Roberto Mercurio

A review of the roles of forest canopy gaps

Treefall gap, canopy opening caused by the death of one or more trees, is the dominant form of disturbance in many forest systems worldwide. Gaps play an important role in forest ecology helping to preserve bio- and pedo-diversity, influencing nutrient cycles, and maintaining the complex structure of the late-successional forests. Over the last 30 years, numerous reviews have been written describing gap dynamics. Here we synthesize current understanding on gap dynamics relating to tree regeneration with particular emphasis on gap characteristics considered critical to develop ecologically sustainable forest management systems and to conserve native biodiversity. Specifically, we addressed the question: how do gaps influence forest structure? From the literature reviewed, the size of gaps induces important changes in factors such as light intensity, soil humidity and soil biological properties that influence tree species regeneration and differ in gaps of different sizes. Shadetolerant species can colonize small gaps; shade-intolerant species need large gaps for successful regeneration. Additionally, gap dynamics differ between temperate, boreal, and tropical forests, showing the importance of climate differences in driving forest regeneration. This review summarizes information of use to forest managers who design cutting regimes that mimic natural disturbances and who must consider forest structure, forest climate, and the role of natural disturbance in their designs.

New approaches concerning forest restoration in a protected area of central Italy: an introduction

Abstract Following a review of the traditional afforestation techniques in Italy, the new forest restoration criteria and techniques require creativity with a solid scientific knowledge and further aims need to be pursued to maintain or enhance biodiversity and repair ecosystem functions. A case study concerning forest restoration of abandoned agricultural land in the Gran Sasso and Monti della Laga National Park (central Italy) was analysed. The choice of native tree species was carried out according to the symphytosociological approach; the restoration of vegetation may be accelerated by planting early successional tree species belonging to the same series of vegetation. The cultural techniques included the partial release of shrub vegetation invading abandoned land, and site preparation techniques of low environmental impact (i.e. clustered arrangement, curved rows) applied according to soil morphology. Five years after planting, damage by animals, survival rates, vitality status and total height of different tree species, and effects of competition by shrub vegetation on tree growth were assessed.