SAPWOOD HEARTWOOD PROPORTION RELATED TO TREE DIAMETER, AGE, AND GROWTH-RATE IN PICEA-ABIES

The relationships of sapwood radial width and transverse area to tree diameter, age, and growth rate were investigated in Picea abies (L.) Karst. A total of 125 trees growing with (suppressed trees) and without (dominant trees) competition for light were sampled. Both sapwood and heartwood amounts showed an increase with diameter at the stem base, with the heartwood portion increasing more rapidly. In young trees sapwood prevails both in terms of diameter and transverse area. After trees have reached a certain age, the width of the sapwood band remains more or less constant (on average 7.8 cm for dominant and 2.0 cm for suppressed trees), and the heartwood amount exceeds that of sapwood. The percentage of heartwood in suppressed trees is substantially greater than in dominant trees of the same age. Sapwood amount is closely correlated with the tree diameter, but not with age. Tree age controls the number of rings in sapwood, while the sapwood width depends on the tree's radial growth rate as well.