Terpenoid emissions of Mediterranean oaks and their relation to taxonomy

This paper presents results of a laboratory screening study of biogenic emi ssions from Mediterranean oak species. The experiment aimed at improving ou r understanding of oak contributions to overall emissions of volatile organ ic compounds and to the atmospheric chemistry in the Mediterranean area. We measured type and amount of terpenoid emissions (isoprene, mono- and sesqu iterpenes) under standard conditions of light and temperature from 14 diffe rent Quercus species of Mediterranean and American origin. Tree saplings we re exposed in a controlled environment chamber, and leaf-level trace-gas ex change was analyzed with a minicuvette system and gas chromatography, to st udy the relation between the emission types and emission spectra found and the taxonomy of Quercus. The holarctic group Lepidobalanus and the North Am erican groups Erythrobalanus and Protobalanus were found to be strong isopr ene emitters. The Eurasian oak group Sclerophyllodrys emits monoterpenes; C erris include mostly non-emitters, but also an isoprene and a monoterpene e mitter has been found in this group. Results are discussed with respect to their implications for presently used emission scenarios.