398 



George E. Nichols, 



sharp line can be drawn between woodlands of this description, 

 which constitute an edaphic climax association-type, and forests 

 of the regional climax type. Essentially the same species may 

 be present in both cases. Here, however, the trees average 

 scarcely twenty-five feet in height, and black spruce may be quite 

 as abundant as balsam, while swamp species, notably Osmimda 

 cinnamomea and the sphagnums, commonly predominate in the 

 undergrowth. Associations of this sort may originate through a 



Figure 51. — Summit of low hill in barrens ; mountains west of Ingonish ; 

 vegetation in immediate foreground, dwarf shrub heath ; in mid-distance 

 (vicinity of figure and beyond), mainly dwarf shrub-spruce heath. The 

 low, bushy spruce in center foreground was about 150 years old. 



hydrarch successional series, but more commonly the pioneer 

 stages are xerophytic, the swampy condition being induced very 

 largely through the activity of vegetation in retarding drainage. 

 Parts of the plateau occupied by barrens are commonly skirted on 

 all sides by low woodland, which forms a transition zone between 

 these areas and those congenial to forests of a more mesophytic 

 character. Raised bogs have been developed locally on uplands 

 in the forested region, but these are especially characteristic 

 of the barrens and will be discussed under that head. 



