caa a22 4500 445383402 CHVBK 20180317143024.0 cr unu---uuuuu 170323e20110101xx s 000 0 eng 10.1007/s10021-010-9389-3 doi (NATIONALLICENCE)springer-10.1007/s10021-010-9389-3 Variability in Light-Use Efficiency for Gross Primary Productivity on Great Plains Grasslands [Elektronische Daten] [H. Polley, Rebecca Phillips, Albert Frank, James Bradford, Phillip Sims, Jack Morgan, James Kiniry] Gross primary productivity (GPP) often is estimated at regional and global scales by multiplying the amount of photosynthetically active radiation (PAR) absorbed by the plant canopy (PARa) by light-use efficiency (ε g; GPP/PARa). Mass flux techniques are being used to calculate ε g. Flux-based estimates of ε g depend partly on how PAR absorption by plants is modeled as a function of leaf area index (LAI). We used CO2 flux measurements from three native grasslands in the Great Plains of USA to determine how varying the value of the radiation extinction coefficient (k) that is used to calculate PARa from LAI affected variability in estimates of ε g for each week. The slope of linear GPP-PARa regression, an index of ε g, differed significantly among the 18 site-years of data, indicating that inter-annual differences in ε g contributed to the overall variability in ε g values. GPP-PARa slopes differed among years and sites regardless of whether k was assigned a fixed value or varied as an exponential function of LAI. Permitting k to change with LAI reduced overall variability in ε g, reduced the slope of a negative linear regression between seasonal means of ε g and potential evapotranspiration (PET), and clarified the contribution of inter-annual differences in precipitation to variation in ε g. Our results imply that greater attention be given to defining dynamics of the k coefficient for ecosystems with low LAI and that PET and precipitation be used to constrain the ε g values employed in light-use efficiency algorithms to calculate GPP for Great Plains grasslands. Springer Science+Business Media, LLC (outside the USA), 2010 absorbed photosynthetically active radiation nationallicence CO2 flux measurements nationallicence grassland nationallicence leaf area index nationallicence mixed grass prairie nationallicence precipitation nationallicence radiation extinction coefficient nationallicence shortgrass steppe nationallicence Polley H. Grassland, Soil and Water Research Laboratory, USDA-Agricultural Research Service (ARS), 808 East Blackland Road, 76502, Temple, Texas, USA aut Phillips Rebecca Northern Great Plains Research Laboratory, USDA-ARS, 58554, Mandan, North Dakota, USA aut Frank Albert Northern Great Plains Research Laboratory, USDA-ARS, 58554, Mandan, North Dakota, USA aut Bradford James Southern Plains Range Research Station, USDA-ARS, 73801, Woodward, Oklahoma, USA aut Sims Phillip Southern Plains Range Research Station, USDA-ARS, 73801, Woodward, Oklahoma, USA aut Morgan Jack Crops Research Laboratory, USDA-ARS, 80526, Ft. Collins, Colorado, USA aut Kiniry James Grassland, Soil and Water Research Laboratory, USDA-Agricultural Research Service (ARS), 808 East Blackland Road, 76502, Temple, Texas, USA aut Ecosystems Springer-Verlag 14/1(2011-01-01), 15-27 1432-9840 14:1<15 2011 14 10021 https://doi.org/10.1007/s10021-010-9389-3 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10021-010-9389-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Polley H. Grassland, Soil and Water Research Laboratory, USDA-Agricultural Research Service (ARS), 808 East Blackland Road, 76502, Temple, Texas, USA aut NATIONALLICENCE 700 1- Phillips Rebecca Northern Great Plains Research Laboratory, USDA-ARS, 58554, Mandan, North Dakota, USA aut NATIONALLICENCE 700 1- Frank Albert Northern Great Plains Research Laboratory, USDA-ARS, 58554, Mandan, North Dakota, USA aut NATIONALLICENCE 700 1- Bradford James Southern Plains Range Research Station, USDA-ARS, 73801, Woodward, Oklahoma, USA aut NATIONALLICENCE 700 1- Sims Phillip Southern Plains Range Research Station, USDA-ARS, 73801, Woodward, Oklahoma, USA aut NATIONALLICENCE 700 1- Morgan Jack Crops Research Laboratory, USDA-ARS, 80526, Ft. Collins, Colorado, USA aut NATIONALLICENCE 700 1- Kiniry James Grassland, Soil and Water Research Laboratory, USDA-Agricultural Research Service (ARS), 808 East Blackland Road, 76502, Temple, Texas, USA aut NATIONALLICENCE 773 0- Ecosystems Springer-Verlag 14/1(2011-01-01), 15-27 1432-9840 14:1<15 2011 14 10021 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer