84 



of trees above 4| feet in girth Btanding in the forest. In practice, since the exploit- 

 able size is a minimum only and eince merely a portion of the forest is gone over 

 annually, a stock of exploitable trees has to be accumulated and the possibility is 

 necessarily something less. 



As an adjunct to cultural rules, and subject to such re- 

 strictions as common sense and a knowledge of sylviculture 

 dictate, the principle here sketched may often be applied 

 with advantage. It may even, with some sacrifice of accu- 

 racy, be used to limit the fellings in forests in which, for 

 any reason, it is inexpedient or impossible to carry out com- 

 plete enumeration surveys in advance of the working. 



In such cases, all that is necessary is to determine the 

 average rate of growth of the principal species when ap- 

 proaching maturity and the length of the felling rotation, 

 and to prescribe, by a simple rule, the proportion of the 

 trees above certain dimensions growing in each coupe that 

 may be removed in each felling. 



Thus, snppose that for the forest dealt with in the last example it were determined 

 to work over the whole area in ten years by annual coupes of one-tenth of the 

 area. Each of these coupes, it might be assumed, would contain about one-tenth of 

 the trees growing in the whole area, so tbat to fell one-third (that is ten times one- 

 thirtieth) of the exploitable trees in a coupe would be equivalent (as regards the num- 

 ber of trees felled) to the felling over the entire forest of one-thirtieth of the stems 

 exceeding a certain prescribed minimum girth. This, however, pre-supposes that the 

 accumulation of trees 6 feet in girth and over is such that the requisite number is 

 available on one-tenth of the area, and does not justify the felling of trees over 4,\ but 

 less than 6 feet in girth. A rule, therefore, prescribing that there will be felled 

 each year on one'tenth of the area, in tuccestion, one-third oj the total number of 

 trees of from 4\ to 6 feet in girth growing on that area, provided no tree is felled 

 before it attains the exploitable size, would, in the restriction of fellings, have much 

 the same effect as if the whole of the trees in the forest were counted in advance 

 aud the exact numbei to be felled each year were prescribed. 



It is unnecessary to discuss in detail either the errors 

 involved in this method or the cases in which it is applicable. 

 There are undoubtedly many instances in which the method 

 might be applied, and in which it would lead to better re- 

 sults than any attempt, with the means usually available in 

 India, to enumerate in advance the whole stock. 



Limitation of fellings. derived from an enumeration of the 

 trees. — ^The principle explained in the preceding paragraph 

 may also, it is obvious, be applied to the results of an enu- 

 meration of the growing stock made in advance of the ex- 

 ploitation. The number of trees of each kind and size-class 

 and their rates of growth being known, it is possible to esti 



