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Contrasting Effects Of Plant Richness And Composition On Insect Communities: A Field Experiment, Nick M. Haddad, David Tilman, John Haarstad, Mark Ritchie, Johannes M.H. Knops

School of Biological Sciences: Faculty Publications

We experimentally separated the effects of two components of plant diversity—plant species richness and plant functional group richness—on insect communities. Plant species richness and plant functional group richness had contrasting effects on insect abundances, a result we attributed to three factors. First, lower insect abundances at higher plant functional group richness were explained by a sampling effect, which was caused by the increasing likelihood that one low-quality group, C4 grasses, would be present and reduce average insect abundances by 25%. Second, plant biomass, which was positively related to plant functional group richness, had a strong, positive effect on insect abundances. …