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Harvard Forest Symposium Abstract 2008

  • Title: Ground-Based Lidar Scanning of Two Stands in the Harvard Forest To Retrieve Canopy Structural Parameters
  • Primary Author: Alan Strahler (Boston University)
  • Additional Authors: David Jupp (CSIRO Marine and Atmospheric Research, Australia); Wenge Ni-Meister (CUNY Hunter College); Crystal Schaaf (Boston University); Curtis Woodcock (Boston University)
  • Abstract:

    An under-canopy, upward-scanning, lidar field instrument, named Echidna®, provides rapid, accurate, and automated measurements of forest stand structure, including tree diameters, stand basal area, stems per unit area, stand height, leaf area index, foliage profile, and foliage area volume density for a hemlock stand (Fig. 1) and a mixed-hardwood stand (Fig. 2) in the Harvard Forest in late July, 2007. Retrievals of stand characteristics are validated by ground measurements of tree stems in a large circular plot centered on the scan position; of canopy characteristics by LAI-2000 measurements, hemispherical digital photographs, and allometric calculations. The Echidna® instrument, built by CSIRO Australia, directs a horizontal 1064 nm laser beam with 5 mr divergence and a pulse rate of 2 kHz to a rotating mirror at 45° incidence to scan a vertical circle, recording data from +137° to –130° zenith angles and all azumuths as the instrument revolves 180° on a tripod mount. The return signal is sampled at 2 gigasamples per second, digitizing the full scattered waveform. The shape of the return pulse distinguishes readily between hard targets (tree boles, branches) and soft targets (leaves). Echidna® data were also acquired at stands in the Howland Experimental Forest (Maine), and the Bartlett Experimental Forest (New Hampshire) during the 2007 field deployment.

    Fig. 1. Hemlock stand mean lidar return, equal-angle projection.

    Fig. 2. Hardwood stand mean lidar return, equal-angle projection.

  • Research Category: Conservation and Management, Forest-Atmosphere Exchange

  • Figures:
  • Harvard_Hem_CP.jpg