RING WIDTH VARIATION AND HEARTWOOD DEVELOPMENT IN QUERCUS FAGINEA

High-value exploitation of endogenous forest species may help in fighting the threat to their sustainability, as is the case for Quercus faginea Lam. (Portuguese oak) for which research is underway to determine the wood potential for high-quality products. Ring widths were measured in 20 trees in two sites in Portugal and within-tree heartwood and sapwood development was determined. The wood shows distinct ring porosity. The mean annual radial growth at dbh was 2.3 and 1.0 mm for the two sites, respectively. Ring width decreased with cambial age, ie 3.1 +/- 1.2 mm in the first 10 rings to 1.3 +/- 0.8 mm at around 40 yr (site 1). Ring width decreased axially from the tree base upward but the variation was small. The trees showed a relatively high proportion of heartwood, ie 60-70% heartwood for 20-25 cm wood diameters that decreased with height, and followed the stem profile. Heartwood diameter was modeled as a function of stem diameter, to be used for heartwood estimation in standing trees. Sapwood width was relatively constant. Overall the stem quality was found to be good for production of solid wood products regarding ring and heartwood features.