Early postfire vegetation recovery of Pinus brutia forests: effects offire severity, prefire stand age, and aspect

Abstract

Forests dominated by serotinous tree species are usually generalized to follow an autosuccessional model of postfire recovery. However, recent studies have suggested that prefire conditions, topography, and idiosyncrasies of the fire disturbance can have notable effects on how such forests respond to fire. We investigated the effects of fire severity, prefire stand age, and aspect (slope orientation) on the early postfire recovery of Pinus brutia forest. The study site was the area of 2008 Serik-Tasağıl Fire, one of the largest forest fires in Turkish recorded history. We sampled early postfire conditions at five sites having different conditions in terms of fire severity, prefire stand age, and aspect. Sampling was carried out for 5 years after fire. First year floristic composition was clearly different from the following years and floristic differentiation generally slowed by the fifth year. Plant species richness declined in young stands and mature stands experiencing crown fire, whereas it was more stable in mature stands experiencing surface and mixed fire. In mature stands, richness of annual and obligate seeders varied according to fire severity while stands of different prefire stand age showed differences in richness of annuals, Asteraceae and Poaceae. Young stands with different aspects were also significantly differentiated in terms of annuals, obligate seeders, and Asteraceae. Every site in the study was dominated by woody plants but no P. brutia regeneration was observed in stands that were still young when they burned, suggesting that in the absence of direct P. brutia planting such sites will remain under the dominance of other woody plants. Our results showed that differences in stand age, fire severity, and topography play an important role in defining the actual direction and velocity of forest recovery after fire. Regenerative traits of species play important roles as well. Our findings provide valuable information for managers and scientists interested in the postfire restoration of P. brutia forests. Managers should take into account prefire conditions, topography, and fire severity when developing restoration strategies for forests dominated by serotinous species.