102 FIKST BOOK OF FORESTRY 



THE NUMBER OF TREES ON ONE ACRE IF FULLY STOCKED 



By dividing these figures by 160 (the number of square 

 rods in an acre) we can readily find how many trees we 

 may leave on one square rod. 



Many foresters are guided by the crowns and thin just 

 enough to keep the crowns from crowding. 



Naturally enough, trees which, like spruce, balsam, 

 beech, and maple, can tolerate much shade, are thinned 

 later, and must be thinned less thoroughly, if they are 

 to clean themselves and grow smooth stems, than the 

 intolerant kinds, which clean more easily. On the whole, 

 thinning is one of the most difficult things the forester 

 has to learn, and much good sense and care, as well as 

 experience, are needed to do it well. 



That injured and crippled trees and also those with 

 unduly spreading crowns should be taken out is self- 

 evident. After a thinning our woods should be evenly 

 and well stocked with as perfect trees as can be produced. 



