With a machete through the jungle: some thoughts on community diversity

This short communication includes comments on a single sentence cited from a recent paper by C. Ricotta. I discuss shortly the relationship between diversity and classification as well as the possibility of expressing diversity for continuous variables. A simple example shows that the notion of diversity can be expanded to situations without an underlying classification. I suggest an evenness formula based on absolute deviations from the perfectly even distribution. If expressed for species data and multiplied by number of species in the community, this becomes an easily interpretable diversity measure. It is stressed that conventional diversity formulae cannot be informative on community structure, but there is a solution.