THINNING AND PRUNING 135 



capacity for weakening each other, and the struggle for 

 supremacy, instead of being over in a few years, sometimes 

 continues throughout the life of the plantation. Such varia- 

 tions will of course necessitate different methods and 

 degrees of thinning, and it is in the discrimination 

 between the necessities of different cases that the skill of 

 the forester lies. 



Let us glance at a process of thinning which would be 

 applicable to a fast-growing crop of any one species, and 

 which is expected to grow big timber, and has been planted 

 at not more than 3 to 4 feet apart. In this case thinning is 

 rarely necessary before the tenth or twelfth year after plant- 

 ing, according to the shade - bearing or light - demanding 

 qualities of the species. At that stage the plantation may 

 be gone through, and all rubbish, dead or sickly trees, taken 

 out. This process is simply cleaning, and is only a pre- 

 liminary to the first thinning. The latter may take place 

 at any time between the tenth and twentieth year, according 

 to the species. Beech, spruce, silver fir, etc., rarely require 

 touching before the twentieth year, as close order is necessary 

 if they are to produce clean timber. Mixed plantations in 

 which larch has been used with oak or other slow-growing 

 hardwoods will probably require attention first, so that the 

 latter may not be weakened or overdrawn. The first 

 legitimate thinning should be confined to the removal of 

 suppressed or nearly suppressed trees, which can be removed 

 without leaving gaps in the canopy above. Such trees will 

 probably be of little value and scarcely pay more than the 

 cost of cutting, but the temptation should steadily be resisted 

 of endeavouring to make this thinning a more profitable 

 operation by taking out larger and more valuable poles. 

 In the case of larch mixed with hardwoods, the former 

 should of course form the bulk of the first thinning, as the 

 intention throughout is to render them subordinate to the 

 permanent crop. A great deal can often be done to relieve 

 the hardwoods by 'pruning the side branches of encroaching 

 larch, without actually taking them out, and this is often 

 preferable to forming gaps in the leaf canopy. 



The following thinnings may take place at intervals of 

 about ten years, until about the fiftieth year, when the 



