RSS-4 BOREAS Operations 1994

Objectives:
The objectives of the research proposed by RSS-4 were to examine methods for deriving LAI, Fpar and leaf chlorophyll/nitrogen concentration from remotely sensed data for input into the Forest-BGC Model using constrained empirical methods and by comparison with a forward canopy radiation model.

Current Status:
To achieve the first element of the research it was necessary to acquire point estimates of forest LAI, Fpar and canopy chemistry. In 1993 several indirect methods for determining LAI were compared at three of the four flux tower sites in the Southern Study Area (Plummer and Lucas, 1993). Based on this experience it was decided to restrict further data collection to one species, Jack Pine, and cover as many of the tower/auxiliary sites as possible. As in 1993 measurements were obtained with the LAI-2000 and a Ceptometer to derive LAI and Fpar. In addition samples were acquired from the upper canopy for determination of canopy chemistry -- water, nitrogen, chlorophyll, lignin, cellulose. These samples were divided into current and previous year needles, frozen and shipped back to the UK in CO₂ where they are being analyzed. Data were acquired at the following sites and will be released to BORIS shortly:

Site  Ceptometry   LAI-2000   Chemistry
G1K9P  *    x    x        *   *    
G4K8P  *    x    x        *   *
G9L0P  *    x    x        *   *
G7K8P  *    x    x        x    *
G8L6P  *    x    x        *   *
F7J0P  *    x    x        x    *    *
F7J1P  *    x    x        x*   *
F5I6P  *    x    x        x*   *
G2L3T  *    x    x        x*   *
F8L6T  *    x    -        x    *
D06HS  *    x    -        -
D6H4T  *    x    -        -
D9I1M  *    x    -        -

These data will be compared with AVIRIS and possibly CASI data. The second element of the work comprised the development and testing of a forest reflectance model. The model was tested on ASAS data from the FED-MAC site at Howland, Maine and the simulation results for this site were presented at IGARSS'94 and will shortly be published (North and Plummer, 1994, North, 1995). It is intended to extend this model by inclusion of a conifer needle reflectance model, LIBERTY, currently under development by a doctoral student (Dawson et al. 1995) and to explore methods for inversion of the model using neural networks. The latter element is the subject of a grant proposal. Research is also underway to test the predictions of a global ecosystem model over the BOREAS sites.

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Last Updated: October 21, 1997