Impact of soil structure on microbial responses to environmental change

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Environmental change and perturbation due to human activities can have devastating impacts on essential activities in soils, like biogeochemical cycling, that are essential to the earth's ecosystem functions. However, the influence of key physical variables like soil structure ("the soil phenotype") on ecosystem responses to such perturbations is very poorly understood. Such knowledge is critical to appreciate and predict the resilience of soil ecosystems to perturbations over time. Microorganisms drive biogeochemical cycles in soils and provide ideal, tractable indicators of soil ecosystem function. A major biological factor known to promote microbial resilience to soil perturbations is variation, as variant organisms may be better adapted to the altered conditions. Recent breakthroughs through NERC-funded projects in the Avery laboratory and other laboratories have established a novel form of biological variation that promotes microbial survival in soil systems; that is, phenotypic variation between individual cells that have the same DNA composition. It is now widely accepted that this variation within genetically-uniform populations (non-genotypic heterogeneity, NGH), is important for microbial survival in soils. The major challenge now is to understand how the type of soil environment may alter the impact of NGH on microbial survival over time. Specifically, with soils having different scales of spatial structure, this project will test the hypothesis that physical heterogeneity (soil structure) modulates the impact of NGH in soil populations. By addressing this major question, this studentship will help describe the resilience of soil ecosystems to environmental perturbation. The project will apply state-of the-art technologies underpinned by interdisciplinary collaboration to tackle this problem, addressing these key objectives:Does NGH confer a competitive advantage in structured soils?Does soil structure affect long-term evolution of NGH in stressed soil ecosystems?