306 A NATURALIST IN THE GREAT LAKES REGION 



1 6. Ash-elm association Green heron association 



In steep-sided ponds this last may be replaced by the 

 17. Swamp white oak association, which gives place to the oak forest 



1 8. Floating sedge association 



19. Sphagnum-Cassandra association ^ Northern locust association 



20. Tamarack association 



21. The flood-plain or elm-soft maple association 



This is subdivided into 



22. The bare river margin Spotted sandpiper association 



23. Ragweed-sunflower association Plant bug association 



24. Willow association Cecropia association 



25. Young ash-elm-maple association Yellow warbler association 



26. Mature elm-maple association Tanager association 



The flood-plain association is stratified like the climax forest (which 

 see) and the several strata may be named as in the climax forest though 

 the constituent plants and animals will be somewhat dissimilar. 



ASSOCIATIONS THAT ARE RELATIVELY PERMANENT, THE CLIMAX 

 OF CONSTRUCTIVE PROCESSES, KNOWN AS CLIMAX 



ASSOCIATIONS 

 They are: 



27. The prairie or Andropogon furcatus Meadow lark association 

 association 



28. The oak-hickory association Green tiger association 



29. The beech-maple association Wood frog association 



Each of these is subdivided. In addition to the prairie grasses 

 other plants are conspicuous, and several types of prairie may be 

 distinguished in addition to the wet prairie (bobolink) and the Andro- 

 pogon furcatus (meadow lark) prairie. 



30. High prairie or Silphium association Jumping spider association 



31. Very dry or Eryngium association Leaf hopper association 



32. Thin soil, rock bottom, prairie clover 

 association 



The oak-hickory and beech-maple forests each have a 



33. Forest margin or Crategus association Brown thrasher association 



Each is divisible into successive strata, much alike in the two except 

 for variations in the abundance of the constituent forms. 



34. The forest crown association Tree cricket association 



