PRESENT FORESTS OF NORTH AMERICA 31 



and (3) the Southeastern Evergreen Coniferous forest. The char- 

 acter of the topography, soils and cHmate as well as the geological 

 history of the forests have resulted in interfingered areas and out- 

 liers of one type within the area of another, and their boundaries 

 are in most cases covered by a broad transition zone between forest 

 and prairie or between evergreen needle leaved and broad leaved 

 deciduous forest. ^ 



The Northern Evergreen Coniferous forest extends from New- 

 foundland west to the 96th meridian, and from James Bay south- 

 ward beyond the Great Lakes. On the east its southern limits 

 include most of Maine and areas in New Hampshire, Vermont 

 and New York, with a southern extension along the higher Appalach- 

 ian ridges to West Virginia, and isolated patches to the southward 

 along these mountains in the Great Smoky Mountain region along 

 the North Carolina-Tennessee boundary. 



In its typical development this forest is characterized by pure 

 or nearly pure stands of needle leaved conifers among which the 

 white pine {Pinus strohus) is the most important if not the most 

 widely distributed tree. Virgin stands range 60 to 125 feet in 

 height and vary from heavy stands with a shaded floor almost 

 devoid of undergrowth to more open stands with an undergrowth 

 of deciduous under-trees and shrubs. Nearly pure stands of the 

 black spruce are also important features of this region, especially 

 toward the north. 



Within this area the hemlock (Tsiiga canadensis), the arbor vitae 

 (Thuja occidentalis) the basswood (Tilia americana), the black ash 

 {Fraxinus nigra), the white ash {Fraxinus americana), the sugar 

 maple (Acer saccharum) and several species of birch {Betiila) and 

 elm (Ulmus) reach their northern limits and the center of their 

 maximum distribution. The hickories and oaks, so characteris- 

 tic of the deciduous forests of the Atlantic region, reach their 

 northern limits of distribution in this area of Northern Evergreen 

 Coniferous forest as do the chestnut {Castanea dentata), the horn- 

 beam {Ostrya virginiana), the sassafras (Sassafras sassafras), the 



2 See Shreve, F., A Map of the Vegetation of the United States. Geograph- 

 ical Review, vol. 3, pp. 119-125, pi. 3, 1917. 



