Effect of harvesting age on the amount and composition of wood extractives from Eucalyptus camaldulensis

Effect of harvesting age on wood extractive composition and quantity from Eucalyptus camaldulensis was studied. Wood extractives were analyzed from 6, 8, 10 and 12 year old trees. Main emphasis was concentrated into 12 year old trees. All trees in this study were Eucalyptus clones from tree farms in East Thailand. Basic densities of the whole wood and each growth ring seem to increase with tree age. Age of the tree seems not to affect the lignin content of the wood. Within the variation of tree samples, extractives level decreased from pith to bark, lipophilic extractives and tylose formation gradually decreased in a respective way. Microscopic analysis using wood cross cutting sections shows that there was no tylose formation in outer growth rings, but clear tylose formation could be observed in inner growth rings (area inside 6th year growth ring). Phenolic compounds (gallic acid, vanillin and ellagic acid) seem to reach highest level in the middle growth rings from 4-6 to 7-9 years.