Predicting branch diameters on second-growth Douglas-fir from tree-level descriptors

The quality of lumber and veneer recovered from logs of Douglas-fir (Pseudo tsuga menziesii (Mirb.) Franco) is directly influenced by the maximum limb size attained on the crop tree. Because limb sizes are influenced by stand- density regimes, a need has arisen for quantitative tools that link a wide array of silvicultural regimes to wood-product quality by accounting for si lvicultural effects on crown development. An equation for estimating maximu m branch size at a given level within the live crown was developed from dat a collected on 96 felled sample trees in the Coast Ranges and Cascade footh ills of Oregon and Washington. Height and basal diameter of the largest bra nch within each live whorl were measured on each felled tree, and a predict ive equation was developed by various regression techniques. The final mixe d-effects nonlinear model estimates maximum branch size as a function of de pth into crown and tree diameter at breast height, height, and live crown l ength.