Stability of pre- and post-fire spatial structure of pine trees in Aleppo pine forest

The study reported here describes for the first time the similarity between pre- and post-fire spatial patterns of the trees in a Mediterranean pine forest demonstrating that the pre-fire ancestor microsite is occupied also by the next generation. Although Aleppo pine Pinus halepensis Mill. is an obligatory post-fire seeder, it is adapted to regenerate in its pre-fire growing microsite, thus keeping suitable growing sites From generation to generation. We studied the effect of the dead burned adult pines on the density and size of their recruited saplings 2, 5, 11 and 20 yr after fire. A comparison of pine sapling density and size was made between the 'near' zone (under the former effect of the burned canopy) and the 'far' zone (beyond the former effect of the burned canopy). In the site 2 yr after fire, seedling density was 56% higher in the 'far' zone than in the 'near' zone, but seedling size was similar. However in the site 20 yr after fire, densities were similar in both zones, but the size was bigger by 89% in the 'near' zone. Thus, population recruitment after fire seems to peak near the burned pine trees rather than at a distance from them, in contrast to Janzen's original 'distance hypothesis' model suggested for undisturbed rainforest. Here we present a new hypothetical model for the spatial pattern of post-fire regeneration of obligate seeder tree species forming open forests. It is proposed that in such trees the microsites which were kept by the burned adult trees, which are killed by the fire, are also the Favorable regeneration microsite for the post-fire generation.