Analysis of Heartwood –Sapwood Demarcation Methods and Variation of Sapwood and Heartwood within and Between 15 Year Old Plantation Grown Eucalyptus Regnans
Githiomi J. K., Dougal E

Abstract
This study was carried out using 15-year old Eucalyptus regnans F. Muell trees from three seedlots in a progeny trial in Norbethong, Victoria in Australia. Colour, stain and light table methods were used to demarcate the boundary between the sapwood and heartwood on the discs cross sectional surface. The main objective of this study was to examine the variation within and between tree in heartwood and sapwood in plantation grown Eucalyptus regnans material and also to compare the three techniques used in demarcating the boundary between sapwood and heartwood. Wood discs were removed from the base, breast height, 20%, 40%, 60% and 80% of the total tree height. Measurements were made on cross sectional surfaces of the discs to determine the sapwood width and heartwood percentage. The results showed that there was no significant difference in heartwood-sapwood demarcation methods using natural colour and stain. However sapwood-heartwood demarcation method using light table method had significant differe nce with both colour and stain methods with P = 0.000. The mean sapwood and heartwood width varied significantly between trees and along the height. The lowest mean sapwood width of 21.0 mm was found at breast height which increased with height to 33.9mm at 80% tree height it also increased from breast height to 29.9mm at the base of the tree. The largest heart wood percentage of 69.51% was found at breast height and decreased with height to zero at 80% height and it also decreased from breast height to 65.75% at the base. A very high correlation was found between the heartwood diameter and disc diameter.

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