Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: May 4, 2006
Publication Date: October 28, 2007
Citation: Lehman, R.M. 2007. Microbial distributions and their potential controlling factors in terrestrial subsurface environments. In, AL Mills and R Franklin [Eds.], Spatial Distribution of Microorganisms in Terrestrial Systems: Implications for the Distribution of Function in Ecosystems. Springer, Dordrecht, The Netherlands. pp. 135-178. Interpretive Summary: A key question in environmental microbiology as it relates to agricultural production, contaminant remediation, and other applications is: how are microbial populations and functions distributed? This question is immediately followed by: what factors influence these distributions? In answering these two questions, application-specific questions can be approached from an experimental perspective, i.e., does a specified practice or event influence the microbial populations or functions in a significant manner, and is the influence positive or negative? This paper synthesizes data on distributions of microbial populations and functions in the terrestrial environment, emphasizing (i) the transitions between soils and subsoils, and (ii) the transition from vadose zone to aquifer. Conceptual models (some new, some that are modifications of existing models) are presented that are best supported by the aggregate data.
Technical Abstract: It has become apparent that microorganisms are distributed in the environment in an extremely patchy manner and that the patch sizes are quite variable in magnitude. In terrestrial systems, patchiness appears to generally increase with depth. Neither the factors that control these distributions nor the distributions themselves have been rigorously quantified. To quantify relationships between microbial spatial distributions and their controlling factors, the relevant scales and most probable controlling factors need to be identified. To that end, published data on subsurface microbial properties from spatially arranged sample sets are reviewed and used to construct and support conceptual models of microbial distributions in terrestrial subsurface environments.