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The unseen invaders: introduced earthworms as drivers of change in plant communities in North American forests (a meta‐analysis) |
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| Authors: | Dylan Craven Madhav P. Thakur Erin K. Cameron Lee E. Frelich Robin Beauséjour Robert B. Blair Bernd Blossey James Burtis Amy Choi Andrea Dávalos Timothy J. Fahey Nicholas A. Fisichelli Kevin Gibson I. Tanya Handa Kristine Hopfensperger Scott R. Loss Victoria Nuzzo John C. Maerz Tara Sackett Bryant C. Scharenbroch Sandy M. Smith Mark Vellend Lauren G. Umek Nico Eisenhauer |
| Affiliation: | 1. German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐Leipzig, Leipzig, Germany;2. Institute of Biology, Leipzig University, Leipzig, Germany;3. Metapopulation Research Centre, Department of Biosciences, University of Helsinki, PO Box 65, 00014 Helsinki, Finland;4. Center for Macroecology, Evolution and Climate Change, Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, K?benhavn, Denmark;5. Center for Forest Ecology, University of Minnesota, St. Paul, MN, USA;6. Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada;7. Department of Fisheries, Wildlife, and Conservation Biology, University Of Minnesota, St. Paul, MN, USA;8. Department of Natural Resources, Cornell University, Ithaca, New York, USA;9. Faculty of Forestry, University of Toronto, Toronto, ON, Canada;10. Schoodic Institute at Acadia National Park, Forest Ecology Program, Winter Harbor, ME, USA;11. Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA;12. Département des sciences biologiques, Université du Québec à Montréal, Montréal, QC, Canada;13. Department of Biological Sciences, Northern Kentucky University, Highland Heights, KY, USA;14. Department of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, OK, USA;15. Natural Area Consultants, Richford, NY, USA;16. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA;17. College of Natural Resources, University of Wisconsin – Stevens Point, Stevens Point, WI, USA;18. Plant Biology and Conservation, Northwestern University, Evanston, IL, USA;19. Department of Plant Science, Chicago Botanic Garden, Glencoe, IL, USA |
| Abstract: | Globally, biological invasions can have strong impacts on biodiversity as well as ecosystem functioning. While less conspicuous than introduced aboveground organisms, introduced belowground organisms may have similarly strong effects. Here, we synthesize for the first time the impacts of introduced earthworms on plant diversity and community composition in North American forests. We conducted a meta‐analysis using a total of 645 observations to quantify mean effect sizes of associations between introduced earthworm communities and plant diversity, cover of plant functional groups, and cover of native and non‐native plants. We found that plant diversity significantly declined with increasing richness of introduced earthworm ecological groups. While plant species richness or evenness did not change with earthworm invasion, our results indicate clear changes in plant community composition: cover of graminoids and non‐native plant species significantly increased, and cover of native plant species (of all functional groups) tended to decrease, with increasing earthworm biomass. Overall, these findings support the hypothesis that introduced earthworms facilitate particular plant species adapted to the abiotic conditions of earthworm‐invaded forests. Further, our study provides evidence that introduced earthworms are associated with declines in plant diversity in North American forests. Changing plant functional composition in these forests may have long‐lasting effects on ecosystem functioning. |
| Keywords: | introduced earthworms plant communities plant diversity biological invasions earthworm invasion community composition meta‐analysis |