WITHIN AND BETWEEN-TREE VARIATION OF BARK CONTENT AND WOOD DENSITY OF EUCALYPTUS GLOBULUS IN COMMERCIAL PLANTATIONS

Abstract

Eucalyptus globulus trees, 15 years old, were sampled at different heights from commercial pulpwood plantations in two sites in Portugal. Bark thickness was higher in the site with better growth and always decreased from the tree base to the top. Bark content was site independent and on average 11% of stem dry weight, higher at the base and top, and lower at 35% height level. Tree mean wood basic density averaged 600 kg /m3 and 568 kg /m3 for best and worst site, respectively, and was not correlated with tree growth. Wood density increased from base to top of the tree. Between-tree variation was low with coefficients of variation of site mean below 10%. Bark density (374 kg /m3 and 454 kg /m3 for best and worst site, respectively) did not show significant within tree variation. Average tree wood density could not be predicted with reasonable accuracy using a breast height sampling and better results were obtained using a sampling as a percentage of total height (e.g. 15%).