240 CLIMAX AND SERE 



or seasonal, in the climax, and to similar socies in the sere. Sub- 

 dominants are the successful competitors among the species that ac- 

 cept the conditions imposed by the dominants. In grassland, they are 

 the outcome of a double competition, namely, among themselves as 

 well as with the dominants; in forest the struggle is chiefly between 

 the species of the layers. They regularly differ from the dominants in 

 life form, consisting of forbs in grassland and desert, and of forbs and 

 shrubs in forest. Their alternation over an area or through the sea- 

 son is largely determined by competition, which is decreased or evaded 

 in some degree by such a disposition. 



From the nature of their relation to both habitat and dominant, 

 subdominants on land are very generally restricted to plants, the cor- 

 responding groups among animals being termed influents. In water, 

 where the chief dominants are animals, societies, and to a smaller 

 extent socies, are undoubtedly to be found (Eddy, 1934) , but the 

 necessary analysis has barely begun in lake and river, and in the 

 ocean. It is already evident, however, that subdominants occur in 

 the pelagic communities, both fresh-water and marine, and often char- 

 acterize striking seasonal societies. 



Dominants in Aquatic Communities. In fresh water, no true cli- 

 maxes appear to be established outside of sluggish rivers and large 

 lakes, and the dominants are hence usually serai in character. The 

 rooted marginal vegetation, which produces such notable reactions 

 as the filling of lakes, marshes, and bayous, all belongs to the hydro- 

 sere of the climax of the region in which the body of water occurs. 

 The tidal climaxes exhibit successions (Hewatt, 1935), and both serai 

 and climax dominants occur in them, though the latter are much more 

 numerous and important. Since this includes a belt of the marine 

 algae, it also exhibits codominants, which form faciations or locia- 

 tions in respective climaxes. 



Serai dominants probably play a small part in the deeper parts 

 of the ocean, owing to the constancy of conditions and the lack of 

 processes that produce bare areas. However, the great physical dif- 

 ferences at various depths appear to dcmark horizontal climates with 

 corresponding climaxes and dominants (Fig. 73, p. 317). The latter 

 differ greatly in life form as a rule and exhibit even greater differences 

 in size. For these reasons in particular, it seems possible to set the 

 phytoplankton or producents and the small zooplankton consuments 

 apart as miniature dominants. The chief organisms of the pelagic 

 and bcnthic climaxes are best characterized as dominants in the usual 

 sense, while those less important but still significant in abundance or 

 importance are miniature dominants. As suggested earlier, it is not 



