Whereas these and other studies have attempted to identify the cause of ring shake, assessments of the occurrence and variability of ring shake have not been conducted on a broad geographical scale.
The first objective is to determine whether any tree characteristics are prominent indicators of ring shake in hemlock lumber.
Because ring shake is one of the more important attributes affecting lumber yields, detection and evaluation of shake was an important aspect of this study.
Ring shake is a serious wood utilization problem in hemlock because of its frequency of occurrence and potential for degrading a high proportion of lumber when it is present.
From Figure 3, in trees with no birdpeck, the probability of ring shake is between 50 and 60 percent, and considerably higher for trees with birdpeck, 70 to 75 percent.
1962, A survey of the incidence of ring shake in eastern hemlock.