Invasive plants in Minnesota are “joining the locals”: A trait-based analysis

Alexandra G. Lodge, Timothy J.S. Whitfeld, Alexander M. Roth, Peter B. Reich

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


Questions: Predicting which newly arrived species will establish and become invasive is a problem that has long vexed researchers. In a study of cold temperate oak forest stands, we examined two contrasting hypotheses regarding plant functional traits to explain the success of certain non-native species. Under the “join the locals” hypothesis, successful invaders are expected to share traits with resident species because they employ successful growth strategies under light-limited understorey conditions. Instead, under the “try harder” hypothesis, successful invaders are expected to have traits different from native species in order to take advantage of unused niche space. Location: Minnesota, USA. Methods: We examined these two theories using 109 native and 11 non-native plants in 68 oak forest stands. We focused on traits related to plant establishment and growth, including specific leaf area (SLA), leaf carbon-to-nitrogen ratio (C:N), wood density, plant maximum height, mycorrhizal type, seed mass and growth form. We compared traits of native and non-native species using ordinations in multidimensional trait space and compared community-weighted mean (CWM) trait values across sites. Results: We found few differences between trait spaces occupied by native and non-native species. Non-native species occupied smaller areas of trait space than natives, yet were within that of the native species, indicating similar growth strategies. We observed a higher proportion of non-native species in sites with higher native woody species CWM SLA and lower CWM C:N. Higher woody CWM SLA was observed in sites with higher soil pH, while lower CWM C:N was found in sites with higher light levels. Conclusions: Non-native plants in this system have functional traits similar to natives and are therefore “joining the locals.” However, non-native plants may possess traits toward the acquisitive end of the native plant trait range, as evidenced by higher non-native plant abundance in high-resource environments.

Original languageEnglish (US)
Pages (from-to)746-755
Number of pages10
JournalJournal of Vegetation Science
Issue number4
StatePublished - Jul 2018

Bibliographical note

Funding Information:
Rachael Nicoll, Yasha Horstmann, Kayla Altendorf, Stephanie Hall, Steve Zweber and Emily Lowery assisted with data collection. The study received site support from Minnesota State Parks, Wildlife Management Areas and State Forests; Three Rivers Park District, Warner Nature Center, Katherine Ordway Nature Preserve, Dakota County, Ramsey County, Rice County, Stearns County, U.S. Fish and Wildlife Service, St. Croix Watershed Research Station, the College of St. Benedicts and St. John’s Arboretum. Funding was provided by the Legislative-Citizen Commission on Minnesota Resources (M.L. 2010, Chp. 362, Sec. 2, Subd. 6c “Healthy Forests to Resist Invasion,” to P.B.R.); IGERT: Risk Analysis for Introduced Species and Genotypes (NSF DGE-0653827); the Hubachek Wilderness Research Foundation; the Dayton Fund of the Bell Museum of Natural History. A.L. designed the study with the assistance of T.W., A.R. and P.R. A.L., T.W. and A.R. collected the data. A.L. drafted the manuscript with contributions from all co-authors.


  • Alliaria petiolata
  • Rhamnus cathartica
  • community-weighted mean
  • functional trait
  • invasive species
  • ordination
  • specific leaf area
  • temperate forest
  • wood density

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