FORMATION OP WO BRING C{B0L-E3. 89 



Thus, for instance, it seltiom happens that when those differences 

 are at aAi pronounced, different rotations are not necessary. The 

 work of separation being now complete, each portion thus arrived, 

 at forms a separate Working Circle. 



All the various crops composing a Working Circle ought to 

 •require one and the same Rotation. The lengtli of the rotation 

 depends on the climate, soil and species. These vary more or less 

 from compaj-tnaent to compartment, so that, strictly speaking, the 

 rotation would be different for each ■compartment. But it is clear 

 that unless these differences are marked, it would be absurd to 

 ■consider them to be opposed to the inclusion of the compartments 

 in question in the same Working Circle. No one can fix within ten 

 years the exact exploitable age of high forests of our large species or 

 within one or two years that of our copses. Hence it is only whea 

 differences of 30, 40 ot 50 years in the case of high forests, and of 

 from 5 to 10 years in the case of copses present themselves between 

 two several compartments, tbat it is necessary to place these in 

 different Working Circles. Such differences cannot be discovered 

 until after the Working Circles have been formed; but facts that 

 help to discover them must be noted, as for instance, the girtk of 

 the trees at known ages. 



A proper Gradation of Ages in a Working Circle is necessary 

 in order that the series of annual exploitations may go on continu- 

 o\isly without any hitch and that all the standing timber may be 

 felled at the right time. This gradation can never be dispensed 

 with, but in order to be able to extract more or less equal quanti- 

 ties of exploitable wood every year it is enough if we have certain 

 principal broadly defined age-classes represented in sufficient 

 proportions. Thus we must liave in each Working Circle old high 

 forest, high forest, high poles, loio poles and thickets, or, in more 

 general terms, at least these three great classes, viz., old, middle aged 

 and young crops. After what we have just said, it is obvious that 

 if the old crops, instead of covering one-third of the whole area, 

 occupies only one-sixth, they are in insufficient quantity. 



It is often very difficult to satisfy this condition of the grada- 

 tion of ages. Thus it may happen that a certain age-class is 

 insufficiently represented in the forest or is too irregularly distri- 

 <iuted to be included in each of the natural Working Circles. 

 12 



