J. Phys. I France
Volume 5, Number 9, September 1995
Page(s) 1233 - 1238
DOI: 10.1051/jp1:1995193
J. Phys. I France 5 (1995) 1233-1238

The Self-Organized Critical Forest-Fire Model with Trees and Bushes

B. Strocka1, J.A.M.S. Duarte2 and M. Schreckenberg3

1  Institut für Theoretische Physik, Universität zu Köln, 50937 Köln, Germany
2  Departamento Fisica, Faculdade de Ciencias, 4000 Porto, Portugal
3  Theoretische Physik - FB 10, Universität Duisburg, 47048 Duisburg, Germany

(Received 2 May 1995, accepted 16 May 1995)

We present a forest-fire model with trees and bushes. Additional to the usual nearest-neighbour fire spreading both populations can ignite each other at the same lattice site. Simulations in two dimensions show that the bushes with the higher growth rate remain critical while the self-organization of the trees is destroyed by quick bush fires which ignite the tree clusters before they can become large. A mean-field treatment leads to coupled equations for the densities at the stationary point, depending on the ratio k of the growth rates.

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