Mediterranean forest vulnerability to climate pressure: the case of Quercus ilex L. dieback and mortality in central and southern Italy

Forest vulnerability to climate change has significantly increased in recent decades, affecting the vegetation productivity and health. Climate-driven hotter droughts are leading to widespread canopy dieback episodes, rising tree mortality rates and today representing a significant threat to forests, also in Mediterranean areas, where evergreen sclerophyllous vegetation is considered resistant and adapted to drought stress. In Italy, the first reports of dieback of Q. ilex forests due to climatic events date back to 2012 and, in a more extensive manner, concern the extreme drought in the year of 2017 (1, 2). During the summer of 2024 a widespread decline occurred in several regions of central (Tuscany) and southern Italy (Apulia and Basilicata) and on the islands (Sicily and Sardinia, fig. 1a, 1b). Symptoms of dieback, such as total or partial leaf browning (fig. 2a, 2b, leaves and twigs desiccation, emission of epicormic shoots, crown defoliation and tree mortality were observed on evergreen sclerophyllous vegetation, mainly in Quercus ilex L. and Q. suber L. stands and shrubs (Myrtus communis L., Phillyrea sp., Arbutus unedo L., Pistacia lentiscus L.). The decline events were often associated with pathogens, such as Phytophthora species and Biscognauxia mediterranea. This contribution provides an overview of the current Mediterranean evergreen vegetation decline in Italy, which is now of national importance. Due to the severity and increasing frequency of these decline events, there is an urgent need to improve forest monitoring networks, with regional initiatives aimed at assessing the dynamics of the environmental drivers (climate, site, management) and impacts, by means of a multidisciplinary approach, with ecological, physiological and phytopathological investigations, as well as the involvement of forest managers and citizens in the early detection of impacts