222 Studies in Forestry [CHAP. x. 



2. Instead of the full crop, with small annual increment on 

 a larger number of individual stems, three factors are favourably 

 introduced and combined, viz. : 



i. Good intermediate returns are available, capable of 



producing interest for themselves. 



ii. The enhanced annual increment on the remaining crop 

 equals, and often exceeds, that produced by the full 

 crop previous to its partial clearance. 



iii. The young crop produced naturally or artificially under 

 the parent standards often practically equals in incre- 

 ment a young crop formed artificially by sowing or 

 planting. 



What Loudon says l of the Oak may be applied to all our 

 forest trees grown as crops with a view to remunerative returns 

 from the capital invested : 



' The age at which Oak timber ought to be felled, with a view to profit, 

 must depend on the soil and climate in which the tree is grown, as 

 well as on other circumstances. Whenever the tree has arrived at that 

 period of its growth, that the annual increase does not amount in value 

 to the marketable interest of the money which, at the time, the tree 

 would produce if cut down, then it would appear more profitable to cut 

 it down than to let it stand.' 



Whilst this is perfectly correct for each individual tree 

 grown in the comparatively isolated positions that timber 

 trees usually occupied in Britain at the time the above was 

 written, it in no way precludes the possibility, which in fact 

 we know from actual experience to be the case, that when the 

 current annual increment per acre has sunk below the point 

 up to which it is not unprofitable to allow a crop to remain in 

 the full normal canopy of its species, it can be stimulated and 

 rendered more profitable, often very considerably so, by the 

 above-indicated method of partial clearance with a view to the 

 earlier production of valuable stems of large girth. In regular 

 high forest, with natural reproduction, the time of regeneration 

 1 Arboretum et Fruticetum Britannicum^ 1838, vol. iii. p. 1809. 



