154 



A MANUAL OF FORESTRY. 



with a complete and uninterrupted cover overhead. 

 When the whole process has been completed the young 

 wood consists of trees varying in age by 20 to 50 years, 



Fig. 71. 



1, 1, 1. Points of attack (groups of advance growth). 



2, 2, 2., 



3, 3, 3. 



4, 4, 4. 



5, 5, 5J 



t. Successive enlargements pi groups. 



according to circumstances ; it is in fact an uneven- 

 aged wood. 



a. Selection of Groups. 



The time when the different parts of the wood are at- 

 tacked depends chiefly on the following considerations : 



