CHAPTER L. 



FOREST SOCIETIES. 



I. General Character of Forest Societies. 



1006. Extent of forest societies. Forests represent the highest 

 stage of evolution in plant communities. Some forests represent 

 also the most complex stage. In their distribution forests range 

 from the tropics to subarctic regions, from wet and marshy low- 

 lands to high mountain altitudes, and they are also transconti- 

 nental. Their farthest north is limited by arctic cold, their 

 highest altitude by alpine cold and winds, their breadth of distri- 

 bution by bodies of water, by wind, and by desert conditions. The 

 forest is the climax type in the evolution of plant communities, 

 and the only hindrance to complete occupation of the land are 

 exteme cold, dryness, frequent and severe winds and fire, and 

 the needs of human civilization. 



1007. Complexity of forest societies. All plant communities are 

 more or less complex, but the forest type is the most complex of all. 

 This is due to the fact that in the forest there is the greatest diver- 

 gence among its members in point of style, form, character and 

 work. The abundance of the tree type stamps the community as 

 a forest. Trees are the largest plants. The bacteria, abundant in 

 all aerated soils and in decaying vegetation, represent the smallest 

 individuals. Between these two extremes there are gradations in 

 size, form, habit, and habitat, in the forest society. The forest 

 teems with many kinds of algae, fungi, lichens, mosses, ferns, herbs, 

 undershrubs and other shade plants, epiphytes, etc., to say 



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