Plant Communities of the World 



By Eduard Rubel 



COMMUNITY is the sociologic unity of any rank from the 

 lowest to the highest. In a short synopsis only the widest 

 ranks can be discerned, but one must tell how one builds 

 them up and understands them. As fundamental unit one 

 has the "association!' Its definition, proposed by Flahault and 

 Schroter and adopted by the International Botanical Congress 

 of 1910, held in Brussels, runs, "An association is a community 

 of certain floristic composition, of uniform habitat conditions, 

 and of uniform physiognomy!' This definition has proved very 

 satisfactory, and is better than all the others which since have 

 sprung up here and there. By composition is meant not only the 

 list of species; it includes their abundance, dominance, sociabil- 

 ity, constancy, fidelity, vitality, periodicity, rhythm. The con- 

 stants and characteristics are the main feature; they form the 

 normal characteristic combination of species. Something so very 

 ecologic as an association can only have its conditioning cause 

 from an environment of a certain ecologic uniformity. Phys- 

 iognomy is the effect of habitat. Habitat is the ecology of en- 

 vironment; physiognomy is the ecology of the vegetation itself, 

 which expresses itself by its morphology, including its anatomy 

 (life form of the dominants) . 



Species combine to genera, these to families (characterized by 

 the ending -aceae), these to orders, ending in -ales (femininum 

 plurale), to classes, and to other subdivisions. Quite analogous 

 associations, ending in -etum, combine to a "federation" as Du- 

 Rietz proposed to the International Congress, or "alliance" as 

 Braun-Blanquet calls it, with the ending -ion (originally pro- 



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