Unusual meteorological phenomena: Vallombrosa forest windthrow caused by the storm of March 5th, 2015. Analyses and evaluations

Catastrophic meteorological events cause relevant economical losses in social and environmental fields, demanding expensive restoration efforts to the public administrations. The windstorm of March 5th, 2015 in Northern and Central Tuscany, besides damaging nursery activity and urban green, caused severe damage to natural stands as well. The stands of the Vallombrosa Forest (Foresta Naturale Statale Biogenetica di Vallombrosa, Firenze, Italy) suffered many windthrows of considerable size. According to preliminary evaluations, 50 hectares of forest, corresponding to 20000 m3 of lumber, were almost entirely destroyed in a matter of few hours. Aim of this work was to analyse the key factors involved in the susceptibility of the Vallombrosa Forest in the effort to provide forest management directions, which focus more on plant stability as well as prevention against the more frequent extreme atmospheric events. Study areas were designed inside the forest reserve. The key factors for forest stability were observed following a posterior approach. By a multidisciplinary logic, the sampling included data regarding: climate, soil, flora, plant pathogens, forest pests, and forest management. Furthermore, consequences on fauna, wood quality, and forestry activities were also considered. This study was conceived as a multi-angle investigation on the causes of such a remarkable event, thus highlighting how all forest dynamics depend on a range of interrelated factors, rather than a single one.