Lumber grade yield, and value of plantation-grown black spruce from 3 stands in northwestern Ontario

Abstract

Three black spruce plantations in northwestern Ontario, with varied stand densities and site indices were studied to determine lumber properties and yield. Based on visual grading rules, each stand produced at least 87% No. 2 and Better grade lumber. Wane and skip were the 2 most prominent defects causing lumber downgrades. The compliance of visually graded No. 2 and Better lumber with bending modulus of elasticity (MOE) design values for visual grades varied among stands, as did the proportion that qualified as machine stress-rated (MSR) lumber. MOE and Modulus of Rupture (MOR) differed among stands, consistent with differences in MSR yield. The stand with the highest density and the lowest site index produced the highest yield of MSR grade lumber, but not the highest compliance with bending MOE design values. Regardless of the grading scenario, the most productive stand with the largest average tree size produced the highest value per hectare ($28K per ha) under an MSR grading scenario. These results suggest that MSR grading can improve revenues, and that it will be needed to maintain market confidence in the quality of lumber from second-growth black spruce stands. Key words: lumber quality, Picea mariana (Mill.) BSP, market value, density regulation, stand-level effects, intensive silviculture