Early reduction of post-fire recruitment of Pinus nigra by post-dispersal seed predation in different time-since-fire habitats

This study analyses the effects of post-dispersal predation of Pinus nigra seeds on the initial recruitment of this species in areas burned by large wildfires, where P. nigra shows very low regeneration. In three different habitats obtained in a gradient of time since fire in Catalonia (NE Spain), we have evaluated the effects of seed predators (ants, rodents and birds) on post-dispersal seed removal and early seedling establishment of P. nigra by using selective exclosures limiting their access to seeds. Ants were the most efficient seed predator group, followed by rodents and birds. The contribution of each group to overall predation showed large seasonal variations. The first seeds dispersed in winter were mainly predated by rodents, which also registered their highest abundance in this season of the year. In spring, at the end of the natural dissemination period of P. nigra seeds, ants became the major predators, this fact coinciding with their increased abundance. Birds showed the lowest predation values. In the seedling establishment experiment, only in the exclusion treatment of the three predator groups was there initial establishment in all habitats, especially in the recently burned area, where there was seedling establishment in all exclusion treatments. The post-dispersal seed predation by different animal groups and low seedling emergence in the different habitats obtained in this study, together with the low seed availability of P. nigra seeds in burned areas, do not predict a favourable outlook for the natural post-fire recolonization of this species, which might even affect its overall distribution area in the region.