312 DETERMINATION AND REGULATION OF THE YIELD. 



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 forest is divided into as 

 many lots, as there are periods in the rotation ; during each 

 period one of these lots is dealt with. Thus, operations 

 extend over the whole area once in each rotation. Devia- 

 tions from this arrangement occur occasionally, for instance, 

 if a subcompartment is not cut over, or twice cut over, 

 during the tirst rotation, in order to make the compartment 

 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 

 first rotation ; it may be equal to, smaller, or larger than the 

 normal yield. 



An essential part uf this method of regulating the yield is 

 the preparation of a framework or general working plan, drawn 

 up for one rotation and divided into a number of periods, 

 showing during which period each wood is to be cut over. The 

 allotment can be made according to area, volume, or the two 

 combined, so that practically three different methods are 

 established, which must be described separatel}'. 



1. llic Mt'tliod of Periods hi) Area, 

 a. Descriplion of the Method. 



The woods of a forest are so allotted to the several periods 

 of one rotation, that each contains the same, or approximately 

 the same, area, called the periodic coupe. 



Where few or no differences exist in the quality of the 

 locality in the different parts of the forest, the size of each 



periodic coupe will be = — , where t represents the number of 



periods in the rotation. If such differences exist, the areas 

 must be reduced to one common quality standard, and the size 



