A. G. Tansley, one of the greatest of the 'founding fathers' of plant ecology, studied competition between two species of bedstraw (Tansley, 1917). Galium hercynicum is a species which grows naturally in Great Britain at acidic sites, whilst G. pumilum is confined to more calcareous soils. Tansley found in experiments that as long as he grew them alone, both species would thrive on both the acidic soil from a G. hercynicum site and the calcareous soil from a G. pumilum site. Yet, if the species were grown together, only G. hercynicum grew successfully in the acidic soil and only G. pumilum grew successfully in the calcareous soil. It seems, therefore, that when they grow together the species compete, and that one species wins, whilst the other loses so badly that it is competitively excluded from the site. The outcome depends on the habitat in which the competition occurs.
Was this article helpful?