Increases in Atmospheric [CO2] and the Soil Food Web

  • D. A. Phillips
  • T. C. Fox
  • H. Ferris
  • J. C. Moore
Part of the Ecological Studies book series (ECOLSTUD, volume 187)


Organic inputs to soil are comprised largely of plant debris and root exudation, which is responsible for rhizodeposition. Increases in organic matter inputs from plants growing under elevated [CO2] affect soil microorganisms and a limited set of conclusions can be drawn.
  • Bacterial and fungal communities in soil ecosystems use such plant materials as resources to support multiple levels of tiny grazers and predators, which comprise soil food webs.

  • Ten years of elevated [CO2] at the ETH FACE site produced data on soil protozoa and nematodes that are consistent with adjustments predicted for availability of soil bacteria and fungi.

  • Disparate changes in soil microorganisms and complex adjustments in food web structure reported under higher [CO2] in a multitude of other experiments suggest that a better understanding of C resource availability is needed.

  • Increases in living root mass under elevated [CO2] could affect soil food webs through additional exudation, but limited information is available on changes in root exudation under such conditions. We summarize here a new, more complex, understanding of root exudation that includes mechanisms by which microorganisms, and possibly their predators within the food web, can actively enhance root exudation. Initial experiments indicate that higher [CO2] can increase root exudation of amino acids under axenic conditions by two separate mechanisms and these could result in more rhizodeposition.

  • Little is known about how elevated [CO2] levels alter predation, another key connection between the soil food web and the plant, but reductionist studies are beginning to support the concept that specific molecules affect predation and influence many organismic interactions in the root zone.

  • Because the fossil record suggests soil food webs were exposed to widely varied levels of [CO2] for long periods, a certain stability of these interactions should be expected as global atmospheric [CO2] increases.


Fine Root Root Exudation Root Colonization Global Change Biol Biol Fertil Soil 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • D. A. Phillips
    • 1
  • T. C. Fox
    • 1
  • H. Ferris
    • 2
  • J. C. Moore
    • 3
  1. 1.Department of Plant SciencesUniversity of CaliforniaDavisUSA
  2. 2.Department of NematologyUniversity of CaliforniaDavisUSA
  3. 3.Department of Biological SciencesUniversity of Northern ColoradoGreeleyUSA

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