INFLUENCE OF INTRA-SPECIFIC AND INTER-SPECIFIC INTERFERENCE ON TERPENE EMISSION BY PINUS-HALEPENSIS AND QUERCUS-ILEX SEEDLINGS

Seedlings of two common Mediterranean trees, Pinus halepensis L. and Q uercus ilex L., were grown alone and together with seedlings of the sa me or of the other species in the same pot during one year to test the effects of intra- and inter-specific interference on terpene emission . Light, nutrients and water were amply supplied. There were higher em ission rates in P. halepensis than in Q. ilex. The emission increased when the neighbour was a pine and decreased when the neighbour was a h elm oak. Volatile organic compound and terpene emission rates followed inverse trends to foliar biomass or growth, which decreased when the neighbour was a pine.