trees of 4| feet girth attain the minimum exploitable girth-limit of 6 feet. In the 

 course of 30 years all the trees now 4-| to 6 feet in girth would be removed. Pro- 

 vided, therefore, that trees of all sizes now from 4| to 6 feet girth were properly 

 represented in the crop, and were felled as they attained to 6 feet girth, the annoal 

 possibility would theoretically amount to one-lhirlieth of the total number of trees 

 above 41 feet in girth standing in the forest. In practice since the exploitable size 

 is a minimum only and since 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 will be explained in the example given below. 



As an adjunct to cultural rules, and subject to sucli 

 restrictions as common sense and knowledge of sylviculture 

 dictate, the principle here sketched may often be applied with 

 advantage. It may evefl, with some sacrifice of accuracy, 

 be used to 'limit the fellings in forests in which, for any 

 reason, it is inexpedient or impossible to carry out 

 complete 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 

 approaching 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 deter- 

 mined 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- 

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

 times one-thirtieth) of the exploitable trees in a coupe would be equivalent (as 

 regards the number 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 treeg 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 44 but less than 6 feet in girth. A rule, therefore, 

 prescribing that there -will be felled each gear on one-tenth of the area, in succes- 

 sion, one-third of the total number of trees of froti 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 foiest were counted in advance and the exact number to be felled each year 

 were prescribed. 



It is unnecessary to discuss in detail either the errors 

 involved in this method or the oases in which it is applic- 

 able. There are undoubtedly many instances in which the 

 method might be applied, and in which it would lead to 

 better results than any attempt, with the means usually 

 available in India, to enumerate in advance the whole stock. 



{ii) Brandis' method. 



The principle explained in the preceding paragraph 

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

 entuneration of the growing stock made in advance of the 

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



