Application of terrestrial laser scanning to tree trunk bark structure characteristics evaluation and analysis of their effect on the flow resistance coefficient

Abstract

The paper presents an original method for the evaluation of bark structure characteristics of tree trunks on the basis of terrestrial laser scanning data. Measurements testing the method proposed were performed in laboratory conditions for trunks of pine (Pinus sylvestris L.) and oak (Quercus robur L.). The laser scanner used was a FARO Focus 3D. The scanning was carried out in two variants for natural trunks (variant I: samples Oak-I, Pine-I) and for trunks wrapped in foil (variant II: samples Oak-II, Pine-II). The point clouds obtained were combined into a three-dimensional (3D) model, filtered, and exported to the *.xyz format in SCENE (v. 5×) software provided by FARO. For calculation of the bark structure characteristics the geoprocessing Tree Trunk Bark Structure Model (TTBSM) operating in the ArcGIS environment was developed. The mean bark height factor (BHF) of the natural pine and oak tree trunks was calculated to be 0.39 cm and 0.37 cm, while the values for the trunks wrapped in foil were 0.27 cm and 0.25 cm, respectively. The BHF of the tree trunks wrapped in foil varied in the range 0.26-0.28 cm and 0.24-0.26 cm for pine and oak, respectively, while for the natural tree trunks the range was 0.38-0.46 cm and 0.35-0.38 cm for pine and oak, respectively. The effect of BHF on the flow resistance was evaluated in a measuring trough and proved to be significant. The coefficient of flow resistance was on average 20% higher for the natural tree trunks than for those foil-wrapped.