title: Microbial diversity affects self-organization of the soil-microbe system with consequences for function.
abstract: Soils are complex ecosystems and the pore-scale physical structure regulates key processes that support terrestrial life. These include maintaining an appropriate mixture of air and water in soil, nutrient cycling and carbon sequestration. There is evidence that this structure is not random, although the organizing mechanism is not known. Using X-ray microtomography and controlled microcosms, we provide evidence that organization of pore-scale structure arises spontaneously out of the interaction between microbial activity, particle aggregation and resource flows in soil. A simple computational model shows that these interactions give rise to self-organization involving both physical particles and microbes that gives soil unique material properties. The consequence of self-organization for the functioning of soil is determined using lattice Boltzmann simulation of fluid flow through the observed structures, and predicts that the resultant micro-structural changes can significantly increase hydraulic conductivity. Manipulation of the diversity of the microbial community reveals a link between the measured change in micro-porosity and the ratio of fungal to bacterial biomass. We suggest that this behaviour may play an important role in the way that soil responds to management and climatic change, but that this capacity for self-organization has limits.
authors.affiliation: Faculty of Agriculture, Food and Natural Resources, University of Sydney, Sydney, New South Wales 2006, Australia. john.crawford@sydney.edu.au
authors.forename: John W
authors.initials: JW
authors.lastname: Crawford
authors.forename: Lewis
authors.initials: L
authors.lastname: Deacon
authors.forename: Dmitri
authors.initials: D
authors.lastname: Grinev
authors.forename: James A
authors.initials: JA
authors.lastname: Harris
authors.forename: Karl
authors.initials: K
authors.lastname: Ritz
authors.forename: Brajesh K
authors.initials: BK
authors.lastname: Singh
authors.forename: Iain
authors.initials: I
authors.lastname: Young
mesh_terms: D018407:Bacterial Physiological Phenomena; D002450:Cell Communication; D003198:Computer Simulation; D017753:Ecosystem; D008954:Models, Biological; D012987:Soil; D012988:Soil Microbiology
chemical_list: D012987:Soil