Food webs control the strength of diversity-productivity relationships

One of the most important and controversial findings in ecology is the demonstration that plant productivity increases with diversity in experimentally assembled plant communities. While these studies generally have not accounted for the roles of heterotrophs, herbivores, pollinators, or pathogens may increase or decrease the diversity-productivity relationship by consuming plant biomass or by enhancing plant productivity. Our experimental removal of three heterotroph groups (arthropods, foliar fungi, and soil fungi) from a long-term biodiversity experiment show that heterotrophs remove three times more biomass in diverse communities relative to monocultures. Our study demonstrates that biodiversity effects on productivity have been significantly underestimated.