Models of Knot Characteristics in Young Coastal US Douglas-Fir: Are the Effects of Tree and Site Data Visibly Rendered in the Annual Ring Width Pattern at Breast Height?

Abstract

Abstract The large variation in knot characteristics within and between trees and stands makes proper interpretation of wood properties in the different steps along the forest–to–forest product conversion chain difficult and makes production and use of wood a challenge. Finding good methods and models to interpret the knot characteristics along the different steps of this chain is therefore important. In all, 28 young Douglas-fir (Pseudotsuga menziesii) trees were sampled from four stands with different site indices and tree densities. This gave working material consisting of 189 whorls of knots total. Models predicting knot diameter and sound knot length were developed. Important variables reducing the residual variance were mean annual ring width at breast height, mean annual ring width for different annual ring intervals at breast height, site index, and number of trees per hectare. The study shows that models estimating knot diameter and sound knot length with mean annual ring width for certain annual...