Functional imbalance not functional evenness is the third component of community structure

It is generally assumed that functional richness, diversity and evenness are complementary and, taken together, describe different facets of the distribution species their abundances in space. However, although these three primary components community structure commonly accepted by most ecologists, measures usually fail to properly capture regularity In this paper we will use an underexplored decomposition Rao’s index introduce notion imbalance, indicator strength interaction between dissimilarities. Functional always increases with increasing imbalance. Therefore, imbalance seems a more appropriate facet than evenness. A worked example aimed at evaluating influence grazing on plant showed all proposed were able highlight main changes dry calcareous grassland Tuscany (Italy) following exclusion.