Tracking an invasion: community changes in hardwood forests following the arrival of Amynthas agrestis and Amynthas tokioensis in Wisconsin
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Because Upper Midwest temperate forests lack native earthworms, the invasions of European and Asian earthworms can significantly alter soils and understory vegetation. Earthworms’ ability to increase leaf litter decay, alter nutrient cycling by mixing the organic layer with mineral soil, and decrease plant species richness leads to concern about the Asian ‘jumping earthworm’ (Amynthas agrestis and A. tokioensis) species that were recorded in the University of Wisconsin—Madison Arboretum in 2013. In 2015, we found A. agrestis and A. tokioensis in a distinct 8-ha region of a 23-ha hardwood forest surveyed in the Arboretum; by 2016 A. agrestis and A. tokioensis had spread over an additional 7 ha. Plots also contained the European earthworm species Lumbricus terrestris, L. rubellus, and Apporectodea spp., whose distributions decreased from 2015 to 2016. While leaf litter, plant species richness, and tree and shrub seedling abundance were generally reduced in areas with European earthworms, they were typically slightly increased in areas with A. agrestis and A. tokioensis versus those without. Although our results do not show substantial impacts of A. agrestis and A. tokioensis on vegetation in the initial years of invasion, the rapid replacement of European earthworms by A. agrestis and A. tokioensis suggests continued monitoring of these new invasive species is important to better understand their potential to change the Upper Midwest’s forests.
KeywordsMegascolecidae Lumbricidae Amynthas agrestis Amynthas tokioensis Asian jumping worm Biological invasion Wisconsin
We thank the staff of the University of Wisconsin—Madison Arboretum for assistance with this research, and Jiangxiao Qiu and Carly Ziter for assistance with research design and collaboration. We thank Nicholas Keuler for statistical expertise and guidance, Mark Wegener for GIS support and map-making, and Will Vincent for figure drafting. We also thank Bernadette Williams, of the Wisconsin Department of Natural Resources, for sharing her knowledge of earthworm history and research in the area, and two anonymous reviewers for their helpful feedback.
- Bouché MB (1971) Relations entre les structures spatiales et fonctionelles des ecosystems, illustrées par le role pédobiologique des vers de terre. In: Pesson P (ed) La vie dans les sols, aspects nouveaux, études experimentales. Gauthier-Villars, Paris, pp 187–209Google Scholar
- Gorres JH, Bellitürk K, Keller E (2014) Failure of an Amynthas agresitis (Goto & Hatai 1899) (Oligochaeta: Megascolecidae) population to expand its range within a sugar maple (Acer saccharum) stand. Megadrilogica 17:7–13Google Scholar
- Gunn A (1992) The use of mustard to estimate earthworm populations. Pedobiologia (Jena) 36:65–67Google Scholar
- Hale CM, Host GE (2005) Assessing the impacts of European earthworm invasions in beech-maple hardwood and aspen-fir boreal forests of the western Great Lakes region. Natl Park Serv Gt Lakes Invent Monit Netw Rep GLKN/2005/:1–35Google Scholar
- Mueller-Dombois D, Ellenberg H (1974) Community sampling: the releve method. In: Aims and methods of vegetation ecology. Wiley, New YorkGoogle Scholar
- R Development Core Team (2009) R: a language and environment for statistical computing. http://www.r-project.org
- RStudio Team (2015) RStudio: integrated development for R. RStudio Inc., Boston, MA. http://www.rstudio.com/
- Snyder BA, Callaham MA, Hendrix PF (2011) Spatial variability of an invasive earthworm (Amynthas agrestis) population and potential impacts on soil characteristics and millipedes in the Great Smoky Mountains National Park, USA. Biol Invasions 13:349–358. https://doi.org/10.1007/s10530-010-9826-4 CrossRefGoogle Scholar
- U.S. Climate Data (2017) http://www.usclimatedata.com
- UW Arboretum (1981) The Arboretum: the outdoor laboratory after its first fifty years. Madison, WisconsinGoogle Scholar
- Wisconsin State Herbarium (2015) Flora of Wisconsin. In: Univ. Wisconsin. http://wisflora.herbarium.wisc.edu/. Accessed 1 Jan 2016