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Harvard Forest Symposium Abstract 2018

  • Title: Modeling Tree Volume with a Lightweight, Rapid-Scanning Terrestrial Lidar Scanner
  • Primary Author: Crystal Schaaf (University of Massachusetts - Boston)
  • Additional Authors: Audrey Barker Plotkin (Harvard Forest); Peter Boucher (University of Massachusetts - Boston); Z Li (Yale School of Forestry & Environmental Studies); David Orwig (Harvard Forest); Ian Paynter (UMass Boston); Phil Radtke (Virginia Polytechnic Institute and State University)
  • Abstract:

    Peter B. Boucher, Crystal Schaaf, Francesco Peri, David A. Orwig, Audrey Barker-Plotkin, Alan Strahler, Zhan Li, Phil Radtke, Ian Paynter, and Pasi Raumonen

    School for the Environment, University of Massachusetts Boston
    Harvard Forest, Harvard University
    Earth and Environment, Boston University
    Dept of Forest Resources and Environmental Conservation, Virginia Tech
    Tampere University of Technology, Finland

    Terrestrial lidar scanners (TLS) are changing the way that researchers estimate Aboveground Biomass (AGB) for individual trees and forest stands. TLS instruments sample the three-dimensional structure of the forest environment, producing a set of x, y, and z coordinates (a ‘point cloud’) that correspond to the surrounding trees and topography. Quantitative Structure Models (QSMs) can be used to fit 3D geometric primitives (usually cylinders) to the point cloud data of individual trees in order to reconstruct tree structure and directly estimate woody volume and ultimately biomass (by multiplying this volume by wood density).
    During August 2017, the NSF-funded Research Coordination Network (RCN): Coordinating the Development of Terrestrial Lidar Scanning for Aboveground Biomass and Ecological Applications organized a collaborative calibration field campaign to scan, measure, model, and destructively sample 30 trees of 5 different species from the Tom’s Swamp tract of Harvard Forest. The goals of this international effort were to calibrate and validate AGB estimates from TLS data with field measurements of volume and weight.
    TLS instruments, deployed at ground level, often do quite well in characterizing the lower portions of trees and the lower canopy layers. However, their ability to characterize the upper canopy can be limited by the range to the target and the occlusion of intervening trunk and branches. To ameliorate these issues, the rapid-scanning Canopy Biomass Lidar (CBL), developed at UMass Boston, used the Harvard Forest bucket lift to scan two red oaks of similar height (Quercus rubra) from additional vantage points, 20 m above the ground. Scan data from the multiple scanning heights were then combined to produce point clouds. QSM tree models (Raumonen et al., 2013) were then fit to calculate the woody volume of these two trees, resulting in total woody volumes of 2477 ± 276 L and 3849 ± 709 L respectively. Future work will compare the QSM derived volumes to the field measured volumes in order to examine the contributions of the scans at different heights to the woody volume estimate and to quantify the uncertainties of these non-destructive estimates of woody volume and AGB.

  • Research Category: Ecological Informatics and Modelling