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The article presents the possible methods of interpretation of Shannon-Wiener index values determined for communities of wastewater saprobes and calculated on species abundances (H) or abundances of morphological-functional groups (H*). To calculate the index, the species richness index Sr (or morphological -functional group richness index Delta*) and n(T) value (total individual number) as well as abundances of particular species (or groups) n(i) (or n*(i)) are needed. It is also possible to determine the index H-max = log(z)Delta(Sr) (or H*(max) = log(z Delta)*) based on Delta(Sr) values (or Delta* values). The value of H-max (or H*(max)) can be used for calculation of the evenness index, V.
The value of this index can, after multiplication by 100, express a percentage "evenness deficiency" in relative abundances of species ( or morphological-functional groups). Having the value of the H index ( or H* index) it is possible to calculate Mac Arthur's index E = z(H) (or E* = z(H)*). In fact, the E index ( or E* index) represents a value of the species richness index Delta Sr ( or group richness Delta*) for a community in which all species ( groups) have the same abundances ( thus relative abundances - Pi(i) are also the same) and the calculated H value (or H* value) is H-max (or H*(max)). Using the E index (or E*) it is possible to calculate " proportionality" index P = E/Delta Sr center dot 100 (or P* = E*/Delta* center dot 100), expressing in percent, taxa "number shortage." For the complete characterization of a community, not only the calculated H (H*) values, but also the values of Delta(Sr) (Delta*), V (V*) and P (P*), should be presented.
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