A multi-echo airborne LiDAR-based method for estimating leaf area density distribution of individual trees

We demonstrate a method for estimating the leaf area density (LAD) distribution of individual trees using multi-echo airborne light detection and ranging (LiDAR). This method improves upon the previously developed method which calculates LAD based on the contact frequency between the laser beams and leaves by tracing the paths of the laser beams. The proposed method exploits the last and intermediate echoes in addition to the first and single echoes to capture the foliage distribution in the inner part of the crown. We verify the estimation accuracy using terrestrial LiDAR data of a single tree. The estimated LAD distribution is compared to the terrestrial LiDAR-derived LAD distribution. We confirmed that using the last and intermediate echoes improves the estimation accuracy of the entire crown area.