TENDING THE PLANTATIONS 137 



the different species. Fast-growing trees and light- 

 demanders, as a rule, need thinning earlier than the 

 slower-growing ones and shade-bearers. 



Larch and Ash, for instance, which grow very quickly 

 and whose branches are easily suppressed, should be 

 given a slight thinning about 15 years of age. Douglas 

 Fir, although a shade-bearer, is a very quick grower, and 

 should be lightly thinned at about 15 to 20 years to 

 prevent them being overdrawn. 



About 18 to 20 years is the age for thinning Pine woods, 

 while Beech and Spruce seldom need thinning before 

 20 to 25 years, and Silver Fir from 25 to 30 years. 



Nature is a good guide in the matter, and thinning 

 should be done principally as a means of assisting 

 Nature, by cutting out trees that are naturally in 

 danger of suppression before injury is done to better 

 trees. 



Thinnings at all ages should be light and frequent. 



In the working plan they should be so arranged that 

 each plantation is attended to every five years or so, 

 till the trees have attained their principal height growth. 

 After that they may be less frequent, and may take the 

 form of partial clearances to allow the trees to increase 

 more rapidly in girth. 



The number of trees to be taken out at each thinning 

 depends upon the kind of tree and also upon the class 

 of soil. 



Shade-bearing trees, whose branches are usually very 

 persistent, must be kept relatively closer than light- 

 demanders, and trees growing vigorously on good soil 



