JP1.6 Effect of elevated CO2 on net ecosystem carbon production in Florida scrub oak during a nine year study

Tuesday, 29 April 2008
Floral Ballroom Magnolia (Wyndham Orlando Resort)
Thomas L. Powell, Smithsonian Environmental Research Center, Kennedy Space Center, Florida; and D. P. Johnson, T. J. Seiler, C. R. Hinkle, and B. G. Drake

The effect of elevated atmospheric CO2 on net ecosystem carbon production (NEP) of forests has seldom been determined using gas exchange. We used open top chambers to periodically measure NEP of a Florida scrub oak ecosystem exposed to elevated atmospheric CO2. At the same time, we continuously measured NEP of the ecosystem using a nearby eddy covariance system. A comparison between simultaneous measurements from the eddy covariance system and chambers at normal ambient CO2 concentrations confirmed that the chambers produced less than a +/-10% difference on gas exchange. We used the chamber data to scale the eddy covariance measurements and compared the results of NEP with the CO2 effect to the sum of biomass estimates for shoots, roots, and soil carbon measured in the elevated CO2 chambers. After nine years of CO2 fumigation, the estimated stimulation of elevated atmospheric CO2 on NEP was 10.72 tCha-1 compared to biomass stimulation of 6.36 tCha-1.
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