ABSENCE OF CHAOS IN A SELF-ORGANIZED CRITICAL COUPLED MAP LATTICE

Although ecologists have been aware for almost 20 years that populatio n densities may evolve in a chaotic way, the evidence for chaos in nat ural populations is rather poor. The lack of convincing evidence may h ave its origin in the difficulty of estimating the effect of external environmental noise, but it may also reflect natural regulation proces ses. In this paper we present a meta-population-dynamical model, in wh ich the nearest neighbor local population fragments interact by applyi ng a threshold condition. Namely, each local population follows its ow n temporal evolution until a critical population density is reached, w hich initiates dispersal (migration) events to the neighbors. The type of interaction is common to self-organized critical cellular automato n models. Depending on the threshold level, the global behavior of our model can be characterized either by noisy dynamics with many degrees of freedom, by a periodical evolution, or by an evolution towards a f ixed point. Low dimensional collective chaos does not occur. Moreover, self-organized criticality with power law distributions emerges if th e interaction between the neighboring local populations is strong enou gh.