VARIATION OF SPECIFIC GRAVITY WITHIN Eucalyptus grandis TREES GROWING IN DIFFERENT SITE CLASSES.

Abstract

Wood is a very remarkable material with variability and flexibility The variability of woodincreases its utility It may be also a major drawback to its efficient use as raw materialTherefore understanding of pattern of wood properties within the tree has becomeimportant. In addition, growth rate and its effect on wood properties are of practicalimportance to maximize wood and fiber production. In this study, variations of specificgravity within the trees of 30-years old Eucalyptus grandis extracted from Pattipola,Saruhipura and Piduruthalagala in Nuwara-Eliya districts were studied. Data werecollected in relation to site class (growth rate) as determined by tree height. The objectiveof the study was to find out whether specific gravity is affected by growth rate of tree.Specific gravity values were collected in a systematic manner, which are essential incommercial utilization of this species. Three sites, namely Slow Growth Site (SGS),Medium Growth Site (MGS) Fast Growth Site (FGS) were chosen. Five trees from eachsite were taken for the investigation. Tree height difference between SGS (33.8 meters )FGS (45 meters) was significantly different (PS:005) but not between SGS and MGS (387meters)

Variation patterns of specific gravity in racial direction were studied using two linearsections extracted across the diameter of every sample disc, from north to south and cast towest at different height levels at breast height and at 20'Yo,40%, 60% and 80% of total treeheight. 3021 wood samples of 2*2* 1 em dimensions were used for specific gravitydetermination.

In general, low specific gravity values were observed at pith in all three sites. In fastgrowth site, specific gravity increased from uith; thereafter it remained constant towardsthe bark with small fluctuation. In slow and medium growth sites, however specific gravityincreased gradually towards the bark. Fast growth site maintained the highest specificgravity values throughout piths to bark The specific gravity of SGS and MGS increasedrapidly with increasing distance from pith.

In general, specific gravity increased with tree height in all sites except at 20% height levelin SGS and MGS. Mean specific gravity values in SGS at breast height, 20%, 40'%, 60'Y<,and 80% height levels were 0.432, 0.431, 0433, 0.468 and 0.475 respectively. Specificgravity values for these levels in MGS were 0.441,0.435,0.467,0.477,0.542 and Specificgravity values were 0.479.0.482,0.493,0525, .J.553 for FGS respectively.