Prominent effect of soil network heterogeneity on microbial invasion
  Using a network representation for real soil samples and mathematical models for microbial spread, we show that the structural heterogeneity of the soil habitat may have a very significant influence on the size of microbial invasions of the soil pore space. In particular, neglecting the soil structural heterogeneity may lead to a substantial underestimation of microbial invasion. Such effects are explained in terms of a crucial interplay between heterogeneity in microbial spread and heterogeneity in the topology of soil networks. The main influence of network topology on invasion is linked to the existence of long channels in soil networks that may act as bridges for transmission of microorganisms between distant parts of soil. 
F.J. Perez-Reche, S.N. Taraskin, W. Otten, M.P. Viana, L. da F. Costa   and C.A. Gilligan
q-bio.PE physics.bio-ph physics.soc-ph