Within-tree variation of heartwood and ring width in maritime pine (Pinus pinaster Ait.)

The number of heartwood rings was strongly correlated with cambial age. Heartwood formation was estimated to start at approximately 21 years of age and to proceed at a constant annual rate that increased with age (0.5 and 0.7 rings year−1 below and above 50 years of age). Within the tree, heartwood decreased with stem height, but in the lower part of the stem two patterns of variation were shown: a continuous decrease or an increase from stem base to a maximum at 2-3 m and a decrease afterwards. Sapwood radial width remained approximately constant within the tree and correlated positively with tree growth.