Assessment of forest stand parameters in Britain using satellite lidar

Satellite lidar observations obtained by NASA’s former Geoscience Laser AltimeterSystem (GLAS) aboard the Ice, Cloudand land Elevation Satellite (ICESat) offer the opportunity to estimate forest parameters on regional to global scales (Baccini et al., 2008; Boudreau et al., 2008; Lefsky, 2010; Los et al., 2012). The UK Forestry Commission maintains a comprehensive subcompartment database of public forests, containing details about species, silvicultureand site conditions (including elevation). For this research, this information was used in Forestry Commission yield models to estimate parameters for forest stands throughout Britain. The models provide good predictions of growth trends however discrepancies can occur where management strategies or habitat conditions differ from those initially assigned. Estimates of forest parameters from satellite lidar (Los et al., 2012) were used to compare with yield model predictions. This offers the opportunity for remote sensing observations to be used to adjust the contents of the subcompartment database or to identify areas of uncertainty which may require field survey to verify data. The large GLAS footprint causes greater uncertainty in vegetation height estimates on slopes, where signals from the ground surface and vegetation can be combined within the waveforms. Confidence assessment in satellite lidar height estimates was made through a comparison of estimated ground elevation from GLAS using waveforms Gaussian decomposition and mean ground elevation from a 10m resolution DTM (Ordnance Survey Land-Form Profile DTM product) within GLAS footprints.