Individual tree measurements in a planted woodland with terrestrial laser scanner
Authors: HÜSEYİN YURTSEVEN, SÜLEYMAN ÇOBAN, MUSTAFA AKGÜL, ANIL ORHAN AKAY
Abstract: Terrestrial light detection and ranging technology provides an accurate measurement of individual tree parameters that are essential for managing forest resources, modeling forest fires, planning forest operations, etc. This study aimed to measure individual tree parameters to model a single tree using terrestrial laser scanner (TLS) data. A high-resolution digital terrain model (DTM) was generated using point cloud data (2,800,430 points) to obtain the tree parameters. Next, the diameter of breast heights (DBH), tree heights, tree lengths, tree projection areas, and crown parameters were calculated using 3D Forest 0.42 software. In order to evaluate the capabilities of TLS data, estimated tree parameters were compared with the parameters obtained by field measurements. Regression analysis and paired sample t-test were performed to compare the DBH and tree height values estimated by TLS with those obtained from field measurements. We found a strong relationship between the field measurements and TLS estimates for DBHs (R2 = 0.99) with 1.65 cm root mean square error (RMSE) and tree heights (R2 = 0.98) with RMSE = 0.724 m. The paired Wilcoxon signed-rank test for DBH groups showed no significant difference (P = 0.7285 > 0.05), whereas according to the results of the paired sample t-test for the height groups, there were significant differences between tree heights (P = 0.015 < 0.05; t = -2.55). The results also indicate that TLS is an effective measurement tool to provide highly accurate and precise results for 3D modelling of tree structure parameters without cutting trees. TLS also has great potential to provide many individual tree attributes with high accuracy, which can be used for further evaluations in many forestry disciplines such as silviculture, nature conservation, forest management, and urban forestry.
Keywords: Individual tree parameters, light detection and ranging, point cloud, tree model, accuracy assessment, forestry
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