When competition does not matter: grassland diversity and community composition

  • Author(s) / Creator(s)
  • We examined whether the intense root competition in a rough fescue grassland plant community in central Alberta, Canada, was important in structuring plant species diversity or community composition. We measured competition intensity across gradients of species richness, evenness, and community composition, using pairs of naturally occurring plants of 12 species. One plant in each pair was isolated from neighbors to measure competition; community structure and environmental conditions were also measured at each pair. We used structural equation modeling to examine how competition influenced community structure. Competition intensity was unrelated to species richness and community composition, but increased competition intensity was associated with a slight decline in evenness. Sizesymmetric root competition was probably unimportant in structuring this plant community because there are no feedback mechanisms through which size-symmetric competition can magnify small initial differences and eventually lead to competitive exclusion. In plant communities with little shoot competition, competition and community structure should be unlinked regardless of competition intensity. In more productive systems, we propose that interactions between root and shoot competition may indirectly structure communities by altering the overall asymmetry of competition.

  • Date created
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  • Type of Item
    Article (Published)
  • DOI
  • License
    Copyright 2008 by The University of Chicago. 0003-0147/2008/17106-42650$15.00. All rights reserved.
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  • Citation for previous publication
    • Lamb, E. G., & Cahill, J. F. (2008). When competition does not matter: grassland diversity and community composition. The American naturalist, 171(6), 777-787.