Forest vulnerability to extreme climatic events in Romanian Scots pine forests

In the last years, large-scale mass forest withering and dieback have been reported for Scots pine (Pinus sylvestris) across eastern Europe, particularly in Romania. In these regions, the climate models forecast an increase in intensity and frequency of extreme climate events such as drought. Taking into account these aspects, the exact identification of the influences of drought on the loss of radial growth and vitality in Scots pine stands becomes mandatory. To achieve this aim, we developed the first country-wide Scots pine dendrochronological network in Romania consisting of 34 chronologies of basal area increment (BAI), and including 1401 individual tree-ring width series. Romanian Scots pine forests were severely impacted by the 2000 and 2012 droughts. The high temperatures and low precipitation from April to August were the main climatic causes of radial-growth reduction and large-scale withering in some areas. By mapping post-drought growth resilience, we identified locations where resilience was low and could identify foci of future forest dieback and high tree mortality. The projected appearance of similar prolonged and severe droughts in the future will lead to the damage or local extinction of some Scots pine forests in Romania, regardless of their age, composition or spatial location. The elaboration of adaptive forest management strategies to the impact of climate changes, specifically designed for the Scots pine stands, is not possible without knowing and understanding these aspects.