Variation in density and shrinkage of six eucalyptus species and interspecific hybrid combinations at three sites in Northern New South Wales

Abstract

Abstract The study aimed to investigate the variation of density and shrinkage at radial and axial directions of nine eucalypt taxas at three different sites (Muller, Convery, and Ironbolt). The data used in this research was collected from six years old trials of nine Eucalyptus taxa at those three sites. Density and shrinkage were collected from 145 selected trees based on British Standard (BS 373 1957). A two-way analysis of variance and Tukey HSD were used to analysis density and shrinkage parameters. The effect of site, taxa, and interaction between sites and taxas on oven-dry density and shrinkage were statistically significant different (p<0.05). In terms of density, Corymbia variegata provenance Wodum had the highest oven-dry density at 781 kg/m3 (CV=11.7%). There was a significant variation in oven-dry density at the radial and axial directions. The oven-dry density at Diameter at Breast Height (DBH) of all taxas, except E. cloeziana and the hybrid E. grandis x E. camaldulensis, tended to be lower than at the top point of measurement (TMS). In terms of variation in the radial direction, there were three types of trends of oven-dry density from pith outward. In terms of shrinkage, C. variegata provenance Richmond and Wodum, and E. saligna had the lowest radial shrinkage, tangential shrinkage and T/R ratio, while E. dunnii and E. pilularis showed the highest one. Another important finding is that the hybrid between E. grandis x E. camaldulensis and E. urophylla x E. grandis showed higher radial and tangential shrinkage than their parent species (E. grandis).