Analysis of some factors influencing variation of cellulose in Douglas fir

The aim of this study was to determine how several growth factors influence cellulose content in Douglas fir wood. Standard samples from eight Douglas fir trees originating from the U.B.C. Research Forest at Haney, B.C. were submitted to a slightly modified Cross and Bevan extraction procedure. In addition, the newly-developed method of Yundt and Bradway was used to give an independent estimate of cellulose from the trees which yielded extreme values for Cross and Bevan cellulose. The main factors considered as influencing cellulose yields were crown class, site and radial position within the same tree. In addition, the largest tree among the eight tested was studied to further define the extent of cellulose variation with increasing age from the pith. By analysis of a single tree lower cellulose yields were obtained for juvenile wood as compared with the mature wood in the same tree. Most of the variation in cellulose due to age was found in rings for 1-15 years. Despite the fact that two growth factors (crown class and site) were shown to have a statistically significant influence on cellulose yield, it was shown that their influence was independent of rate of growth. The four largest trees had higher cellulose yields than the four smallest trees on each plot. On the average, cellulose yields were higher for the poor site than the good site, yet the variations could not be related to size, growth rate, or per cent summerwood. There was a definite variation in cellulose content among the trees. The highest cellulose percentage was found in an individual dominant tree on the poor site and the lowest in an intermediate tree on the good site. Actual causes and controls of cellulose content among individual trees remain to be established. However, it can be stated that there is an important variation in the cellulose yields from tree to tree, and that in this sample of eight trees, yields of Cross and Bevan cellulose ranged from 54 to 66 per cent. The desirability of propagating trees with high cellulose content is discussed briefly.Forestry, Faculty ofGraduat