CONIFEROUS FORESTS 



339 



The Forest Types in Detail 



The Boreal or Spruce Type.- — The northernmost type of forest, 

 which covers almost the whole of eastern North America from .the 

 arctic tundra down to latitude 45°, with many more or less isolated 

 areas farther south, especially in the mountains, is mainly composed of 

 jack pine (Pinus BanJcsiana), tamarack (Larix laricina), two or three 

 species of spruce (Picea), halsam fir (Abies balsam ea), and arbor-vitas 



Dense Growth of Spruce {Picea Mariana) and Arbor-vit.e (Thuja) in a Cold 

 Swamp, Cheboygan Co., Michigan. August, 1912. 



or northern white cedar (Thuja occidental-is) . In places some one of 

 these may cover considerable areas exclusively (this is especially true 

 of the pine), but usually two or three of them are mixed together. 

 They have much in common in general appearance, mature trees being 

 as a rule spindle-shaped or narrowly conical in outline, with more or less 

 defiexed branches, and leaves an inch or less in length. The tamarack 

 is deciduous, and the rest evergreen. 



Forests of similar aspect, and made up mostly of trees of the same 

 genera, cover large areas in all the cooler parts of the northern hemi- 

 sphere. Doubtless on account of the abundance of such trees in north- 

 ern Europe, where most of our Anglo-Saxon traditions originated, the 

 spindle-shaped tree has become firmly established as the conventional 

 type of conifer. Illustrations of these trees in their native haunts 

 abound in publications dealing with outdoor life in the extreme north- 



