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 II

Abstract

Fairly strong positive relationships between stiffness and density have often been reported. No stronger relationships have been found when using parameters of density profiles based on an earlywood-latewood boundary. In this study, we attempt to model the relationships among the stiffness of different samples and simple parameters derived from microdensity profiles; not established according to an earlywood-latewood boundary. Furthermore, we try to determine if there is a genetic variation for the relationship between stiffness and density. From the results, we find that the strongest relationship between a single density parameter and stiffness is r2 = 0.78, whereas it is r2 = 0.37 when involving a classical within-ring density parameter. At clone level, r2 ranges from 0.88 to 0.95, while it is 0.51 for the bulked samples. The mathematical form of the models differ from one clone to another: there is a genetic effect on the models. This could mean that different clones different build their stiffness in different ways.