Physiological aging and site effects on wood properties of Pinus radiata

Effects of physiological ageing on physical wood properties of Pinus radiata D.Don trees were assessed. In the first trial, seedlings and cuttings propagated from 1- to 5-year-old parent trees grown in field trials on two contrasting forest sites (Kaingaroa Forest— pumice, Tairua Forest—clay) were sampled at 11 years. The second trial involved 25-year-old seedlings and cuttings, physiologically aged 12 to 16 years, which were sampled in Kaingaroa Forest. Wood characteristics assessed were stem volume, wood density, heartwood development, spiral grain, compression wood, tracheid length, and corewood percentage. In the trial with trees aged 11 years (physiological age <5 years), there were no significant differences or trends in wood properties associated with physiological age. However, the impact of site was significant for all wood properties measured. In the trial with trees aged 25 years (physiological age 12—16 years), aged cuttings had significantly lower wood density, longer tracheids in rings 2 and 5, and higher spiral grain angles in the first 14 rings when compared to seedlings