ECOLOGICAL SUCCESSION. 357 



including all clearly influenced by a given climate in the case 

 of land formations and (if recognizable in fresh water) by topo- 

 graphic age of a large area and by climate in the case of aquatic 

 formations. For example, all of the thicket and other early 

 stages of forest development of the area dominated by the 

 deciduous forest formation constitute the deciduous forest exten- 

 sive formation. Such formations occupy large areas which may 

 be termed ecological provinces (Gleason, '10). 



8. Animal Communities in the Forest Border Region. 



The forest border region is the western line of demarkation of 

 the deciduous forest climate. The following is a list of some 

 animal communities about the south end of Lake Michigan. It is 

 not intended to be complete, but rather to illustrate the use of the 

 terms with particular reference to the communities mentioned in 

 this series of papers. 



I. Stream Communities. 



A. Intermittent Stream Communities. 



i. Horned Dace or Pool Association. 



B. Permanent Stream Communities. 



1. Hydropsyche or Riffle Formation. 



2. Anodontoides ferussacianus Sand or Gravel Bot- 



tom Formations. 



3. Baselevel or Sluggish Stream Communities. 



a. Pelagic Formation. 



b. Hexagenia lineata or Silt Bottom Formation. 



c. Planorbis bicarinatus or Vegetation Formation. 

 II. Lake-Pond Communities. 



A. Pelagic Formations. 



B. Pleurocera subulare or Terrigenous Bottom Formation. 



C. Vegetation Formation. 



1. Leptocerince or Submerged Vegetation Association. 



2. Neuronia or Emerging Vegetation Association. 



D. Temporary Pond Formation. 



III. Prairie or Grassland Formation of the Savanna Climate. 



A. Grassland Associations of Moist and Marshy Soil in the 



Savanna and Forest Climates. 



B. Prairie Chicken or Prairie Associations of the Savanna 



Climate. 



