Modelling the Gaia Hypothesis: Daisyworld

Abstract

The Gaia hypothesis examines the global effects of local interactions among organisms. A model commonly used to examine the global emergent properties proposed by the Gaia hypothesis is Daisyworld. The original Daisyworld relies on a deterministic set of equations to determine the outcome of the model. This project develops a two dimensional cellular automata (CA) representation of Daisyworld. By using a cellular automata and incorporating stochastic effects into the model, this project is able to develop a Daisyworld that takes into account both the spatial and stochastic characteristics of natural ecosystems. The model developed is found to closely resemble results produced by a mathematical Daisyworld. The effects of death rate and solar luminosity on the CA Daisyworld are examined. It is found that lower death rate causes the daisies to adjust to varying solar luminosities more slowly, but it also enables them to survive longer when the solar luminosity is extremely high. The model is found to be able to adjust to changing solar luminosity and maintain a temperature that is close to the optimum temperature for daisy growth. Finally, the model is extended to include four species of daisies. The general properties of the four species Daisyworld are studied as well as the impacts of solar luminosity on this variant of the model.