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Harvard Forest Symposium Abstract 2018

  • Title: TLS Scanning and Destructive Sampling to Calibrate Virtual Tree Volume and Aboveground Biomass Retrieval from TLS at Harvard Forest
  • Primary Author: Alan Strahler (Boston University)
  • Additional Authors: Audrey Barker Plotkin (Harvard Forest); Jereme Frank (University of Maine); David MacFarlane (Michigan State University); David Orwig (Harvard Forest); Phil Radtke (Virginia Polytechnic Institute and State University); Crystal Schaaf (Boston University)
  • Abstract:

    How accurate are estimates of the woody volume and above-ground biomass of forest trees that are obtained from terrestrial laser scanning (TLS) and associated retrieval algorithms? Can TLS improve the precision of stand-based biomass estimation and provide accurate allometric equations from virtual volume and biomass estimates? How well do TLS instruments estimate leaf area, leaf biomass, and the foliage profile of leaf area with height? A field calibration experiment, combining multiple TLS instruments and destructive sampling of scanned trees, is presently answering these questions for a mix of hardwoods and conifers in and near a 50 x 50 m stand at Harvard Forest, Petersham, Massachusetts, using data acquired in the Tom’s Swamp tract in August, 2017, by participants in the NSF-funded TLS Research Coordination Network (RCN). The experiment includes scanning with both commercial (Riegl, Faro, Zebedee) and research instruments (SALCA, CBL, PCL) at varying scan settings and scan location plans, acquiring point-cloud and/or return-intensity data that are processed by appropriate algorithms to estimate volume, biomass, and leaf area. A sample totaling 20 trees of four species (red oak, red maple, eastern hemlock, and white pine), each represented in 5 size classes, was harvested after scanning to estimate volume and biomass from dimensional measurements and weights of trunks, stems, branches, and leaves, as well as wet and dry wood-density measurements of tree components. Volume and biomass by higher branch order and height stratum within the tree were acquired for some harvested individuals. A smaller nearby group of four red oaks was scanned and sampled in finer detail, allowing comparison of actual biomass and volume in 2-m voxels encompassing the trees. The main plot was also scanned with a Riegl TLS in April, 2017, while deciduous trees were leafless, as a comparison benchmark. At the present time (March 2018), data processing of TLS scans and destructive samples is proceeding. Results are due within a few months The TLS RCN is supported by NSF (DBI-1455636); leafless scanning is provided by UNAVCO (NSF/NASA EAR-0735156).

  • Research Category: International Research Projects
    Large Experiments and Permanent Plot Studies
    Soil Carbon and Nitrogen Dynamics

  • Figures:
    • Figure 1.docx