title: The unseen invaders: introduced earthworms as drivers of change in plant communities in North American forests (a meta-analysis).
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.
authors: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103, Leipzig, Germany.|Institute of Biology, Leipzig University, Johannisallee 21, 04103, Leipzig, Germany.
authors: Dylan
authors: D
authors: Craven
authors: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103, Leipzig, Germany.|Institute of Biology, Leipzig University, Johannisallee 21, 04103, Leipzig, Germany.
authors: Madhav P
authors: MP
authors: Thakur
authors: Metapopulation Research Centre, Department of Biosciences, University of Helsinki, PO Box 65, 00014 Helsinki, Finland.|Center for Macroecology, Evolution and Climate Change, Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, København, Denmark.
authors: Erin K
authors: EK
authors: Cameron
authors: Center for Forest Ecology, University of Minnesota, St. Paul, MN, USA.
authors: Lee E
authors: LE
authors: Frelich
authors: Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada.
authors: Robin
authors: R
authors: Beauséjour
authors: Department of Fisheries, Wildlife, and Conservation Biology, University Of Minnesota, 2003 Upper Buford Circle Suite 135, St. Paul, MN, 55108, USA.
authors: Robert B
authors: RB
authors: Blair
authors: Department of Natural Resources, Cornell University, Ithaca, New York, USA.
authors: Bernd
authors: B
authors: Blossey
authors: Department of Natural Resources, Cornell University, Ithaca, New York, USA.
authors: James
authors: J
authors: Burtis
authors: Faculty of Forestry, University of Toronto, Toronto, ON, Canada.
authors: Amy
authors: A
authors: Choi
authors: Department of Natural Resources, Cornell University, Ithaca, New York, USA.
authors: Andrea
authors: A
authors: Dávalos
authors: Department of Natural Resources, Cornell University, Ithaca, New York, USA.
authors: Timothy J
authors: TJ
authors: Fahey
authors: Schoodic Institute at Acadia National Park, Forest Ecology Program, Winter Harbor, ME, USA.
authors: Nicholas A
authors: NA
authors: Fisichelli
authors: Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA.
authors: Kevin
authors: K
authors: Gibson
authors: Département des sciences biologiques, Université du Québec à Montréal, Montréal, QC, Canada.
authors: I Tanya
authors: IT
authors: Handa
authors: Department of Biological Sciences, Northern Kentucky University, Highland Heights, KY, USA.
authors: Kristine
authors: K
authors: Hopfensperger
authors: Department of Natural Resource Ecology and Management, Oklahoma State University, Stillwater, OK, USA.
authors: Scott R
authors: SR
authors: Loss
authors: Natural Area Consultants, 1 West Hill School Road, Richford, NY, USA.
authors: Victoria
authors: V
authors: Nuzzo
authors: Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA.
authors: John C
authors: JC
authors: Maerz
authors: Faculty of Forestry, University of Toronto, Toronto, ON, Canada.
authors: Tara
authors: T
authors: Sackett
authors: College of Natural Resources, University of Wisconsin - Stevens Point, Stevens Point, WI, USA.
authors: Bryant C
authors: BC
authors: Scharenbroch
authors: Faculty of Forestry, University of Toronto, Toronto, ON, Canada.
authors: Sandy M
authors: SM
authors: Smith
authors: Département de Biologie, Université de Sherbrooke, Sherbrooke, QC, Canada.
authors: Mark
authors: M
authors: Vellend
authors: Plant Biology and Conservation, Northwestern University, Evanston, IL, USA.|Department of Plant Science, Chicago Botanic Garden, Glencoe, IL, USA.
authors: Lauren G
authors: LG
authors: Umek
authors: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103, Leipzig, Germany.|Institute of Biology, Leipzig University, Johannisallee 21, 04103, Leipzig, Germany.
authors: Nico
authors: N
authors: Eisenhauer
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D065928:Forests; D058865:Introduced Species; D009835:Oligochaeta; D010944:Plants; D014481:United States
keywords: biological invasions; community composition; earthworm invasion; introduced earthworms; meta-analysis; plant communities; plant diversity