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| Titel |
CH4 and N2O dynamics in the boreal forest–mire ecotone |
| VerfasserIn |
B. Tupek, K. Minkkinen, J. Pumpanen, T. Vesala, E. Nikinmaa |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 2 ; Nr. 12, no. 2 (2015-01-16), S.281-297 |
| Datensatznummer |
250117772
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| Publikation (Nr.) |
 copernicus.org/bg-12-281-2015.pdf |
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| Zusammenfassung |
In spite of advances in greenhouse gas research, the spatiotemporal
CH4 and N2O dynamics of boreal landscapes remain challenging, e.g.,
we need clarification of whether forest–mire transitions are occasional
hotspots of landscape CH4 and N2O emissions during exceptionally
high and low ground water level events.
In our study, we tested the differences and drivers of CH4 and N2O
dynamics of forest/mire types in field conditions along the soil moisture
gradient of the forest–mire ecotone. Soils changed from Podzols to Histosols
and ground water rose downslope from a depth of 10 m in upland sites to
0.1 m in mires. Yearly meteorological conditions changed from being
exceptionally wet to typical and exceptionally dry for the local climate. The
median fluxes measured with a static chamber technique varied from −51 to
586 μg m−2 h−1 for CH4 and from 0 to
6 μg m−2 h−1 for N2O between forest and mire types
throughout the entire wet–dry period.
In spite of the highly dynamic soil water fluctuations in carbon rich soils
in forest–mire transitions, there were no large peak emissions in CH4
and N2O fluxes and the flux rates changed minimally between years.
Methane uptake was significantly lower in poorly drained transitions than in
the well-drained uplands. Water-saturated mires showed large CH4
emissions, which were reduced entirely during the exceptional summer drought
period. Near-zero N2O fluxes did not differ significantly between the
forest and mire types probably due to their low nitrification potential. When
upscaling boreal landscapes, pristine forest–mire transitions should be
regarded as CH4 sinks and minor N2O sources instead of CH4 and
N2O emission hotspots. |
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