Microenvironments within our urban environments tend to select for the microorganisms that will eventually populate them. Here is an example of the microgeographical principle of substrate dependence. The asbestos roof of a factory in Petersfield. The roof is made from two types of asbestos that result in subtle changes in its microgeography. The asbestos that makes up the larger area of roof is inimical to the orange lichen but set within this are small panels of a different kind of asbestos that allows the same lichen to flourish.
THIS IS MICROGEOGRAPHY 