EFFECT OF HABITAT AND AGE ON VARIATIONS IN VOLATILE ORGANIC-COMPOUND (VOC) EMISSIONS FROM QUERCUS-ILEX AND PINUS-PINEA

A dynamic branch enclosure was used to measure emission rates of volat ile organic compounds (VOCs) under field conditions from two common na tive Mediterranean species, Quercus ilex and Pinus pinea. In addition to alpha-pinene, beta-pinene, sabinene, limonene and cineole, a suite of lesser known compounds were tentatively identified including cis- a nd trans-ocimene, cis-and trans-linalool oxide and sabinaketone. Emiss ions of isoprene from Quercus ilex were insignificant in comparison to those of the monoterpenes and were nor detected from Pinus pinea. Var iability in emission rates between two habitats, the forest and the du nes, were assessed for Quercus ilex. Temperature sensitivities of emis sions and total summed emission rates from Quercus ilex were clearly r elated to environmental conditions. Emission rates from Pinus pinea sh owed great variability, but differences between normalised mean emissi on rates from mature forest and young plantation trees may be signific ant. Existing emission rate models were found to inadequately describe the observed data. (C) 1997 Elsevier Science Ltd.