ABSTRACT
A theory of competition is presented in the form of evidence for five axioms:
Plants modify their environment as they grow and reduce the resources available for growth by other plants. This defines the existence of competition.
The primary mechanism of competition is spatial interaction.
Plant death due to competition is a delayed reaction to the mechanism of reduced growth following resource depletion.
Plants respond in plastic ways to environmental change, and this affects not only the result of competition, but its future outcome.
There are species differences in the competition process.
An almost universal approach to modeling competition between plants in single species communities has been to consider competition for space. Four categories of plant competition models of this type are reviewed; lattice models based on experiments, neighborhood models aimed at simulating processes in vegetation, forestry models designed to predict the distribution of yield between individuals, and models of the self-thinning relationship. The use these models make of the five axioms, and their contribution to them, is discussed.
In conclusion, models are discussed that simulate competition directly as a two-part process of (a) direct resource acquisition by plants, and where spatial patterns of resource depletion in the environment are calculated, and (b) individual plant growth, and where spatial pattern of the growth made then determines new patterns of resource acquisition. The requirement that (b) should include plasticity is discussed, and the suggestion is made that for models to contribute further to the advance of competition theory, they must describe differences between species and the environments in which they grow.
