DISTRIBUTION OVER THE FOREST. 



229 



more likely to occur : hence in extensive forests cuttings must 

 be made in several localities in each year so as to clear only a 

 small area in one and the same locality. 



Insects and fire are most injurious when several annual 

 cuttings adjoin each other, because the former wander from 

 one coupe to the next, while fire spreads more rapidly in 

 young woods than if the area is interrupted by older woods. 



These circumstances demand in many cases, and especially 

 where clear cutting is practised in coniferous woods, that a 

 second cutting should 

 not be made in any lo- 

 cality until the first coupe 

 has been successfully re- 

 stocked. This leads to 

 the splitting up of a 

 working section or a 

 series of age gradations, 

 into several sub-divisions 

 which are called "cutting 

 series." Supposing, in a 

 forest worked under a 

 rotation of 20 years, it 

 was considered neces- 

 sary not to cut in the 

 same locality more fre- Fi g> 49. 



quently than once in 



every 4 years, the series of age gradations would be divided 

 into 4 cutting series, of which each would comprise 5 coupes. 

 (Figure 49.) 



Cutting 

 Series 



A would comprise the coupes now old 20, 16, 12, 8, 4 years. 



C 18,14,10,6,2 



D 17,13, 9,5,1 



As a general rule, a careful distribution of the age classes 



