348 
Indian Forest Records. 
[VOL. I. 
Buxa Division,* Eastern Bengal, may be taken into consideration. 
It will be seen that the method therein followed has the inconveni- 
ence of prescribing an unequal periodical yield. 
The plains series of the Buxa forests . — This has been divided into 15 coupes 
which are to be worked in succession for exploitable sal trees. The number of 
such trees marked in each coupe should include — 
(i) the existing Class I trees, including ward-falls but excluding trees 
required as seed bearers, and 
(ii) such of the existing Class II trees as attaii the minimum exploitable 
size before the exploitation of the coupe. 
Theoretically, the average diametral increment being assumed to be 0‘2 
inches, one-thirtieth of the Class II trees should attain the minimum exploitable 
size every year, and the total number of Class II trees over that size found in 
any coupe at the time of its exploitation should equal one-thirtieth of the 
number of existing Class II trees multiplied by the serial number of the coupe. 
But in practice it will probably be found that the numbers of Class II trees 
attaining the minimum exploitable size are less than the estimates obtained by 
such a calculation. For though the diametral increment assumed is very 
moderate, the diameters of the existing Class II trees do not vary evenly between 
1 foot 6 inches and 2 feet, and the number of trees just over 1 foot 6 inches 
in diameter must be much greater than the number just under 2 feet in 
diameter. In these circumstances it is thought reasonable to estimate the 
yield as follows : — 
It is assumed that in the first five years of the felling rotation (1905-06 to 
1909-10) the number of Class II trees attaining the exploitable size will about 
blanace Class I trees which must be left for seed or become windfalls, and 
that the number of exploitable trees out in coupes 1 to 5 will therefore about 
equal the number of Class I trees they now contain, which is 15,020. Thus the 
average yearly yield of these coupes should be about or, say 3,000 ex - 
ploitable trees. 
For the next five years (1910-11 to 1914-15) during which coupes 6 
to 10 w'ill be worked, it is assumed that the number of exploitable 
trees available for felling will be the existing number of Class I 
trees, or 10,622 
plus five-thirtieth of the existing number (70,654) of Class II trees in 
coupes 6 to 10, i.e 11,755 
Total . 22,397 
Deduct for seed bearers and wind-faUs, at 25 per cent, say ... 5 397 
Balance of exploitable trees available for cutting • ... 17 000 
Average yearly yield .......... 3 400 
Similarly for the last five years (1915-16 to 1919-20) of the felling 
rotation the yield has been estimated as follows : — 
Existing number of Class I trees 10,236 
Ten-thirtieth of existing number of Class II trees .... 21,424 
Total . 31,660 
. Working Plan for the reserved forests in the Buxa Division, Eastern Bengal 
by C. C. Hatt, 1905. ® • 
