Assessing multitemporal airborne laser scanning data and satellite-derived active fire observations for estimating structural change and biomass consumption in forests affected by compound disturbances

Abstract

Multitemporal airborne laser scanning (ALS) data provide an avenue to quantify three-dimensional changes in forest structure, but fire-affected areas with both pre- and post-fire ALS data are rare. Satellite-derived active fire products provide a potential alternative dataset that could be used to estimate changes in forest structure and biomass given fire radiative energy (FRE) is proportional to the biomass consumption. We assessed the ability of pre- and post-fire ALS and active fire observations to characterize fire-induced forest structure changes. ALS data and FRE derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the Terra and Aqua satellites were used to quantify fire-induced forest structural changes across a fire in central Oregon, US. Significant reductions in ALS-derived canopy density and canopy volume were observed over most of the fire extent and were positively related to FRE. Areas with greater mountain pine beetle tree mortality prior to the fire had greater FRE and canopy volume loss than unaffected areas. Results demonstrate the potential of both multitemporal ALS and FRE for assessing forest structure change and canopy consumption. Active fire products may be useful for estimating structure change in fire affected areas where multitemporal ALS data are not available.