The uncertainty of biomass estimates from modeled ICESat-2 returns across a boreal forest gradient

Simulation results of the bright daylight and low vegetation reflectivity conditions for collecting photon counting LiDAR with no topographic relief show that 1-2 photons are returned for 79%-88% of LiDAR shots. Signal photons account for ~ 67% of all LiDAR returns, while ~ 50% of shots result in 1 signal photon returned. The proportion of these signal photon returns do not differ significantly (p > 0.05) for AGB intervals > 20 Mg · ha− 1. The 50 m link-scale approximates the finest horizontal resolution (length) at which photon counting LiDAR collection provides strong model fits and minimizes forest structure uncertainty in the synthetic Larix stands. At this link-scale AGB > 20 Mg · ha− 1 has AGB error from 20-50% at the 95% confidence level. These results suggest that the theoretical sensitivity of ICESat-2 photon counting LiDAR measurements alone lack the ability to consistently discern differences in inferred AGB at 10 Mg · ha− 1 intervals in sparse forests characteristic of the taiga-tundra ecotone.