Samuel Bickel

icroorganisms are tiny and their ranges of active dispersal in soil are very limited. Direct observation of their life is scarce and remains in the shadows of opaque soil components. How the physical soil structure together with nutrient and hydration conditions affects soil microbial diversity and abundance is among my main research interests.

Global statistical analysis of environmental factors shaping soil bacterial richness and diversity reveal a hierarchy of covariates with a predominant role soil moisture conditions at climatic scales; termed the soil climatic water content (Bickel et al. 2019). We developed a theoretical framework to quantify sizes and numbers of aqueous habitats and their carrying capacity. The model predicts highest bacterial diversity at intermediate climatic water contents where carrying capacity supports sufficiently high cell density and aqueous habitats remain fragmented; thereby sheltering bacterial species from competition (Bickel and Or 2020). This has direct implications for rare soil bacterial species that constitute a soils functional potential and vary across biomes. Such low abundant and globally rare members of the microbial community increase in proportion towards drier soils where the physiological advantage of common species is suppressed (Bickel and Or submitted). The balance of accessibility to resources and protection from competition is expected to be reflected at the scale of soil bacterial habitats. My current research focuses on unraveling spatial patterns of bacterial abundance in natural soils using controlled experiments. Direct observation and quantification of spatial patterns of bacterial abundance would advance our understanding of bacterial life in natural soils.

Bickel, Samuel, Xi Chen, Andreas Papritz, and Dani Or. “A Hierarchy of Environmental Covariates Control the Global Biogeography of Soil Bacterial Richness.” Scientific Reports 9, no. 1 (August 20, 2019): 1–10. https://doi.org/10.1038/s41598-019-48571-w.

Bickel, Samuel, and Dani Or. “Soil Bacterial Diversity Mediated by Microscale Aqueous-Phase Processes across Biomes.” Nature Communications 11, no. 1 (January 8, 2020): 1–9. https://doi.org/10.1038/s41467-019-13966-w.