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Title: A comparison of carbon dioxide and water vapor fluxes between winter wheat and tallgrass prairie ecosystems in Oklahoma

Author
item BAJGAIN, RAJEN - University Of Oklahoma
item XIAO, XIANGMING - University Of Oklahoma
item BASARA, JEFF - University Of Oklahoma
item Wagle, Pradeep
item ZHOU, YUTING - University Of Oklahoma
item Mahan, Hayden
item Gowda, Prasanna
item Steiner, Jean

Submitted to: Grazinglands Research Laboratory Miscellaneous Publication
Publication Type: Abstract Only
Publication Acceptance Date: 5/13/2017
Publication Date: 6/7/2017
Citation: Bajgain, R., Xiao, X., Basara, J., Wagle, P., Zhou, Y., Mahan, H.R., Gowda, P.H., Steiner, J.L. 2017. A comparison of carbon dioxide and water vapor fluxes between winter wheat and tallgrass prairie ecosystems in Oklahoma [abstract]. FLUXNET Workshop 2017. Available at: https://ucanr.edu/sites/Fluxnet2017/files/261958.pdf.

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 - 9.4 and -8.8 g C m-2 d-1 in 2015 and -6.2 and -7.5 g C m-2 d-1 in 2016 at winter wheat and tall grass prairie ecosystems, 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 (56 ± 13 and 33 ± 9 g C m-2 yr-1 in 2015 and 2016) when fluxes from summer fallow period were considered. In contrast, the tallgrass prairie ecosystem was a net sink of carbon on an annual scale (-128 ± 69 g and -119 ± 53 g C m-2 yr-1 in 2015 and 2016). The daily ET reached seasonal maximum of 6.0 and 5.3 mm day-1 in 2015 and 7.2 and 8.2 in 2016 mm day-1 at winter wheat and tallgrass prairie ecosystems, respectively. 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.