Details

Autor(en) / Beteiligte

• Strahler, A H
• Woodcock, C E
• Schaaf, C B
• Myneni, R
• Liu, J
• Newnham, G J
• Culvenor, D S
• Jupp, D L
• Lovell, J L
• Yao, T
• Zhao, F
• Yang, X
• Zhang, Q
• Zhang, Y
• Schull, M
• Roman, M
• Lee, S
• Wang, Z
• Shuai, Y

Titel

Rapid Retrieval of Forest Structure using an Under-Canopy, Upward-Scanning Lidar (EchinaR)

Ist Teil von

• Eos (Washington, D.C.), 2007-12, Vol.88 (52)

Erscheinungsjahr

2007

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• An under-canopy, upward-scanning, lidar field instrument, named EchidnaR, provides rapid, accurate, and automated measurements of forest stand structure, including tree diameters, stand basal area, stems per unit area, stand height, leaf area index, foliage profile, and foliage area volume density. We report results from scans at stands of varying characteristics at Harvard Forest (Massachusetts), Howland Experimental Forest (Maine), and Bartlett Experimental Forest (New Hampshire). Retrievals of stand characteristics are validated by ground measurements of tree stems in a large circular plot centered on the scan position; of canopy characteristics by LAI-2000 measurements, hemispherical digital photographs, and allometric calculations. The EchidnaR instrument, built by CSIRO and Ensis Australia, directs a horizontal 1064 nm laser beam with 5 mr divergence and a pulse rate of 2 kHz to a rotating mirror at 45 deg incidence to scan a vertical circle, recording data from +137 deg to -130 deg zenith angles and all azumuths as the instrument revolves 180 deg on a tripod mount. The return signal is sampled at 2 gigasamples per second, digitizing the full scattered waveform. The shape of the return pulse distinguishes readily between hard targets (tree boles, branches) and soft targets (leaves), and also measures the distribution of canopy gaps, including within-crown and between-crown gaps. The instrument is well-suited to ground sampling for calibration of airborne lidars, allowing accurate mapping of biomass and leaf area over large areas.