The influence of tree spacing on Sitka spruce growth.

In Northern Ireland Sitka spruce is the most important single species planted, but often it is found on sites where thinning operations are costly. There is interest in growth development without thinning for the species with particular regard to gross increment and size of individual trees. The experiment used a 12 year old crop with mean height of 4 metres just before thicket stage. Tree height, DBH, mean volume per tree, basal area per sub-plot and per hectare, volume per hectare, branchiness, tree volume, frequency distributions, form factor, form height of crop, mortality and volume/basal area relationship were assessed. It is suggested that much better financial returns would be obtained by longer rotations under usual conditions.