You are not currently logged in.
Access JSTOR through your library or other institution:
If You Use a Screen ReaderThis content is available through Read Online (Free) program, which relies on page scans. Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Brown Ground: A Soil Carbon Analogue for the Green World Hypothesis?
Steven D. Allison
The American Naturalist
Vol. 167, No. 5 (May 2006), pp. 619-627
Stable URL: http://www.jstor.org/stable/10.1086/503443
Page Count: 9
You can always find the topics here!Topics: Enzymes, Soil microorganisms, Soil biochemistry, Herbivores, Organic soils, Enzyme substrates, Microorganisms, Soil enzymes, Detritivores, Forest soils
Were these topics helpful?See somethings inaccurate? Let us know!
Select the topics that are inaccurate.
Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Preview not available
Abstract: For many decades, ecologists have asked what prevents herbivores from consuming most of the plant biomass in terrestrial ecosystems, or “Why is the world green?” Here I ask the analogous question for detritivores: what prevents them from degrading most of the organic material in soils, or “Why is the ground brown?” For fresh plant detritus, constraints on decomposition closely parallel constraints on herbivory: both herbivore and decomposer populations may be controlled by plant tissue chemistry from the bottom up and predators from the top down. However, the majority of soil carbon is not plant litter but carbon that has been consumed by detritivores and reprocessed into humic compounds with complex and random chemical structures. This carbon persists mainly because the chemical properties of humic compounds and interactions with soil minerals constrain decomposition by extracellular enzymes in soil. Other constraints on decomposers, such as nutrient limitation of enzyme production and competition with opportunistic microbes, also contribute to brown ground. Ultimately, the oldest soil carbon persists via transformation into complex molecules that are impervious to enzymatic attack and effectively decoupled from processing by the soil food web.
© 2006 by The University of Chicago.