Response of Pinus leucodermis to climate and anthropogenic activity in the National Park of Pollino (Basilicata, Southern Italy)

Pinus leucodermis (=P. heldreichii var. leucodermis) is widespread in the Balkan Peninsula and is present as a post-glacial relict in Southern Italy. The oldest Italian populations of this species are located at high elevation in the National Park of Pollino, where grazing and logging had endangered their survival, especially during the 20th century. In 1993 the National Park was founded and anthropogenic activities were restricted. To understand the response of P. Leucodermis at the upper tree-line to climatic and anthropogenic activity variations, we developed a tree-ring width chronology (1464–2003). For the period 1804–2003 separate chronologies for the earlywood and latewood were built, and resin duct density was assessed on total ring, earlywood and latewood. Age structure of saplings was also determined. After 1950 a steep decline in tree-ring width was followed by a recovery since 1981. During the 20th century radial growth response to climate was not strong and not stable. In the period 1953– 2000 P. leucodermis radial growth seemed to take advantage of high temperatures and low precipitation. Resin duct density chronologies were not a reliable dendroecological variable, but they documented a metabolic trade-off between growth and differentiation processes. The gap in the age structure between long-lived trees (over 200 years old) and saplings around 40 years old, which mainly grow in protected microsites between rocks, could indicate a negative influence of grazing and related human activities. We suggest that the protection strategies introduced by the National Park could play a positive role in the recruitment of new saplings and in the ring growth recovery of old trees of P. leucodermis