Variations in the radial growth and wood density components in relation to cambial age in 30-year-old Pinus brutia Ten. at two test sites

Abstract

Radial growth and wood density are important traits in assessing wood quality. Our objective was to investigate patterns of variation of radial growth (ring width, earlywood width, latewood width, latewood proportion) and wood density (ring average density, earlywood density, latewood density) components in a 30-year-old Pinus brutia at two test sites in Turkey. Wood increment cores at a height of 1.30 cm (dbh) from 1,010 trees at age 30 years were evaluated at two test sites. The radial growth and wood density traits of the individual rings were measured using X-ray densitometry. The test sites showed statistically significant differences in the radial growth traits but not in the wood density traits, suggesting that the wood density traits are less subject to environmental changes. The ring average density was relatively low (485 kg/m3) at early cambial ages (near the pith) and increased to 501 kg/m3 at later cambial ages (near the bark). The latewood density was 550 kg/m3 near the pith, increased steadily to 630 kg/m3 at cambial age 12, and remained stable thereafter. In contrast, the earlywood density and latewood proportion were highest near the pith. The twelfth ring from the pith appeared to represent the transition from juvenile to mature wood. The unique relationships among early and latewood densities and latewood proportion in the juvenile and mature wood contribute to more uniform wood both within a given annual ring and between the juvenile and mature portions of the stem in P. brutia. Thinning increased the ring width, latewood proportion, and ring average density.