Grazer diversity counteracts plant diversity effects on ecosystem functioning in seagrass beds
Several influential experiments have shown that high plant diversity enhances ecosystem productivity, animal diversity, and invasion resistance. Yet theory predicts that plant and herbivore diversity, which often co vary in nature, should have countervailing effects on ecosystem properties. In the July issue of Ecology Letters, Duffy, Canuel, and Richardson provide experimental support for this prediction. In a seagrass system, increasing grazer diversity reduced both algal biomass and total community diversity, and facilitated dominance of a grazing-resistant invertebrate. In parallel with previous plant results, however, grazer diversity enhanced grazer biomass production, an important det