Volume recovery, grade yield, and properties of lumber from young-growth Sitka spruce and western hemlock in Southeast Alaska

Wood volume recovery, lumber grade yield, and mechanical properties of young-growth Sitka spruce (Picea sitchensis (Bong.) Carr.) and western hemlock (Tsuga heterophyla (Raf.) Sarg.) were examined. The sample included trees from commercially thinned and unthinned stands and fluted western hemlock logs obtained from a sort yard. Mean cubic recovery of lumber volume from all sawn logs was 44.9 percent. More than 90 percent of the lumber was graded as No. 2 or better; about 5 percent was Clear (C-Select or D-Select), and about 10 percent was Select Structural. No differences in volume recovery or grade yield due to thinning were noted for Sitka spruce logs. For western hemlock, more volume was recovered from trees in unthinned stands; more Select Structural and No. 1 lumber and less No. 2 lumber was produced from thinned stands. No differences in volume recovery or grade yield were noted between fluted and unthinned western hemlock. Bending properties were found to be excellent for this resource. All grades for both species exceeded or matched published bending modulus of elasticity (MOE) values for these species. No differences in MOE were noted between thinned and unthinned lumber from both species. Slightly higher MOE values were noted in fluted western hemlock for the No. 1 and No. 2 lumber grades. Lumber from this young-growth resource appears best suited for structural light framing or molding and millwork, based on visual grading rules and mechanical properties observed.