Spatially explicit models like cellular automata are widely used in ecology. The spatio-temporal order of events is a new feature of these models that does not have to be considered in equivalent non-spatial models. We considered simple stochastic cellular automata to test sensitivity of model response under different spatial and temporal sequences of events. The results indicate that very important differences in model output can be found as spatio-temporal ordering is changed, even in a very simple model. A careful choice of the way events are evaluated has to be made: the spatio-temporal ordering must be selected to match the biological characteristics of the target ecological system to be modelled. Further, a complete description of the details of this ordering should be specified in order to let others reproduce published simulation experiments.