144 VALUATION OF THE GROWING STOCK. 



I. The Cost Value. 



(1) Calculated for the year m + x : 



Value = (S+E) (l'op m+x - 1) + c x l'op m+x -(T a x l-op m +*- 

 + ...)- [(S + E) (l'op m - 1) + c x l'op m 

 -(T a xl'op m -" + ...)]. 



Value = l'op w fs+jE+c -(- + . . .Yl (l'op x -l). 



(2) Calculated for the year m : 



Value = l-op w - a! [s+JS+c-y^M-. . .Yj (l-op*-l.) 



The cost value becomes equal to the expectation value, if the 

 expectation value of the soil is substituted for S, a matter 

 which is easy to show. In either case it becomes, calculated 

 for the year m + x : 

 Value 



For the year m this value has to be divided by l'op x . 



SECTION III. VALUE OF THE GROWING STOCK OF A NORMAL 

 SERIES OF AGE GRADATIONS. (NORMAL GROWING STOCK.) 



If a forest is so .managed that it yields annually an equal 

 return, it must contain a regular series of woods of equal 

 yield capacity ranging in age from 1 year up to r years, with 

 one year's difference between every two successive gradations. 

 Whether these age gradations are found on separate areas, or 

 are mixed with each other, makes no difference. In either 

 case, every year the oldest age gradation will be cut over, 

 giving a yield = Y r , and every year there will be thinnings in the 

 gradations which have reached the ages of a, b . . . q 

 years ; at the same time every year formation would cost 

 c shillings, while supervision would cost r X e shillings. It 

 is of interest to the forester to ascertain the value of the 

 growing stock in such a forest, the same being known as 

 " the growing stock of a normal series of age gradations." 



