Stem eccentricity, crown dry mass distribution, and longitudinal growth strain of plantation-grown Eucalyptus nitens after thinning

Silvicultural treatments that aim to improve tree growth rates also have the potential to alter physical characteristics of the tree stem and thus affect the recovery of solid-wood products. We tested the hypothesis that manifest crown asymmetry in thinned Eucalyptus nitens (Deane & Maiden) Maiden plantations was affecting the development of stem shape. The crown and stem characteristics of 15 E. nitens trees, from a 22-year-old thinning trial in northeastern Tasmania were examined. The trial had been thinned 16 years previously. Lowering the intensity of local intraspecific competition through thinning increased the crown dry mass in the north-facing aspect. No direct link was found between crown dry mass distribution and stem eccentricity. The direction of pith eccentricity at 3.0 m height was confined to the northwest and southeast sectors and averaged 11%; the degree of noncircularity in stems at 3.0 m height was strongly related to the ratio of stem diameter to total height squared. These results suggest that the dynamic loading from wind exposure plays a greater role in determining the extent and direction of pith eccentricity and stem cross-sectional circularity in E. nitens than does the static load from asymmetrical crown dry mass distribution.