Light detection and ranging (LiDAR) is an effective method to estimate broad-scale forest structure and aboveground biomass. Aboveground biomass can be estimated by LiDAR based tree height, which is usually represented by digital canopy model (DCM). However, steep terrains magnify the difference between DCM and the actual tree height based on ground-truth measurement. Thus, estimation of forest structure and aboveground biomass in steep terrain is a technical challenge of LiDAR. In this study, we investigated the factors affecting the difference between DCM and actual tree height and discuss how to estimate actual tree height from DCM.

Our results confirmed that the difference between tree height and DCM increases with surface inclination. The difference might be magnified by larger horizontal distance from the tree base because stem inclination increases with surface inclination. Thus, surface inclination must be considered when estimating tree height from DCM. The relationship between stem inclination and surface inclination were different for each species. Thus, information on species traits in response to steep terrain might increase the precision of LiDAR based biomass estimation in steep mountains.