Modelling the influence of radiata pine log variables on structural lumber production

22 We run logit models to explain the variability of Pinus radiata structural lumber in 71 second and third 23 unpruned logs. The response variable was the proportion of lumber with a static modulus of elasticity 24 greater or equal than 8 GPa, p MSG8+, and the explanatory variables were log volume, branch index, 25 largest branch, log internode index, wood basic density, and acoustic velocity. The average p MSG8+ 26 volume was 44,30 % and 36,18 % in the second and third log respectively. Ten models were selected 27 based on meeting statistical assumptions, their goodness of fit, and the statistical significance of their 28 parameters. The best models (R 2 - adj. > 0,75) included acoustic velocity (AV) as explanatory variable, 29 which explained 56,25 % of the variability of p MSG8+. Models without AV presented goodness of fit 30 ranging from 0,60 to 0,75 (R 2 - adj.), and variables with the highest weight to explain the variability of 31 p MSG8+ were volume, followed by wood basic density, branch index, and largest branch. It is possible 32 to model p MSG8+ from log variables even when acoustic velocity is not available; however, this 33 requires wood basic density models calibrated for the Pinus radiata growing zone.