Finite-size effects in the self-organized critical forest-fire model

We study finite-size effects in the self organized critical forest-fire mod el by numerically evaluating the tree density and the fire size distributio n. The results show that this model does not display the finite-size scalin g seen in conventional critical systems. Rather, the system is composed of relatively homogeneous patches of different tree densities, leading to two qualitatively different types of fires: those that spall an entire patch an d those that do not. As the system size becomes smaller, the system contain s less patches, and finally becomes homogeneous, with large density fluctua tions in time.