HR: 11:25h
AN: B22A-05    [Abstracts]
TI: Relationship between Total Chlorophyll Content and CO2 Fluxes in Crops: Implications for the Remote Estimation of Net Ecosystem Carbon Dioxide Exchange
AU: * Vina, A
AF: Center for Advanced Land Management Information Technologies, School of Natural Resources, University of Nebraska-Lincoln, 102 E Nebraska Hall, Lincoln, NE 68588-0517 United States
AU: Ciganda, V
AF: Center for Advanced Land Management Information Technologies, University of Nebraska-Lincoln, 102 E Nebraska Hall, Lincoln, NE 68588-0517 United States
AU: Arkebauer, T
AF: Department of Agronomy and Horticulture, University of Nebraska-Lincoln, 106 KCR, Lincoln, NE 68583-0817 United States
AU: Verma, S
AF: School of Natural Resources, University of Nebraska-Lincoln, 244 L.W. Chase Hall, Lincoln, NE 68583-0728 United States
AU: Rundquist, D
AF: Center for Advanced Land Management Information Technologies, School of Natural Resources, University of Nebraska-Lincoln, 102 E Nebraska Hall, Lincoln, NE 68588-0517 United States
AU: Gitelson, A
AF: Center for Advanced Land Management Information Technologies, School of Natural Resources, University of Nebraska-Lincoln, 102 E Nebraska Hall, Lincoln, NE 68588-0517 United States
AB: The ratio of leaf surface area to ground surface area, called leaf area index (LAI), is a measure of carbon and water balance in plants, because it describes the potential surface area available for leaf gas exchange. LAI can be separated into its photosynthetic and non-photosynthetic components. Total chlorophyll content in the canopy, expressed as the product of green LAI (portion of LAI composed of green leaf area) and leaf chlorophyll (Chl) content, is a quantitative measure of the photosynthetically functional component. Total Chl content is directly expressive of the photosynthetic apparatus of the vegetation, and it may relate to the photosynthetic potential of a vegetation stand. The goal of this study was to investigate whether total chlorophyll content in crops can be used as a proxy of the net ecosystem CO2 exchange (NEE) that a vegetation stand could reach under optimal radiation conditions. We studied the relationship between total Chl content and mid-day NEE of maize and soybean grown in irrigated and rainfed fields. Total Chl content and NEE relate very closely (r2=0.85) for both species. This close relationship between total Chl and NEE allowed the use of a technique, recently developed for the remote estimation of total Chl, to assess NEE. The technique uses two spectral bands: near infra-red and either green (around 550 nm) or red-edge (near 700 nm). The technique was able to predict 5-day maximum value mid-day NEE composite, ranging from 0 to 2.5 mgC/m2s, with an overall root mean square error (RMSE) of less than 0.33 mgC/m2s.
DE: 3322 Land/atmosphere interactions
DE: 3360 Remote sensing
DE: 0315 Biosphere/atmosphere interactions
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting