[Simpraga2011a] "Comparing monoterpenoid emissions and net photosynthesis of beech ( Fagus sylvatica L.) in controlled and natural conditions",
, vol. 45, no. 17: Elsevier, pp. 2922–2928, 2011.
<p>Although biogenic volatile organic compounds (BVOCs) only represent a very limited fraction of the plant’s carbon (C) budget, they play an important role in atmospheric chemistry for example as a precursor of tropospheric ozone. We performed a study comparing BVOC emissions of European beech (Fagus sylvatica L.) in controlled and natural environmental conditions. A young and adult beech tree was exposed to short-term temperature variations in growth room conditions and in an experimental forest, respectively. This study attempts to clarify how short-term temperature variations between days influenced the ratio between monoterpenoid (MT) emissions and net photosynthesis (Pn). Within a temperature range of 17–27 °C and 13–23 °C, the MT/Pn carbon ratio increased 10–30 fold for the growth room and forest, respectively. An exponential increasing trend between MT/Pn C ratio and air temperature was observed in both conditions. Beech trees re-emitted a low fraction of the assimilated C back into the atmosphere as MT: 0.01–0.12% and 0.01–0.30% with a temperature rise from 17 to 27 °C and 13–23 °C in growth room and forest conditions, respectively. However, the data showed that the MT/Pn C ratio of young and adult beech trees responded significantly to changes in temperature.</p>
[Joo2011] "Constitutive versus heat and biotic stress induced BVOC emissions in Pseudotsuga menziesii",
, vol. 45, no. 22: Elsevier, pp. 3655–3662, 2011.
Induced volatiles have been a focus of recent research, as not much is known of their emission behavior or atmospheric contribution. BVOC emissions were measured from Pseudotsuga menziesii saplings under natural environmental conditions, using a dynamic branch enclosure system and GC–MS for their analysis. We determined temperature and light dependency of the individual compounds, studied seasonality of the emissions and discuss the effect of heat stress in comparison with two specific biotic stresses that occurred naturally on the trees. A standardized emission rate of 6.8 μg g(dw)−1 h−1 for monoterpenes under stressed conditions was almost a magnitude higher than that obtained for healthy trees (0.8 ± 0.2 μg g(dw)−1 h−1), with higher beta factors characterizing the stressed trees. The response of the emissions to light intensity was different for the individual compounds, suggesting a distinct minimum light intensity to reach saturation. Heat stress changed the relative contribution of specific volatiles, with larger extent of increase of sesquiterpenes, methyl salicylate and linalool emissions compared to monoterpenes. Biotic stress kept low the emissions of sesquiterpenes, (E)-4,8-dimethyl-1,3,7-nonatriene and methylbutenol isomers, and increased the level of methyl salicylate and monoterpenes. The ratio of β-pinene/α-pinene was also found to be significantly enhanced from 1.3 to 2.4 and 3.2 for non-stressed, heat stressed and combined biotic and heat stressed, respectively.
[Laffineur2011a] "Isoprene and monoterpene emissions from a mixed temperate forest",
, vol. 45, no. 18: Elsevier, pp. 3157–3168, 2011.
<p>We measured the isoprene and monoterpene fluxes continuously above a mixed forest site at Vielsalm in the eastern part of Belgium, using the disjunct eddy covariance technique with proton transfer reaction-mass spectrometry. Simultaneously, we also measured the carbon dioxide fluxes in order to deduce the gross primary production. The measurements were conducted from July to September 2009. During the day, the seasonal evolution of the isoprene/monoterpene emissions was studied using a monthly temperature and light dependence function deduced from our results to standardize the fluxes. A seasonal decrease in the standard emission factors was observed, probably linked to acclimation or senescence. The standard emission factor for isoprene fluxes (30 °C, 1000 μmol m−2 s−1) fell from 0.91 ± 0.01 to 0.56 ± 0.02 μg m−2 s−1 and for monoterpene fluxes from 0.74 ± 0.03 to 0.27 ± 0.03 μg m−2 s−1. During the night, a slight positive flux of monoterpenes was observed that seemed to be driven by air temperature. The standard emission factor (30°C) for nighttime monoterpene fluxes was equal to 0.093 ± 0.019 μg m−2 s−1. Finally, we studied the seasonal evolution of the relationship between the gross primary production and the isoprene/monoterpenes fluxes. A linear relationship was observed, highlighting the strong link between carbon assimilation and isoprene/monoterpene emissions.</p>
[Laffineur2011] "What can we learn from year-round BVOC disjunct eddycovariance measurements? A case example from a temperate forest",
5th International PTR-MS Conference on Proton Transfer Reaction Mass Spectrometry and its Applications
: Innsbruck university press, 2011.