Genetic control of stiffness of standing Douglas fir; from the standing stem to the standardised wood sample, relationships between modulus of elasticity and wood density parameters. Part I

Abstract

The Institut national de la recherche agronomique (Inra) developed a tree-bending machine, similar to the device elaborated by Koizumi and Ueda, and used it to measure the stiffness of standing tree trunks (modulus of elasticity, MOE). There are moderate or good relationships between trunk MOE and MOE based on destructive samples successively sawn in the study stems: the modulometre is able to rank genetic units for a trait related to the MOE of the wood of the stem. Our study showed that there exists a strong genetic effect on trunk MOE. This trait and the MOE measured on destructive samples are moderately related (best r2 from 0.37 to 0.42) with ring density parameters (based on trimming the ring in two parts: earlywood and latewood), and closely related (best r2 from 0.58 to 0.73) with parameters describing the shape of a mean density profile segment, mostly located in the latewood part of the ring.