Part II.] 
Caccia : Development of Sal. 
189 
Besides stem volume tables, volume tables may also be prepared for 
trees of different diameters and merchantable lengths of timber ; or for 
trees grouped by diameter and number of logs ; or for trees of different dia- 
meters and tree-classes. In addition, tables may be prepared showing 
the ratio of merchantable to total contents, so that the volume of mer- 
chantable timber may be obtained by the use of the ordinary stem volume 
tables. The preparation of graded volume tables, showing the amount 
of timber of different grades for trees of different sizes has also been 
suggested : such tables enable the determination of the money value of 
standing trees better than the ordinary volume table?.* 
Section 8. — Volume Increment per cent. 
Laws governing development of volume incremen per cent, of single trees 
in general : — 
I. — The volume increment per cent, is very high during very early youth. ; 
subsequently it steadily decreases, though slower and slower, until the 
death of the tree. 
II. — All the factors which influence the volume increment equally affect the 
volume increment per cent. : the closer the crop, the lower the incre- 
ment per cent. ; whilst any change of state affecting the growing space 
allotted to the tree will entail a corresponding change in its increment 
per cent., so much so, that the latter may temporarily increase three- 
fold a® the result of judicious thinnings in over-crowded woods. 
In calculating the volume increment per cent, in order to avoid errors 
due to years of exceptional growth, the increment is tak n for a series 
of years, generally 5 to 10 years, t The volume increment per cent, is 
chiefly used for the purpose of testing the activity of the capital invested 
in forestry, and in predicting fuTire growth of a tree or wood : but no 
statistical data are at present available from which such tables could be 
prepared for the Sal in India. 
* Sec “ Forest Jlensuration ” by Henry Sohni Craves. 
fin calculating the Volume Increment per cent., Pressler's formula may be employed, 
V— V 200 
Increment per cent. = — — x 
V + V n 
See Schlich’s Manual of Forestry, Vol. Ill, page 1S5. 
