Retrieval of the Leaf-Area Index and Foliage Profile of New England Forest Stands Using a Ground-Based Lidar Instrument (EchidnaŽ)
Feng
Zhao, Boston University, zhao26@bu.edu
(Presenting)
Miguel
Roman, Boston University, mroman@bu.edu
Alan
Strahler, Boston University, alan@bu.edu
Curtis
Woodcock, Boston University, curtis@bu.edu
Crystal
Schaaf, Boston University, schaaf@bu.edu
Jicheng
Liu, Boston University, jcliu@bu.edu
Glenn
Newnham, CSIRO Forest Biosciences, glenn.newnham@csiro.au
David
Jupp, CSIRO Marine and Atmospheric Research, david.jupp@csiro.au
Darius
Culvenor, CSIRO Forest Biosciences, darius.culvenor@csiro.au
Jenny
Lovell, CSIRO Marine and Atmospheric Research, jenny.lovell@csiro.au
Wenge
Ni-Meister, Hunter College of CUNY, wenge.ni-meister@hunter.cuny.edu
Shihyan
Lee, Hunter College of CUNY, shihyanlee@yahoo.com
Xiaowen
Li, Beijing Normal University, lix@bnu.edu.cn
Qingling
Zhang, Boston University, zql@bu.edu
Zhuosen
Wang, Boston University, wangzhs@bu.edu
Yanmin
Shuai, Boston University, shuaiym@bu.edu
A prototype upward-scanning, under-canopy, near-infrared lidar, the EchidnaŽ validation instrument (EVI), built by CSIRO Australia, retrieves values of leaf-area index (LAI) and stand foliage profile (LAI with height) that match well with those derived from other indirect optical methods. We validated retrievals of these parameters with data from stands of hardwoods and conifers of varying sizes and stocking densities at Harvard Forest, MA; Bartlett Experimental Forest, NH; and Howland Experimental Forest, ME; using LAI estimates from hemispherical photographs taken over a grid of 10-20 m spacing, and using measurements of the LAI-2000 Plant Canopy Analyzer. LAI and the foliage profile are key parameters in carbon balance models and in the surface radiation balance modules of regional and global climate models. The lidar instrument has the potential to provide more accurate estimates of LAI and foliage profile because the lidar provides its own light source and also detects the distance and direction to each light scattering event. Conventional optical measurements rely on solar illumination and require clear skies at dawn or dusk or use complex algorithms to remove the sun and its aureole from a hemispherical image. Foliage area volume density, which measures the amount of leaf area in a given volume of canopy and is used in models of vegetation reflectance, is also retrievable.
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