As a canopy vertical structure parameter

the Leaf Area Density（LAD） of horizontal layers is generally applied to quantify the leaf area within a given volume. It is important in characterizing the vertical distribution of leaf chemical components and canopy biomass.Light Detection And Ranging（Li DAR） has been widely applied to obtain the three dimensional structural properties of vegetation in the past ten years. Terrestrial Li DAR data can be utilized to estimate LAD. The objective of this studyisto develop a new method for woody canopy LAD estimation through the use of terrestrial Li DAR data.High-resolution point clouds and true-color images of Magnolia woody were acquired with Leica Scan Station C10 and a digital camera device

respectively.The study sites arelocated in the University of Electronic Science and Technology of China. Leaves were labeled through supervised classification of true-color images based on the registration of point clouds and true-color images.The laser-scanning points over leaves were accurately extracted with the classification acquired from the corresponding image pixels. Through the voxelization of point clouds

the two dimensional convex hull algorithm was introduced to determine the boundaries of each vertical layer of tree crowns and the contact frequency of laser canopy. With the Eigenvalue method

leaves at different tree heights were randomly selected to fit leaf planes and estimate leaf angles.Together with the zenith angle

the adjustment factor of leaf angles was identified. Finally

the vertical profiles of LAD were retrieved with the Voxel-based Canopy Profiling（VCP） method.The voxelization of point cloud data can be used to accurately determine forest canopy boundaries and the statistical contact frequency of LAD inversion. The LAD profile is in agreement with the vertical distribution of canopy leaves. The LAD values increased with the height of trees in the middle and lower canopies

and the maximum LAD was 1 m2/m3 at a height of 4 m.The LAD valuesdecreased in the upper canopy as the height increased. The Leaf Area Index（LAI） calculated from LAD was 3.20 m2/m2. Comparison with the field measurements acquired by LAI-2200 suggested that the relative error was 1.26%.By combining true-color image classification and canopy point cloud registration

point clouds over leaves can be accurately extracted from original Li DAR data. The LAD of woody canopy can be estimated from point clouds over leaves through the VCP method;in particular

the blade of the point cloud voxel can accurately determine the forest canopy boundaries and statistical contact frequency and can also be used in LAD estimation. However

the accuracy of LAD estimation cannot be evaluated directly because LAI does not reflect the vertical layer of LAD. LAD values need to be investigated in future studies.