Post-fire germination: The effect of smoke on seeds of selected species from the central Mediterranean basin

摘要

In regions with a Mediterranean-type climate wildfires are a frequent occurrence: in such environments fire tolerant/favoured species are frequently encountered. In the Mediterranean basin, many species of fire prone habitats are resprouters while others are known to germinate after fire. Fire causes an enhancement of seed germination in many species from fire prone habitats in the other regions with a Mediterranean-type vegetation such as Western Australia, California and South Africa. Seeds of a number of these species are stimulated to germinate by the smoke generated from burning of plant material in either an aerosol or aqueous form. However, for species from the Mediterranean basin the role of smoke in germination is poorly known, despite thefact that in the field many species seems to be encouraged to germinate after fire. We examined the germination of 10 species native to the Mediterranean basin that were treated with aerosol smoke. Some species were from fire prone habitats while otherswere not. In relation to the controls, increased germination occurred in three of the species (e.g. Cistus incanus), three had more rapid germination but no total increase (e.g. Rhamnus alaternus), two showed reduced germination (e.g. Asphodelus ramosus)and two exhibited no difference in germination (e.g. Clematis flammula). There was additionally no consistent pattern of germination behaviour depending on the habitat from which the species came. Comparison is made between the results of this study andthose of other studies on seed germination response to heat and smoke in other areas of Mediterranean-type climate. An understanding of the importance of fire in relation to other disturbances in the vegetation dynamics in the Mediterranean basin needsto be clarified by further detailed studies of the effect of heat and smoke products on seed germination of Mediterranean species. Outcomes of further research, also on a broader range of species, would have important impacts also for conservation, environment management, horticulture and ecosystem restoration.