Plant physiological influences on the fluxes of oxygenated volatile organic compounds from ponderosa pine trees
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abstract
Fluxes of oxygenated volatile organic compounds were measured above a ponderosa pine plantation, adjacent to the Blodgett Forest Research Station (385342.9N, 1203757.9W, 1315 m elevation), with a fully automated relaxed eddy accumulation system coupled to a dual gas chromatograph-flame ionization detector (GC-FID) system. These measurements were initially reported by Schade and Goldstein [2001]. Here we further analyze these data to explore the physiological controls on emissions of 2-methyl- 3-buten-2-ol (MBO), ethanol, and acetaldehyde. Measured MBO fluxes were compared to fluxes predicted by a detailed leaf-level emission model. Although the match was very good in general, the model failed to predict a declined emission potential on cooler days following a very cold night. It also consistently overpredicted fluxes in the morning, while underpredicting fluxes in the afternoon, particularly on warm days. We conclude that the ponderosa pine MBO emission potential changes in response to recent environmental temperatures on diurnal and daily timescales, similar to changes reported for isoprene emissions. Though ambient temperature appeared to be the most important driver of ethanol and acetaldehyde fluxes, vapor pressure deficit strongly influenced ethanol emissions from ponderosa pine, suggesting that stomatal opening impacts emissions. Ethanol emissions were also found to increase after high ozone deposition fluxes, which supports the theory that ozone-induced stress may trigger fermentation processes in the leaves.
