Effects of wide spacing and thinning strategies on wood quality in Norway spruce (Picea abies) stands in southern Sweden

The initial density of a stand influences both the prethinning growth and the quality of the harvested trees. This study investigated the effects of different square spacings (2.0, 2.5 and 3.0 m) with thinning from above and thinning from below on stand development and tree characteristics in a 33-year-old Norway spruce [ Picea abies ( L.) Karst.] plantation in southern Sweden. Before thinning the total standing volume was not significantly different between treatments. Diameter at breast height (dbh) and diameter of the thickest branch were positively correlated. Before thinning, dbh of the trees and their thickest branches were significantly higher in the stands with 3.0 m spacing. After thinning, the dbh and the diameter of the thickest branch did not significantly differ between the 3.0 m spacing with thinning from above and 2.0 and 2.5 m spacing with thinning from below. Spacing did not significantly influence the presence or size of spike knots. The results suggest that a combination of wide spacing with thinning from above may yield timber of similar quality to denser spacing with thinning from below.