394 Forestry Quarterly 



autecology and synecology. Autecology is defined as the relation 

 of the individual plant to the external world. It is a study of 

 the influence of environment as it is mirrored in the structure of 

 the plant. Synecology deals with the relations of plant communi- 

 ties to external factors. It is essentially the study of the influ- 

 ence of the environment as mirrored in the structure, behavior, 

 and the development of the plant formation and it also deals with 

 its origin, migration, and succession. The former division deals 

 with individuals, the latter with groups of individuals or com- 

 plexes. The further subdivision of these two groups of ecological 

 knowledge will undoubtedly come in time so that ecologists will 

 have a well-built framework upon which to erect the super- 

 structure of the future. 



Modern ecology has shown a strong tendency towards establish- 

 ing a more rational ecological classification of vegetation. The 

 views of Drude (24), Clements (1, 18, 79), Warming (15), 

 Cowles (76), Moss (77), Tansley (78), and others are practically 

 unanimous as to the relative weights the terms "plant formation" 

 and "plant association" should have in descriptive ecology. These 

 terms have been used with a variety of meanings for almost a cen- 

 tury, but today the conception that a formation is an ecological 

 genus and an association an ecological species is becoming gener- 

 ally accepted in principle. A plant association is defined as a com- 

 munity of plants of definite floristic composition. It may be 

 characterized by a single dominant species or by a number of 

 prominent species. Associations may be further subdivided into 

 plant societies, communities, and families. A plant formation is 

 group of associations occupying habitats which are in essentials 

 identical with each other. The connection, therefore, between 

 the habitat and the formation is so close that it would be illogical 

 to apply the term formation to a division greater or smaller than 

 the habitat (1). Plant formations may be classified upon two dis- 

 tinct bases, namely: the identity of habitat conditions, and a 

 common plant form. 



Numerous American and English investigators (53) have done 

 a great deal in the last 20 years not only to systematize the science, 

 but also to give us a better understanding of the relation of the 

 individual plant and the plant formation to their physical environ- 

 ment, and they have also suggested original methods for determin- 

 ing this relation. In America, Clements, Livingston, Cowles, 



