Species evenness

The Äquität (English "species evenness " or "species equitability ," even balance of species or species equality ) is a measure that can be used to characterize the biodiversity. As Ungleichverteilungsmaß expresses the Äquität how frequently or infrequently occurring individuals of a species in a given habitat, based on the number of individuals of the other species occurring in this habitat. The higher the Äquität food, the more the number of individuals between species are distributed.

The balance of species in addition to biodiversity an important criterion for Beurteiling of endangering the species of a habitat. In many cases it decreases the Äquität because heavy use of habitat (pollution, habitat fragmentation ) lead to the species spectrum is dominated increasingly by a few resistant ( or euryöke ) species.

If there are only two species in a biotope, namely foxes and dogs, then at 40 foxes and 1,000 dogs only a small Äquität would be given. But if 40 dogs and 42 foxes are present, the Äquität would be very high. If in a biotope occur ten species and a total of 100 individuals are counted, the maximum Äquität would be reached any kind in ten individuals. In contrast, the minimum Äquität would be given at 91 individuals of one species and one animal each of the remaining nine species.

The most comprehensive presentation of Äquität provides a logarithmic plot of the number of individuals above the rank of their frequency. In addition, there are several approaches that Äquität is expressed as a single, normalized number. In this form, the evenness flows into the Shannon index.