Germination of Pinus pinaster, P-radiata and Eucalyptus globulus in relation to the amount of ash produced in forest fires

Many studies have found that ash beds favour seedling growth, but the effec t of ash on the germinative behaviour of tree species has received little a ttention. We therefore designed an experiment in which Pinus pinaster, P. r adiata and Eucalyptus globulus seeds underwent four different ash treatment s and one control. The treatments chosen were three solutions of ash in wat er (0.5, 1 and 5 g L-1) which were used to periodically water the seeds of each species, and a treatment in which a certain amount of ash was applied directly to seeds which were moistened with distilled water only. Six repli cates of 30 seeds per replicate from each species were used for each treatm ent. Seeds were incubated on a double layer of filter paper in Petri dishes under laboratory conditions. Germination counts were taken every 2 days un til the end of the germination period. The results indicated that ash (in t he quantities and under the conditions studied) had no postive effect on th e germination of these species. The ash solutions did not significantly alt er the germination rate with respect to the control. Only the germination p ercentages obtained in the ash treatment markedly reduced the germinative c apacity of P, pinaster and P. radiata and had a completely inhibitory effec t in the case of E. globulus. The mean germination times increased, althoug h only slightly, for each of the three species, with increasing concentrati ons of ash. Temporal distribution patterns were scarcely modified by the tr eatments. (C) Inra/Elsevier, Paris.