Assessing effects of permafrost thaw on C fluxes based on multiyear modeling across a permafrost thaw gradient at Stordalen, Sweden
Northern peatlands in permafrost regions contain a large amount of organic carbon (C) in the soil. Climate warming and associated permafrost degradation are expected to have significant impacts on the C balance of these ecosystems, but the magnitude is uncertain. We incorporated a permafrost model,...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-09-01
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| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/11/4753/2014/bg-11-4753-2014.pdf |
| Summary: | Northern peatlands in permafrost regions contain a large amount of organic
carbon (C) in the soil. Climate warming and associated permafrost degradation
are expected to have significant impacts on the C balance of these
ecosystems, but the magnitude is uncertain. We incorporated a permafrost
model, Northern Ecosystem Soil Temperature (NEST), into a biogeochemical
model, DeNitrification-DeComposition (DNDC), to model C dynamics in
high-latitude peatland ecosystems. The enhanced model was applied to assess
effects of permafrost thaw on C fluxes of a subarctic peatland at Stordalen,
Sweden. DNDC simulated soil freeze–thaw dynamics, net ecosystem exchange of
CO<sub>2</sub> (NEE), and CH<sub>4</sub> fluxes across three typical land cover types,
which represent a gradient in the process of ongoing permafrost thaw at
Stordalen. Model results were compared with multiyear field measurements, and
the validation indicates that DNDC was able to simulate observed differences
in seasonal soil thaw, NEE, and CH<sub>4</sub> fluxes across the three land cover
types. Consistent with the results from field studies, the modeled C fluxes
across the permafrost thaw gradient demonstrate that permafrost thaw and the
associated changes in soil hydrology and vegetation not only increase net uptake of C
from the atmosphere but also increase the annual to decadal radiative
forcing impacts on climate due to increased CH<sub>4</sub> emissions. This study
indicates the potential of utilizing biogeochemical models, such as DNDC, to
predict the soil thermal regime in permafrost areas and to investigate impacts of
permafrost thaw on ecosystem C fluxes after incorporating a permafrost
component into the model framework. |
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| ISSN: | 1726-4170 1726-4189 |