Part II. ] 
Caccia : Development of Sal. 
185 
III. — The growing space allotted to a tree is the chief factor influencing the 
rate of volume increment ; the more crowded the wood, the slower the 
volume mcrement. A tree grown in a close crop will at once respond 
by increased volume increment to any enlargement of the growing 
space allotted to it. 
IV. — The volume mcrement of standards reserved in a wood treated under 
the system of coppice with standards differs from that of similar 
trees grown in crowded woods. The volume increment of standards 
is said to increase appreciably in the year immediately following the 
exploitation of the surrounding coppice.* 
Data indicating the progress of the growth in volume of Sal trees 
are not at present forthcoming ; and the absence of distinct annual rings 
renders the immediate solution of this problem a matter of some difficulty. 
Indeed, existing conditions would point to the fact that the elaboration 
of tables of co-efficients (stem form factors), and the preparation of stem 
volume tables shoidd alone for the present engage the attention of Forest 
Officers. These subjects are dealt with in the Sections immediately 
following. 
Section 6. — Stem Form Factors. 
Form factors are used primarily to determine the volume of trees. 
They imdoubtedly also help to indicate the shape of a stem : but stems 
having similar form factors need not necessarily have the same shape ; 
and conversely, if so called artificial form factors be used, trees having 
the same shape but differing in height will not have the same form factors. 
Stem form factors may be prepared from diameter measurements 
taken at any height from the ground. European Forest Kesearch Bure- 
aux have, however, agreed to measure all trees at breast-height (1'3 
metres) ; and these so called “ artificial ” form factors are the only ones 
now used. Form factors vary with the height of the tree, and unless 
the greatest accuracy is required it is unnecessary to take into consi- 
deration either age or quahty of locahty ; though in Germany a distinc- 
tion is usually made between young, middle-aged, and old trees. It has 
been found that form factors for particular species prepared for a definite 
tract are apphcable to widely separated districts. 
It is hoped that the collection of data, which will lead to the pre- 
paration of stem form-factor tables, will be taken in hand at an early date. 
The following form of table may be found convenient for the pur- 
pose of recording results obtained : — 
* In the Kode.rma Reserve of the Palamau Division, and in the Rhagatpoii Reserve 
of the. Sainbalpur Division, Bengal, sample plots have been established to test the rate 
of growth of Sal standards after coppice fellings : but figures are not at ptesent available. 
