Terpenoid Emissions of Mediterranean Oaks and their Relation to Taxonomy.

Abstract

The experiment aimed at improving our understanding of oak contributions to overall emissions of volatile organic compounds and to the atmospheric chemistry in the Mediterranean area. We measured type and amount of terpenoid emissions (isoprene, mono- and sesquiterpenes) from 14 different Quercus species of Mediterranean origin under standard conditions of light and temperature in controlled environment chambers. Leaf level trace gas exchange was analyzed with the help of a minicuvette system and of gas chromatography. We also studied the seasonal fluctuations of the emission factors over the year from one species. At the same time we compared the relation between the emission types and emission spectra found at the Quercus taxonomy. The holarctic group Lepidobalanus and the North American groups Erythrobalanus and Protobalanus were all found to be strong isoprene emitters. All Eurasian Sclerophyllodrys oaks emit monoterpenes, Cerris oaks include mostly non-emitters, but also an isoprene emitter has been found in this group. Results are discussed with respect to their implications for presently used emission scenarios.