Tree ring and wood anatomical traits responses to climate in Scots pine

Human-induced climate change has already influenced the distribution range of many tree species with several impacts on ecosystem structure and function. In this scenario, many tree species will migrate northward, while at lower latitudes, there will be a more significant loss of present-day species and the likely arrival of organisms adapted to warmer climates. The study aims, combining the methodological approach of dendrochronology with quantitative wood anatomy, to highlight how climate has influenced and is influencing certain xylem anatomical traits of Pinus sylvestris L. We established a transect from the leading edge at northern latitudes to the southernmost limits in Italy and correlated temperature and precipitation records with time series of several parameters associated to cambial activity (mean ring width, number of cells per ring), hydraulic architecture (mean lumen area, theoretical hydraulic conductivity) and plant carbon budget (mean radial, tangential and total cell wall thickness). At the leading edge in Norway, July temperature resulted as the primary limiting factor for tree-ring growth however, mean lumen area and cell wall thickness showed significant negative correlations with temperature during the vegetative period. At the southern limit in the Parma-Reggio Apennines, the species exhibits opposite correlations respect the northern site together with an extended time sensitive window and a high frequency of ring anomalies, e.g. frost rings and intra-annual density fluctuation. By expanding our network to include new sites in various climate settings, we can significantly advance our understanding of how climatic factors influence Scots pine growth within its current natural range. This will provide valuable insights into the species' xylogenesis and offer a crucial perspective on how climate change may impact this important species across the European continent.