Germination patterns of endemics vs. more widely distributedplant species in relation to factors associated with fire

摘要

The germinative response of 59 Iberian plant species was analysed in relation torntheir distribution range and to factors associated with the changes induced by fire in the germinationrnenvironment. A set of 32 chamaephytes and 27 hemicryptophytes were selected and forrnevery analysis species were arranged in three distribution groups: endemics to the Iberian Peninsularn(17 spp.), species with distribution restricted to the Mediterranean region (27 spp.), andrnwidely distributed species (15 spp.). Optimum temperature for germination was explored by incubatingrnseeds under four temperatures (10oC, 15oC, 20oC and 25oC). Fire conditions were simulatedrnby subjecting seeds to three heat-shocks (80oC, 100oC and 120oC) for 10 minutes and postfirernconditions were simulated by incubating seeds in light or darkness with or without additionrnof nutrients. The results obtained indicate that species with differences in their distribution rangernwill be affected differently by the germination conditions associated to fire. Species with a restrictedrndistribution range showed lower seed viability, higher sensitivity to temperature conditionsrnand to heat shock, and their germination was not enhanced by postfire conditions (light andrnnutrients). Widely distributed species had better seed viability, showed similar responses to arnlarge range of temperatures and heat shock intensities, and their germination was enhanced underrnsimulated postfire conditions (light and light plus nutrients).