Comparison of non-destructive assessment techniques for shrinkage and collapse in Eucalyptus nitens

In recent years, E. nitens growers in southern Australia have established substantial areas of plantation to produce sawlog- and veneer-quality timber in addition to pulpwood. Drying degrade, manifested as checking (radially-oriented cracks) brought about by excessive collapse (excessive shrinkage of timber caused by the buckling or flattening of cells), has been identified as a problem that may significantly reduce recovery of appearance-grade sawntimber from such plantations. Collapse occurs in the initial stages of timber drying as free water is removed from cell lumens. True shrinkage occurs later in the drying process as water is removed from cell walls (Raymond et al. in press). This study expands on work undertaken by Kube and Raymond (2001) and Raymond et al. (in press) aimed at developing a suitable low-cost non-destructive technique to assess the propensity of an individual tree's timber to collapse upon drying. It investigates different methods of assessing total core shrinkage (i.e. true shrinkage plus collapse) in dried wood cores. Genetic parameters are presented for each method of total shrinkage assessment, DBH and basic density.