SAMPLE PLOT INVESTIGATIONS IN SCOTLAND. 1 67 



periodic thinnings, both from a silvicultural and economic 

 point of view, has probably not been fully appreciated in this 

 country, largely no doubt owing to difficulties of marketing, 

 resulting from plantations being on a relatively small scale 

 and scattered. 



In order to gain a clear picture of the influence of systematic 

 thinnings and a knowledge of the problems involved, one may 

 consider the subject from different view-points. First of all, 

 thinning methods should be directed to the improvement of the 

 type of tree. We know that there are good and bad races of 

 the different species for particular conditions, and it is of the 

 utmost importance that the best type should be obtained in 

 the first instance. It is not enough, however, to stop there, 

 A good race is rarely if ever pure, but consists of a mixture 

 of good and bad types. Its superiority over a bad race consists 

 in its having a greater proportion of good type trees. Further, 

 the influence of the locality on the growing trees brings out the 

 advantages or disadvantages of particular points of race, such 

 as, for example, types of branching. The thinning method 

 should be directed to the favouring of what is seen to be the 

 best type of tree for the conditions. It should be noted that 

 the most desirable type may not be the most aggressive, hence 

 under faulty thinning methods or neglect undesirable types such 

 as "wolf" or coarse branching types may persist and pre- 

 dominate. If, however, desirable types are selected and 

 favoured by systematic and regular thinnings, the final crop 

 will consist largely of good type trees suitable for the conditions. 

 The resulting crop from these mother trees, whether regenerated 

 naturally or artificially, will be an advance on the first. 



The second point it is desired to note is the control thinning 

 exercises on the size and quality of the timber produced. It is 

 an axiom that, within limits, light thinnings produce many 

 small trees per acre, and heavy thinnings fewer but larger 

 trees per acre. Both systems have their uses for particular 

 objects of management. The heavy war cuttings have removed 

 practically all our large dimension timber, and one problem 

 is how to replace it at the earliest time. It seems indicated, 

 therefore, that part of our wooded area should be thinned as 

 heavily as the growth response permits. It is important, 

 however, that this large size timber should be got with the 

 minimum reduction in quality. This is a large problem 



