AUTOSAW simulations of lumber recovery for small-diameter Douglas-fir and ponderosa pine from southwestern Oregon.

Abstract

Small-diameter (5- to 10-inch diameter at breast height) Douglas-fi r (Pseudotsuga menziesii (Mirb.) Franco) and ponderosa pine (Pinus ponderosa Dougl. ex Laws) trees were assessed for product potential by diagramming the location, size, and type of knots visible on the wood surface (inside bark) and using the AUTOSAW sawing simulator to evaluate the resulting log descriptions. The logs were then sawn to dimension lumber, dried, and graded. More than 85 percent of the resulting Douglas-fir lumber was assigned to the "No. 2 and better" group, whereas about 50 percent of the pine was assigned to the "Standard and better" group. AUTOSAW consistently underestimated (by 10 to 15 percent) the volume recovered from the logs. A correction factor could be applied to compensate for this variance. The simulator predicted higher yields of higher grade lumber than were obtained empirically. This was anticipated given the program’s inability to account for knots hidden beneath the wood surface. Alternative sawing scenarios examined by using AUTOSAW suggest that greater value could have been recovered from the small-diameter Douglas-fir if it had been cut to 1- or 5/4-inch thickness and graded as "Factory" lumber. The ponderosa pine would have been more valuable cut to 1-inch thickness and graded as "Common" rather than dimension lumber.

Citation

Barbour, R. James; Parry, Dean L.; Punches, John; Forsman, John; and Ross, Robert. 2003. AUTOSAW simulations of lumber recovery for small-diameter Douglas-fir and ponderosa pine from southwestern Oregon. Res. Note PNW-RN-543. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 11 p