The effect of frost cracks in sugar pine trees on lumber grade

This study evaluated the association between frost cracks and lumber degrade in sugar pine. Twenty-three sugar pine trees with visible frost cracks in an otherwise high quality (grade 3 or better) butt log were selected throughout the Sierra Nevada in eastern California. A total of 45, 16-foot logs were sawn from the 23 trees. Each piece of lumber was graded twice: 1) including all defects relating to frost cracks; and 2) as it would have been if the shakes and chemical brown stain resulting from frost cracks were not present. About 1,500 boards (two-thirds 5/4-in. Shop grades of lumber and one-third 4/4-in. Common grades of lumber) were sawn from, the 45 logs. Results indicated a 15 percent loss in value (or a decrease of $180 per thousand board feet lumber tally) due to shake and brown stain in lumber produced, thereby reducing the value to that of a grade 5 log.

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