = {{Ström, Lena and Christensen, Torben}},
  language     = {{eng}},
  title        = {{Below ground carbon turnover and greenhouse gas exchanges in a sub-arctic wetland subject to permafrost degradation.}},
  year         = {{2007}},
}