New evidence for population-specific responses to drought events from tree ring chronologies of Pinus nigra ssp. laricio across the entire distribution range

The increased frequency and severity of drought events due to climate warming is negatively affecting tree radial growth, particularly in drought-prone regions, such as, e.g., the Mediterranean. In this climate change hotspot, populations of the same tree species may show different growth responses to climate, due to the great variety of microclimates and environments that characterise this biogeographic region. In this study, we analysed growth-climate relationships and growth responses to drought events (i.e., resistance, recovery, and resilience) in 13 forest stands of black pine (Pinus nigra Arnold), encompassing the whole and peculiar distribution range of the ssp. laricio (Calabria, Sicily, Sardinia, and Corsica). Analysis focussed on the 1981–2010 period, which is commonly covered at all sites. Stem radial growth of trees increased under a positive spring/summer water balance. However, abundant winter precipitation had a negative impact on stem radial growth. Populations in Corsica were more sensitive to drought, showing lower resistance and resilience than those in Sicily and Sardinia. Older trees were more resistant to drought events than younger trees. Our results highlight that population-specific responses to drought events are mainly explained by tree age and local environment, suggesting geographically related patterns in tree growth and forest productivity correspond to different populations. Intraspecific variability in sensitivity to drought events should be included in species distribution models to predict the range of forest productivity responses to climate change.