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| Titel |
Drought effect on methane, nitrous oxide and carbon dioxide dynamics along boreal forest-mire ecotone |
| VerfasserIn |
Boris Tupek, Kari Minkkinen, Timo Vesala, Pasi Kolari, Mike Starr, Jukka Alm, Jukka Pumpanen, Frank Berninger, Jukka Laine, Eero Nikinmaa |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082315
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| Zusammenfassung |
| The effect of drought on CH4, N2O and CO2 dynamics of boreal forest and mires has been
seldom observed in a continuum between xeric and wet habitats. Such a continuum
includes a transitional zone between forests and mires which is frequently exposed to
large soil moisture differences, but generally overlooked due to a relatively narrow
extent. Although, it’s known that CH4, N2O and CO2 dynamics are sensitive to soil
moisture.
We evaluated spatiotemporal effects of drought on CH4, N2O and CO2 dynamics in
continuum of nine distinct forest/mire types. Soils changed from well-drained podzols to
poorly-drained histosols and ground water raised downslope from the depth of 10 m in
upland forests to 0.1 m in mires. Meteorological conditions, forest floor respiration, methane,
and nitrous oxide flux data were collected during growing season of exceptionally wet
(2004), intermediate (2005), and exceptionally dry (2006) year. The CH4, N2O and CO2
fluxes were studied by chamber methods.
The seasonal median forest floor CH4, N2O, and CO2 dark fluxes between forest/mire types
and between rainy, intermediate, and dry years varied from -0.07 to 1.68 mgCH4 m2 h-1,
from 1.5 to 24.65 μgN2O m2 h-1, and from 0.26 to 0.76 gCO2 m2 h-1. The CH4
oxidation in upland forest and transitional types was similar between wet and dry years,
though the CH4 production of mires was reduced in dry year. Probably due to low
nitrification potential, larger soil water differences between years 2005 and 2006 did
not seem to trigger corresponding changes in small N2O fluxes. The forest floor
dark CO2 efflux during drought was in comparison to wetter periods significantly
reduced in upland forest and transitional types, but stayed similar or even increased in
mires.
In the carbon rich soil of forest/mire transitions mainly soil CO2 efflux were sensitive to short
term fluctuations between water level drawdown and water saturation, whereas CH4 and N2O
fluxes changed minimally. |
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