WOOD BASIC DENSITY OF EUCALYPTUS GRANDIS FROM PLANTATIONS IN CENTRAL RIFT VALLEY, KENYA: VARIATION WITH AGE, HEIGHT LEVEL AND BETWEEN SAPWOOD AND HEARTWOOD

摘要

GITHIOMI JK & KARIUKI JG. 2010. Wood basic density of Eucalyptus grandis from plantations in Central Rift Valley, Kenya: variation with age, height level and between sapwood and heartwood. Basic wood density was studied in 4-10-year-old Eucalyptus grandis to provide information on variation in basic density between and within trees and at various ages. Wood discs were taken from six height levels of each tree for determination of basic wood density. The density was significantly influenced by age and tree height. It increased with age and was lowest at age 4 years (0.414 g cm(-3)) and highest at age 10 years (0.517 g cm(-3)). An equation, y = 0.0017x(2) - 0.007x + 0.4159 to predict the basic density of E. grandis grown in similar conditions and for ages up to 10 years was derived, where y is the basic density and x is the age. There were significant differences (p <0.05) in basic density between heartwood and sapwood. The basic density of ages 4, 5, 6 and 7 years were also closely related while that of ages 8, 9 and 10 were distinctly different from one another. Therefore, the rotation age of E. grandis for fuelwood plantations cannot be reduced from 10 years to 8 or 9 years since higher basic density at 10 years gives higher calorific values unless other growth and yield factors are considered.