Sapwood thickness in Pinuscontorta var. latifolia

The vertical variation in the number of sapwood growth rings and sapwood thickness in Pinuscontorta Dougl. var. latifolia Engelm. was studied in relation to aspect, tree age, bole diameter, sapwood radial growth rate, and whole-xylem radial growth rate. Samples from 19 trees growing on the western slope of the Rocky Mountains near Kamloops, British Columbia, Canada, formed the data base. Sapwood width for individual trees ranged from 20 to 26 mm for both the east and west aspects, and was constant at various heights of the tree bole. Sapwood width for this species was found to be independent of age, diameter, sapwood radial growth rate, and whole-xylem radial growth rate. Sapwood consisted of 25 to 50 growth rings and decreased from the ground level upward to the tree crown. The number of sapwood growth rings was strongly correlated with age, diameter, and radial growth rates for both sapwood and the whole tree. No significant correlation existed between sapwood width and sapwood growth-ring counts.