268 A MANUAL OF FORESTRY. 



somewhat from snow and rime. It prefers south or 

 west aspects. 



Soil Birch requires only a shallow soil, with a 

 moderate amount of moisture; it is not exacting as 

 regards mineral composition. Although loamy sand 

 suits it best, it accommodates itself to all sorts of other 

 soils. It is found on soils ranging from poor dry sandy 

 soil to swampy ground, but avoids stiff clay and cal- 

 careous soils. 



d. Shape and Development. 



The stem is generally wavy or undulating, and divided 

 into branches in the upper part. The crown assumes 

 an elliptic shape, and is thin. The branches are often 

 drooping. The root-system is weak and shallow. 



It grows quickly from the beginning, but rarely 

 reaches a height of 100 feet, generally not beyond 70 or 

 80 feet. Its volume growth is smaller than that of most 

 other important forest trees. Its life seldom exceeds 

 100 years. 



e. Reproductive Power. 



Birch begins producing full crops of seed when 

 about 25 years old ; they recur every two or three 

 years and sometimes annually, and are heavy. On 

 the whole, the reproductive power by seed is very great. 

 The light seed is easily carried about, and young Birch 

 springs up wherever there is room for it, owing to the 

 accommodating power of the species. 



The reproductive power from the stool is weak; the 

 shoots spring chiefly from the root neck ; the stools are 

 liable to die off after two or three rotations. 



