100 FIRST BOOK OF FORESTRY 



vigorous cues Avhich project abo\"e the general level of the 

 canopy of the woods. The three next best trees are marked 

 as No. 2 ; they represent the tlirifty trees whose crowns 

 make up the body of the canop}'. Let us call the trees 

 of class No. 1 and No. 2 the dominant trees. The trees 

 No. 3 are weaker ; they form a small jDart of the canop}^ 

 and give little promise of ever making good trees. Those 

 of No. 4 are being crowded out, and those like No. 5 are 

 dying or dead. 



If our piece of forest were twent3^-five years old and 

 the trees about thirtv feet in heio-ht and we miofht thin 

 out every ten years, we should take out only trees of the 

 fourth and fifth classes ; and also such ti-ees of the third 

 class, and even of larger size, as interfered evidently with 

 some better trees. Tliis would ))e repeated in ten, in 

 twenty, etc., years, until the tunljer should be cut. 



In places where the pole wood cut during the first and 

 second thinning could not be sold, this jirocess would 

 cost some money; for the material cut in the thinnings 

 should really be taken out to prevent the development 

 of too many injurious beetles. For this reason a more 

 thorough thinning would, in most cases, be better ; and 

 then most of the trees of even the third class would be 

 taken out. 



Where the young growth starts from natural seeding, 

 so that often twenty and more trees start on one square 

 foot, the crowding begins very early and it would 1je 



