, Volume 141, Issue 3, pp 526–535 | Cite as

Competitive impacts and responses of an invasive weed: dependencies on nitrogen and phosphorus availability

  • Katharine N. Suding
  • Katherine D. LeJeune
  • Timothy R. Seastedt
Community Ecology


Changes in competitive interactions under conditions of enhanced resource availability could explain the invasion success of some problematic plant species. For one invader of North American grasslands, Centaurea diffusa (diffuse knapweed), we test three hypotheses: (1) under ambient (high resource) conditions, C. diffusa is better able to tolerate competition from the resident community (competitive response), (2) under ambient conditions, C. diffusa strong impacts the competitive environment (competitive effect), and (3) reductions in nitrogen and/or phosphorus availability diminish these advantages. In support of our first hypothesis, C. diffusa was the most tolerant to neighbor competition of the four focal species under current resource conditions. In opposition to our second hypothesis, however, neighborhoods that contained C. diffusa and those where C. diffusa had been selectively removed did not differ in their impact on the performance of target transplant individuals or on resource conditions. Reduction in resource availability influenced competitive tolerance but not competitive impact, in partial support of our last hypothesis. Reduction in soil nitrogen (via sucrose carbon addition) enhanced the degree of neighbor competition experienced by all species but did not change their relative rankings; C. diffusa remained the best competitor under low nitrogen conditions. Reduction of soil phosphorus (via gypsum addition) weakened the ability of C. diffusa to tolerate neighbor competition proportionately more than the other focal species. Consequently, under low phosphorus conditions, C. diffusa lost its competitive advantage and tolerated neighbor competition similarly to the other focal species. We conclude that C. diffusa invasion may be double-edged: C. diffusa is less limited by nitrogen than the other focal species and is better able to utilize phosphorus to its competitive advantage.


Centaurea diffusa Competitive response and competitive effect Resource ratios Reverse fertilization 



Funding for this work was provided by the United States Department of Agriculture, National Research Institute Competitive Grants Program, no. 01-35320-10628. We thank the city of Boulder for permission to use the study site. M. Davis, S. Emery and E. Miller provided constructive comments of previous versions of this paper. M. Carbone, B. Eader, A. Ruiz, D. Stabler, K. Storey, M. Walsh, and D. Witwicki provided invaluable help in the field and laboratory.


  1. Bais HP, Vepachedu R, Gilroy S, Callaway RM, Vivanco JM (2003) Allelopathy and exotic plant invasion: from molecules and genes to species interactions. Science 301:1377–1380CrossRefPubMedGoogle Scholar
  2. Bakker J, Wilson SD (2001) Competitive abilities of introduced and native grasses. Plant Ecol 157:119–127CrossRefGoogle Scholar
  3. Belnap J, Phillips SL (2001) Soil biota in an ungrazed grassland: response to annual grass (Bromus tectorum) invasion. Ecol Appl 11:1261–1275Google Scholar
  4. Blumenthal DM, Jordan NR, Russelle MP (2003) Soil carbon addition controls weeds and facilitates prairie restoration. Ecol Appl 13:605–615Google Scholar
  5. Callaway RM, Aschehoug ET (2000) Invasive plants versus their new and old neighbors: a mechanism for exotic invasion. Science 290:521–523CrossRefPubMedGoogle Scholar
  6. Callaway RM, Newingham B, Zabinski CA, Mahall BE (2001) Compensatory growth and competitive ability of an invasive weed are enhanced by soil fungi and native neighbours. Ecol Lett 4:429–433Google Scholar
  7. Callaway RM, Mahall BE, Wicks C, Pankey J, Zabinski C (2003) Soil fungi and the effects of an invasive forb on grasses: neighbor identity matters. Ecology 84:129–135Google Scholar
  8. Callaway RM, Thelan GC, Rodriguez A, Holben WE (2004) Soil biota and exotic plant invasion. Nature 427:731–733CrossRefPubMedGoogle Scholar
  9. D’Antonio CM, Mahall B (1991) Root profiles and competition between the invasive exotic perennial, Carpobrotus edulis, and two native shrub species in California coastal scrub. Am J Bot 78:885–894Google Scholar
  10. D’Antonio CM, Meyerson LA (2002) Exotic plant species as problems and solutions in ecological restoration: a synthesis. Rest Ecol 10:703–713CrossRefGoogle Scholar
  11. D’Antonio CM, Hughes RF, Mack M, Hitchcock D, Vitousek PM (1998) The response of native grasses to the removal of invasive exotic grasses in the seasonally dry Hawaiian woodland. J Veg Sci 9:699–712Google Scholar
  12. D’Antonio CM, Hughes RF, Vitousek PM (2001) Factors influencing dynamics of two invasive C4 grasses in seasonally dry Hawaiian woodlands. Ecology 82:89–104Google Scholar
  13. Davis MA (2003) Biotic globalization: does competition from introduced species threaten biodiversity? Bioscience 53:481–489Google Scholar
  14. Davis MA, Grime JP, Thompson K (2000) Fluctuating resources in plant communities: a general theory of invasibility. J Ecol 88:528–534CrossRefGoogle Scholar
  15. Dukes JS, Mooney HA (1999) Does global change increase the success of biological invaders? Trends Ecol Evol 14:135–139CrossRefPubMedGoogle Scholar
  16. Dyer AR, Rice KJ (1999) Effects of competition on resource availability and growth of California bunchgrass. Ecology 80:2697–2710Google Scholar
  17. Ehrenfeld JG (2003) Effects of exotic plant invasions on soil nutrient cycling processes. Ecosystems 6:503–523CrossRefGoogle Scholar
  18. Gaudet CL, Keddy P (1998) A comparative approach to predicting competitive ability from plant traits. Nature 334:242–243CrossRefGoogle Scholar
  19. Gerlach JD, Rice KJ (2003) Testing life history correlates of invasiveness using congeneric plant species. Ecol Appl 13:167–179Google Scholar
  20. Goldberg DE (1996) Competitive ability: definitions, contingency and correlated traits. Phil Trans R Soc London B 351:1377–1385Google Scholar
  21. Goldberg DE (1990) Components of resource competition in plant communities. In: Grace JB, Tilman D (eds) Perspectives on Plant Competition. Academic PressGoogle Scholar
  22. Goldberg DE, Werner PA (1983) Equivalence of competitors in plant-communities—a null hypothesis and a field experimental approach. Am J Bot 70:1098–1104Google Scholar
  23. Gordon DR (1998) Effects on invasive, non-indigenous plant species on ecosystem processes: lessons from Florida. Ecol Appl 8:975–989Google Scholar
  24. Grotkopp E, Rejmanek M, Rost TL (2002) Toward a causal explanation of plant invasiveness: seedling growth and life-history strategies of 29 pine (Pinus) species. Am Nat 159:396–419CrossRefGoogle Scholar
  25. Hager HA (2004) Competitive effect versus competitive response of invasive and native wetland plant species. Oecologia 139:140–149CrossRefPubMedGoogle Scholar
  26. Herron GJ, Sheley RL, Maxwell BD, Jacobsen S, Jeffrey S (2001) Influence of nutrient availability on the interaction between spotted knapweed and bluebunch wheatgrass. Rest Ecol 9:326–331 CrossRefGoogle Scholar
  27. Hierro JL, Callaway RM (2003) Allelopathy and exotic plant invasion. Plant Soil 256:29–39CrossRefGoogle Scholar
  28. Hooper DU, Johnson L (1999) Nitrogen limitation in dryland ecosystems: responses to geographical and temporal variation in precipitation. Biogeochemistry 46:247–293CrossRefGoogle Scholar
  29. Hoopes MF, Hall LM (2002) Edaphic factors and competition affect pattern formation and invasion in a California grassland. Ecol Appl 12:24–39Google Scholar
  30. Huenneke LF, Hamburg SP, Koide R, Mooney HA, Vitousek PM (1990) Effects of soil resources on plant invasion and community structure in Californian serpentine grassland. Ecology 71:478–491Google Scholar
  31. Lambrinos JG (2002) The variable invasive success of Cortaderia species in a complex landscape. Ecology 83:518–529Google Scholar
  32. LeJeune KD (2002) An investigation of relationships between soil resource availability and the invasion and dominance of Colorado Front Range prairies by the non-native Centaurea diffusa. PhD Dissertation, University of ColoradoGoogle Scholar
  33. LeJeune KD, Seastedt TR (2001) Centaurea species: the forb that won the west. Conserv Biol 15:1568–1574CrossRefGoogle Scholar
  34. Levine JM, Vila M, D’Antonio CM, Dukes JS, Grigulis K, Lavorel S (2003) Mechanisms underlying the impacts of exotic plant invasions. Proc R Soc London Ser B 270:775–781CrossRefGoogle Scholar
  35. Lonsdale WM (1999) Global patterns of plant invasions and the concept of invasibility. Ecology 80:1522–1536Google Scholar
  36. Mack RN, Simberloff D, Lonsdale WM, Evans H, Clout M, Bazzaz FA (2000) Biotic invasions: causes, epidemiology, global consequences, and control. Ecol Appl 10:689–710Google Scholar
  37. Marler MJ, Zabinski CM, Callaway RM (1999) Mycorrhizae indirectly enhance competitive effects of an invasive forb on a native bunchgrass. Ecology 80:1180–1186Google Scholar
  38. Marrs RH (1993) Soil fertility and nature conservation in Europe—theoretical considerations and practical management solutions. Adv Ecol Res 24:241–300Google Scholar
  39. Matson P, Lohse KA, Hall SJ (2002) The globalization of nitrogen deposition: consequences for terrestrial ecosystems. Ambio 31:113–119PubMedGoogle Scholar
  40. Prinzing A, Durka W, Klotz S, Brandl R (2002) Which species become aliens? Evol Ecol Res 4:385–405Google Scholar
  41. Rejmanek M, Richardson DM (1996) What attributes make some plant species more invasive? Ecology 77:1655–1661Google Scholar
  42. Ridenour WM, Callaway RM (2001) The relative importance of allelopathy in interference: the effects of an invasive weed on a native bunchgrass. Oecologia 126:444–450CrossRefGoogle Scholar
  43. Schirman R (1981) Seed production and spring seedling establishment of diffusa and spotted knapweed. J Range Manage 34:45–47Google Scholar
  44. Seastedt TR, Gregory N, Buckner D (2003) Effect of biocontrol insects on diffuse knapweed (Centaurea diffusa) in a Colorado grassland. Weed Sci 51:237–245Google Scholar
  45. Shea K, Chesson P (2002) Community ecology theory as a framework for biological invasions. Trends Ecol Evol 17:170–176CrossRefGoogle Scholar
  46. Sher AA, Hyatt LA (1999) The disturbed resource-flux invasion matrix: a new framework for patterns of plant invasion. Biol Invas 1:107–114CrossRefGoogle Scholar
  47. Skinner K, Smith L, Rice P (2000) Using noxious weed lists to prioritize targets for developing weed management strategies. Weed Sci 48:640–644Google Scholar
  48. Smith MD, AK Knapp (2001) Physiological and morphological traits of exotic, invasive exotic, and native plant species in tallgrass prairie. Int J Plant Sci 162:785–792CrossRefGoogle Scholar
  49. Sperber TD, Wraith JM, Olson BE (2003) Soil physical properties associated with the invasive spotted knapweed and native grasses are similar. Plant Soil 252:241–249CrossRefGoogle Scholar
  50. Suding KN, Gross KL, Houseman G (2004) Alternative states and positive feedbacks in restoration ecology. Trends Ecol Evol 19:46–53CrossRefGoogle Scholar
  51. Vitousek PM, D’Antonio CM, Loope LL, Westbrooks R (1996) Biological invasions as global environmental change. Am Sci 84:468–478Google Scholar
  52. Watson AK, Renny AJ (1974) The biology of Canadian weeds: 6. Centaurea diffusa and Centaurea maculosa. Can J Plant Sci 54:687–701Google Scholar
  53. Wilson SD, Tilman D (1995) Competitive responses of eight old-field plant species in four environments. Ecology 76:1169–1180Google Scholar
  54. Zabinski CA, Quinn L, Callaway RM (2002) Phosphorus uptake, not carbon transfer, explains arbuscular mycorrhizal enhancement of Centaurea maculosa in the presence of native grassland species. Funct Ecol 16:758–765CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2004

Authors and Affiliations

  • Katharine N. Suding
    • 1
    • 2
  • Katherine D. LeJeune
    • 2
    • 3
  • Timothy R. Seastedt
    • 2
  1. 1.Department of Ecology and Evolutionary BiologyUniversity of California at IrvineIrvineUSA
  2. 2.Institute of Arctic and Alpine ResearchUniversity of ColoradoBoulderUSA
  3. 3.Stratus Consulting Inc.BoulderUSA

Personalised recommendations