cH.m THINNINGS AND PRUNING 239 



the crop, that the forester comes in and carries out 

 thinnings. 



The most intense struggle goes on while the trees 

 grow in height ; a time comes when they have attained 

 their maximum height, after which there is no longer a 

 struggle for light above, but for expansion of the crown 

 and girth development. It is then during the stage of 

 upward growth that the young trees require the most 

 constant attention in order that they may develop in the 

 best manner possible. 



It will depend on the object with which the crop is 

 raised, on its nature and composition, and on the soil 

 and locality, when these thinnings are to be started, how 

 often they are to be repeated, and how heavy they are 

 to be made. 



Generally speaking, it may be said that while the 

 object of the forester must be to keep the soil well pro- 

 tected and to keep the leaf-canopy complete, not only 

 for its preservation, but, in forest grown for high-class 

 timber, to produce it of as good a quality as possible, 

 it is advantageous to start thinnings as soon as the 

 struggle for existence begins. It may be that if this be 

 done the cost of the operation will not be covered by 

 any means by the money return from the sale of the 

 produce thus obtained ; but, nevertheless, the benefit 

 done to the young crop may be sufficiently great to 

 more than compensate lor the immediate loss on the 

 transaction. In practice the beginning of thinnings is 

 usually delayed until the thicket has turned into youno- 

 pole forest, i.e. until the lower branches have died down, 

 and the boles have been sufficiently cleared to allow 

 fairly easy access into the young crop. 



The intensity of the thinnings is also regulated by 

 the factors which have been stated above. If the object 

 of the forester be to produce clean timber, as free of 

 knots as possible and of even growth, and to obtain tall 

 trees, the leaf-canopy should be interrupted as little as 

 possible, at any rate during the period of upward growth. 

 During this period the lower branches die down, while 



