CHAPTER X 

 INTERMEDIATE CUTTINGS (Continued). THINNINGS 



Cuttings made in immature stands for the purpose of 

 increasing the rate of growth of the trees that remain and 

 the total production of the stand are termed thinnings. 



Natural Development of the Stand. — The theory of mak- 

 ing thinnings finds its basis in the natural process of develop- 

 ment of the stand. The average stand starts life with a 

 relatively large nimiber (usually expressed in the thousands 

 or even tens of thousands) of trees per acre. At the end of 

 its hfe, when ready for the reproduction cuttings, the number 

 has been reduced to a few himdred trees per acre — sometimes 

 less than loo. (See Fig. 57.) 



Ruthless competition for light, growing space, moisture 

 and nourishment has accompUshed this diminution in niun- 

 bers. The individual trees which survive are well pruned of 

 branches and contain a high percentage of clear lumber, but 

 among them there are apt to be individuals of undesirable 

 species or of poor form. 



The struggle for existence may have been so fierce as to 

 reduce the diameter and height growth. The competition 

 between the trees is well expressed by the changes in relative 

 position in the crown cover which are in constant progress. 

 As the weaker trees are crowded by their associates their 

 crowns are restricted and forced out of the normal shape, 

 they bend aside seeking for light, are finally overtopped and 

 ultimately die. It is a steady progression downward which 

 only the strongest are able to escape. This diflFerentiation is 



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