58 Application of the Exploitabilities. 



To realize the object of Commerciar Exploitability, we must 

 exploit forest And individual tree at the age at which the rate of 

 interest on the capital value is at ils maximnm. In the case of in- 

 dividual trees it is obvious that they must be as numerous as possi- 

 ble, since the resulting income is ofcourse directly proportional to 

 their number. 



The conditions of Compound Exploitability are never fully satis- 

 fied except in high-forest crops consisting of trees of the same age. 

 But this being so, it is sufficient to fell the standing crops at com- 

 plete maturity in order to obtain from them the highest sum of 

 utility. 



In a forest worked on the Selection System the larger trees are 

 found only here and there in the midst of younger ones. Each of 

 the former, felled at maturity, yields the most useful produce the 

 forest can ever furnish. But owing to the rate of growth being an 

 indeterminate quantity, it is impossible to estimate the loss of pro- 

 duction resulting from the maintenance of the tree above the young- 

 er individuals of the same species, the free development of which it 

 impedes. In the case then of forests worked by Selection we must 

 be satisfied with Qualitative Exploitability, which is all that we need 

 require, as quantity of produce must give way to utility. 



From a forest in the state of simple copse it would be vain to 

 expect the largest quantity and the most useful kinds of produce that 

 the soil can yield ; but we may endeavour to obtain as much of such 

 produce as this claSs of forest can furnish. Now the mean rate of 

 production of the soil in a copse goes on increasing up to an age be- 

 yond that at which we could maintain the standing crop, if we are 

 to regenerate it by meaus of regrowth from the stool. Hence we 

 must exploit such oo[)..e8as late as possible, consistent with security 

 of regeneration, in order to obtain the laigest quantity of material 

 possible under the circumstances of the case. 



In a forest under treatment as a copse with standards, tiie under- 

 wood must be exploited under the same conditions as a simple copse 

 and this for the reasons already explained in the foregoing paragraph. 

 With respect to the standards, which are intended to yield timber, 

 they must be felled only one by one as they become mature, in order 

 that they may furnish the most useful classes of timber. JNo atten- 



