Quantifying the effects of nutrient addition on community diversity of serpentine vegetation using parametric entropy of type alpha

A desirable property of a diversity index is the so-called sum property. For a diversity index that possesses the sum property, such as species richness N, Shannon's entropy H or Simpson's index I ID, the community diversity is decomposable into species-level patterns and the sum of single species diversities gives the pooled diversity of the species collection. In this paper, parametric diversity of type a is used to quantify how fertilizer applied to soil affects the relative contribution of species endemic or preferential to serpentine soils within a garigue plant community in Tuscany (Italy). Soil fertilizer significantly improved the biomass production of the original species pool without any significant colonization by alien species. However, the major biomass increments were experienced by species that are not exclusive to serpentine soils. In this view, the reduced abundance of species endemic or preferential to serpentine soils can be interpreted as a loss of 'ecological quality' of the analyzed community.