Modelling the standing timber volume of Baden-Württemberg—A large-scale approach using a fusion of Landsat, airborne LiDAR and National Forest Inventory data

•The paper shows the potential of airborne LiDAR in combination with Landsat for estimating timber volume on a large scale.•We analyze the potential of the German National Forest Inventory data for usage as terrestrial reference for interpolating timber volume.•We show the excellent functioning of generalized additive models (GAM) for large scale timber volume estimations.•The study reveals that human impact on forest strongly influence timber volume estimations.