242 



DISTRIBUTION OF PLANT COMMUNITIES 



tion of the southern end of Florida, is occupied by coniferous forests 

 although the rainfall is 50 inches or more throughout (Fig. 107). 

 The limiting factors here are primarily, the high evaporation rate, 

 the sandy soil which is relatively infertile, and the recurring fires. 

 The dominant trees in these forests are pines but there are also 

 many cypress swamps along the Atlantic Coast and in the valley of 

 the Mississippi River. 



Fig. 108. — Mature spruce forest. Adirondack Mountains, Xew York. (Pho- 

 tograph by A. Gaskill. Courtesj^ of H. L. Shantz and the U. S. Department 

 of Agriculture.) 



Elsewhere in the United States coniferous forests are foimd in the 

 greater part of IMaine, the Green IMountains of Vermont, the Adiron- 

 dack IMountains of New York (Fig. 108) and the highest parts of the 

 Appalachian Mountains farther south. They are also found in the 



