The role of dominant tree cover and silvicultural practices on the postfire recovery of Mediterranean afforestations

Abstract

Fire is one of the major disturbance factors in Mediterranean-type ecosystems, where since long time man has deeply modified the natural fire regime. To know how woody species recover after fire is of prominent importance for understanding vegetation dynamics, as well as for the management of Mediterranean plantations, especially where broadleaved and coniferous trees coexist. Our research was carried out at Monte Petroso (Sicily), within an historical afforestation intervention in the Mediterranean basin. We assessed the post-fire response of mixed oaks and oak-pine afforestations within six experimental plots (two plots per homogeneous sector) differing in dominant tree species (Quercus ilex or Pinus pinea), time since last wildfire (1954 or 1982), and post-fire management (understory cleaning and removal of dead biomass or no management). Dendrometric surveys and phytosociological relevés were carried out to characterize the tree layers, the regeneration by woody species plus Ampelodesmos mauritanicus, as well as plant species richness. Our field surveys have confirmed a notably high resilience to fire by Mediterranean woody species, regardless of post-fire management practices. The dominant tree species played a significant role as Quercus ilex seems to foster stand development and the regeneration dynamics in the understory, especially that of Quercus pubescens. By contrast, Pinus pinea seems to slow down the regeneration by woody species, especially at higher stand density. Post-fire management practices seemed to favor mantle shrubs (Prunetalia spinosae) and grassland species (Hyparrhenietalia hirtae), while negatively affecting shrub species (Cisto-Ericetalia multiflorae). In presence of sufficient propagules of native woody species, the option of no management after fire has to be considered. The results of our research may be useful to improve the management of fire-prone Mediterranean plantations, taking into account the differences in plant strategies to cope with fire, as well as the dominant canopy.