Combining Above-Canopy Downward-Looking and Below-Canopy Upward Hemispherical-Scanning LIDAR for Improved Above-Ground Biomass Retrieval
Wenge
Ni-Meister, Hunter College of The City University of New York, wenge.ni-meister@hunter.cuny.edu
(Presenting)
Shihyan
Lee, Hunter College of The City University of New York, shihyanlee@yahoo.com
Alan
Strahler, Boston University, alan@bu.edu
James
Bryan
Blair, NASA Goddard Space Flight Center, bryan@arthur.gsfc.nasa.gov
Nadir-viewing above-canopy airborne and spaceborne lidar measured vegetation height parameters are being used for large scale above-ground biomass estimates. However much uncertainty exists due to the lidar&rsquos limited viewing direction and many woody structure characteristics not directly measured except vegetation height. A below canopy lidar directly measuring woody structure characteristics could improve above ground biomass estimate at large scale. This study combines the above-canopy airborne Laser Vegetation Imaging Sensor (LVIS) and a below-canopy Echidna™ Validation Instrument (EVI) lidar to estimate above ground biomass in deciduous and coniferous forests of the northeast U.S. Our analysis of ground measurements of tree structure shows that the product of basal area and vegetation height is the most closely related to the stand scale above ground biomass. Our lidar remote sensing data analysis confirms that when using EVI-derived basal area with LVIS derived tree height measurements, above ground biomass estimate accuracy is greatly improved than using LVIS tree height or EVI basal area alone. This study also found that the product of crown cover and tree height is better related to biomass than tree height alone is. Our LVIS data analysis shows that combining both LVIS derived tree cover and tree height improved above ground biomass estimate than using LVIS derived tree height alone. However accurate retrieval of tree cover from LVIS is challenging due to the large uncertainty of the above ground canopy element and ground reflectivity ratio.
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