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| Titel |
Atmospheric nitrous oxide uptake in boreal spruce forest soil |
| VerfasserIn |
Henri Siljanen, Nina Welti, Juha Heikkinen, Christina Biasi, Pertti Martikainen |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250154001
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| Publikation (Nr.) |
 EGU/EGU2017-19044.pdf |
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| Zusammenfassung |
| Nitrous oxide (N2O) uptake from the atmosphere has been found in forest soils but
environmental factors controlling the uptake and its atmospheric impact are poorly known.
We measured N2O fluxes over growing season in a boreal spruce forest having control plots
and plots with long nitrogen fertilization history. Also methane (CH4) fluxes were measured
to compare the atmospheric impact of N2O and CH4fluxes. Soil chemical and physical
characteristics and climatic conditions were measured as background data. Nitrous oxide
consumption and uptake mechanisms were measured in complementary laboratory
incubation experiments using stable isotope approaches. Gene transcript numbers of nitrous
oxide reductase (nosZ) I and II genes were quantified along the incubation with elevated N2O
atmosphere. The spruce forests without fertilization history showed highest N2O
uptake rates whereas pine forest had low emissions. Nitrous oxide uptake correlated
positively with soil moisture, high soil silt content, and low temperature. Nitrous oxide
uptake varied seasonally, being highest in spring and autumn when temperature
was low and water content was high. The spruce forest was sink for CH4.Methane
fluxes were decoupled from the N2O fluxes (i.e. when the N2O uptake was high the
CH4 uptake was low). By using GWP approach, the cooling effect of N2O uptake
was on average 30% of the cooling effect of CH4 uptake in spruce forest without
fertilization. Anoxic conditions promoted higher N2O consumption rates in all soils. Gene
transcription of nosZ-I genes were activated at beginning of the incubation. However,
atypical/clade-II nosZ was not detected. These results suggests, that also N2O uptake
rates have to be considered when accounting for the GHG budget of spruce forests. |
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