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    Implications of foliar terpene content and hydration on leaf flammability of Quercus ilex and Pinus halepensis

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    6 páginas, 4 figuras, 1 tabla.We investigated the implications of foliar hydration and terpene content on leaf flammability in two widely distributed forest species of the Mediterranean basin, Quercus ilex, which does not store terpenes, and Pinus halepensis, a terpene-storing species. The experiments were carried out in plants grown under different water regimes that generated a wide range of foliar hydration and terpene contents. We monitored the temperatures and time elapsed to reach the smoke, pyrolysis and flame phases. Smoke appeared much earlier (37 versus 101 s) and at lower temperatures (96 versus 139 °C) in Quercus ilex than in Pinus halepensis. Quercus ilex reached pyrolysis earlier than Pinus halepensis (278 versus 338 s) but at the same temperature (365–371 °C). There were no significant differences in time elapsed nor in temperature for flammability (386–422 s; 505–487 °C in both species). Quercus ilex had lower water hydration than Pinus halepensis (41 versus 100%) and the leaf content of terpenes in Quercus was three orders of magnitude lower. The results of this study show no differences in the flame phase between the two species and the absence of a significant relationship between temperature and elapsed time of the different flammability phases in relation to monoterpene content; thus indicating that the role of monoterpenes in flammability phases is smaller than that of the water content. This, however, does not exclude the effects of terpene content on plant combustibility and fire propagation once fires start.Our research was supported by ISONET (Marie Curie network contract MC-RTN-CT-2003 504720) from the European Union, by the European Science Foundation ‘VOCBAS’ programme, by grants CGL2004-01402/BOS and CGL2006-04025 / BOS from the Spanish Government (MEC), by a 2004 grant from the Fundación BBVA and by a SGR 2005-00312 grant from AGAUR (Generalitat de Catalunya).Peer reviewe
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