Health condition of forests in central Italy (Tuscany) after recurrent droughts and heat events

Recently, extreme drought and heat events impacted forest vegetation in several European countries. In central Italy (Tuscany) the impacts on broadleaved tree species were assessed by field observation from 2017 to 2022. The most severe impacts are still occurring on tall evergreen trees and on aged coppices (Quercus ilex and Quercus suber). Deciduous broadleaved species, such as Fagus sylvatica and Quercus pubescens, showed strong summer defoliation in steep sites with shallow soils and on southern slopes. According to our observations, these species can recover the damaged crowns in the years following the summer drought. Quercus cerris showed sudden leaf desiccation and tree mortality in individual or groups of trees. Extensive attacks of opportunistic parasites, favored by drought, are often the ultimate cause of mortality. Heat waves and drought significantly affected also sporadic tree species of the xero-thermic and mesophilous forests (for ex., Fraxinus ornus, Fraxinus angustifolia, Ostrya carpinifolia, Carpinus betulus, Sorbus sp.pl., Acer campestre, Acer monspessulanum etc.), with defoliation, desiccation, and, in the most serious causes, with the death of the trees. The meso-hygrophilous species and relict populations of mountain species (F. sylvatica) are also severely declining, with negative consequences for forest biodiversity. The implementation of an early-warning regional monitoring system, with the installation of “sentinel plots” in the most vulnerable forests, is recommended. A crucial point is the need to adjust forest management to the changed climate-ecological conditions, to preserve canopy cover and the microclimate inside the forest, thus ensuring a suitable environment for tree regeneration and the conservation of ground vegetation.