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

Abstract

Many studies have found that ash beds favour seedling growth, but the effect of ash on the germinative behaviour of tree species has received little attention. We therefore designed an experiment in which Pinus pinaster, P. radiata and Eucalyptus globulus seeds underwent four different ash treatments and one control. The treatments chosen were three solutions of ash in water (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 replicates of 30 seeds per replicate from each species were used for each treatment. Seeds were incubated on a double layer of filter paper in Petri dishes under laboratory conditions. Germination counts were taken every 2 days until the end of the germination period. The results indicated that ash (in the quantities and under the conditions studied) had no positive effect on the germination of these species. The ash solutions did not significantly alter the germination rate with respect to the control. Only the germination percentages obtained in the ash treatment markedly reduced the germinative capacity of P. pinaster and P. radiata and had a completely inhibitory effect in the case of E. globulus. The mean germination times increased, although only slightly, for each of the three species, with increasing concentrations of ash. Temporal distribution patterns were scarcely modified by the treatments.