Listy Biometryczne – Biometrical Letters vol. 39(1), 2002 pp. 21-27
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ON THE MOLINARI SHAPE OF EVENESS MEASURES
Carlo Ricotta Department of Plant Biology, University of Rome “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome, Italy, carlo.ricotta@uniromal.it |
The degree to which abundances are divided equitably among community species or evenness is a basic property of any biological community. Several evenness indices have been proposed to summarize community structure. In addition, a number of desirable properties have been suggested that an evenness index should meet to reasonably behave in ecological research. The most basic of these properties is consistence with the Lorenz ordering. Subordinately, one additional property for an ecologically meaningful evenness index is that, in cases of two-species communities, it should keep a linear relationship between minimum and maximum evenness. It is showed here that only two evenness indices thus far proposed in ecological literature show a linear relationship between minimum and maximum evenness being at the same time consistent with the Lorenz ordering.
Gini index, Lorenz ordering, species replication.
