382 
Indian F urest Records. 
[VOL. I. 
Then the area occupied by each age gradation in a normal regu- 
lar forest would be= ^ acres. And the number of exploitable 
trees standing on the oldest age gradation would be : this 
representing the number of trees, which may be felled annually. 
This method is based on certain hypotheses which may vitiate 
the accuracy of the results obtained. In the first place, it is by no 
means an accepted fact that the exploitable trees in a selection 
forest occupy the same area that they would in a regular forest.* 
In the second place, the possibility is based on a determination of 
the exploitable age, a calculation which does not always yield posi- 
tive results in a selection forest. Thirdly, it necessitates the cal- 
culation of the crown cover of the exploitable tree, which is an 
operation requiring great care ; though probably fairly satisfactory 
results might be obtained by the direct observation and measure- 
ment of small groups of exploitable trees. 
To take a concrete example. Suppose the area of the forest be 
1,400 acres; and the exploitable age required to produce a tree 6 
feet in girth 140 years. The area which should be occupied by the 
trees 140 years in age, if these were collected together in one place, 
would be 10 acres. If now it is found that the average tree with a 
girth of 6 feet occupies an area of 600 square feet, the number of 
trees of the exploitable size that can grow on 10 acres, that is the 
number which may be felled annually, will be — 
726 trees, 
600 
or ‘5 tree per acre per annum. 
It does not appear that this method has ever been applied in 
practice either in Europe or in India. t 
vi. — Possibility based on the Normal Forest. 
This method will be found fully described in the third volume of 
G. Huffel’s Economie Forestiere^ from which the following ex- 
tracts are taken. It will be best understood by giving an example 
from a working plan prepared in 1906 for the Eein des Boules Work- 
ing Circle of the Ban d’Etival State forest situated in the Vosges, 
France. The forest is a mixed Pine and Beech forest. 
* ib’ee Part I of this Note. 
t See also Preparation of Forest Working Plans in India by W. E. D’Arcy. 
3rd Edition, pages 88-89. 
t Economie Foresti^re, by G. Huffel, Volume III, Lucien Laveur, Editeur. 
Paris, 1907. 
