ON A FOREST-FIRE MODEL WITH SUPPOSED SELF-ORGANIZED CRITICALITY

We study a stochastic forest fire model introduced by P. Bak et al. as a model showing self-organized criticality. This model involves a growth parameter p, and the criticality is supposed to show up in the limit p --> 0. By stimulating the model on much larger lattices, and with much smaller values of p, we find that the correlations with longest range do not show a nontrivial critical phenomenon in this limit, though we cannot rule out percolation-like critical behavior on a smaller but still divergent length scale. In contrast, the model shows nontrivial deterministic evolution over time scales >> 1/p in the limit p --> 0.