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The operational ef® ciency of single-tree and group selection with a single-grip harvester was studied in uneven-aged spruce forests at high altitudes in southern Norway. Three harvest intensities of single-tree selection and two group sizes were examined in group selection. Single-tree selection included harvest intensities of 25, 45 and 65% of basal area. Group sizes for group selection were 0.063 and 0.250 ha. Normally, single-tree selection is considered less ef® cient than group selection or clear-cutting. In this study, because time consumption per cubic metre was primarily dependent upon average harvested tree volume, the large harvested tree size for single-tree selection allowed this treatment to be more ef® cient than group selection. The two blocks in this study were part of a larger design of ® ve blocks with identical treatments under varying stand conditions. The relative operational ef® ciency of single-tree selection compared with group selection was greatest in stands of low stocking. Other studies have also shown that mechanical damage to the residual stand is lowest under these conditions.

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