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Re: Why Is The Ground Brown

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  • Pat Neuman
    http://www.terradaily.com/reports/Why_Is_The_Ground_Brown.html ... leaves.
    Message 1 of 2 , Apr 3, 2006

      > Why Is The Ground Brown
      > by Staff Writers
      > Irvine CA (SPX) Apr 03, 2006
      > Ecologists have long asked, Why is the world green? In other words,
      > why aren't herbivores, such as insects and grazing animals, more
      > successful at eating the world's green leaves, also known as plant
      > biomass?
      > In the May 2006 issue of American Naturalist, Steven D. Allison
      > (University of California, Irvine) asks the same questions a different
      > way: Why is the ground brown? Why don't the organisms that break down
      > the carbon in the soil consume it all?
      > Some of the same ecological factors make the world green and the
      > ground brown, especially the carbon in plant material, the role of
      > herbivores and decomposer organisms in consuming that carbon, and the
      > role of predators in eating the consumers of the carbon. As it turns
      > out, as Allison observes, "the chemical structure of soil carbon makes
      > it far more difficult to consume than plant carbon."
      > There is about three times as much carbon in soil than in plant
      > biomass. In addition, minerals in the soil can block decomposers from
      > feeding on soil carbon. Allison also points out that most decomposers
      > are of relatively small size compared to the animals eating green
      > "Instead of digesting material in their guts, decomposers depend on
      > enzymes to partially digest their food sources outside their bodies,"
      > Allison explains. "This strategy is a major constraint on the
      > breakdown of soil carbon that helps make the ground brown."
      > Founded in 1867, The American Naturalist is one of the world's most
      > renowned, peer-reviewed publications in ecology, evolution, and
      > population and integrative biology research. AN emphasizes
      > sophisticated methodologies and innovative theoretical syntheses--all
      > in an effort to advance the knowledge of organic evolution and other
      > broad biological principles.
      > Steven D. Allison "Brown ground: a soil carbon analog for the green
      > world hypothesis," The American Naturalist 167:5.
      > Related Links
      > University of California, Irvine
      > University of Chicago Press Journals
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