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    Author(s): Stephen G. Pallardy; Lianhong Gu; Paul J. Hanson; Tilden Myers; Stan D. Wullschleger; Bai Yang; Jeffery S. Riggs; Kevin P. Hosman; Mark Heuer
    Date: 2007
    Source: e-Gen. Tech. Rep. SRS–101. U.S. Department of Agriculture, Forest Service, Southern Research Station: 13-20. [CD-ROM].
    Publication Series: Miscellaneous Publication
    PDF: View PDF  (312 KB)


    A long-term experiment to measure carbon and water fluxes was initiated in 2004 as part of the Ameriflux network in a second-growth oak-hickory forest in central Missouri. Ecosystem-scale (~ 1 km2) canopy gas exchange (measured by eddy-covariance methods), vertical CO2 profile sampling and soil respiration along with meteorological parameters were monitored continuously. Early results from this forest located on the western margin of the Eastern Deciduous Forest indicated high peak rates of canopy CO2 uptake (35-40 μmol/m2/second) during the growing season in the relatively wet year of 2004. Late growing-season CO2 uptake rates declined despite the absence of drought, suggesting declining leaf photosynthetic capacity that preceded leaf fall or removal of leaf area by herbivory. Canopy CO2 profile measurements in summer indicated substantial accumulation of CO2 (~ 500 ppm) near the surface in still air at night, venting of this buildup in the morning hours under radiation-induced turbulent air flow, and small vertical gradients of CO2 during most of the subsequent light period with minimum CO2 concentrations in the canopy. Flux of CO2 from the soil ranged from 2 to 8 μmol/m2/second during the growing season and increased with temperature. Flux of forest floor CO2 fell below 1 μmol/ m2/second during mid-winter periods. Data from this site and others in the network will also allow characterization of regional spatial variation in carbon fluxes as well as inter-annual differences attributable to climatic events such as droughts.

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    Pallardy, Stephen G.; Gu, Lianhong; Hanson, Paul J.; Myers, Tilden; Wullschleger, Stan D.; Yang, Bai; Riggs, Jeffery S.; Hosman, Kevin P.; Heuer, Mark. 2007. Carbon dioxide fluxes in a central hardwoods oak-hickory forest ecosystem. e-Gen. Tech. Rep. SRS–101. U.S. Department of Agriculture, Forest Service, Southern Research Station: 13-20. [CD-ROM].

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