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| Titel |
Sensitivity of the boreal forest-mire ecotone CO2, CH4, and N2O global warming potential to rainy and dry weather |
| VerfasserIn |
Boris Tupek, Kari Minkkinen, Timo Vesala, Eero Nikinmaa |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104487
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| Publikation (Nr.) |
 EGU/EGU2015-4170.pdf |
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| Zusammenfassung |
| In a mosaic of well drained forests and poorly drained mires of boreal landscape the weather
events such as drought and rainy control greenhouse gas dynamics and ecosystem global
warming potential (GWP). In forest-mire ecotone especially in ecosystems where CO2 sink is
nearly balanced with CO2 source, it’s fairly unknown whether the net warming effect of
emissions of gases with strong radiative forcing (CH4 and N2O) could offset the net cooling
effect of CO2 sequestration.
We compared the net ecosystem CO2 exchange (NEE) estimated from the carbon
sequestrations of forest stands and forest floor CO2 fluxes against CH4 and N2O fluxes of
nine forest/mire site types along the soil moisture gradient in Finland. The ground
water of nine sites changed between 10 m in upland forests and 0.1 m in mires, and
weather during three years ranged between exceptionally wet and dry for the local
climate.
The NEE of upland forests was typically a sink of CO2, regardless the weather. Though, xeric
pine forest was estimated to be a source of CO2 during wet and intermediate year and
became a weak sink only in dry year. The NEE of forest-mire transitions ranged
between a sink in dry year, while increased stand carbon sequestration could offset the
reduced forest floor CO2 emission, and a source in wet year. The NEE of two sparsely
forested mires strongly differed. The lawn type mire was balanced around zero and the
hummock type mire was relatively strong NEE sink, regardless the weather. Generally,
nearly zero N2O emission could not offset the cooling effect of net CH4 sink and
net CO2 sink of upland forest and forest-mire transitions. However in sparsely
forested mires, with N2O emission also nearly zero, the CH4 emission during wet and
intermediate year played important role in turning the net cooling effect of NEE into a net
warming. When evaluating GWP of boreal landscapes, undisturbed forest-mire
transitions should be regarded as net cooling ecosystems instead of hotspots of net
warming. |
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