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| Titel |
Plant physiological and environmental controls over the exchange of acetaldehyde between forest canopies and the atmosphere |
| VerfasserIn |
K. Jardine, P. Harley, T. Karl, A. Guenther, M. Lerdau, J. E. Mak |
| 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 ; 5, no. 6 ; Nr. 5, no. 6 (2008-11-19), S.1559-1572 |
| Datensatznummer |
250002923
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| Publikation (Nr.) |
 copernicus.org/bg-5-1559-2008.pdf |
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| Zusammenfassung |
| We quantified fine scale sources and sinks of gas phase acetaldehyde in two
forested ecosystems in the US. During the daytime, the upper canopy behaved
as a net source while at lower heights, reduced emission rates or net uptake
were observed. At night, uptake generally predominated throughout the
canopies. Net ecosystem emission rates were inversely related to foliar
density due to the extinction of light in the canopy and a respective
decrease of the acetaldehyde compensation point. This is supported by branch
level studies revealing much higher compensation points in the light than in
the dark for poplar (Populus deltoides) and holly oak
(Quercus ilex) implying a higher light/temperature sensitivity for
acetaldehyde production relative to consumption. The view of stomata as the
major pathway for acetaldehyde exchange is supported by strong linear
correlations between branch transpiration rates and acetaldehyde exchange
velocities for both species. In addition, natural abundance carbon isotope
analysis of gas-phase acetaldehyde during poplar branch fumigation
experiments revealed a significant kinetic isotope effect of
5.1±0.3‰ associated with the uptake of acetaldehyde. Similar
experiments with dry dead poplar leaves showed no fractionation or uptake of
acetaldehyde, confirming that this is only a property of living leaves. We
suggest that acetaldehyde belongs to a potentially large list of plant
metabolites where stomatal resistance can exert long term control over both
emission and uptake rates due to the presence of both source(s) and sink(s)
within the leaf which strongly buffer large changes in concentrations in the
substomatal airspace due to changes in stomatal resistance. We conclude that
the exchange of acetaldehyde between plant canopies and the atmosphere
is fundamentally controlled by ambient acetaldehyde concentrations, stomatal
resistance, and the compensation point which is a function of
light/temperature. |
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