Variation in growth rate and wood properties were studied from breast-height increment cores from 31 selected P. strobus L, trees growing in Morgan County, Tenn. The average amount of extractives was equal to 8.4 percent of the unextracted young wood (10-20 yrs. from the pith) and 7.2 percent of the older wood (20-30 yrs. from the pith). Older wood had longer tracheids and higher specific gravities than young wood. Variation among trees was significant at the 0.1 percent level for all characteristics except two: specific gravities of extracted and unextracted young wood. The correlation coefficients for radial growth and extracted specific gravities accounted for 11.5 percent of the variation in specific gravity of young wood; 9.5 percent for old wood. Relationships between radial growth and extractives, and tracheid length were weak, being significant only in young wood. Thus, growth differences did not account for a large proportion of the variation in these wood properties. Relationships such as those between specific gravity before and after extraction, between tracheid length at 20 and 30 years, and between extracted specific gravity of young and old wood, accounted for large proportions of the variations. Extractives accounted for only about 17 percent of the variation in young wood density, but 44 percent in the density of old wood. The relationship between specific gravity and tracheid length was very weak.
Document Type: Journal Article
Associate Professor, Dept. of Forestry, The Univ. of Tenn., Knoxville