Ground-Penetrating Radar System, Measurement and Data Analysis for Investigating and Understanding Tree Root System Architecture

Abstract

Purpose: Ground-penetrating radar has been used for tree root mapping as a non-destructive technique. The conventional data collection is performed on a predefined grid, which is not very suited for tree roots. A method optimised for tree roots, a system that enables the method and data analyses are proposed in the paper. Methods: The performance of ground-penetrating radar depends on how clearly reflections are recorded and it can be optimised using a circular scan for tree roots, in contrast to the conventionally employed grid scan. A ground-penetrating radar system combined with a total station enabled us to record the accurate locations of the scans, thereby enabling the post-processing of circular scan data. Results: Data were acquired using circular scanning around a tree. The results clearly exhibited the presence of roots. Thus, the distribution and extension of the root system were mapped. Additionally, detailed root paths were reconstructed in a 3D space based on manually selected hyperbolic signatures on B-scans. The result corresponded excellently to the actual roots observed during the excavation. Conclusion: Tree root mapping by applying an imaging algorithm provided an easy and quick means of understanding the distribution. Further analysis enabled us to reconstruct the details of the tree root shape and distribution. Both data analyses required accurate positioning for improved results. The system and data analyses were very useful in understanding root architecture and studying the impact of subsurface conditions on the growth of tree roots.