The BOREAS Information System
Terrestrial Ecology (TE)


TE-23: Canopy Architecture of Boreal Forests: Studies of Solar Radiation, Leaf Area Index, and Forest Dynamics


P.I.(s): Paul M. Rich -- University of Kansas

Objectives: The primary goal of this project is to characterize canopy architecture as it influences within-canopy solar radiation regimes, with implications for forest ecosystem dynamics and remote sensing. The project will also provide indirect estimates of fPAR and LAI, measurements of canopy surface topography, and detailed maps of stand architecture. Hemispherical (fisheye) photography will be used to:

  1. measure the angular distribution of canopy openings
  2. estimate fPAR
  3. estimate LAI and leaf inclination for the BOREAS project study sites (tower flux, auxiliary, and mixed boreal forest sites)
Acquisition of arrays of hemispherical photographs will permit examination of horizontal variation within each site and vertical variation in the understory and throughout low canopies. Photographs taken from towers will permit examination of complete vertical profiles for Tower Flux and TE Tower Sites. Estimates of fPAR (direct, diffuse, and total) from photographs will be validated using PAR sensor measurements, while LAI and leaf inclination estimates will be validated using both direct and indirect methods. Field measurements, construction of detailed stand maps, and analyses will be coordinated with TE-9, TE-13, TE- 20, RSS-7, RSS-19, BOREAS staff efforts and Canadian contributions to biometric measurements.

TE-23 Data Sets

  • Catalog of Hemispherical Photos (PhotoCDs)
  • LAI derived from Hemi photos
  • Gap Fraction derived from Hemi photo
  • FPar derived from Hemi photos

  • Get some TE-23 data using FTP (BOREAS Investigators only, password required). [FTP Help]

    TE-23 BOREAS Operations 1994


    Objectives:

    1. To acquire and analyze a catalog of upward looking hemispherical (fisheye) photography from beneath the forest canopy to provide BOREAS investigators with extensive estimates of canopy architecture (LAI...) and radiative transfer (FPAR...) properties for most major BOREAS study sites.
    2. To set up mapped forest plots (typical dimensions 50 m x 60 m) to characterize canopy architecture and understory cover. The mapped plots serve two general functions:
      • to provide comprehensive canopy architecture measurements for a site representative of a specific type of forest
      • to provide a study area for field measurements, such as studies of light regime, leaf area index, and tree population dynamics.
      More specifically, the mapped plots serve as the location for:
      • 1intercomparison and calibration of techniques
      • testing geometric models concerning radiative transport in canopies.


    Types of Data Collected:

    1. A comprehensive catalog of hemispherical photographs were acquired using to calculate:
      • gap fraction as a function of zenith angle
      • canopy architecture indices (effective LAI, extinction coefficient, and LAI)
      • radiative transfer indices (daily direct FIPAR at monthly, intervals, and diffuse FIPAR).
    2. Mapped plot characterization: stand density, basal area, average height, average crown radius; Measurements for all trees (> 2 m height) in mapped plot: X-Y location, diameter at breast (DBH), dominance class (dominant, codominant, suppressed, juvenile, dead standing, dead leaning); Measurements for a subset of trees: height, height to base of first branches, height to base of green crown, crown radius in four azimuth directions; and Understory Cover for 10 m x 10 m Subplots: hand-drawn maps of major cover classes, description of dominant species and features, catalog of photographs.


    Summary of Places and Times of Measurements:
    Hemispherical photographs were acquired at all forested tower sites during IFC-1 and IFC-2, at all auxiliary sites, and at aspen tower sites at intervals of 2-4 weeks throughout the growing season. Trees within mapped plots were measured as possible through the summer.

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    Last Updated: October 29, 1997