An anomalous event of drought and heat occurred in central Italy during the summer of 2017. Based on the SPI (Standardized Precipitation Index) and data from the European Space Agency, this event started in November 2016 and was characterized by a strong reduction of precipitation and soil moisture, especially in lowland areas with Mediterranean climate. The aim of this case report were to describe the impact of this event on representative forest communities in central Italy, to analyze the different responses of deciduous and evergreen tree and shrub species in contrasting environmental conditions and to assess their subsequent capacity of recovery or, if not, mortality. Trees suffered severe impacts consisting of widespread crown defoliation, leaf desiccation, crown dieback and whole tree mortality. Deciduous tree species (Fagus sylvatica, Quercus pubescens, Quercus cerris) shed their leaves during the summer, but apical buds and twigs were preserved. This allowed these species to produce new shoots in the following year (2018) and to restore the canopy closure of the stands. Mediterranean evergreen broadleaves, such as Quercus ilex and Phillyrea latifolia suffered of total or partial crown desiccation with wilting leaves and branch dieback. These species partially resprouted in 2018 from axillary and latent buds. The case presented here is discussed within the wider context of the impacts of climate change on Mediterranean forests. Future research directions should include an effective forest monitoring system that combines terrestrial and remote sensing surveys, ad hoc field climate change experiments and silvicultural trials from the perspective of proactive management for the adaptation of forests to future climatic conditions.

Climate change in progress: observations on the impacts of drought events on Tuscan forestsThe empirical observation of the impacts of drought and heat waves that occurred between 2017 and 2022 in several forest areas of Tuscany allowed to describe various processes and effects on forest trees and shrubs. The most severe impacts were observed on the evergreen Mediterranean tall woodlands and the aged coppices (on holm oak trees), causing defoliation and even mortality. In most cases, the attempts of resprouting from dormant buds (from the base of the tree trunk or in the crown), following the drought events, were not successful. Deciduous broad-leaved trees (beech, downy oak) suffered a strong summer defoliation, especially on steep slopes with shallow soils and south-facing aspect. These species were generally able to replenish the foliage the following year. In the most unfavorable conditions, however, we observed extensive attacks of opportunistic parasites, such as the fungi of the genus Biscogniauxia, which were favored by drought and were the ultimate cause of mortality. Turkey oak showed mortality in small groups or individual trees. Heat and drought also affected several minor tree species, with defoliation, desiccation and, in the most serious causes, death of the tree. Some mesohygrophilous species that are restricted with relict populations to specific microclimatic sites within the Mediterranean and sub-Mediterranean habitats were also impacted, with consequences on biodiversity, regeneration, and production of fruits for wildlife. Increasing drought and heat will trigger regressive dynamic processes that will lead in many sites to the transformation of holm oak forests into bushy forms of scrub, and of scrublands into sparse garrigues or even steppes. A more intense natural thinning of aged coppice stands with especially Turkey oak is also occurring, due to the combined effect of drought and intra-or inter-specific competition. The implementation of a regional monitoring system is recommended, based on the integration of past and existing experiences with new initiatives, to quantify the dynamics, extent and severity of the impacts. A crucial point is the need to adapt forestry, and especially utilization of coppice woods, to the changed ecological conditions to avoid increasing the impact on them.