The Influence of Early Respacing on the Wood Density of Sitka Spruce

Wood density at breast height in a 32-year-old Sitka sprucerespacing experiment in Northern Ireland ranged from 0.42 gcm^–3 in the narrowest spacing to 0.38 g cm^–3 inthe widest. Estimation of variance components showed that only12 per cent of the variation in wood density could be ascribedto crop spacing and 63 per cent to the differences between treeswithin spacings. Regressions of wood density on the basal areafor each spacing indicated extremely weak relationships, thehighest r² not exceeding 0.25. It is concluded that the possibilitiesof manipulating wood density through spacing and thinning areinsignificant in comparison to the potential from breeding orvegetatively propagating trees with desirable characteristics.