Use of canopy gap openings to restore coniferous stands in Mediterranean environment

Abstract

In Mediterranean regions, climate change increasingly affect tree species distributions. Conifer forests under continuing disturbance show a more rapid shift to dominance by beech and other temperate broadleaves. Thus, there is an urgent need to conserve coniferous vegetation to avoid local extinction. Gap opening has profound effects on the structure and dynamics of most forests and may represent a sustainable way to restore coniferous ecosystems in Mediterranean habitats. What kind of artificial canopy opening is the most sustainable and effective means for restoring coniferous ecosystem functions? We explored the efficacy of artificial gaps in regeneration and dynamics of coniferous in Mediterranean environment. We examined how regeneration of different tree species is associated with soil environmental conditions and how gaps of different sizes influence the ecology and management of Mediterranean forest. Specifically, we analyzed gap disturbance in silver fir and black pine stands, as they dominate central and southern Italian forests. We demonstrated a specificity between gap size and coniferous species regeneration, indicating that small gaps (about 200 m2) favor silver fir regeneration, while black pine, depending on its subspecies, regenerates both in small and medium gaps (about 500 m2). Further, we found that gap characteristics (age and shape) and suitable substrate availability are the primary factors affecting seedling establishment. Our results provide functional information to design a silvicultural system useful to manage the natural regeneration of Mediterranean forest minimizing the environmental and visual impact.