Relationship between species richness and productivity in plants: the role of sampling effect, heterogeneity and species pool

Abstract

The relationship between environmental productivity and the number of species [species richness-productivity relationship (SRPR)] has been thoroughly studied, but the mechanisms responsible for its form are still largely unknown, possibly because the majority of studies have focused on evaluating the sole effect of a single hypothesis. 2. We tested whether variation in species richness along a productivity gradient is due to variation in (i) the number of individuals, (ii) the number of species in the species pool or (iii) habitat heterogeneity.