A simple space competition model using stochastic and episodic disturbance

Communities of organisms competing for homogeneous and limited resources such as space or light can appear to coexist indefinitely. There have been several models that have explored the mechanisms by which this can occur. (Armstrong, Sebens, Levins and Culver, Dayton and others). This paper extends the model developed by Armstrong (Ecology 57 (1976) 953)) and Sebens (Theor. Pop. Biol. 32 (1987) 430)) to explore the effects of random variability in disturbance rates and episodic disturbances on community structure. Results of this model show that the combined effects of variable disturbances and episodic disturbances can lead to major changes in expected community structure. These changes can include the persistence of one or more species that would normally be out-competed and major competitive reversals in which the competitive dominant is excluded from the resource.