130 STRUCTURE AND UNITS OF VEGETATION. 



though frequently for a group of related or associated dominants. It is here 

 restricted to the climax community formed of a single dominant, i. e., the 

 consociation, for example, Boutelouetum, BulMletum, Aristidetum, Quercetum, 

 Rhoetum, etc. 



Society. — The society is a community characterized by a subdominant or 

 sometimes by two or more subdominants. By a subdominant is understood 

 a species which is dominant over portions of an area already marked by the • 

 dominance of consociation or association. The society is a localized or 

 recurrent dominance within a dominance. In the case of grassland, the 

 striking subdominance of many societies often completely hides the real 

 dominance of the consociation. In forest, societies are found only beneath 

 the primary layer of trees, and their subdominance is obvious. The society 

 comes next below the consociation in rank, but it is not necessarily a, division 

 of it, for the same society may extend through or recur in two or more con- 

 sociations, i. e., throughout the entire association. This seems readily under- 

 standable when we recognize that the life-forms of the society subdominants 

 are regularly different from those of the dominants of grassland and forest. The 

 societies of grassland are composed of herbs or of undershrubs rather than 

 grasses, those of woodland, of herbs, bushes, and shrubs. They may occur 

 more or less uniformly over wide stretches, or they may be repeated wherever 

 conditions warrant (plate 37, a, b). 



The concept of the society was proposed by Clements (1905 : 296) and was 

 defined as follows: 



"The seasonal changes of a formation, which are called aspects, are indicated 

 by changes in composition or structure, which ordinarily correspond to the 

 three seasons, spring, summer, and autumn. The latter affect the facies 

 [consociations] relatively little, especially those of woody vegetation, but they 

 influence the principal species profoundly, causing a grouping typical of each 

 aspect. For these areas controlled by principal species, but changing from 

 aspect to aspect, the term society is proposed. They are prominent features of 

 the majority of herbaceous formations, where they are often more striking 

 than the facies. In forests they occur in the shrubby and herbaceous layers, 

 and are consequently much less conspicuous than the facies." 



Later (1907 : 226), the concept was somewhat broadened: 



"An area characterized by a principal [subdominant] species is a society. A 

 society, moreover, is often characterized by two or more principal species. 

 Societies have no essential connection with consocies. A consocies may include 

 several or many societies, or it may not show a single one. Finally, a society 

 may lie in two consocies, or it may occur in any of them." 



Tansley (1911 : 12) and his co-workers have adopted the concept of the 

 society, and have stated it as follows : 



" Locally within an association there occur more or less definite aggregations 

 of characteristic species or of small groups of species, and these, which appear as 

 features within the association, may be recognized as smaller vegetation imits, 

 or plantrsocieties. Sometimes their occurrence may be due to local variations 

 of the habitat, at other times to accident and the gregarious habit originating 

 from a general scattering of seed in one place, or from the social growth of a 

 rhizomic plant. It is a question whether it would not be better to separate 



