Variation of Specific Gravity, Extractive Content, and Tracheid Length in Redwood Trees

The variation of certain wood characteristics was studied with respect to position in a number of old- and young-growth redwood ( Sequoia sempervirens (D. Don) Endl.) trees. Old growth differed from young timber by having lower specific gravity, percentage of latewood and ring width, but slightly higher extractive content and significantly longer tracheids. Density of old growth was highly correlated with percent of latewood. It increased slightly with height, and decreased in the outer growth rings toward the bark as the rings narrowed. Such trends in density were not pronounced and were even reversed in young growth. The maximum amount of extractives was found in heartwood portions immediately adjacent to sapwood in butt sections. Extractive content decreased somewhat with height and appreciably toward the pith. Young trees contained much smaller tracheids because fibers of maximum length developed only after 300 to 350 years of tree growth. In mature timber, tracheids had elongated more as growth rings narrowed.