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| Titel |
The variation of methane flux rates from boreal tree species at the beginning of the growing season |
| VerfasserIn |
Iikka Haikarainen, Elisa Halmeenmäki, Katerina Machacova, Mari Pihlatie |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250131567
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| Publikation (Nr.) |
 EGU/EGU2016-11992.pdf |
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| Zusammenfassung |
| Boreal forests are considered as net sink for atmospheric methane (CH4) because of the CH4
oxidizing bacteria in the aerobic soil layer. However, within the last decades it has
become more evident that trees play an important role in the global CH4 budget by
offering pathways for anaerobically produced CH4 from deeper soil layers to the
atmosphere. Furthermore, trees may also act as independent sources of CH4. To confirm
magnitude, variability and the origin of the tree mediated CH4 emissions more
research is needed, especially in boreal forests which have been in a minority in such
investigation.
We measured tree stem and shoot CH4 exchange of three boreal tree species at the
beginning of the growing season (13.4.–13.6.2015) at SMEAR II station in Hyytiälä, located
in southern Finland (61˚ 51’N, 24˚ 17’E, 181 asl). The fluxes were measured from silver
birch (Betula pendula), downy birch (B. pubescens) and Norway spruce (Picea abies) on two
sites with differing soil type and characteristics (paludified and mineral soil), vegetation and
forest structure by using the static chamber technique. Scaffold towers were used for
measurements at multiple stem heights and shoots. The aim was to study the vertical profile
of CH4 fluxes at stem and shoot level and compare these fluxes among the studied species,
and to observe temporal changes in CH4 flux over the beginning of the growing
season.
We found that all the trees emitted CH4 from their stems and shoots. Overall, the birches
showed higher emissions compared to the spruces. The emission rates were considerably
larger in the lower parts of the birch stems than upper parts, and these emissions increased
during the growing season. The spruces had more variation in the stem CH4 flux, but the
emission rates of the upper parts of the stem exceeded the birch emissions at the same height.
The shoot fluxes of all the studied trees indicated variable CH4 emissions without
a clear pattern regarding the vertical profile and progress of the growing season. |
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