536 



GENERAL CONSIDERATIONS 





Mll>eser/ 

 i/>eci£/wu6 Forest 

 i Western Coniferous forest 

 \North West Comfewus rarest 

 I Southern Conifervus Forest 

 I Northern Coniftrous Forest 



Fig 370.- a diagrammatic map of North America sho^4ng the vegetation regions 

 north of the tropical region. {Areas in the United States based upon Shantz and Zon 

 ^^MasofAJricln AoJulture," Part I, Sec. E; those in British Amer^ca -Pon Wea.^an^ 

 Clements, ^ Plant Ecology- ; and those in Mexico upon both.) One Ime «eparates the prame 

 (Pr) from the plains {PI), and a second the sagebrush area (S) from the southern desert 

 region (D). The existence of elevated areas presenting conditions corresponding to tne 

 northern coniferous forest, the tundra, or the arctic zone in the Alleghenies and the western 

 mountains is indicated by areas of black. 



