The 7th International CO2 Conference Web Site - The Age of Carbon Respired from Terrestrial Ecosystems

by Susan Trumbore

Carbon enters ecosystems through a single process, photosynthesis, and nearly all is returned to the atmosphere through respiration, some 50-80% of which occurs below-ground. Soil (belowground) respiration integrates CO₂ derived from C that has resided in the ecosystem for periods of differing duration, ranging from relatively recent photosynthetic products that fuel root metabolism, to CO₂ derived from decomposition of plant and soil organic matter that may be decades to centuries old. A comparison of the radiocarbon content of CO₂ respired by roots, microbes, and soils with the record of radiocarbon in atmospheric CO₂ allows direct estimation of the mean age of C being respired [Trumbore 2000; Wang et al. 2000, Cisneros Dozal et al. 2005; Borken et al. 2005].

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