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K. George, R. J. Norby, Jason G. Hamilton, and E. H. DeLucia. 2003. "Fiber root respiration in a loblolly pine and sweetgum forest growing in elevated C02," New Phytologist. 160: 511 522.
The loss of carbon below ground through respiration of fine roots may be modified by global change. Here we tested the hypothesis that a reduction in N concentration of tree fine roots grown in an elevated atmospheric C02 concentration would reduce maintenance respiration and that more energy would be used for root growth and N uptake. We partitioned total fine root respiration (RT) between maintenance (RM), growth (Rd, and N uptake respiration -- RN) for loblolly pine (Pinus taeda) and sweetgum (Liquidambar styraciflua) forests exposed to elevated C02.
The hypothesis was rejected because the majority of fine root respiration was used for maintenance and was not reduced by changes in root N concentration in elevated C02. Because of its large contribution to RT and total soil C02 efflux, changes in RM caused by warming may greatly alter carbon losses from forests to the atmosphere.