Are rainforests self-organized in a critical state?

The spatial distribution of low-canopy gaps in the Barro Colorado Island rainforest (Panama) is shown to exhibit fractal properties. A simple cellular automata model (the “Forest Game”) was constructed in order to simulate the gap dynamics of such forests as well as the observed macroscopic spatial regularities. Generalized fractal dimensions are studied as a function of several relevant parameters. The observed and simulated fractal behaviour is shown to be related to self-similar dynamics of biomass. This result is interpreted as related to the emergence of a class of “self-organized critical state”.