METHODS OF MAKING THINNINGS 1 77 



by a dense foliaged, shade enduring, species capable of fur- 

 nishing best protection to the site, profiting by the chance for 

 growth in a shaded position and functioning efficiently as a 

 pruner of the dominant stems. 



For thinning stands of eastern white pine Fernow ^ ad- 

 vdsed the method as early as 1903. He recommended the 

 selection at 30 years of 200 trees to form the final crop and 

 the freeing of their crowns by a thinning for a space of two 

 to three feet on all sides. This would be repeated as often 

 as the crowns touched. 



Borggreve's Method. — Borggreve ^° developed a method 

 of thinning radically differing in principle from either of the 

 two methods already mentioned. His idea is to take out 

 two classes of trees in the thinning: 



(a) The largest dominant trees. 



(6) The suppressed trees; in order to utilize them before 

 they become a total loss. 



The removal of the suppressed trees constitutes a Grade A 

 thinning under the ordinary method, but taking out the 

 largest dominant trees is directly opposed to the principles of 

 the ordinary or French methods, which even in their heaviest 

 cuttings leave the very trees which Borggreve cuts in his 

 first thinning. Selection thinning is another name for this 

 style of thinning. 



The selection of the dominant trees to be removed is made 

 on the basis of their form and the quaHty of the timber they 

 can eventually produce as compared with their associates. 

 This results usually in the cutting of the largest dominant 

 trees, for such trees in attaining their commanding position 

 developed large limbs and possibly forked trunks which the 

 smaller dominant, co-dominant, and intermediate trees have 

 escaped, due to their more restricted opportunities for devel- 



