ARE RAIN-FORESTS SELF-ORGANIZED IN A CRITICAL-STATE

The spatial distribution of low-canopy gaps in the Barro Colorado Isla nd rainforest (Panama) is shown to exhibit fractal properties. A simpl e cellular automata model (the ''Forest Game'') was constructed in ord er to simulate the gap dynamics of such forests as well as the observe d macroscopic spatial regularities. Generalized fractal dimensions are studied as a function of several relevant parameters. The observed an d simulated fractal behaviour is shown to be related to self-similar d ynamics of biomass. This result is interpreted as related to the emerg ence of a class of ''self-organized critical state''.