FOREST ECONOMY 213 



length of rotation, that rotation should be found 

 at which the surplus of the annual values derived 

 from the harvest over the annual expenditures is 

 greatest, the so-called rotation of the highest forest 

 rent. Finally, even this method of calculation can- 

 not satisfy a strict financier, for it neglects to take 

 account of the capital invested and the relation of 

 the revenue to this capital, it neglects the interest 

 account. /--' 



The true financial rotation is that which brings 

 the highest rate of interest on all the capital in- 

 vested in soil and stock of wood, or, as it is techni- 

 cally known, the rotation of the highest soil rent or 

 " soil expectancy value " (Ger. Bodenerwartungs- 

 wertli). 



As we have seen (p. 129), the amount of stock 

 of wood which must be maintained as capital for 

 a sustained yield management increases with the 

 length of rotation. In our example, in order to 

 bring the stock corresponding to an 8o-year rota- 

 tion to the amount needed for a loo-year rotation 

 would require that the owner should abstain from 

 harvesting for about 20 years. The question then 

 arises whether this saving will prove profitable, 

 whether the accumulation of values to the icoth 

 year, which can only then be harvested, will ex- 

 ceed the results which could be had by harvesting 

 in the 8oth year and investing the proceeds. Here 

 appears for the first time the need of that branch 

 of forest economy which may be truly called for- 



