178 



NATURAL REGENERATION 



number are found per acre of the different age classes, just 

 before a felling will take place : 



Years. 



15 



30 



45 



60 



75 



90 



Trees. 

 700 



357 

 188 

 103 



57 

 43 



105 



Then, as the number of age classes is 7, the number of 

 trees found per acre, if stocked with only one age class, will be 

 as shown in the following table, where the number per acre 

 in close-canopied high forest is also shown : 



JUST BEFORE A FELLING. 



Thus it will be seen that, in the above case, the relative 

 density is about correct ; the older age classes being some- 

 what more thin on the ground. 



Now, if it be desired to perpetually retain this density at 

 each felling, some of the trees in all the younger age classes 

 must always be thinned out at the same time that the 

 mature trees are cut. 



The correct principle to observe is to first remove from 

 these younger age classes such trees as appear likely to form 

 large crowns and are occupying more space than their 



