A SUSTAINED TIELB. i 



To assure a sustained yield and to estimate at the beginning of 

 each period the annual yield during that period are thus two perfect- 

 ly distinct operations in the organisation of a high forest. The first, 

 which is the more important of the two, consists, we have said, in 

 the proper distribution of the exploitations between the periods of 

 the rotation. Now in whatever way the distribution is made, it 

 stands to reason d, priori thai it is impossible to succeed at once in 

 perfectly equalizing the total quota of produce for each period. 

 /The problem of assuring a sustained yield is thus not only a 

 difficult one, but also one, of which we can obtain only an approxi- 

 mate solution. It even often happens that it is impossbile to 

 assure a sustained yield without having to exploit a certain number 

 iof the crops either too late or too early. It thus becomes a 

 ' question of importance to ascertain, from the very beginning, how 

 i far it is the interest of the proprietor of a given forest to secure a 

 sustained yield and thus have the annual or periodic quota of 

 produce equal. 



The limits between which the yield of a forest may vary, while 

 still remaining sufficiently uniform to be considered sustained, 

 depend on the condition and situation of the forest, and, above all, 

 on the character of the proprietor. 



If the proprietor is a private individual, his main object will 

 be to obtain the largest pecuniary profits from his property. As a 

 rule, he will not pay any attention to the equalization of the annual 

 or periodic quota of produce, and will admit no other principle but 

 that of the satisfaction of his own personal wants and the increase 

 of his wealth. He will exploit and sell on a large scale when the 

 demand is high, and will diminish or entirely suspend his exploita- 

 tions when the market is dull and prices low. 



Nevertheless, if he possessed a real forest, which would ordi- 

 narily form no small part of his wealth, he could not afford to 

 neglect all considerations of a sustained yield by suspending his 

 exploitations, unless he was in a position to obtain from some 

 source other than his forest the annual income which he required. 

 Such a happy combination of circumstances is, however, the excep- 

 tion and not the rule, and the neeessity of having a sustained yield 



