WATER MARGIN COMMUNITIES 183 



III. GENERAL DISCUSSION 



The areas which we have been discussing in this chapter are the 

 tension lines between the land and the water. It is in such areas that 

 ecologists have learned most about succession and about the tendencies 



141 



FIG. 140. Pond 95, showing the death of the pond by the growth of buttonbush. 

 FIG. 141. The shiny salamander (Phthodon glutinosus); about twice natural 

 size (after Fowler). 



and processes in animal formations and associations. In this chapter 

 we first considered the 1 marshes which border the lakes and ponds about 

 Chicago. Dr. Cowles and others have pointed out that lakes and ponds 

 are filled by organic debris and that bulrushes invade from the shore and 

 "capture" the ponds and lakes. As the bulrushes and other plants 



