The modulus of elasticity of hybrid larch predicted by density, rings per centimeter, and age

A total of 492 specimens from eighteen trees representing fast-growth larch were studied. The mean values of the modulus of elasticity (MOE), density, age, and rings per centimeter were determined for each. Mathematical model s were developed to predict the MOE from the other parameters, Linear model s are first presented showing the dependence of MOE on each of the three pa rameters, density, age, and rings per centimeter. A multivariate linear reg ression model is then developed for MOE as a function of all three paramete rs. The correlation coefficient of this model is 0.66, an improvement over each of the models for which each parameter is taken individually. A predic tion of MOE by visual means alone, i.e., using only age and rings per centi meter in a linear model, is also presented. The correlation coefficient of this model is 0.58, which is superior to any of the parameters taken indivi dually. In order to develop a model useful for extrapolation beyond the ran ge of test data, a nonlinear model is presented. The parameters of this non linear model can easily he interpreted in terms of (1) the maximum attainab le stiffness, (2) the ring age for maximum MOE growth rate vs, age, and (3) the shape parameter of the model. We found that the nonlinear model marche d the data well and incorporated the realistic conditions of zero MOE at ze ro ring age and a limit on the maximum attainable MOE.