60 PLANT SOCIOLOGY 



Fidelity in Relation to Alliances and Orders. — Fidelity grades are 

 primarily related to the association but have value also for any higher 

 unit of vegetation: alliance, order, etc. Species which occur abun- 

 dantly in several associations may be more or less confined to one 

 certain alliance and so help to characterize it, e.g., Potamogeton lucens 

 in the Potamion eurosibiricum, Salicornia macrostachya and S. radicans 

 in the Salicornion fruticosae, Cardamine alpina and Arenaria hi flora in 

 the Sahcion herbaceae of the Alps. The same is true of the orders. 

 The higher the systematic rank of the unit of vegetation the richer it is 

 in characteristic species. Exceptionally large numbers of character- 

 istic species in a community often indicate that we are dealing with two 

 or more associations or with an alliance. 



Determination of Fidelity. — Since fidelity can be correctly estimated 

 only when a sufficient number of exact records are available, all state- 

 ments of fidelity which are not supported by association lists are 

 poorly founded and are to be taken with caution. 



The first requirement for the determination of fidelity is a knowl- 

 edge, as exact as possible, of the plant groups of the region. From 

 such records it may be seen that certain groupings constantly occur 

 under certain conditions. Some species (the exclusive) are confined to 

 certain groupings, others (the selective or preferential) show their 

 membership in certain groups by great vitality, especially vigorous 

 growth, crowding of individuals, or high constancy. Groupings that 

 correspond floristically are tabulated together. These tables, if 

 characteristic species (fid. 3 to 5) or a large number of differential 

 species are present, supply the indispensable foundation for further 

 work on the associations. The association tables are to be established 

 by records of as many stands as possible. 



From a comparison of all the association tables of a region it then 

 appears that certain species occur in only one table, others in several or 

 in all of the tables, and further that one and the same species shows in 

 the several tables (i.e., in the several associations) very different degrees 

 of constancy, frequency, sociability, and vitality. 



The preparation and study of these tables are the work of years; 

 but since they are fundamental to the determination of fidelity and the 

 delimitation of the association, they cannot be omitted. In case the 

 segregation of the exclusive and preferential species presents great 

 difficulties, at least a preliminary group of characteristic species may be 

 distinguished. 



For the objective demonstration of degrees of fidelity by means of 

 association tables, Szafer and Pawlowski (1927) have given a chart 

 which is shown with slight modifications in Table 3. 



