Tree Properties and Yield of Picea abies Planted in Shelterwoods

Tree properties affecting timber quality and yield were examined in six stands of Norway spruce [Picea abies (L.) Karst.] planted in shelterwoods. For each stand a pairwise comparison was made with trees planted in the open. When compared 16–32 yrs after planting, the sheltered trees were generally shorter and had thinner trunks than the open-grown ones. Furthermore, sheltered Norway spruce had thinner branches, a lower average annual ring width and a lower frequency of defects such as spike knots, forked stems and sharp bends. The reduction in ring width was significant for ring numbers 1–5 and 6–10. No significant differences in basic density were detected between treatments. The yield of Norway spruce was lower for sheltered trees than for those growing in the open. Total volume yield, however, including shelter trees, was higher on the sheltered plots.