2l6 ECONOMICS OF FORESTRY. 



lay for planting (c), if any, occurring at the begin- 

 ning of the rotation, and hence to be extended to 

 the end of the rotation, in order to bring it into 

 relation with the yield, and the annual expenditures 

 for administration, which can be expressed as a capital 

 (A), furnishing yearly forever the needed amount. 

 With these items we can then express the soil rent 

 value — 



„ Yr+ral-Op'-<'+TbI-Opr-h...^T,l-Op^-i-C-l-Opr 



Oe= ■ /9. 



I -Op^—l 



By entering values which correspond to different 

 rotations, that one may be found in which the soil 

 rent value appears as a maximum, the true financial 

 rotation. 



It will readily appear that, while theoretically this 

 is the only correct financial method of calculating, 

 practically it is difficult, almost impossible, to deter- 

 mine values for the various items, on account of 

 varying prices and uncertainty of interest rate 

 for the future. Although all calculations in for- 

 estry must necessarily be approximations, such 

 calculations may serve as a guide for a time, to be 

 recalculated with change of conditions. 



Where, as in well-estabHshed state forest ad- 

 ministrations, the question is not one of strict 

 financial business, and where absolute forest soils, 

 which could not be used for other purposes, are 

 involved, the simpler forest rent calculation is 

 probably more satisfactory. It is of historical 



