312 DETERMINATION OF THE YIELD. 



if the division of the area is based upon the reduced area of 

 the several parts ; but it achieves this object only by heavy 

 sacrifices, because the returns during the first rotation must 

 be very uneven, unless at the outset a proper proportion and 

 distribution of age classes existed. The method takes no 

 notice of disturbances nor of the state of the market, hence 

 it is very rigid. Above all, it neglects the fundamental 

 principle, that the mdst important measure must always be 

 the establishment of the normal increment within the shortest 

 possible period of time. 



The method is applicable to coppice woods, coppice with 

 standards, and, with modifications, to selection forests. For 

 all other methods of high forests it is quite unsuited, except, 

 perhaps, for clear cutting with a very low rotation. 



SECTION II. ALLOTMENT OF WOODS TO THE DIFFEKENT 

 PERIODS OF A ROTATION. 



In order to remove the great rigidity of the fixed annual 

 coupes, and to obtain a method which is suitable for the 

 treatment of high forests, especially those managed under the 

 shelter-wood systems, the several woods comprising a forest 

 are allotted to a number of periods. The latter are generally 

 from 3 to 6 in number, and each comprises from 10 to 30 

 annual coupes. In this way the woods are divided into as 

 many lots as there are periods in the rotation ; during 

 each period one of these lots is dealt with. Thus opera- 

 tions extend over the whole area once in each rotation. 

 Deviations from this arrangement occur occasionally, for 

 instance, if a sub-compartment is not cut over, or twice cut 

 over during the first rotation, in order to make the compart- 

 ment uniform. 



It is evident that during the first rotation the total yield is 

 represented by the growing stock which happens to stand in 

 the forest at the commencement of operations plus that part 

 of the increment which is added to it during the course of the 



