The effect of growth strain and other defects on the sawn timber quality of 10-year-old Eucalyptus globulus Labill

Abstract

Summary Fifty-nine trees were sampled from three provenances of Eucalyptus globulus Labili, in 10-year-old plantations at two separate sites. The butt logs were selected as the study sawlogs. Growth strain was measured at three heights along the log length and three circumferential positions at each height. The logs were sawn and graded before and after seasoning to appearance grade. The impact of each grade-limiting defect on the result was examined. Particular attention was given to the effect of growth strain on the percentage of sawn boards that exceeded the permissible distortion limits of Australian standard AS2796.1 as feedstock. The logs were from young, small-diameter, unpruned trees knots and pith were the primary grade-limiting defects. Average growth strain of the sawlogs and the tree diameter at breast height in combination accounted for 42% of the total variation in the percentage of excessively distorted boards. Density had no direct causal effect on this percentage, but had an indirect effect through its significant correlation with growth strain.