You are here

Harvard Forest >

Harvard Forest Symposium Abstract 2016

  • Title: Vertical Structure Measurements of Leaves and Woody Materials with Dual-Wavelength Laser Scanning
  • Primary Author: Zhan Li (University of Massachusetts - Boston)
  • Additional Authors: Supriya Chakrabarti (University of Massachusetts - Lowell); Timothy Cook (University of Massachusetts - Lowell); Kuravi Hewawasam (University of Massachusetts - Lowell); Glenn Howe (University of Massachusetts - Lowell); David Jupp (CSIRO Marine and Atmospheric Research, Australia); Ian Paynter (UMass Boston); Edward Saenz (University of Massachusetts - Boston); Crystal Schaaf (University of Massachusetts - Boston); Alan Strahler (Boston University); Xiaoyuan Yang (Boston University); Tian Yao (Boston University)
  • Abstract:

    Forest canopy structure regulates radiation interception through the canopy, affects the canopy microclimate, and consequently influences the energy, water, and carbon fluxes between soil, vegetation and atmosphere through its interaction with leaf physiological functioning. Leaves in forests assimilate carbon from the atmosphere and woody components store the net production of that assimilation. Separate structure measurements of leaves and woody components advance the monitoring and modeling of forest ecosystem functions. To achieve this goal, we retrieved vertical profiles of leaf and woody components separately with a terrestrial laser scanner, the Dual-Wavelength Echidna Lidar (DWEL). DWEL scans of a hardwood site at the Harvard Forest, Petersham, Massachusetts, USA, in early May and in late September in 2014, revealed the spatial heterogeneity of the canopy vertical structure of the two vegetation components: leaves and woody materials. The DWEL collects simultaneous scans of forests with two lasers at different wavelengths, 1064 nm (NIR) and 1548 nm (SWIR). Power returned from leaves is much lower than from woody materials such as trunks and branches at the SWIR wavelength due to the liquid water absorption by leaves, whereas returned power at the NIR wavelength is similar from both leaves and woody materials. This spectral contrast between leaves and woody materials, along with spatial context information, discriminates leaves and woody materials accurately in 3D space, thus allowing the measurement of separate leaf and woody area profiles.

  • Research Category: Forest-Atmosphere Exchange

  • Figures:
  • separate_leaf_woody_area_volume_density_profiles.jpg