Hosoi F, Omasa K. Factors contributing to accuracy in the estimation of the woody canopy leaf area density profile using 3D portable lidar imaging.
JOURNAL OF EXPERIMENTAL BOTANY 2007;
58:3463-73. [PMID:
17977852 DOI:
10.1093/jxb/erm203]
[Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Factors that contribute to the accuracy of estimating woody canopy's leaf area density (LAD) using 3D portable lidar imaging were investigated. The 3D point cloud data for a Japanese zelkova canopy [Zelkova serrata (Thunberg) Makino] were collected using a portable scanning lidar from several points established on the ground and at 10 m above the ground. The LAD profiles were computed using voxel-based canopy profiling (VCP). The best LAD results [a root-mean-square error (RMSE) of 0.21 m(2) m(-3)] for the measurement plot (corresponding to an absolute LAI error of 9.5%) were obtained by compositing the ground-level and 10 m measurements. The factors that most strongly affected estimation accuracy included the presence of non-photosynthetic tissues, distribution of leaf inclination angles, number (N) of incident laser beams in each region within the canopy, and G(theta(m)) (the mean projection of a unit leaf area on a plane perpendicular to the direction of the laser beam at the measurement zenith angle of theta(m)). The influences of non-photosynthetic tissues and leaf inclination angle on the estimates amounted to 4.2-32.7% and 7.2-94.2%, respectively. The RMSE of the LAD estimations was expressed using a function of N and G(theta(m)).
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