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@PHDTHESIS{Komenda:13467,
author = {Komenda, M.},
title = {{I}nvestigations of the emissions of monoterpenes from
{S}cots pine},
volume = {3866},
issn = {0944-2952},
school = {Univ. Köln},
type = {Dr. (Univ.)},
address = {Jülich},
publisher = {Forschungszentrum, Zentralbibliothek},
reportid = {PreJuSER-13467, Juel-3866},
series = {Berichte des Forschungszentrums Jülich},
year = {2001},
note = {Record converted from VDB: 12.11.2012; Köln, Univ., Diss.,
2001},
abstract = {Plants produce and emit a large number of volatile organic
compounds (VOC) such as isoprene and monoterpenes
(C<sub>10</sub>H<sub>16</sub>). Monoterpene emission rates
from Scots pine (Pinus sylvestris), a typical central
European conifer, were measured under ambient conditions
within the scope of this work. The studies focused on
diurnal and seasonal cycles of monoterpene emissions,
branch-to-branch and plant-to-plant variability of emission
rates, and on the transferability ofresults from laboratory
(studies of Dr. J. Wildt and coworkers) and outdoor
measurements.<br> Generally, no significant differences
between the results obtained under laboratory and ambient
environmental conditions were found. Under both laboratory
and ambient conditions, monoterpene emissions were found to
increase with needle temperature at a rate of 5 $\%$ to 16
$\%$ per Kelvin and fonowed under otherwise unchanged
conditions an Arrhenius type dependence on temperature. The
temperature dependence of emissions was without a clear
seasonal trend and without significant differences from
plant-to-plant. Only in the laboratory a dependence of
emission rates on photosynthetic active radiation (PAR) was
found (increase of $20-30\%$ at a constant temperature,
saturation in the light dependence at about 15 $\%$ of fun
sunlight). Under outdoor conditions, a PAR dependence was
not detected.<br> Seasonal variations of a single branch and
branch-to-branch variations in the spectrum of emitted
monoterpenes were small, but different individual Scots
pines emitted a completely different spectrum of
monoterpenes. The temperature normalized standard emission
rates were found to be highly variable. Values for the sum
of monoterpenes ranged between 0.06 and 0.65 $\µg$
g(dW)<sup>-l</sup>h<sup>-1</sup> (microgram monoterpenes per
gram dry weight of needles and hour) for young pines and
between 0.24 and 3.7 $\µg$
g(dW)<sup>-l</sup>h<sup>-1</sup> for the adult pine. The
variations of the standard emission rates from the same
plant at different times of the year were on the same order
of magnitude as the plant-to-plant variability. Stress to
the plant was a possible explanation for these variations,
but this effect could not be described quantitatively.
ßased on the results a monoterpene flux was calculated for
a forest in Southern Germany (Hartheimer Wald, near
Freiburg), ranging between 54-941 ng
m<sup>-2</sup>s<sup>-l</sup> at T = 30°C.<br> Future
laboratory studies should focus on stress effects and their
impact on VOC emissions. The effect of stress on VOC
emission rates must be quantified and included in the
existing models for better predictions of emission rates and
fluxes.},
cin = {ICG-II},
cid = {I:(DE-Juel1)VDB48},
pnm = {Troposphärische Chemie},
pid = {G:(DE-Juel1)FUEK74},
typ = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
url = {https://juser.fz-juelich.de/record/13467},
}