European Beech, Fire and Post-fire management in the Southern Alps

Land-use and climate changes may favor future wildfire activity throughout the distribution of the European beech (Fagus sylvatica L.). As a consequence, silviculture in beech forests should adapt to increased fire disturbance. However, the fire ecology of beech is not yet fully understood and post-fire management measures targeted to beech are missing.In this study we assessed the interactive effect of fire severity, masting and silvicultural measures on natural beech regeneration. We studied a stored beech coppice (~55 yrs) affected by a large (480 ha) and intense fire (up to 4000 kW m-1) during the anomalous heat wave in the summer of 2003 in the NW Italian Alps. The survey took place in 2010 in unmanaged stands and sites cut at different times after the fire. In unmanaged sites, residual beech canopy cover and timeliness of stem mortality were related to proxies of fire intensity in complex topographies (i.e., slope; aspect). Where fire severity was high, mortality was immediate and beech failed to regenerate by both vegetative and generative means. In moderate severity patches, beech tree mortality was progressive, permitting abundant seedling emergence as the effect of a masting in 2006. The canopy opening provided intermediate light conditions which favored sapling establishment. In managed sites, sites logged in winter 2007 displayed higher beech regeneration in comparison to delayed cut or unmanaged stands.Our results provide new hints to interpret the environmental prediction hypothesis of beech masting in relation to fire. Post-fire silviculture to increase beech natural regeneration should account for mast years, the time-lag between cutting and the masting, and the timing of the canopy opening. Some surviving beech trees, even if highly damaged, should be retained to serve as seed sources and shelter for their seedlings, and guarantee a woody debris input within the system once they will upset.