Part I.j 
Troup : Teak Forests of Burma. 
19 
CHAPTER IV. 
Rate of Growth and Exploitable Age of Teak. 
1. General. 
In Appendix III will be found the tabulated resalts of all working- 
Tabulated results. ^ showing rate of growth up to 
7 feet m girth, together with the exploitable 
age and girth limit, in different localities. 
Rate of growth how ascer¬ 
tained. 
In the earlier teak working-plans the use of Pressler’s borer for 
ascertaining the rate of growth of teak was 
much more general than it is at the present 
time. This instrument, in fact, has of late 
years been discarded almost entirely, as it has not been found to give 
accurate results. At the present time the rate of growth is as a rule 
ascertained only by counting rings on stumps, and there can be no doubt 
that in consequence of this the figures deduced in the later working-plans 
are more accurate than those of the earlier plans where Pressler’s borer 
was largely employed. 
In the various working-plans the general custom has been to add 
_ , . 10 years to the age of a teak tree, as repre- 
Reduction to same basis. . . . . ■ r 
sentmg the approximate time required for 
a seedling to establish itself : in many cases, however, no such addi¬ 
tion has been made, while in one case 15 years has been added. In 
order to be of any value for purposes of comparison, the figures for each 
working-plan must be reduced to the same basis, and for this reason the 
figures showing the average ages of trees of different girths have been 
made out on the assumption that nothing has been added to allow for a 
seedling to establish itself, i.e., the countings all commence from 0 year 
and not from 10 or 15 years. 
In some of the older working-plans diameter and not girth measure¬ 
ments have been recorded : in all such cases the ages have been corrected 
to correspond with the usually recognised girth classes. 
Again, it has not been the rule in these countings to ailow for bark, 
Thickness of bark and ^ ence figures given do not take the 
thickness of bark into account except in the 
case of the Mawku working circle. 
[19] 
