Climate variability, soil aridity, and growth rate of Pinus pinea L. in Castelporziano forest: an exploratory data analysis

Sensitivity to climate change and anthropogenic disturbance is a typical feature of Mediterranean forests growing under dynamic and manipulated environmental conditions. In the present study, a large sample of stone pines (Pinus pinea L.) was analyzed in five sites of Castelporziano and Castelfusano forests (Rome, central Italy) to assess tree-growth variability (1964–2009) with the aim to derive information on long-term climatic trends possibly reflected in the radial growth response. The multivariate exploratory analysis of tree ring widths, which were standardized to remove the age trend, showed a marked spatial variability among sites and a heterogeneous time pattern that allows for the classification of the investigated years into three homogeneous groups: 1964–1974, 1975–1997, and 1998–2009. The years 1975 and 1998 were identified as the candidate break points in the local climate regime. Coherence of the 1998 break point was verified by comparing two time intervals (1981–1997 and 1998–2011) of the meteorological time series of precipitation and temperatures available for Castelporziano station. Results indicate a significant shift toward aridity and warming in the area supporting the information obtained from the analysis of dendro-chronological time series. Implications of the spatio-temporal monitoring of climate variations through indirect sources are discussed in the light of conservation of the residual pristine forest of Castelporziano taken as a paradigmatic example for other Mediterranean coastal forests.