Estimates of forest canopy height and aboveground biomass using ICESat

TLDR

Forest–atmosphere carbon exchange is a key global cycle component, and satellite laser altimetry uniquely estimates canopy height, which is directly linked to aboveground carbon storage. Using ICESat GLAS lidar waveforms and SRTM topography, the authors estimated maximum forest height in tropical Brazil, temperate Tennessee, and temperate Oregon, despite challenges from pulse broadening in large‑footprint waveform sampling. The models explained 59–68% of canopy height variance (RMSE 4.85–12.66 m) and ICESat heights in Brazil correlated strongly with field aboveground biomass (r² = 73%, RMSE = 58.3 Mg ha⁻¹).

Abstract

Exchange of carbon between forests and the atmosphere is a vital component of the global carbon cycle. Satellite laser altimetry has a unique capability for estimating forest canopy height, which has a direct and increasingly well understood relationship to aboveground carbon storage. While the Geoscience Laser Altimeter System (GLAS) onboard the Ice, Cloud and land Elevation Satellite (ICESat) has collected an unparalleled dataset of lidar waveforms over terrestrial targets, processing of ICESat data to estimate forest height is complicated by the pulse broadening associated with large‐footprint, waveform‐sampling lidar. We combined ICESat waveforms and ancillary topography from the Shuttle Radar Topography Mission to estimate maximum forest height in three ecosystems; tropical broadleaf forests in Brazil, temperate broadleaf forests in Tennessee, and temperate needleleaf forests in Oregon. Final models for each site explained between 59% and 68% of variance in field‐measured forest canopy height (RMSE between 4.85 and 12.66 m). In addition, ICESat‐derived heights for the Brazilian plots were correlated with field‐estimates of aboveground biomass (r 2 = 73%, RMSE = 58.3 Mgha −1 ).