1 86 OUR FORESTS AND WOODLANDS 



to become much broken in canopy, and then 

 the best thing is to thin out the plantation 

 and underplant the birch with some sort of 

 tree like spruce, or whatever promises to be a 

 remunerative crop on land of the given descrip- 

 tion, the standards being removed whenever the 

 best financial moment seems indicated by con- 

 sideration of the state of the underwood. In 

 general, birch will have reached its maturity 

 between the age of forty to sixty years. 



The best development of birch and aspen is 

 attained when they are grown along with alder 

 or hornbeam in moist places, or with pine on 

 drier situations. Where they are found thriving 

 in pure woods, it may be safely asserted that 

 other crops of timber could be grown there with 

 greater profit to the owner. This remark cer- 

 tainly applies to parts of Scotland, as in Perth- 

 shire, where open woods of the birch are very 

 often to be found. 



One drawback, not a very serious one, it is 

 true, but still a disadvantage, of having birch 

 and aspen growing along with, or even in the 

 vicinity of, Scots pine or larch, is that two forms 

 of fungous diseases not uncommon on these latter 



