346 SYLVICULTURAL NOTES ON TIMBER TREES 



BIRCH. 



Betula alba = The Common Birch. 



Betula papyracea = The Paper Birch. 

 Betula lutea = The Yellow Birch. 



There are two distinct varieties of the Common Birch : 



(i) The smooth bark variety = Betula alba pubescens. 



(ii) The rough bark variety = Betula alba verrucosa. 



The Common Birch is a native tree, but not the others. 



As to Seed. It produces much seed when about 25 years 

 of age ; and good seed years are very frequent. 



The germinative capacity of the seed is only about 20 per 

 cent. 



One pound of seed contains about 800,000 seeds. The 

 seed ripens about the end of August. 



The timber is moderately hard, and does not split well. 

 It is a very handsome wood. 



Occasionally large " burrs " are met with which are very 

 valuable for cutting into veneers. 



Soil and Situation. Birch will grow on almost any soil, 

 but it seems to avoid chalky soils. It springs up naturally on 

 water-logged land and on dry barren sands. It is quite 

 immune to late spring and early autumn frosts. 



Cultivation, etc. It is a very light-demanding tree. As 

 a timber producer it is of little value in this country ; but it is 

 the "best " nurse " which exists. 



Where it is desired to plant a frost tender species in a 

 locality subject to late spring and early autumn frosts, the 

 growth of Birch affords a ready means of effecting this 

 purpose. Two year seedling Birch may be dibbled in, and 

 the tender species planted in about 10 years' time. Such 

 tender species must be able to withstand some shade ; but 

 the canopy of Birch is very light and thin. 



After the same manner, a few Birch growing over young 

 crops of Silver Fir or Beech, will afford welcome protection, 

 not only from frosts but also from hot summer sun. 



Birch may also be planted as fire lines on very dry sands, 



