METHODS OF MAKING THINNINGS 



163 



Grade C. — Heavy. Removes in addition the remaining 

 intermediate trees. 



Grade D. — Very heavy. Removes in addition many of 

 the co-dominant trees. 



Interlucation or accretion cutting. Removes in addition 

 the remaining co-dominant and a few dominant trees. 



This classification is conservative. Under a more radical 

 one additional trees to those specified might be removed 

 under each of the various grades. (See Figs. 61 to 68.) 



The amount removed in thinnings varies from as low as 

 S per cent in a Grade A thinning to around 40 per cent of the 

 total cubic volume in Grade D. Experience in this country 

 is based upon the first thinning at different ages in stands 

 previously unmanaged. 



Tables of yield in feet, board measure, from thinnings for 

 white pine {Pinus strobus) have been published by the For- 

 estry' Commission of New Hampshire ' and the State Forester 

 of Massachusetts.* From these tables the following percent- 

 ages have been calculated. The thinnings approximated 

 Grade C. 



The author has found that in thinning sprout hardwood 

 stands in Connecticut, 40 to 50 years of age, a Grade C thin- 



