SEED GERMINATION OF SEVERAL INVASIVE SPECIES POTENTIALLYUSEFUL FOR BIOMASS PRODUCTION OR REVEGETATION PURPOSESUNDER SEMIARID CONDITIONS

摘要

The introduction of several plant species to areas beyond their natural distribution has been a global phenome-non that poses critical problems and challenges for the conservation and management of many agricultural and natural ecosystems. Shrub medick (Medicago arborea L.), Spanish broom (Spartium junceum L.) and chaste tree (Vitex agnus castus L.) are three of the most important native shrubs in arid and semiarid Mediterranean regions, being noxious invasive species for some areas but in some cases remarkably useful for several purpos-es. An understanding of their seed germination and seedling emergence should prove useful for their manage-ment. Laboratory and greenhouse experiments were done to examine the effects of high temperature on seed gemination and seedling emergence. Dry heat benefitted (or at high temperatures damaged) seed germination and emergence. This implies potential effects of fire on the dynamics of populations of M. arborea, S. junceum and V. agnus castus, a factor which should be taken into account as fire is a frequent component of Mediterranean-type ecosystems.