THE INFLUENCE OF PINE ASH ON THE GERMINATION AND EARLY GROWTH OF PINUS-HALEPENSIS MILL AND CISTUS-SALVIIFOLIUS L

Black ash circles are found under the burned canopies of big dead pine trees up to three years after fires. Similar circles are formed as th e result of a spatial pattern of seedling recruitment after fires. It has been suggested that the accumulation of ash around the burned tree s, and the differential reaction of seed germination to ash, may be a major cause for the spatial pattern of seedling recruitment after fire s. The results of germination experiments in pots prove that thick cov er of ash has a negative effect on germination of Pinus halepensis Mil ler, and on germination and growth of Cistus salviifolius L. Ash solut ions in petri dishes had no effect on germination and growth of both s pecies. Pinus seems to be more well adapted than Cistus to germination and growth in sites with high amounts of ash after fire. Our results support the hypothesis that the ash around the burned pine trees, and the differential reaction of plant species to the ash may explain the spatial pattern of seedling recruitment after fire. We suggest that th e relatively high resistance of pine seed germination to osmotic stres s is an adaptation to post fire germination rather than to germination in arid zones.