Climatic signals of tree-ring in Quercus gussonei (Borzì) Brullo in the Mediterranean region

Change in growth is among the primary response of trees to environmental variation. Tree-rings contain a wealth of information related to the climatic conditions. A dendroclimatic study on Quercus gussonei (Borzì) Brullo was carried out in the Nature Reserve of “Bosco della Ficuzza, Rocca Busambra, Bosco Del Cappelliere, Gorgo Del Drago” (southern Italy). Q. gussonei is an endemic deciduous oak and thermophilous form of Quercus cerris L. that is found only in Sicily, although with clear sign of decline. The knowledge of ecology of this species should help to establish criteria for forest conservation in the Mediterranean region. For definining the ecological character and understanding the potential causes of the oak decline, we collected cores from ten trees with an increment borer. Precipitation and temperature data were obtained from a meteorological station located nearby from the stand. Annual ring widths, earlywood and latewood analyses were used in order to investigate and better understand the climatic dynamics influencing the oaks’ growth. We determined the stable isotope discrimination of carbon (D13C) in the wood in order to investigate wateruse efficiency variations and the expression of possible plant adaptive traits. Climate-growth relationship, for the chronology 1951-2008, were analyzed using response, correlation and moving correlation functions. Our finding mostly highlight relationships between tree-rings width and climate data. Furthermore, D13C in treerings was used to identify long-term adjustments in water-use efficiency.