CHAPTER IV 

 SYNTHETIC CHARACTERS OF THE COMMUNITY 



Besides the analytical characteristics, which may be traced in 

 every stand or every settlement, there are synthetic characteristics 

 which result from the comparison of the records of as large a number of 

 stands as possible taken from a maximum number of plant associa- 

 tions. The stand is the concrete representative of the association in 

 nature. When a large number of complete records of well-developed 

 stands within one association are tabulated side by side, the first 

 synthetic character observed is the presence of the species — their 

 more or less regular occurrence in the stands. 



When this comparison is extended over the tabulations of all of the 

 associations in a given region, conclusions are reached regarding the 

 more or less rigid ties by which the species are bound to certain com- 

 munities — their fidelity {GeseUschaftstreue). The supreme importance 

 of the lists of species in the characterization of associations thus 

 becomes especially clear. 



Presence. — By presence is meant the more or less persistent occur- 

 rence of a species in all the stands of a certain plant community. 



As far back as the time of Lorenz (1858) this concept was employed. 

 However, it became established in geobotany only after Cajander 

 (1904) had introduced the tabular presentation of individual records 

 of plant lists of associations. 



The first investigator to use this presence factor for the comparative 

 study of plant communities was Brockmann-Jerosch (1907). He 

 designated as "constants" those species which were present in at least 

 half of the stands examined; as "accessory species" those which 

 occurred in one-fourth to one-half of the communities; and as "acci- 

 dental" those which were found in less than one-fourth of the stands. 

 However, many sources of error prevented any striking success in the 

 use of this method for the determination of presence. 



Minimal Area. — A community of plants requires for its normal 

 development a minimum area and also upon this area a minimum 

 number of plant species. Minima of space and number of species are 

 also requirements which must be assigned to an association. This 

 concept has led to the technical use of the term "minimal area" to 

 designate the smallest area which can contain an adequate representa- 



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