Biological conditions for oscillations and chaos generated by multispecies competition

We investigate biological mechanisms that generate oscillations and chaos in multispecies competition models. For this purpose, we use a competition model concerned with competition for abiotic essential resources. Because phytoplankton and plants consume quite a number of abiotic essential resources, the model is particularly relevant for phytoplankton communities and terrestrial vegetation. We show that the predicted dynamics depend crucially on the relationship between the resource requirements and the resource consumption characteristics of the species. More specifically, the model predicts that competition generates (1) stable coexistence if species consume most of the resources for which they have high requirements, (2) oscillations and chaos if species consume most of the resources for which they have intermediate requirements, and (3) competitive exclusion with a winner that depends on the initial conditions if species consume most of the resources for which they have low requirements. The theoretical predictions are compared with available data on resource utilization patterns of phytoplankton species.