Forestry Applications for Satellite Lidar Remote Sensing

This paper presents a method to estimate forest parameters and surface topography from NASA's Geosciences Laser Altimeter System (GLAS). Their potential use as observational inputs to models is demonstrated using a wind-risk model for the UK, ForestGALEs. Relative heights above ground were used as biophysical parameter estimators. Top Height was estimated with R-2 = 0.73, RMSE = 4.5 m. Diameter at breast height estimates differed for conifer-dominated stands (R-2 = 0.72, RMSE = 0.07 m) and for stands containing mostly broadleaves (R-2 = 0.41, RMSE = 0.11 m). Ground elevation estimation produced R-2 = 0.997, RMSE = 2.2 m. These three parameters were applied to ForestGALES for stand-level assessment of wind-throw risk. Stability is sensitive to small differences in tree dimensions, and therefore vegetation parameters require greater accuracy than those currently retrievable from GLAS to more reliably determine risk of wind-throw. Future satellite lidar missions such as NASA's DESDynI sensor aim to produce improved vegetation parameter estimation plus greater spatial coverage which would offer more appropriate inputs for forestry models.