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United States Department of Agriculture

Agricultural Research Service

Title: TOWARDS SCALING-UP TOWER CO2 FLUX MEASUREMENTS IN GRASSLANDS OF THE NORTHERN GREAT PLAINS: PHENOMENOLOLGICAL MODELING USING FLUX PARTITIONING, VEGETATION INDICES AND GEOGRAPHIC INFORMATION SYSTEM (GIS))

Author
item Gilmanov, Tagir
item Tieszen, Larry
item Wylie, Bruce
item Flanagan, Larry
item Frank, Albert
item Haferkamp, Marshall
item Meyers, Tilden
item Morgan, Jack

Submitted to: Society for Range Management Meeting Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 1/6/2004
Publication Date: 1/15/2004
Citation: GILMANOV, T.G., TIESZEN, L.L., WYLIE, B.K., FLANAGAN, L.B., FRANK, A.B., HAFERKAMP, M.R., MEYERS, T.P., AND MORGAN, J.A. 2004. TOWARDS SCALING-UP TOWER CO2 FLUX MEASUREMENTS IN GRASSLANDS OF THE NORTHERN GREAT PLAINS: PHENOMENOLOLGICAL MODELING USING FLUX PARTITIONING, VEGETATION INDICES AND GEOGRAPHIC INFORMATION SYSTEM (GIS). SOCIETY FOR RANGE MANAGEMENT MEETING ABSTRACTS #112.

Interpretive Summary:

Technical Abstract: Estimates of gross primary productivity (Pg) and ecosystem respiration (Re) were derived from 20 minute net CO2 fluxes monitored at five Northern Great Plains locations using light-response analysis. At the weekly scale, daytime ecosystem respiration ('day) was correlated (0.64<R2<0.95) with measured nighttime respiration ( 'night). 'day tended to be higher than 'night and regressions of 'day on 'night for all sites were different from the 1:1 line. Pg varied from 459 to 2491 g CO2 m-2 yr-1, Re from 996 to 1881 g CO2 m-2 yr-1, and net ecosystem exchange from '537 (source) to +610 g CO2 m-2 yr-1(sink) over all 13 site-years. Maximum daily light-use efficiencies 'd,max = Pg/PAR ranged from 0.014 to 0.032 mol CO2 (mol quanta)-1. Maximum weekly 'wk,max = Pg,wk/PARwk ranged from 0.008 to 0.019 mol CO2 (mol quanta)-1. Ten-day averages of PAR, Tair, Tsoil, soil moisture, temperature sum above 5 °C, and tower derived Pg and Re were compared to ten-day smoothed SPOT VEGETATION Normalized Difference Vegetation Index (NDVI). Pg was significantly higher correlated with NDVI than Pd (R2 0.46 to 0.77 and 0.05 to 0.58 respectively). A positive correlation was found between Re and NDVI (0.56<R2<0.77). Other ecological factors that are available as spatial-temporal data sets have potential to improve NDVI relationships using multivariate functions (Pg = fP(NDVI, X1, X2, ', Xn) and Re = fR(NDVI, Y1, Y2, ',Ym)). This will allow accurate scaling-up of local flux-tower measurements to larger geographical regions using GIS data, remote sensing, and environmental factors.

Last Modified: 8/24/2016
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