Lumber Grade Recovery from Straight Aspen Logs

A total of 609 straight trembling aspen logs, ranging in diameter from 6 to 17 inches and in length from 8 to 16 feet, were grade sawn into either 2-inch framing lumber or l-inch factory lumber. The framing lumber, graded by West Coast Lumber Bureau (WCLB) rules, contained almost 90 percent Standard (No. 2) and better grades; while the factory lumber, graded by National Hardwood Lumber Association (NHLA) rules, contained approximately 25 percent No. 1C and better. For logs less than 10 inches in diameter sawn into NHLA-graded lumber, the yield of No. 1C and better dropped to 6 percent. In contrast, even in logs having diameters of only 6 or 7 inches, the yield of framing lumber averaged 75 percent Standard (No. 2) and better. Thus, more extensive utilization of the available aspen resource appears to hinge upon the market acceptance of framing lumber. The product value of each log, expressed as the value of lumber and pulp chips per gross cubic foot, was used as an index of log quality for the derivation of log grading rules. Although special measures describing log-surface-defect indicators were found to be statistically important, and were incorporated in the grading rules, almost half of the variation in log quality was accounted for by log diameter and the percentage by volume of decayed wood.

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