Vessel Area Studies in Black Walnut ( Juglans Nigra L.)

This study examined factors that influence variation in vessel lumen area (a measure of wood texture) in black walnut ( Juglans nigra L.) trees. The effects of management type (plantation and naturally grown trees) and location within the tree (both longitudinally and radially) on earlywood vessel lumen area, latewood vessel lumen area, and total growth ring vessel lumen area were examined. In general, faster grown, managed, plantation-grown trees had a higher earlywood vessel lumen area than slower grown, unmanaged, naturally grown trees; but naturally grown trees had a greater total vessel lumen area per growth ring. No correlation was observed between rate of growth and earlywood vessel lumen area, but there was a correlation between rate of growth and area of latewood vessel lumens and the area of vessel lumens within growth rings. Significant differences were observed longitudinally within trees; that is, samples from disks removed from the 8 1/2-foot level had a higher vessel lumen area (in both earlywood and total vessels) than samples from disks removed from the base of the tree. In addition, with increasing distance from the pith, there was an increase in vessel lumen area within the earlywood and an increase in vessel lumen area within the entire growth ring. Results of this study suggest that management activities can influence the area of vessel lumens within growth rings of black walnut through an effect on growth rate of the trees. However, within-tree variations in these properties occur also and these must be considered.