1. Site Harvard Hemlock Site 305 Site Harvard EMS tower  The LAI estimates are impacted by changes in the occlusion effect at the different scales.  75 m is considered as the appropriate scale due to the layout of the EVI scans.  Modeled G vs. G=0.5: more work is needed to define the transition between the two in intermediate sites. Virtual Direct Measurement of Leaf Area Index and Above-Ground Biomass Using Echidna ® Terrestrial Laser Scanning Xiaoyuan Yang 1, Crystal Schaaf 1, Alan Strahler 2, Zhan Li 2, Zhuosen Wang 1, Tian Yao 3, Feng Zhao 4, Curtis Woodcock 2, David Jupp 5, Darius Culvenor 6, Glenn Newnham 6, and Jenny Lovell 7 1 Department of Environmental, Earth and Ocean Sciences, University of Massachusetts Boston, Boston, MA 2 Center for Remote Sensing, Department of Earth and Environment, Boston University, Boston, MA 3 Remote Sensing Laboratory, Montclair State University, Montclair, NJ 4 Department of Geographical Sciences, University of Maryland, College Park, MD 5 CSIRO Marine and Atmospheric Research, Canberra, ACT, Australia 6 CSIRO Land and Water, Melbourne, VIC, Australia 7 CSIRO Marine and Atmospheric Research, Hobart, TAS, Australia  Foliage Area Volume Density & Leaf Area Index  Three-Dimensional Forest Reconstruction  Voxelization Voxelization transform s the irregular, unorganized cloud of data points in the 3- D forest reconstruction into volumetric datasets.  Voxel Based LAI & FAVD Estimation FAVD Model for point cloud The total effective area of objects in volume V or Leaf area index: Noted: In the case of multiple observations: the average of LAI is used for each voxel G-functionLeaf reflectance Apparent reflectance of the point Probability of gap Horizontal fraction of canopy cover Site IDField LAI Voxel based LAI by Diameter G=0.5 50m75m100m Hemlock 4.32±0.27 4.954.733.662.68 EMS tower 4.67±0.82 5.304.863.522.83 3052.03±0.50 6.54*5.554.862.77 X. Yang, A. Strahler, C. Schaaf, D. Jupp, T. Yao, F. Zhao, Z. Wang, D. Culvenor, G. Newnham, et al., “Three-Dimensional Forest Reconstruction and Structural Parameter Retrievals Using a Ground-Based Full-Waveform Lidar Instrument (Echidna ® )”. Remote Sensing of Environment, submitted.(2012) A new method for retrieval of leaf area index (LAI; m^2) foliage area volume density (FAVD; m^2 LAI/m^3 volume), and wood volume of forest stands uses voxels derived from a three- dimensional point cloud of scattering events observed in registered forest scans using a full-waveform, terrestrial Echidna ® lidar scanning at 1064 nm. The voxelization process uses the attributes of scattering events, including the gap probability to the event, its apparent reflectance at one or both laser wavelengths, and the geometric volume associated with the return of the laser pulse, to produce the volumetric dataset. Classification procedures (Yang et al. 2012), based on the shape of the laser pulse and the ratio of apparent reflectance at the two wavelengths are used to separate trunk from foliage scattering events. Leaf angle distribution is accommodated with a simple model based on gap probability with zenith angle as observed in individual scans of the stand. An important advantage of the method is that coarse-scale clumping (between crowns and within crown interiors) is observed directly and does not require parametric correction. For validation, we compare LAI, FAVD, and biomass profiles retrieved directly from the voxelized 3-D forest reconstructions with those observed in airborne and field measurements. Voxelized 3-D forest reconstructions can be used to validate large-footprint spaceborne and airborne lidar systems, thus facilitating large-area inventories. The enhanced characterization of leaf area and biomass is of interest to both land biogeoscientists who require bulk vegetation biomass measures and to atmospheric biogeoscientists, who require information on surface roughness, photosynthesis, and respiration processes. Moreover, Echidna-style lidars can be deployed to monitor disturbance and deforestation detected by optical sensors, such as MODIS or Landsat, to provide better calibration of the type and nature of change.  Overview  Site Characteristics Site ID Leading dominants Top canopy height (m) Mean DBH (m) Stem count density (ha –1 ) Above- ground biomass (t ha –1 ) Hemlock 22.60.24±0.02906±71234±7 EMS Tower Red maple, red oak 26.40.28±0.02951±69373±36 305Red fir45.20.58±0.02284±401215±150 While the two instruments detected the top of the canopy pretty well, LVIS sees more upper canopy component while EVI sees more lower canopy component over the same forest area. (Profiles are compared at 75 m plot diameter.) Site Harvard Hemlock Site 305Site Harvard EMS tower  Terrestrial (EVI) vs. Airborne (LVIS) Lidar  Future Direction The Dual-Wavelength Echidna ® Lidar (DWEL), the successor instrument to the EVI, emits simultaneous laser pulses at 1064 nm and 1548 nm wavelengths. DWEL scans provide the capability to separate hits of leaves from hits of trunks and branches because of the reduced response of foliage at 1548 nm due to water absorption by leaf cellular contents.