THE VOLUMETRIC METHOD, 14 



the annual yield by taking into account every kind of produce 

 realizable. 



In practice this method inevitably yields uncertain results, 

 for how is it possible to estimate the future increment, for an 

 interval of time as long as 50 or 100 years, of craps now much 

 below the age of maturity ? Whatever procedure is adopted, it 

 can offer no adequate guarantee of accuracy. 



This uncerta;inty of the results obtainable oould not, of course, 

 escape the originators of the method ; and, in order to avoid 

 an undue accumulation of errors necessarily arising from a 

 too low or too high figure fixed for the a,nnual yield, they 

 laid down the rule that the Working Scheme was to be frequently 

 verified, every 10 years for instance. These frequent verifications 

 are a necessary concomitant of every system of forest organisation 

 based on volume. They amount to the drawing up each time of 

 an entirely new Workiug Sjcheme, since it naturally follows that all 

 the original crops must have undergone radical and characteristic 

 changes since the da,te of the previous Working Scheme. The 

 consequence Is the inevitable instability of the prescriptions 

 relative to the treatment of the forest, and indeed of the whole of 

 the Organisation Project itself. The time for exploiting any parti- 

 cular crop, as it depends on the figure of the annual yield, of course 

 varies with it ; and it may thus happen that all the operations now 

 prescribed for any compartment may have to be changed at the 

 next verification. These disadvantages, which are inherent in the 

 method itself, would of themselves suffice to justify its condemna- 

 tion, especially in France where the desire for order, simplicity, 

 and stability in forest organisation h^id led to the universal adoption 

 of the system of Tire et Aire. But all volumetric methods 

 must be rejected on account of the very principle they imply. 

 Basing, as they do, the distribution of the exploitations entirely on 

 the element of volume, they have for esseAtial obj^ect tl;e exact 

 determination of the annual yield. As ^ matter of prin.ciple, they 

 seek to obtain a sustained yield, independently of all considerations 

 relative to the improvement of the forest. Whether the quantity 

 of old timber is excessively large or totally insufficient, a certain 

 fixed quota of it must be worked out every year. In the former case 

 the last old trees will be found in full decay by the time their 

 turn for ex'^i'^-'ition comes; in the second case, after a few years all 



