A Spiral Grain Classification System and Its Application

A system was devised for classifying pith-to-cambium changes in spiral grain. The system, consisting of nine characteristic patterns, was used to classify spiral grain in 2-inch disks cut from 113 lodgepole pine, 97 western larch, 775 Douglas-fir (inland), and 104 Engelmann spruce trees. Each pattern was identified according to the initial direction of slope of grain and subsequent changes in both direction and amount of slope. Only 5.9 percent of all the samples showed no spiral grain. There were no geographic differences among the Douglas-fir samples obtained from four separate locations. The initial spiral direction, by species, was: lodgepole pine, 30 percent left and 69 percent right; Douglas-fir, 45 percent left and 48 percent right; Engelmann spruce 59 percent left and 37 percent right; western larch, 77 percent left and 18 percent right. Each species is characterized by a unique distribution of spirality pattern. However, for all species the initial left spiral tended to subsequently change to a right spiral, while the initial right spiral tended to increase.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member