METHODS OF MAKING THINNINGS 



169 



ning in a stand on good soil previously unthinned will remove 

 approximately one-third of the cubic foot volume, while a 

 second thinning five to eight years after the first takes out 

 20 to 25 per cent. 



As an indication of what may be obtained when stands are 

 repeatedly thinned, the following table showing the per cent 



Fig. 66. 



Diagram showing the arrangement of crowns in a 50 year old hardwood 

 stand in need of a thinning. The crowns of overtopped trees are indicated by 

 broken lines. Compare with Figs. 67 and 68. 



of the total cubic foot volume removed in thinnings has been 

 prepared from yield tables given in Schhch's^ Manual of 

 Forestry and secured by him from the original tables com- 

 piled by Wimmenauer for oak and Schwappach for pine. 



