Biodiversity-productivity theory predicts that ecosystems with increased productivity due to excessive limiting-nutrient loading will have decreased taxonomic diversity. In this 4-year study, we elevated productivity by adding NPK fertilizer to 20m diameter plots in an old-field grassland to test the effects of anthropogenically mediated nutrient loading on plant and epigeal arthropod communities. While plants responded as predicted by the biodiversity-productivity theory, the epigeal arthropod community had highest species richness within the fertilized high-productivity treatments. We conclude that the contradictory response of the largely detrital-based epigeal community should alter conventional biodiversity-productivity theory and could affect terrestrial biodiversity conservation strategies.
