The BOREAS Information System
Remote Sensing Science (RSS)

RSS-7: Retrieval of Boreal Forest Leaf Area Index From Multiple Scale Remotely Sensed Vegetation Indices

P.I.(s): Jing M. Chen -- Canada Centre for Remote Sensing (CCRS)
Co-I(s): Margaret Penner -- Forestry Canada/PNFI; Josef Cihlar -- CCRS

Objectives: To develop and validate an algorithm that allows the retrieval of the spatial distribution of LAI from remotely sensed vegetation indices. Field measurements of LAI and FPAR (fraction of Absorbed Photosynthetically Active Radiation) were undertaken for major boreal forest species (jack pine, quaking aspen, black spruce) and stand types. For each species, stands with different percentages of forest cover were studied. Field measurements of effective LAI were taken both along transects and on a regularly spaced grid with the LAI-2000 sensor. For selected stands (OJP, YJP and OBS tower flux sites in both SSA and NSA), high frequency data (1 sample/cm) were obtained from a LI-COR quantum sensor carried by a person walking along transects beneath the overstory to improve LAI calculations and to characterize the architecture of the canopy. Measurements from the moving sensor (a sunfleck-LAI instrument dubbed the Talkman) were used to calculate FPAR.
These field measurements allow us to establish relationships between LAI, FPAR and remotely sensed radiances and their transformations including vegetation indices. These relationships will then be used to test the performance of spatial mapping of LAI by extrapolation. High resolution images will be provided by the CASI and MEIS airborne instrument which will be flown over the pre-established transects. Lower resolution images will be obtained from LANDSAT and/or SPOT and possibly from other remote sensing instruments available through other BOREAS studies.

RSS-7 Data Sets

  • LAI-2000
  • AVHRR LAI (Region)
  • AVHRR fPAR (Region)
  • Landsat TM LAI (SSA, NSA)
  • Landsat TM fPAR (SSA, NSA)

  • Get some RSS-7 data using FTP (BOREAS Investigators only, password required). [FTP Help]

    RSS-7 BOREAS Operations 1994

    To develop algorithms for calculating LAI and FPAR for BOREAS study areas and the region based on improved ground measurements.

    Types of Data Collected:

    1. LAI, effective LAI, foliage clumping index, needle-to-shoot area ratio, destructive LAI
    2. FAPR, APAR, PAR transmitted, PAR reflected from TOC and forest floor

    Equipment Used:

    1. TRAC (Tracing Radiation and Architecture of Canopies) developed by Chen due to BOREAS. It consists of three LI-COR quantum sensors for measuring the transmitted total and diffuse PAR and the reflected PAR from the forest floor at an interval of 10 mm over transects of up to 300 m by a walking and a high frequency sampling technique.
    2. LI-COR LAI-2000 Plant Canopy Analyzer (PCA) which measures the effective LAI from canopy gap fraction at zenith angles.
    3. A computerized video-camera/light-table system (AgVision) for measuring the needle-to-shoot area ratio.

    Summary of Places and Time of Measurements in 1994
    Site Time Equipment Transect Length and Direction
    SSA-OBS IFC 1-3 TRAC, PCA, AgVision 300 m, SE from flux tower (FT)
    SSA-OJP IFC 1-3 TRAC, PCA, AgVision 200 m, SE from FT
    SSA-YJP IFC 1-3 TRAC, PCA, AgVision 150 m, SE from FT; 150 m, NW of FT
    SSA-OA   TRAC, PCA 300 m, SW from FT
    SSA-Fen IFC 2 TRAC, PCA 2*50 m, 150 m to S of FT
    NSA-OBS IFC 1-3 TRAC, PCA, AgVision 300 m, SE from FT
    NSA-OJP IFC 1-3 TRAC, PCA, AgVision 250 m, SE from FT; 170 m, NW from FT
    NSA-YJP IFC 1-3 TRAC, PCA, AgVision 170 m, SE from FT; 170 m, NW from FT
    NSA-Fen IFC 2 TRAC, PCA 300 m, SE from FT; 250 m, W from FT
    NSA-OA IFC 1-3 TRAC, PCA 50 m, E-W

    In addition, PCA and/or TRAC measurements were made in IFC 2-3 in auxiliary sites T3U9S, T6R5S, T7R9S1, T7R9S2, T8Q9P, F7J0P, F7J1P, G2I4S, G4I3M, G9I4S, G1K9P, T9Q8P,T7T3S and G2I7M in the SSA and W0Y5A, T4U9S, T6T6S, T8S4S and T8T1P in the NSA.
    In IFC (September) 1993, TRAC and PCA measurements were made in SSA-OBS, SSA-OJP, SSA-YJP, NSA-OBS, NSA-OJP and NSA-YJP.

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    Last Updated: October 21, 1997