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Net ecosystem exchange, evapotranspiration and canopy conductance in a riparian forest |
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| Authors: | John Kochendorfer Eugenia G CastilloEdward Haas Walter C OechelKyaw Tha Paw U |
| Institution: | a Atmospheric Turbulence and Diffusion Division/NOAA, P.O. Box 2456 Oak Ridge, TN 37831, USA b University of California at Davis, 1 Shields Ave, Davis, CA 95616, USA c CH2M HILL, 2485 Natomas Park Dr, Suite 600, Sacramento, CA 95833, USA d San Diego State University, 5500 Campanile Drive, San Diego, CA 92182, USA |
| Abstract: | The ecosystem fluxes of mass and energy were quantified for a riparian cottonwood (Populus fremontii S. Watson) stand, and the daily and seasonal courses of evapotranspiration, CO2 flux, and canopy conductance were described, using eddy covariance. The ecosystem-level evapotranspiration results are consistent with those of other riparian studies; high vapor pressure deficit and increased groundwater depth resulted in reduced canopy conductance, and the annual cumulative evapotranspiration of 1095 mm was more than double the magnitude of precipitation. In addition, the cottonwood forest was a strong sink of CO2, absorbing 310 g C m−2 from the atmosphere in the first 365 days of the study. On weekly to annual time scales, hydrology was strongly linked with the net atmosphere-ecosystem exchange of CO2, with ecosystem productivity greatest when groundwater depth was ∼2 m below the ground surface. Increases in groundwater depth beyond the depth of 2 m corresponded with decreased CO2 uptake and evapotranspiration. Saturated soils caused by flooding and shallow groundwater depths also resulted in reduced ecosystem fluxes of CO2 and water. |
| Keywords: | Heterogeneity Advection Populus fremontii Flooding Hydrology Cottonwood |
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