Use of Ground Penetrating Radar for Assessing Interconnections between Root Systems of Different Matured Tree Species

This study presents recent advances achieved in the use of ground penetrating radar (GPR) for the assessment of tree root systems. The primary objectives of the study were to provide a valid and high-resolution mapping of the root systems belonging to different species of matured trees, as well as to investigate areas of roots interconnection. To this effect, a data processing methodology based on three main stages was developed. A pre-processing algorithm was first proposed to remove noise-related information from the raw data and to improve deep reflections from attenuated targets. Afterwards, an algorithm was developed for target identification (i.e. the vertices of the reflection hyperbolas) and their automatic tracking in a three-dimensional environment. A third stage was focused on estimating tree root density with emphasis on the interconnection area. To test the feasibility of the proposed method, the soil around two different tree species (i.e. maple and ash trees) was surveyed using a ground-coupled GPR system equipped with a 700 MHz central frequency antenna. The approach has proven to identify peculiar characteristics of both trees, in terms of surface (i.e. within the first 25 cm from the soil surface) and deep (i.e. deeper than 25 cm from the soil surface) root systems. In addition, results have allowed to assess how different root systems interact with each other.