Selvicoltura e schianti da vento : il caso della “tempesta Vaia”

On October 29th, 2018, storm Vaia hit forests in north-eastern Italy, causing the loss of 8 million cubic meters of standing trees and, more importantly, the sudden reduction of forest-related ecosystem services. Such event is not unprecedented: a similar storm had occurred in the same regions in 1966. Every year, an average of two extratropical storms affects the European continent, where wind is the most important agent of forest damage, contributing to more than half of total forest losses (38 million cubic meters of downed wood per year). The probability of storm damage in forests depends on four drivers: weather, site conditions, topography, and tree and stand characteristics. However peak wind speed is the dominant factor: over certain gust velocities, trees are broken or uprooted regardless of their characteristics - such velocities were certainly met by the Vaia event. In this case it may be impossible to avoid or mitigate wind damages. Nonetheless, management options to enhance the long-term forest resistance and resilience always exist. In this perspective, the storm Vaia (after the emergency management) and its consequences could be considered as a key lesson to be learned and as an important opportunity to enhance the resilience of Italian forest stands.