Relationships between mountain pine and climate in the French Pyrenees (Font-Romeu) studied using the radiodensitometrical method

Abstract

A radiodensitometrical study was carried out on 46 Pinus uncinata (Ramond) in Font-Romeu (French Pyrenees). Correlation functions with monthly climatical data were calculated using separately the ring-widths, the earlywood and the latewood densities. The Mountain Pine shows narrow rings (1.5 mm) and a high sensitivity to climate (M.S. = 0.221), but it does not seem to suffer from drought despite the dryness of the climate (788 mm rainfall per year). This species is more sensitive to temperature than to precipitation, since temperature governs latewood formation. A hot spring and a mild autumn with maximum temperatures above threshold levels will extend the growing period. A warm autumn also increases the latewood density, whereas cold nights during the previous year's autumn are unfavourable to growth because they may affect the cambium and bud initiations.