Modelling the variation in modulus of elasticity and modulus of rupture of Scots pine round timber

Abstract

Recovery from the forest-wood chain is directly influenced by how different qualities of logs are used. Logs used directly as load-carrying members in structures are products in which MOE (modulus of elasticity when bending) and MOR (modulus of rupture) are of great importance. To achieve a more optimal bucking process in the forest, models that enable such presorting of logs for quality are desirable. In all, 533 logs from 150 trees were sampled from 10 stands with different site indices and altitudes in southern Norway. Models were developed that predicted MOE and MOR by using different stand and tree characteristics. The MOR models were compared with a model including MOE alone and a model including both MOE and different tree characteristics. The study showed that it may be a good option to combine different tree and stand characteristics with MOE. MOE and the single-tree variables diameter at breast height and mean annual ring width at breast height most reduced the residual variance when MOR was modelled. The study also showed that it is possible to perform a coarse sorting by simple stand and single-tree characteristics.