Soil organic matter, long thought to be a semi-permanent
storehouse for ancient carbon, may be much more vulnerable to climate change
than previously thought.
Plants direct between 40 percent and 60 percent of
photosynthetically fixed carbon to their roots and much of this carbon is
secreted and then taken up by root-associated soil microorganisms. Elevated
carbon dioxide (CO2) concentrations in the atmosphere are projected to increase
the quantity and alter the composition of root secretions released into the
soil.