MODIFICATIONS OF THE METHOD 



97 



aged form. With larger groups one of the distinctive char- 

 acteristics of the selection method is lost, namely the protec- 



80 years 



40 years 



60 years 



90 years 



10 years 



100 years 



20 years 



30 years 



70 years 



50 years 



FIG. 32. 



A portion (one acre) of a stand reproduced by the group selection method. 

 Small groups are shown in the illustration averaging one-tenth of an acre in size. 

 Length of rotation is 100 years; length of cutting cycle 10 years. Compare 

 with Figs. 27 and 28. Ten age classes are represented in this stand each group 

 containing a different number of trees depending upon its age. The numbers 

 indicate the age of the trees in each group. 



tion of the site and of seedlings so essential for successful 

 natural reproduction. The groups must be small enough, so 



