INVESTMENTS AND COSTS IN FOREST PRODUCTION 79 



the year. All income is equivalent to negative costs, and in 

 this case the item is best carried with interest to the final 

 year, when its total may be subtracted ( 77). Otherwise a 

 separate balance would be required for the year of receipt of 

 this income, which would serve no useful purpose. 



Let T p , T q , T r = value of thinnings or other incidental rev- 

 enue received at p, q and r years. The future value, at end of 

 period, will be 



T p (i.op*->) + T q (i. <#--) + T r (i.op"-'). 



Subtracting this income from total cost, including C d , C e and 

 C f , we have the net cost of the growing stock, G c . 

 G c = (C + S C + E) i.op n + C d (i.op n ~ d ) 



+ C e (i.o/>"-) + C f (i.o^-O - T p (i.op"->) 



- T q (i. <#"-) - T r (i.o^-") - (S e + E). (AO 



There is no way of avoiding these separate calculations for 

 single sums occurring in odd years. As each item is independent 

 of the others, the apparent complexity of these formulae need 

 not be a source of confusion. 



To obtain the cost of a forest, including both soil and timber, 

 the cost of soil is not subtracted. 

 Let F c = cost of forest. 



Then F c = (C + S c + ) i.op* - E, 



and for the year a, 



F C = (C + S c + E) i.op* - E. (A 2 ) 



106. Total Cost of Investments in Standing Timber. Only 

 a few instances are found in America where forest crops have 

 been brought from seed to maturity under management, and 

 it is still less frequently that actual total costs of production 

 have been recorded. Practically all past transactions in land, 

 for forest purposes, dealt with property which already contained 

 standing timber. 



Cost accounts for such property begin with the purchase price 

 and carry all subsequent net expenses to the present, to final 

 sale of the property, or to the year when the timber is sold. 

 Since such property is purchased in a partially or fully developed 



