The importance of importance


  • Rob Brooker,

  • Zaal Kikvidze,

  • Francisco I. Pugnaire,

  • Ragan M. Callaway,

  • Philippe Choler,

  • Christopher J. Lortie,

  • Richard Michalet

R. Brooker, NERC, Centre for Ecology and Hydrology, Banchory Research Station, Banchory, Aberdeenshire, Scotland AB31 4BW. ( – Z. Kikvidze and F. I. Pugnaire, Estacion Experimental de Zonas Aridas, Consejo Superior de Investigaciones Cientificas, General Segura 1, ES-04001 Almeria, Spain. – R. M. Callaway, Division of Biological Sciences, Univ. of Montana, Missoula, MT 59812, USA. – P. Choler, Laboratoire d'Écologie Alpine (UMR UJF-CNRS 5553) & Station Alpine du Lautaret, Université J. Fourier-Grenoble I, Bât. D-BP 53 X, FR-38041 Grenoble cedex 09, France. – C. J. Lortie, Mail Stop 370, UNR, Reno, NV 89557, USA. – R. Michalet, UMR INRA 1202 BIOdiversité, Gènes et ECOsystèmes, Université Bordeaux 1, Bâtiment B8, Avenue des Facultés, FR-33405 Talence-France.


Failure to distinguish between ‘importance’ and ‘intensity’ of competition has hindered our ability to resolve key questions about the role interactions may play in plant communities. Here we examine how appropriate application of metrics of importance and intensity is integral to investigating key theories in plant community ecology and how ignoring this distinction has lead to confusion and possibly spurious conclusions. We re-explore the relationship between competition intensity and importance for individuals across gradients, and apply our review of concepts to published data to help clarify the debate. We demonstrate that competition importance and intensity need not be correlated and show how explicit application of the intensity and importance of competition may reconcile apparently incompatible paradigms.