Compressing and Drying of Bunched Trees from a Commercial Thinning

Abstract

This study focuses on the power needed to compress bunches of tree-parts (undelimbed trees, cross-cut into two or more pieces) and the change in moisture content of bunches during air-drying. Thirty-five bunches (green weights 209-954 kg) were formed, 5.5 m long. The bunches were compressed by a chain being wound once around them at three points and tightened, one at a time. The bunches were air-dried and then chipped. A small bunch was more tightly compressed at a specific force than a large bunch. The bulk density (green weight) was 270-460 kg m^-3 (16 kN compression) and 520-780 kg m^-3 (53 kN compression). Small forces resulted in a higher bulk density for pine or birch bunches than for spruce bunches, while large forces caused the opposite result. A compressed bunch dried almost as well as if not compressed. Chipping bunches was found to be less time consuming than chipping individual trees.