Effects of cheats on Daisyworld

Critics of Daisyworld argued that if unpigmented or grey daisies (which do not have to expend energy synthesizing pigment and so grow faster) were added, the model would not work. The second model incorporated cheating grey daisies. A 5 per cent growth tax was imposed on the coloured daisies for making pigment. The graphs show that grey daisies flourish only when conditions are optimal. They do not prevent temperature regulation by the light and dark daisies

Foxes, rabbits, and daisies

In an attempt to simulate a real world, herbivores (rabbits) and predators (foxes) are introduced into the Daisyworld model. The model is also subjected to periodic catastrophes: on four occasions 30 per cent of the daisy population is destroyed by a plague (see above). Surprisingly, neither the addition of herbivores and predators, nor plagues, seriously affects the daisies’ ability to regulate climate. The crashes of daisy populations, and the corresponding dips in herbivores and predators, all are short lived. So too are the dips in temperature regulation, from which the system rapidly recovers. In fact, this model exhibits a remarkable robustness to perturbation, which only fails when solar output becomes too great. Geophysical models such as this are stable because the populations are constructed as they would be in the real world, by environmental conditions. (see variation 30)