Remote sensing of forest aboveground biomass using the Geoscience Laser Altimeter System

Abstract

Accurate estimates of forest aboveground biomass are needed to reduce uncertainties in the terrestrial carbon flux. The Geoscience Laser Altimeter System (GLAS) onboard the Ice, Cloud and land Elevation Satellite is now the first spaceborne lidar sensor that will provide global estimates of vegetation height. This study investigated the utility of the GLAS sensor for large-scale biomass inventories by focusing on two important factors: the regional accuracy of GLAS-estimated forest height algorithms and the accuracy of general height-biomass allometric equations. Field data from the U.S Forest Service Inventory and Analysis (FIA) program was used to compare regional height estimates with GLAS predictions. GLAS algorithms provided generally accurate estimates of height and were on average 2-3 m lower than FIA estimates. The analysis of the regional variability of height-biomass relationships in the FIA data suggests that general non-species specific equations are applicable without a significant loss in prediction accuracy. Regional estimates of forest biomass from GLAS were about 20% lower than FIA estimates (difference between 39.7 – 58.2 Mg ha⁻¹).