A Comparison of Forest Biophysical Parameters Assessed with Lidar Data on Three Platforms: Ground, Airborne, and Satellite

7 Lidar remote sensing from three platforms – ground, airborne, and spaceborne – has 8 the capability to acquire direct three-dimensional measurements of the forest canopy that 9 are useful for estimating a variety of forest inventory parameters, including tree height, 10 volume, and biomass, and also for deriving useful information for characterizing wildlife 11 habitat or forest fuels. 12 The overall goal of this paper was to compare biomass estimates and forest structure 13 metrics obtained by processing ICESat waveform data and spatially coincident discrete-14 return airborne lidar and ground-based data over varied terrain conditions. For mostly 15 flat-terrain conditions, we investigated lidar data over forests in east Texas, which are 16 characteristics for most of the southeastern United States, thus allowing terrain to be 17 largely excluded as a source of error. For sloped-terrain, we used lidar data over forests in 18 Oregon. With biomass estimates derived from waveform height metrics, we also 19 compared ground elevation measurements and canopy parameters. Specific objectives 20 were to: compare ground elevations and canopy height parameters derived from ICESat 21 and airborne lidar; (2) investigate above ground biomass estimates; (3) develop a 3D ray-22 tracing model to simulate lidar waveforms over forests with sloped terrain; and (4) test 23 model performance with real lidar data over terrain with varied topography. Over flat 24 terrain, results indicated a very strong correlation for terrain elevations between ICESat 25 and airborne lidar, with R-square values of 0.98 and sub-meter RMSE. ICESat height 26