ECOLOGICAL SUCCESSION. 355 



* 



Dahl ('08) . . . Plant and Animal Ecologists Taxonomic Groups. 



Form (Mos) mores (Shelf ord, 'n) Form (forms) (Species). 



Consocium (Clements, '06) Genus. 



( Stratum or Story (Warning)... . .Family. 



Bioconose. . . . < 



I Association or Society (Warning) Order. 



"Formation (Grisebach, '48; Class. 



fide Clements). 



Zootope. 



Extensive or Climatic Formations Phylum. 



(Aquatic and Terrestrial.) Vertebrates and Inver- 

 tebrates. 



logical life histories shown by the details of habitat preference, 

 time of reproduction, reactions to physical factors of the environ- 

 ment, etc. The organisms constituting a mores usually belong 

 to a single species but may include more than one species as 

 specificities of behavior are not primarily significant (see p. 338) . 



Consocies are groups of mores usually dominated by one or two 

 of the mores concerned and in agreement as to the main features 

 of habitat preference, reaction to physical factors, time of repro- 

 duction, etc. Example: the prairie aphid consocium; the aphids 

 control a group of organisms which for the most part prey 

 upon them, as for instance, certain species of lace-wings, lady 

 beetles, syrphus flies, etc. 



Strata are groups of consocies occupying the recognizable 

 vertical divisions of a uniform area. Strata are in agreement as 

 to materials for abode and general physical conditions, but in 

 less detail than the consocies which constitute them. (For 

 differences of physical conditions see Table V., p. 84; Shelford, 

 '12). For example, the beech forest animal community is clearly 

 divisible into the subterranean-ground stratum, field stratum 

 (level of the tops of the herbaceous vegetation), the shrub 

 stratum (level of the tops of the dominant shrubs), the lower tree 

 stratum (level of the shaded branches of the trees), and the upper 

 tree stratum. A given animal is classified primarily, with the 

 stratum in which it breeds, as being most important to it, and 

 secondarily with the stratum in which it feeds, etc., as in many 

 cases most important to other animals. The migration of ani- 

 mals from one stratum to another makes the division lines difficult 

 to draw in some cases. Still the recognition of strata is essential 

 though a rigid classification is undesirable. Consocies boring into 



