Studies have shown that increasing species richness leads to higher ecosystem productivity. This effect has been attributed to more efficient portioning of multiple resources in communities with higher numbers of competing species, indicating the role of balanced resource supply for biodiversity-ecosystem functioning relationships. In this study, we merge theory on ecological stoichiometry with a framework of biodiversity-ecosystem functioning to understand how resource use transfers into primary production. We combine structural equation modelling with meta-analysis to define patterns of resources-diversity-productivity relationships across ecosystems (marine, freshwater and terrestrial), and approaches (field observations and laboratory experiments). In addition to the effects of richness on resource use, we also present effects of evenness within the same framework across systems.
Results/Conclusions
Our results confirm that the realized productivity of autotrophs is positively related to the supply of resources. In field studies, these effects are either direct or mediated by changes in the number of species, but in aquatic experimental studies and unmanipulated grasslands, we found no significant effect of resources on species richness. We also found no evidence that evenness is directly related to changes in resource supply suggesting that the dominance structure of producer communities might be primarily driven by trophic interactions and external forces. We show that more even communities have overall lower productivity, indicating that biomass production is often maintained by a few dominant species, and reduced dominance generally reduces ecosystem productivity. This synthesis elucidates similarities and differences in the resources-diversity-functioning relationships among ecosystem types advancing mechanistic understanding of these relationships.