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| Titel |
Drought reduced monoterpene emissions from the evergreen Mediterranean oak Quercus ilex: results from a throughfall displacement experiment |
| VerfasserIn |
A.-V. Lavoir, M. Staudt, J. P. Schnitzler, D. Landais, F. Massol, A. Rocheteau, R. Rodriguez, I. Zimmer, S. Rambal |
| 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 ; 6, no. 7 ; Nr. 6, no. 7 (2009-07-15), S.1167-1180 |
| Datensatznummer |
250003907
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| Publikation (Nr.) |
 copernicus.org/bg-6-1167-2009.pdf |
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| Zusammenfassung |
| The effects of water limitations on the emission of biogenic volatile
organic compounds are not well understood. Experimental approaches studying
drought effects in natural conditions are still missing. To address this
question, a throughfall displacement experiment was set up in a natural
forest of Quercus ilex, an evergreen Mediterranean oak emitting monoterpenes. Mature
trees were exposed in 2005 and 2006 either to an additional drought, to
irrigation or to natural drought (untreated control). In both years,
absolute monoterpene emission rates as well as the respective standard
factors of the trees exposed to normal and additional drought strongly
declined during the drought periods. Monoterpene emissions were lower in
year 2006 than in year 2005 (factor 2) due to a more pronounced summer
drought period in this respective year. We observed a significant difference
between the irrigation and additional drought or control treatment:
irrigated trees emitted 82% more monoterpenes during the drought period
2006 than the trees of the other treatments. However, no significant effect
on monoterpene emission was observed between normal and additional drought
treatments, despite a significant effect on leaf water potential and
photochemical efficiency. During the development of drought, monoterpene
emissions responded exponentially rather than linearly to decreasing leaf
water potential. Emissions rapidly declined when the water potential dropped
below −2 MPa and photosynthesis was persistently inhibited. Monoterpene
synthase activities measured in vitro showed no clear reduction during the same
period. From our results we conclude that drought significantly reduces
monoterpene fluxes of Mediterranean Holm oak forest into the atmosphere due
to a lack of primary substrates coming from photosynthetic processes. |
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