Papers in the Biological Sciences



Eric W. Seabloom, University of MinnesotaFollow
Elizabeth T. Borer, University of MinnesotaFollow
Yvonne Buckley, University of QueenslandFollow
Elsa E. Cleland, University of California - San DiegoFollow
Kendi Davies, University of Colorado BoulderFollow
Jennifer Firn, Queensland University of Technology
W. Stanley Harpole, Iowa State University
Yann Hautier, University of ZurichFollow
Eric Lind, University of MinnesotaFollow
Andrew Macdougall, University of Guelph
John L. Orrock, University of WisconsinFollow
Suzanne M. Prober, CSIRO Ecosystem Sciences
Peter Andler, Utah State University
Juan Alberti, Instituto de Investigaciones Marinas y Costeras (UNMdP-CONICET)
T. Michael Anderson, Wake Forest UniversityFollow
Jonathan D. Bakker, University of WashingtonFollow
Lori A. Biederman, Iowa State UniversityFollow
Dana Blumenthal, USDA-ARSFollow
Cynthia S. Brown, Colorado State University
Lars A. Brudvig, Michigan State University
Maria Caldeira, Technical University of Lisbon
Chengjin Chu, Lanzhou University
Michael J. Crawley, Imperial College London
Pedro Daleo, Instituto de Investigaciones Marinas y Costeras (UNMdP-CONICET)
Ellen I. Damschen, University of WisconsinFollow
Carla M. D'Antonio, University of California, Santa Barbara
Nicole M. Decrappeo, U.S. Geological Survey Forest and Rangeland Ecosystem Science Center
Chris R. Dickman, University of Sydney
Guozhen Du, Lanzhou University
Philip A. Fay, USDA-ARSFollow
Paul Frater, Iowa State University
Daniel S. Gruner, University of Maryland at College Park
Nicole Hagenah, Yale University
Andrew Hector, University of Zurich
Aveliina Helm, University of Tartu
Helmut Hillebrand, Carl-von-Ossietzky University
Kirsten S. Hofmockel, Iowa State University
Hope C. Humphries, University of Colorado Boulder
Oscar Iribarne, Instituto de Investigaciones Marinas y Costeras (UNMdP-CONICET)
Virginia L. Jin, USDA-ARSFollow
Adam Kay, University of St. Thomas
Kevin P. Kirkman, University of KwaZulu-Natal
Julia A. Klein, Colorado State University - Fort Collins
Johannes M. H. Knops, University of Nebraska-LincolnFollow
Kimberly J. La Pierre, Yale University
Laura M. Ladwig, University of New Mexico
John G. Lambrinos, Oregon State University
Andrew D. B. Leakey, University of Illinois at Urbana-Champaign
Qi Li, Chinese Academy of Sciences
Wei Li, Southwest Forestry University
Rebecca McCulley, University of KentuckyFollow
Brett Melbourne, University of Colorado BoulderFollow
Charles E. Mitchell, University of North Carolina at Chapel HillFollow
Joslin L. Moore, University of Melbourne
John Morgan, La Trobe University
Brent Mortensen, Iowa State University
Lydia R. O'Halloran, Oregon State University
Meelis Partel, University of Tartu
Jesus Pascual, Instituto de Investigaciones Marinas y Costeras (UNMdP-CONICET)
David A. Pyke, U.S. Geological Survey Forest and Rangeland Ecosystem Science CenterFollow
Anita C. Risch, Swiss Federal Institute for Forest, Snow and Landscape Research
Roberto Salguero-Gomez, University of Queensland
Mahesh Sankaran, National Centre for Biological Sciences
Martin Schuetz, Swiss Federal Institute for Forest, Snow and Landscape Research
Anna Simonsen, University of Toronto
Melinda Smith, Colorado State University - Fort CollinsFollow
Carly Stevens, Lancaster UniversityFollow
Lauren L. Sullivan, Iowa State UniversityFollow
Glenda M. Wardle, University of Sydney
Elizabeth M. Wolkovich, University of British ColumbiaFollow
Peter D. Wragg, University of MinnesotaFollow
Justin Wright, Duke UniversityFollow
Louie Yang, University of California, DavisFollow

Date of this Version



Global Change Biology (2013) 19, 3677–3687, doi: 10.1111/gcb.12370


U.S. government work.


Invasions have increased the size of regional species pools, but are typically assumed to reduce native diversity. However, global-scale tests of this assumption have been elusive because of the focus on exotic species richness, rather than relative abundance. This is problematic because low invader richness can indicate invasion resistance by the native community or, alternatively, dominance by a single exotic species. Here, we used a globally replicated study to quantify relationships between exotic richness and abundance in grass-dominated ecosystems in 13 countries on six continents, ranging from salt marshes to alpine tundra. We tested effects of human land use, native community diversity, herbivore pressure, and nutrient limitation on exotic plant dominance. Despite its widespread use, exotic richness was a poor proxy for exotic dominance at low exotic richness, because sites that contained few exotic species ranged from relatively pristine (low exotic richness and cover) to almost completely exotic-dominated ones (low exotic richness but high exotic cover). Both exotic cover and richness were predicted by native plant diversity (native grass richness) and land use (distance to cultivation). Although climate was important for predicting both exotic cover and richness, climatic factors predicting cover (precipitation variability) differed from those predicting richness (maximum temperature and mean temperature in the wettest quarter). Herbivory and nutrient limitation did not predict exotic richness or cover. Exotic dominance was greatest in areas with low native grass richness at the site- or regional-scale. Although this could reflect native grass displacement, a lack of biotic resistance is a more likely explanation, given that grasses comprise the most aggressive invaders. These findings underscore the need to move beyond richness as a surrogate for the extent of invasion, because this metric confounds monodominance with invasion resistance. Monitoring species’ relative abundance will more rapidly advance our understanding of invasions.

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