MONOTERPENE EMISSION FROM PONDEROSA PINE

We explore the variability in monoterpene emissions from ponderosa pin e beyond that which can be explained by temperature alone. Specificall y, we examine the roles that photosynthesis and needle monoterpene con centrations play in controlling emissions. We measure monoterpene conc entrations and emissions, photosynthesis, temperature, and light avail ability in the late spring and late summer in a ponderosa pine forest in central Oregon. We use a combination of measurements from cuvettes and Teflon bag enclosures to show that photosynthesis is not correlate d with emissions in the short term. We also show that needle monoterpe ne concentrations are highly correlated with emissions for two compoun ds, alpha-pinene and beta-pinene, but that DELTA-carene concentrations are not correlated with emissions. We suggest that direct effects of light and photosynthesis do not need to be included in emission algori thms. Our results indicate that the role of needle concentration bears further investigation; our results for alpha-pinene and beta-pinene a re explainable by a Raoult's law relationship, but we cannot yet expla in the cause of our results with DELTA-carene.