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Title: Carbon dioxide and water vapor fluxes of winter wheat and tallgrass prairie ecosystems

Author
item BAJGAIN, RAJEN - University Of Oklahoma
item XIAO, XIANGMING - University Of Oklahoma
item BASARA, JEFFREY - University Of Oklahoma
item Wagle, Pradeep
item ZHOU, YUTING - University Of Oklahoma
item MAHAN, HAYDEN - University Of Oklahoma
item Gowda, Prasanna
item Steiner, Jean

Submitted to: Annual American Geophysical Union Hydrology Days
Publication Type: Abstract Only
Publication Acceptance Date: 8/15/2016
Publication Date: 12/12/2016
Citation: Bajgain, R., Xiao, X., Basara, J., Wagle, P., Zhou, Y., Mahan, H., Gowda, P., Steiner, J.L. 2016. Carbon dioxide and water vapor fluxes of winter wheat and tallgrass prairie ecosystems [abstract]. American Geophysical Union, December 12-16, 2016, San Francisco, California. Available: https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/149023.

Interpretive Summary: Abstract only.

Technical Abstract: Winter wheat (Triticum aestivum L.) and tallgrass prairie are common land cover types in the Southern Plains of the United States. In recent years, agricultural expansion into native grasslands has been extensive, particularly either managed pasture or dryland crops such as wheat. In this study, we measured the exchange of carbon dioxide and water vapor fluxes from two major ecosystems (winter wheat and tallgrass prairie) in the Southern Plains of the United States using the eddy covariance technique. The major objective of this study was to compare and contrast carbon dioxide and water vapor fluxes between these two ecosystems for providing insights on how the conversion of tallgrass prairie grassland to winter wheat could impact the carbon and water budgets of the region. Daily net ecosystem CO2 exchange (NEE) reached seasonal peaks of - 9.24 g C m-2 d-1 and - 6.23 g C m-2 d-1in winter wheat and tall grass prairie, respectively. The wheat ecosystem was a net sink of carbon for four months (February-May), whereas the tallgrass prairie ecosystem was a net sink of carbon for seven months (March-September). Although both ecosystems were sinks of carbon during their respective growing seasons, the wheat ecosystem was a net source of carbon on an annual scale (128 ± 46 g C m-2 yr-1) when fluxes from summer fallow period were considered. In contrast, the tallgrass prairie ecosystem was a net sink of carbon on an annual scale (-147 ± 30 g C m-2 yr-1). The daily ET reached seasonal maximum of 6.0 mm day-1 and 7.2 mm day-1in winter wheat and tallgrass prairie, respectively. Although, ecosystem water use efficiency (EWUE, the ratio of cumulative gross primary production (GPP) to evapotranspiration (ET)) was higher in wheat (13.1 g CO2 mm-1 ET) than in tallgrass prairie (7.6 g CO2 mm-1 ET) on a seasonal scale, it was slightly higher in tallgrass prairie (6.9 g CO2 mm-1 ET) than in wheat (6.2 g CO2 mm-1 ET) on an annual scale. Results suggest that the differences in magnitudes and patterns of carbon dioxide and water vapor fluxes between winter wheat and tallgrass prairie can exert influence on the carbon and water budgets of the whole region under land use change scenario.