Biophysical Aspects of Soil Microbial Diversity--Lessons for Disciplinary Survival Strategies.

Notwithstanding the relatively harsh conditions prevailing near the earth surface, soils support the highest prokaryotic density and diversity of all biosphere compartments. The unparalleled biological activity and diversity in soils is often attributed to the extreme heterogeneity in physical and chemical environments formed within complex pore spaces with highly dynamic and fragmented aquatic habitats that affect microbial mobility and nutrient fluxes. In this presentation we will explore the roles of physical factors controlling the extent and dynamics of diffusional pathways affecting microbial activity, colony expansion and coexistence at the micro-scale. A quantitative framework for linking pore scale physical processes and microbial activity and diversity involves challenging and rewarding collaboration across discipline boundaries similar to those observed at natural bio-physical interfaces. Modeling and experimental findings highlight the roles of thin liquid films and fragmented and heterogeneous aquatic habitats in sustaining and promoting microbial coexistence. Guided by modeling, new experiments in simple and observable soil systems elucidate interplay between confined mobility, diffusion lengths, and diversity maintenance in unsaturated soils.
Can these observations help us to draw parallels about the potential coexistence of soil science as a distinct scientific discipline? First, development of quantitative and predictive tools for processes taking place in complex bio-physico-chemical soil environments requires numerous simplifications that must rely on knowledge distributed across disciplinary boundaries. Second, a small and specialized discipline such as soil science may flourish and coexist within a highly fragmented scientific environment. However, a more stable mode of existence for the information age may require a different survival strategy: association and formation of topical consortia capable of solving complex tasks (“scientific biofilms”). Third, adopting long term survival strategies that anticipate changes in societal needs and effectively engage specialized contributions of our “scientific species” (e.g., food and healthy environment with limited land and water resources).