1. Recently a number of rarefaction curves including information on species’ functional traits were proposed for those measures of functional diversity that monotonically increase with species richness.
2. Building on these methods, in this paper, we propose a functional rarefaction curve for species abundance data that is obtained using the classical diversity decomposition of the Rao quadratic diversity into alpha, beta and gamma diversity.
3. The proposed abundance-based functional rarefaction is illustrated with one dedicated case study in sand dune communities in Italy.
4. Although we put emphasis on functional diversity only, because of its mathematical generality, the proposed method can be extended to virtually any abundance-weighted concave measure for comparing diversity among habitats sampled with different effort.