Influence of Position in Tree on Recoverable Collapse in Wood

Describes the results of an investigation on two ash eucalypts of the influence of position in tree on collapse intensity. Material was taken from six Victorian-grown trees of E. regnana approximately 50 years old and 100-120 feet in height; and from two trees of E. gigantea from Tasmania, approximately 300 years old and 200-feet in height. Discs were taken at various intervals from the ground up the tree. From the discs 15/16-inch cubes were taken and weighed in the green state and their tangential and radial dimensions measured to an accuracy of 0.1 percent. A small laboratory kiln with an air velocity of 200 feet per minute was used for drying at 160? F. dry-bulb temperature with 155? F. and 105? F. wet-bulb temperatures, respectively, and at 110? F. dry-bulb temperature with 105? F. wet-bulb temperature. Kiln-drying continued until the material reached 15 to 20 percent moisture content. The results for both species show that considerable differences in the recoverable collapse may occur under various drying conditions. It has also been shown that the total shrinkage decreased with increase in height in the tree. Total shrinkage and recoverable collapse both tended to be higher in the butt than in the top logs. It is concluded that in ash eucalypts collapse intensity decreases with height in the tree, but the amount of variation may differ greatly from tree to tree.

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