Net ecosystem exchange, evapotranspiration and canopy conductance in a riparian forest

作者：Kochendorfer John^*; Castillo Eugenia G; Haas Edward; Oechel Walter C; Paw Kyaw Tha U

来源：Agricultural and Forest Meteorology, 2011, 151(5): 544-553.

DOI：10.1016/j.agrformet.2010.12.012

• Heterogeneity
• Advection
• Populus fremontii
• Flooding
• Hydrology
• Cottonwood

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, CO(2) 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 CO(2), 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 CO(2), with ecosystem productivity greatest when groundwater depth was similar to 2 m below the ground surface. Increases in groundwater depth beyond the depth of 2 m corresponded with decreased CO(2) uptake and evapotranspiration. Saturated soils caused by flooding and shallow groundwater depths also resulted in reduced ecosystem fluxes of CO(2) and water.

• 出版日期2011-5-15