A notable and consistent ecological observation known for\ud a long time is that spatial variance in the abundance of a\ud species increases with its mean abundance and that this relationship typically conforms well to a simple\ud power law (Taylor 1961). Indeed, such models can be\ud used at a spectrum of spatial scales to describe spatial\ud variance in the abundance of a single species at different\ud times or in different regions and of different species across the same set of areas (Taylor et al. 1978; Taylor and Woiwod 1982).