Using Ground-based LiDAR Data to Measure Standing Trees in a Red Cypress Plantation

The three-dimensional (3D) scanning light detection and ranging (LiDAR) system is able to make non-destructive transcriptions of individual tree structures. Gaining 3D information on a forest using a ground-based LiDAR system is a swift and popular method. This study used groundbased LiDAR data and traditional data of field surveys to obtain individual tree characteristic values, such as tree height, diameter at breast height (dbh), individual tree location, and diameter simulations at different heights (DSDHs). This study estimated the feasibility using LiDAR data in a forest area and a predictive model, for mapping individual 3D tree positions. To analyze the accuracy of the determined 3D information, results of 24 investigated trees in a field survey were compared to those using laser scanning. The results showed directional errors of 0.020~0.796 m in the X direction and 0.007~1.774 m in the Y direction. Although the trees were heterogeneous, the results showed good correlations of the LiDAR tree height with field tree height (root mean squared error (RMSE)=0.2584) and the LiDAR DBH with field DBH (RMSE=0.7632). We also found high accuracy in diameter simulations without occlusion. Comparing the LiDAR results with traditional methods showed that the new survey method developed can be pragmatically applied to different measurement fields. The LiDAR-based measurement system in this study was proven to be a valuable tool for measuring physical and structural characteristics of plants, such as tree height, dbh, diameter simulations, and individual tree location maps.