BRITISH FOREST TREES 69 



In general the latter practice has most to recommend it, but 

 the number of standards selected must be small, not exceed- 

 ing ten to fifteen per acre, and for some time previous to 

 the clearance of the crop they should gradually be accus- 

 tomed to greater light and air, and prepared for standing 

 isolated by being cut free from neighbouring trees. Even 

 with such preliminary precautions, however, the standards 

 often become windfall, and that too in localities not unduly 

 exposed to heavy and violent storms, besides being liable to 

 the attacks of insects and of fungous disease in the crown 

 (Peridermium pini\ whilst the young growth around such 

 standards is always more or less interfered with. But 

 where the standards maintain themselves healthy till 

 the close of the second period of rotation, they yield a 

 good return. The retention of standards is only advisable 

 on the better classes of soil, where there is least danger of 

 the younger generation of trees being too much retarded in 

 growth by the light shadow cast around by the former. 

 Without doubt the same object can perhaps be better 

 attained by growing the pine in admixture with spruce or 

 silver fir, and on the whole pure pine forests are only to be 

 recommended on soils unsuited for the formation of 

 mixed forests in which the shade-bearing conifers form the 

 ruling species or matrix. 



Mixed Forests with Scots Pine as the ruling Species. 

 Spruce is the tree most frequently grown in admixture 

 with Scots pine, and even where it is not able to develop 

 as well as the latter, it still performs good service as a 

 subordinate species protecting the soil. In some localities 

 it grows as quickly as the pine ; in others it is at first slower 

 in growth, but ultimately succeeds in forming canopy along 

 with the pine. When this begins to slacken in growth in 

 height and gets overtaken at about thirty to fifty years of 

 age, the spruce often threatens to crush out the pine unless 



