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PLANT SOCIETIES 253 
Forest societies. There are many kinds of forest 
societies, just as there are of herbaceous plants. These 
depend on the elevation, the action of the climate, soil, 
etc., as well as on the kinds of trees. Forests in the 
arctic regions are different from those of the temperate 

Fia. 303. Vegetation on border of marsh. 
zones, and these are different from the forests of the 
tropics. _The society may be at first mixed, cone- 
bearing, and evergreen trees, with broad-leaved trees. 
In the end of the struggle some of these are likely to 
be crowded out. Where the forest growth is even and 
the leafy tops cut off much of the light, the forest floor 
