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

Authors:
  • DMDouglas A. Maguire
    Douglas A. Maguire
  • SJStuart R. Johnston
    Stuart R. Johnston
  • JCJames Cahill
    James Cahill
  • GMGlen E. Murphy
    Glen E. Murphy
  • MAMauricio A. Acuna
    Mauricio A. Acuna
  • IDIan Dumbrell
    Ian Dumbrell
  • OHOlav Høibø
    Olav Høibø
  • GVGeir I. Vestøl
    Geir I. Vestøl
  • GTGuillermo Trincado
    Guillermo Trincado
  • HBHarold E. Burkhart
    Harold E. Burkhart
  • DBDavid G. Briggs
    David G. Briggs
  • RKRapeepan Kantavichai
    Rapeepan Kantavichai
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Abstract
The quality of lumber and veneer recovered from logs of Douglas-fir (Pseudotsuga 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 silvicultural effects on crown development. An equation for estimating maximum branch size at a given level within the live crown was developed from data collected on 96 felled sample trees in the Coast Ranges and Cascade foothills of Oregon and Washington. Height and basal diameter of the largest branch within each live whorl were measured on each felled tree, and a predictive equation was developed by various regression techniques. The final mixed-effects nonlinear model estimates maximum branch size as a function of depth into crown and tree diameter at breast height, height, and live crown length.