Similarity or "relationship" increases between community-types 

 as the number of constant species present in common becomes 

 greater, so they form an important criterion in the classification 

 of the types (associations, sociations) into higher categories 

 (alliances), which is discussed further in Chapter 6.^^ 



Fidelity 



Fidelity refers to the degree that a species is restricted in its 

 occurrence to a particular kind of community (Figures 1-27 and 

 2-4); those with low fidelity occur in a number of different com- 

 munities, those with high fidelity in a few or in only one kind. This 

 is because species differ in ecological amplitude or in capacity to 

 grow in a wide range of ecological conditions, or because some 

 species are able to associate with others or are prevented from 

 doing so because of inability to compete. Other causes are 

 dissimilarities in adaptations for migration and invasion, and 

 also may be found in the history of geographical dispersal, 

 including extinction of a species in local areas. Fidelity and con- 

 stancy are independent characteristics, fidelity being concerned 

 with the occurrence of a species in different kinds of community- 

 types, constancy with various stands in the same kind of 

 community-type. Fidelity can be determined only by analyzing 

 stands in several to many types within a region, constancy by the 

 analysis of several stands in the same community-type. 



Five grades or classes of fidelity are used in the Braun-Blanquet 

 scheme of classification, ^^-^^ as follows: 



(A) Characteristic species (character, faithful species' ^^) 



(5) Exclusive (treu), completely or almost completely 

 restricted to one kind of community 



(4) Selective (feste), occurring most frequently in one 

 kind of community, but also, though rarely, in other 

 kinds 



(3) Preferential (holde), occurring more or less abun- 

 dantly in several kinds of communities but with opti- 

 mum conditions for abundance and vitality in one 

 certain kind of community 



S.26 • TKe Comnnmunity 



