Author
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Emmerich, William |
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Submitted to: Society of Range Management
Publication Type: Proceedings Publication Acceptance Date: 9/6/2004 Publication Date: 2/5/2005 Citation: Emmerich, W.E. 2005. Ecosystem carbon exchange and evapotranspiration in a shrub and grassland plant community. Proc. Soc. for Range Manage. 58th Annual Meeting, Feb. 5-11, Ft. Worth, TX. p. 101. Interpretive Summary: ABSTRACT Understanding carbon exchange and evapotranspiration in semiarid shrub and grassland areas is important in determining the functionality and interaction of the plant communities. The hypothesis is that a C4 grassland can uptake more carbon per unit of water loss than C3 shrub plant community. Evapotranspiration (ET) and CO2 flux were measured with Bowen ratio systems at a shrub and grassland site for four years in southeastern Arizona. Aboveground biomass was determined in the spring and fall as a measure of carbon uptake during the growing season. Three different methods were used to evaluate carbon uptake using ET and CO2 flux, and biomass data. The grassland site was able to take up between 1.6 and 3 times more carbon per unit of water use than the shrub site depending on the method used in the evaluation. Using an estimated total carbon uptake by the biomass and the ET flux, the grassland site had a growing season annual average uptake of 0.64 g C m-2 mm-1 ET and the shrub site 0.37 g C m-2 mm-1 ET. The grassland site was estimated to have more total carbon in the biomass, hence a conversion of grassland to shrub may reduce total biomass carbon in the plant community. Technical Abstract: ABSTRACT Understanding carbon exchange and evapotranspiration in semiarid shrub and grassland areas is important in determining the functionality and interaction of the plant communities. The hypothesis is that a C4 grassland can uptake more carbon per unit of water loss than C3 shrub plant community. Evapotranspiration (ET) and CO2 flux were measured with Bowen ratio systems at a shrub and grassland site for four years in southeastern Arizona. Aboveground biomass was determined in the spring and fall as a measure of carbon uptake during the growing season. Three different methods were used to evaluate carbon uptake using ET and CO2 flux, and biomass data. The grassland site was able to take up between 1.6 and 3 times more carbon per unit of water use than the shrub site depending on the method used in the evaluation. Using an estimated total carbon uptake by the biomass and the ET flux, the grassland site had a growing season annual average uptake of 0.64 g C m-2 mm-1 ET and the shrub site 0.37 g C m-2 mm-1 ET. The grassland site was estimated to have more total carbon in the biomass, hence a conversion of grassland to shrub may reduce total biomass carbon in the plant community. |
