152 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY, 



acre, and underplanted with a good shade-bearing and soil- 

 preserving species. 



The Object of Mixtures. 



The object of having mixed woods in preference to pure 

 woods in the case of hardwoods is twofold — (i) to preserve 

 the fertility of the soil; (2) to improve the quality and outcome 

 of the timber. 



1. Some trees are capable of maintaining or improving the 

 fertility of the soil, whereas others are absolutely incapable 

 of doing either; indeed, under a crop of such the soil is certain 

 to deteriorate, and it is a notable fact that the most valuable of 

 our hardwood timber-trees belong to this class : therefore 

 in forming a mixture, one of the species of trees must of 

 necessity be one which will be capable of preserving the 

 fertility of the soil. 



2. Certain trees, and very notably oak, if grown in pure 

 woods, are apt, in middle and later life, and particularly after 

 a heavy thinning, to develop, from dormant buds in the stems, 

 a crop of shoots which are a very serious objection, insomuch 

 that they do incalculable harm by reducing the quality, and 

 therefore the value, of the timber,^ and it is most essential that 

 such a state of affairs should be prevented. All situations and 

 localities are not alike subject to this evil ; the danger, other 

 conditions of management being equal, seems to be in inverse 

 proportion to the suitability of the soil for the development of 

 the trees. If by any chance, however, a crop is allowed to get 

 into a bad state with side shoots, there is practically no cure. 

 Therefore, as already mentioned, the plan is to prevent the 

 evil, and this can only be attained by having such trees properly 

 mixed with shade-bearers. The proportion of shade-bearers 

 required to prevent this will depend largely on the nature of 

 the soil, fewer being necessary on a deep fertile soil than 

 on a poor shallow one. Of course it is quite possible to grow 

 a crop of hardwoods of light-demanding species on a soil 

 of high quality without any risk of injury from the cause 

 referred to ; but if the preservation of the soil be considered 

 as well, it will be found that under such a crop, with a long 

 rotation, the soil will have deteriorated. There is therefore 



' And Ijy tending to render the timber "stag-headed." — Hon. Ed. 



