2 Studies in Forestry [CHAP. i. 



said roughly to vary from about 60 to 80 years with conifers, 

 up to about 150 years for Oak. But taking a rotation of about 

 90 years as the average, and that would certainly not.be too 

 high a one, this would mean that the present market value 

 of the timber-crops on these three millions of acres of woods 

 (assuming that they range normally from o to 90 years of age) 

 is equal to 3,000,000, multiplied by the average quantity of 

 timber contained in crops 45 years of age, or equal to 1,500,000 

 acres multiplied by the average quantity of timber yielded by 

 a mature crop of 90 years in age. 



Without entering into detailed figures, which of course vary 

 essentially according as the crops may be of Scots Pine, 

 Spruce, Silver Fir, Oak, Beech, &c., or mixed woods, it will be 

 at once intelligible that the monetary value represented by the 

 timber standing on our three million acres of woodland is of 

 sufficient amount to be decidedly of national importance. 



At the very lowest computation, the actual cost of production 

 of the timber-crops, which, even under management of an 

 unsatisfactory economic nature only, must be far below their 

 true market value, equals 

 ((annual rental of 3,000,000 acres) 



f costs of forming or regenerating 3,000,000 acres) i'o r 2 



where ^=the rate per cent, at which the proprietor is content 

 to lock up his capital represented by soil plus growing-stock. 

 If the sylvicultural soil were of equal productive power with that 

 utilized agriculturally, then it would be necessary to estimate r 

 at a higher rate than is permissible in actuarial calculations 

 relating to farming, owing to the greater risk run by forest crops 

 from wind, fire, insects, &c., before attaining their financial 

 maturity. Thus, in central Germany 1 , whilst the rate of 

 interest for ordinary investments is about 3! to 4! %, that for 

 actuarial calculations referring to agricultural soil ranges from 



1 See G. Heyer, Anleitung zur Waldwerthrechnung, 4th edit. 1892' 

 P-I5- 



