1) random fractal using the midpoint displacement algorithm in the package FieldSim as described in Brouste et al. (2007). Note this is the same algorithm that Palmer (1992) used to examine the influence of environmental heterogeneity on species coexistence.
Brouste, A., S. Lambert-Lacroix, and J. Istas. 2007. On Gaussian random fields simulation. Journal of Statistical Software 1:23. pdf
Palmer, M.W. 1992. Coexistence of species in fractal landscapes. American Naturalist 139:375-397. pdf from JSTOR
(last content added: 06/05/10)