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Title: Predicting invasion in grassland ecosystems: is exotic dominance the real embarrassment of richness?

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 temperaturemore » 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.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [1] ;  [8] ;  [9] ;  [10] ;  [11] ;  [12] ;  [13] ;  [14] ;  [6] ;  [15] ;  [16] ;  [17] more »;  [18] ;  [19] ;  [20] ;  [12] ;  [9] ;  [21] ;  [22] ;  [23] ;  [19] ;  [24] ;  [6] ;  [25] ;  [26] ;  [27] ;  [28] ;  [29] ;  [6] ;  [30] ;  [12] ;  [31] ;  [32] ;  [33] ;  [34] ;  [35] ;  [36] ;  [37] ;  [38] ;  [39] ;  [40] ;  [41] ;  [42] ;  [4] ;  [43] ;  [44] ;  [45] ;  [6] ;  [46] ;  [28] ;  [12] ;  [22] ;  [47] ;  [2] ;  [48] ;  [47] ;  [49] ;  [50] ;  [51] ;  [6] ;  [23] ;  [52] ;  [1] ;  [53] ;  [54] « less
  1. Department of Ecology, Evolution, and Behavior, University of MN, St. Paul MN 55108 USA
  2. ARC Centre of Excellence for Environmental Decisions, School of Biological Sciences, The University of Queensland, Brisbane Queensland 4072 Australia
  3. Ecology, Behavior & Evolution Section, University of California, San Diego La Jolla CA 92093 USA
  4. Department of Ecology and Evolutionary Biology, University of Colorado, Boulder CO 80309 USA
  5. Queensland University of Technology, Biogeosciences, Brisbane Queensland 4000 Australia
  6. Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames IA 50011 USA
  7. Department of Ecology, Evolution, and Behavior, University of MN, St. Paul MN 55108 USA; Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190 CH-8057 Zurich Switzerland
  8. Department of Integrative Biology, University of Guelph, Guelph Ontario N1G 2W1 Canada
  9. Department of Zoology, University of Wisconsin, Madison WI 53706 USA
  10. CSIRO Ecosystem Sciences, Private Bag 5 Wembley WA 6913 Australia
  11. Department of Wildland Resources and the Ecology Center, Utah State University, Logan UT 84322 USA
  12. Instituto de Investigaciones Marinas y Costeras (UNMdP-CONICET), Mar del Plata Argentina
  13. Department of Biology, Wake Forest University, Winston-Salem NC 27109 USA
  14. School of Environmental and Forest Sciences, University of Washington, Seattle WA 98195-4115 USA
  15. Rangeland Resources Research Unit, USDA Agricultural Research Service, Fort Collins CO 80526 USA
  16. Department of Bioagricultural Sciences and Pest Management, Colorado State University, Fort Collins CO 80523 USA
  17. Department of Plant Biology, Michigan State University, East Lansing MI 48824 USA
  18. Centro de Estudos Florestais, Instituto Superior de Agronomia, Technical University of Lisbon, Lisbon Portugal
  19. School of Life Sciences, Lanzhou University, Lanzhou 730000 China
  20. Department of Biology, Imperial College London, Silwood Park Ascot SL5 7PY UK
  21. Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara CA 93106 USA
  22. U.S. Geological Survey Forest and Rangeland Ecosystem Science Center, Corvallis OR 97331 USA
  23. Desert Ecology Research Group, School of Biological Sciences, University of Sydney, Sydney NSW 2006 Australia
  24. USDA-ARS Grassland Soil and Water Research Lab, Temple TX 76502 USA
  25. Department of Entomology, University of Maryland, College Park MD 20742 USA
  26. School of Life Sciences, University of KwaZulu-Natal, Scottsville Pietermaritzburg 3209 South Africa; Department of Ecology, Evolutionary Biology, Yale University, New Haven CT 06520 USA
  27. Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190 CH-8057 Zurich Switzerland
  28. Institute of Ecology and Earth Sciences, University of Tartu, Tartu Estonia
  29. Institute for Chemistry and Biology of the Marine Environment, Carl-von-Ossietzky University, Wilhelmshaven Germany
  30. INSTAAR, University of Colorado, Boulder CO 80309-0450 USA
  31. USDA-ARS Agroecosystem Management Research Unit, Lincoln NE 68583 USA
  32. Biology Department, University of St. Thomas, Saint Paul MN 55105 USA
  33. School of Life Sciences, University of KwaZulu-Natal, Scottsville Pietermaritzburg 3209 South Africa
  34. Department Forest, Rangeland & Watershed Stewardship, Colorado State University, Fort Collins CO 80523-1472 USA
  35. School of Biological Sciences, University of Nebraska, Lincoln NE 68588 USA
  36. Department of Ecology, Evolutionary Biology, Yale University, New Haven CT 06520 USA
  37. Department of Biology, University of New Mexico, Albuquerque NM 87103 USA
  38. Department of Horticulture, Oregon State University, Corvallis OR 97331 USA
  39. Department of Plant Biology and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana IL 61801 USA
  40. Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008 Qinghai China
  41. Yunnan Academy of Biodiversity, Southwest Forestry University, Kunming 650224 China
  42. Department of Plant & Soil Sciences, University of Kentucky, Lexington KY 40546 USA
  43. Department of Biology, University of North Carolina, Chapel Hill NC 27599 USA
  44. Australian Research Centre for Urban Ecology, Melbourne, c/o School of Botany, University of Melbourne, Melbourne Victoria 3010 Australia
  45. Department of Botany, La Trobe University, Bundoora 3086 Victoria Australia
  46. Department of Zoology, Oregon State University, Corvallis OR 97331 USA
  47. Swiss Federal Institute for Forest, Snow and Landscape Research, 8903 Birmensdorf Switzerland
  48. National Centre for Biological Sciences, GKVK Campus, Bellary Road Bangalore 560065 India
  49. Department of Ecology & Evolutionary Biology, University of Toronto, Toronto ON M5S 3B2 Canada
  50. Department of Biology, Colorado State University, Fort Collins CO 80523 USA
  51. Lancaster Environment Center, Lancaster University, Lancaster LA1 4YQ UK
  52. Biodiversity Research Centre, University of British Columbia, Vancouver V6T 1Z4 Canada
  53. Department of Biology, Duke University, Durham NC 27708 USA
  54. Department of Entomology, University of California, Davis CA 95616 USA
Publication Date:
OSTI Identifier:
1126900
Report Number(s):
13--08-P
Journal ID: ISSN 1354-1013; na
DOE Contract Number:
AI09-00SR22188
Resource Type:
Journal Article
Resource Relation:
Journal Name: Global Change Biology; Journal Volume: 19; Journal Issue: 12
Publisher:
Wiley
Research Org:
USDA Forest Service-Savannah River, New Ellenton, SC (United States)
Sponsoring Org:
USDOE; USDOE Office of Environmental Management (EM), Project Management (EM-50)
Contributing Orgs:
USDA Forest Service-Savannah River
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES Plant Invasions; Species pools; species richness; relative abundance