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

Abstract

Wood density at breast height in a 32-year-old Sitka spruce respacing experiment in Northern Ireland ranged from 0.42 g cm −3 in the narrowest spacing to 0.38 g cm −3 in the widest. Estimation of variance components showed that only 12 per cent of the variation in wood density could be ascribed to crop spacing and 63 per cent to the differences between trees within spacings. Regressions of wood density on the basal area for each spacing indicated extremely weak relationships, the highest r 2 not exceeding 0.25. It is concluded that the possibilities of manipulating wood density through spacing and thinning are insignificant in comparison to the potential from breeding or vegetatively propagating trees with desirable characteristics.