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Plant species loss decreases arthropod diversity and shifts trophic structure

Authors

  • Nick M. Haddad,

    Corresponding author
    1. Department of Biology, North Carolina State University, Box 7617, Raleigh, NC 27695 7617, USA
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  • Gregory M. Crutsinger,

    1. Department of Ecology and Evolutionary Biology, University of Tennessee, 569 Dabney Hall, Knoxville, TN 37996, USA
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    • Current address: Department of Integrative Biology, University of California, Berkeley, 3060 Valley Life Sciences Bldg. #3140, Berkeley, CA 94720 3140, USA

  • Kevin Gross,

    1. Biomathematics Program, North Carolina State University, Box 8203, Raleigh, NC 27695, USA
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  • John Haarstad,

    1. Ecology, Evolution, and Behavior, University of Minnesota, 1987 Upper Buford Circle, St. Paul, MN 55108, USA
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  • Johannes M.H. Knops,

    1. School of Biological Sciences, University of Nebraska, 348 Manter Hall, Lincoln, NE 68588 0118, USA
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  • David Tilman

    1. Ecology, Evolution, and Behavior, University of Minnesota, 1987 Upper Buford Circle, St. Paul, MN 55108, USA
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*E-mail: nick_haddad@ncsu.edu

Abstract

Plant diversity is predicted to be positively linked to the diversity of herbivores and predators in a foodweb. Yet, the relationship between plant and animal diversity is explained by a variety of competing hypotheses, with mixed empirical results for each hypothesis. We sampled arthropods for over a decade in an experiment that manipulated the number of grassland plant species. We found that herbivore and predator species richness were strongly, positively related to plant species richness, and that these relationships were caused by different mechanisms at herbivore and predator trophic levels. Even more dramatic was the threefold increase, from low- to high-plant species richness, in abundances of predatory and parasitoid arthropods relative to their herbivorous prey. Our results demonstrate that, over the long term, the loss of plant species propagates through food webs, greatly decreasing arthropod species richness, shifting a predator-dominated trophic structure to being herbivore dominated, and likely impacting ecosystem functioning and services.

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