138 THE GENIRAL WORKING SCHEMB. 



the cropa brought under regeneration during any Period 

 must have tlieir regeneration completed during that Period. Now 

 in the majority of our forests it is impossible to effect, in a 

 satisfactory, complete, and sure manner, the regeneration of a mass 

 of high forest treated according to the Natural Method, without 

 exercising great caution and judgment in locating the Primary, 

 Secondary, and Final Fellings. Hence the necessity of making the 

 Periods long enough to give the Executive Forest Officer sufficient 

 time to complete the Secondary and Final Fellings with the care, pre- 

 cautions, and deliberate slowness, which can alone assure the success 

 of such operations. On the other hand, the duration, of the Periods 

 ought not to exceed the number of years beyond which oue could not 

 forecast, with a sufficient degree of certainty, the cultural operations 

 that the condition of the forest would require. These extreme 

 limits for the length of Periods seem now to have been fixed by 

 experience at thirty and forty years respectively, and it can only be by 

 exception that there would be advantage in going above or below 

 those figures. If we had a silver fir forest, the exploitable age of 

 which was fixed at 150 years, we could divide the Rotation into five 

 equal Periods of 30 years each, this duration of time being necessary 

 and sufficient for a complete series of regeneration operations. 



Hand in hand with this the Periodic Blocks have to be formed. 

 To this end, the compartments, the regeneration of which is urgent 

 (that is to say, those, as a rule, which contain the oldest stock), are, 

 first of all, placed in the Block of the First Period, the next oldest 

 compartments in the following Block, and so on up to the last Period, 

 in which must be grouped together the youngest crops. The aim 

 of the organisation must hence be to bring each compartment under 

 regeneration as near as possible the term of its exploitability. 

 But in distributing the various compartments thus, the fact must 

 not be lost sight of that the Regeneration Exploitations should 

 follow the Rules for locating coupes. And as the essential points 

 enforced by these Rules cannot be satisfied except by laying out the 

 coupes in the order in which they are to be exploited, it follows, as 

 a matter of principle, that each Block should be formed of 

 contiguous compartments, or of compartments forming together 

 one continuous mass of forest. 



Conversely, the large continuous masses of more or less uni- 

 form forest as regards age, into which the compartments naturally 



