Assessing Pinus pinea L. resilience to three consecutive droughts in central-western Italian Peninsula

Climate projections for the Mediterranean area forecast drier and hotter conditions and increasing trend in extreme climatic events such as drought. Scientific evidences reported that extreme dry spells affected the stem growth of different Mediterranean low-elevational pine forests inducing a decrease in tree resilience, defined as the capacity to resist to environmental stress and to recover pre-disturbance functioning. Despite its ecological and economic importance, thus far no study examined Pinus pinea L. (stone pine) resilience to drought events. This research reconstructed stone pine resilience by considering resistance, recovery, and the proportion of trees showing high values of both indexes of several planted stands to three consecutive spring-summer droughts occurred during the second half of the 20th century. Local climatic conditions during dry spells modulated the species resistance and recovery. In this sense, wetter conditions promoted recovery, whereas warmer spring-summer affected stone pine resistance. Moreover, spring rather than summer droughts influenced stone pine resistance and recovery, confirming the species sensitivity to climatic conditions at the beginning of the growing season. Results indicated that while recovery did not significantly changed, the species resistance diminished along the analyzed period. Furthermore, more than 60% of the examined trees were not able to reach pre-drought growth, suggesting a moderate resilience of P. pinea to adverse climatic conditions. The results contribute to improve our understanding of stone pine growth dynamics in the climate-change context of increasing aridity actually occurring in the Mediterranean area, providing useful information for the sustainable management of these natural resources.