THINNINGS 



109 



pine it is invariably the practice to make heavy thinnings -^ in order 

 that the crowns may be fully developed when tapping for resin begins. 

 These start at 10 years of age and continue every 5 years until tapping 

 to death begins at about 20 years. Jolyet says [155]: 



A B 



Fig. 9 (a). — Pole stand of spruce at an altitude (west exposure) of 4,590 feet in the 

 communal forest of Beaufort. There are 364 trees per acre, yielding 117 cubic meters 

 (23,000 feet board measure). The thinnings thus far have too much hght to permit 

 crown development. 



(6). — Spruce and fir running 255 trees and 283 cubic meters (74,000 feet board 

 measure) to the acre, in the Canton du Mont, communal forest of Thones-Ville, at an 

 altitude of 3,120 feet on a west exposure. Thinnings have been insufficient to free the 

 crowns of the most promising trees. 



26 This is entirely proper with maritime pine but with spruce or fir, for example, care 

 should be taken not to open up the stand too suddenly. The chief danger in the United 

 States is of too heavy thinnings because of the need of a large cut at one time to reduce 



