Mechanisms causing the transition between spatial pattern long transients.

Regular self-organized spatial patterns can be observed in many ecological systems. Some such patterns are quasi-stable; that is, they can switch to a different spatial pattern on a relatively short time scale in the absence of external changes in environmental conditions, aside from minor stochastic events. They are referred to as long transients. Although long transients have been studied mathematically, the detailed mechanisms by which a pattern can suddenly switch in nature are not well understood. Here we study, through spatial simulation of spatial patterns of an empirically based model, a type of intransitive loop plane travelling wave, which can switch to different spatial patterns through minor events. Close study of the simulations allows the causal chains involved in the switch to be determined in precise ecological detail by focusing on local interactions. In particular, this indicates that in real ecological systems, even though they may be resilient over long time periods, there can be vulnerabilities. These vulnerabilities include time lags in some interactions, which even small perturbations can eventually expose, leading to instabilities changing the spatial pattern. We show that patterns from intransitive loops are especially susceptible to such instabilities. The results are applicable to ecological systems of interest.