34 FOREST VALUATION 



c. Total expenses per acre at end of rotation. 



Cost of planting, c, $6 with interest 



for eighty years or 6 (i.O3 s<) ) ...... $ 63.84 



Care, protection, and taxes, e, 0.25, 

 coming every year with interest. 



Total expense .................. $144.09 



d. The net income per acre at end of rotation: 



$431.40 

 144.09 



$287.31 per acre. 



This net income of $287.31 per acre may be and is expected to 

 come every 80 or r years and the value of all these net incomes or 

 the value of the acre of land producing them is : 



value of land per acre, Se 2 *7-3i = $2980 



(i.o;f i) 



value of 40 acres : $1,192. 



In the above simple case it is assumed that the plantation suc- 

 ceeds and that it does not require any filling in or cultivation, etc. 

 If such work has to be done it is charged exactly like the plantation 

 itself. Similarly, if there are more thinnings as there would be 

 where intensive work is justified and also where there are other in- 

 comes, such as grazing, turpentine, etc., these incomes are credited 

 and prolonged exactly like the thinnings in the above simple case. 



It is evident from the above that this analysis is clear and logi- 

 cal that it resembles computations made in other lines of business, 

 requires only ordinary interest arithmetic and that there is no neces- 

 sity for putting it into a formula which often seems to hinder rather 

 than help. 



Nevertheless it is convenient and makes the matter much clearer 

 and easier to discuss, and to understand the relation and influence 

 of the various factors if it is arranged in a concise formula, and the 

 usual arrangement follows closely the above sample case : 



e. Formula of Se : 



f Tc(.I.O P r-c)_c(l.Op r ) 



- ... 



be = _ . _ (lop i ) 



(i.op p i) 



where Yr is the stumpage value of one acre of timber r years old : 



