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

Fairly strong positive relationships between stiffness and density have oft en been reported. No stronger relationships have been found when using para meters of density profiles based on an earlywood-latewood boundary. In this study, we attempt to model the relationships among the stiffness of differ ent samples and simple parameters derived from microdensity profiles, not e stablished 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 relatio nship between a single density parameter and stiffness is r(2) = 0.78, wher eas it is r(2) = 0.37 when involving a classical within-ring density parame ter. At clone level, r(2) ranges from 0.88 to 0.95, while it is 0.51 for th e bulked samples. The mathematical form of the models differ from one clone to another: there is a gene is effect on the models. This could mean that different clones different build their stiffness in different ways. ((C) In ra/Elsevier. Paris.).