Early vegetation recovery of a burned Mediterranean forest in relation to post-fire management strategies

Abstract

Abstract The risk of wildfires in the Mediterranean region is expected to increase with climate change. Fire is one of the main drivers of plant diversity and composition, triggering succession processes that vary according to the fire regime and species’ regeneration traits. Human management can modulate these processes to promote the recovery of the burned soil-vegetation system, through the application of practices such as salvage logging. Effects of these managements have been studied mostly for coniferous forests, with contrasting results, while little is known about the responses of evergreen broadleaved woodlands. Here, we analysed the 34-month recovery processes of a Quercus ilex forest and an adjacent Pinus pinaster stand in central Italy with respect to their diversity, composition and plant fire-related traits, in relation to three different management strategies applied after fire. These were: (1) no intervention (NT), (2) salvage logging and mulching (SM and SMP for the pine stand), (3) salvage logging, mulching and erosion control measures (e.g. fascines for hill slope stabilization; EC). Overall, the increase of post-fire vegetation cover was negatively affected by SM and EC treatments, while their effects on ɣ- and α-diversity were positive. Species diversity was significantly lower in pine than in broadleaved plots and compositional differences associated with forest type were significant. Abundance of woody species was higher in the unsalvaged sites, except for a few species (e.g. Q. ilex), while herbaceous plants were not affected. Species composition in managed plots was different from control plots after 10 and 22 months, while differences decreased after 34 months. Effects of management strategies on the frequency of resprouters as well as on the proportion of species with persistent vs transient soil seed bank were minor; these traits were mainly driven by forest type. Our findings suggest that non-treatment is the best post-fire management strategy for a fast recovery of woody species in typical Mediterranean broadleaved forests. However, the EC strategy promoted a high diversity level, while not apparently altering species composition compared with the natural post-fire succession process.