TY - JOUR
T1 - CO2 uptake and ecophysiological parameters of the grain crops of midcontinent North America
T2 - Estimates from flux tower measurements
AU - Gilmanov, Tagir G.
AU - Wylie, Bruce K.
AU - Tieszen, Larry L.
AU - Meyers, Tilden P.
AU - Baron, Vern S.
AU - Bernacchi, Carl J.
AU - Billesbach, David P.
AU - Burba, George G.
AU - Fischer, Marc L.
AU - Glenn, Aaron J.
AU - Hanan, Niall P.
AU - Hatfield, Jerry L.
AU - Heuer, Mark W.
AU - Hollinger, Steven E.
AU - Howard, Daniel M.
AU - Matamala, Roser
AU - Prueger, John H.
AU - Tenuta, Mario
AU - Young, David G.
N1 - Funding Information:
This work was performed under USGS contract G10PC00044 and funding was provided by the USGS Geographic Analysis and Monitoring program. This work was also supported in part by the grant from the South Dakota Corn Utilization Council . Measurements at the US-ARM site were supported by the Office of Biological and Environmental Research of the U.S. Department of Energy under contract DE-AC02-05CH11231 as part of the Atmospheric Radiation Measurement Program. We thank Ameriflux database supervisor Dr. Thomas Boden and Ameriflux contributors Drs. J. Baker, T. Griffis, A. Suyker, and S. Verma for assistance with the data needs of this project.
PY - 2013/1/1
Y1 - 2013/1/1
N2 - We analyzed net CO2 exchange data from 13 flux tower sites with 27 site-years of measurements over maize and wheat fields across midcontinent North America. A numerically robust "light-soil temperature-VPD" -based method was used to partition the data into photosynthetic assimilation and ecosystem respiration components. Year-round ecosystem-scale ecophysiological parameters of apparent quantum yield, photosynthetic capacity, convexity of the light response, respiration rate parameters, ecological light-use efficiency, and the curvature of the VPD-response of photosynthesis for maize and wheat crops were numerically identified and interpolated/extrapolated. This allowed us to gap-fill CO2 exchange components and calculate annual totals and budgets. VPD-limitation of photosynthesis was systematically observed in grain crops of the region (occurring from 20 to 120 days during the growing season, depending on site and year), determined by the VPD regime and the numerical value of the curvature parameter of the photosynthesis-VPD-response, σVPD. In 78% of the 27 site-years of observations, annual gross photosynthesis in these crops significantly exceeded ecosystem respiration, resulting in a net ecosystem production of up to 2100g CO2m-2year-1. The measurement-based photosynthesis, respiration, and net ecosystem production data, as well as the estimates of the ecophysiological parameters, provide an empirical basis for parameterization and validation of mechanistic models of grain crop production in this economically and ecologically important region of North America.
AB - We analyzed net CO2 exchange data from 13 flux tower sites with 27 site-years of measurements over maize and wheat fields across midcontinent North America. A numerically robust "light-soil temperature-VPD" -based method was used to partition the data into photosynthetic assimilation and ecosystem respiration components. Year-round ecosystem-scale ecophysiological parameters of apparent quantum yield, photosynthetic capacity, convexity of the light response, respiration rate parameters, ecological light-use efficiency, and the curvature of the VPD-response of photosynthesis for maize and wheat crops were numerically identified and interpolated/extrapolated. This allowed us to gap-fill CO2 exchange components and calculate annual totals and budgets. VPD-limitation of photosynthesis was systematically observed in grain crops of the region (occurring from 20 to 120 days during the growing season, depending on site and year), determined by the VPD regime and the numerical value of the curvature parameter of the photosynthesis-VPD-response, σVPD. In 78% of the 27 site-years of observations, annual gross photosynthesis in these crops significantly exceeded ecosystem respiration, resulting in a net ecosystem production of up to 2100g CO2m-2year-1. The measurement-based photosynthesis, respiration, and net ecosystem production data, as well as the estimates of the ecophysiological parameters, provide an empirical basis for parameterization and validation of mechanistic models of grain crop production in this economically and ecologically important region of North America.
KW - CO sink
KW - Gross photosynthesis
KW - Maize
KW - Net CO exchange partitioning
KW - VPD limitation of photosynthesis
KW - Wheat
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U2 - 10.1016/j.agee.2012.09.017
DO - 10.1016/j.agee.2012.09.017
M3 - Article
AN - SCOPUS:84872033244
SN - 0167-8809
VL - 164
SP - 162
EP - 175
JO - Agriculture, Ecosystems and Environment
JF - Agriculture, Ecosystems and Environment
ER -