Utility of Ground‐Penetrating Radar as a Root Biomass Survey Tool in Forest Systems

Abstract

Traditional methods of measuring tree root biomass are labor intensive and destructive in nature. We studied the utility of ground-penetrating radar (GPR) to measure tree root biomass in situ within a replicated, intensive culture forestry experiment planted with loblolly pine (Pinus tneda L.). The study site was located in Decatur County, Georgia, in an area of the Troup and Lucy (loamy, kaolinitic, thermic Grossarenic Kandiuddts and Arenic Kandiudults, respectively) soils. With the aid of a digital signal processing GPR, estimates of root biomass to a depth of 30 cm were correlated to harvested root samples using soil cores. Significant effects of fertilizer application on signal attenuation were observed and corrected. The correlation coefficient between actual root biomass in soil cores and GPR estimates with corrections for fertilizer application were highly significant ( r = 0.86, n = GO, p < 0.0001). Where site conditions are favorable to radar investigation, GPR can be a powerful cost-effective tool to measure root biomass. Verification with some destructive harvesting is required since universal calibrations for root biomass are unlikely, even across similar soil types. Use of GPR can drastically reduce the number of soil cores needed to assess tree root biomass and biomass distribution. The quality and quantity of information resulting from a detailed GPR survey, combined with soil cores on a subset of plots, mn be used to rapidly estimate root biomass and provide a valuable assessment of lateral root biomass distribution and quantity.

Application of ground penetrating radar for coarse root detection and quantification: a review

“…Hence, a standard protocol for signal processing during scanning may be difficult to establish because of diverse site conditions. Among those studies on the detection of roots using GPR, only Wielopolski et al (2000) and Butnor et al (2003) have particularly described their signal processing settings during scanning, including vertical digital filters (low pass filter and high pass filter) and horizontal smoothing. These filters help improve the signal to noise ratio by reducing low frequency (appears as horizontal bands of noise) and high frequency (appears as spikes or "snow") noise generated by antenna/ground interactions, system noise, or from nearby radio transmitters and other EM frequency interference.…”

“…The general objective of signal post-processing is either to prepare an image that can readily be interpreted or to classify the target return with respect to a known test procedure (Daniels 2004). For root detection, Butnor et al (2003) first provided an advanced data post-processing flow protocol that was accepted and modified in other studies. After being improved by Barton and Montagu (2004) and Stover et al (2007), a standard GPR data post-processing protocol for the detection and quantification of roots has been gradually established.…”

Advances in experimental methods for root system architecture and root development

“…Ground penetrating radar (GPR) should be useful to investigate root systems of forest trees on forest ecosystem level (Nadezhdina and Č ermák 2003;Butnor et al 2003;Barton and Montagu 2004;al Hagrey 2007). GPRs have not only the lowest wave length and resolution to detect small targets but also the highest wave attenuation that limits resolution and penetration in wet conducting media, thus they have been used to estimate single root segments or biomass with a relatively low precision (Butnor et al 2003;Barton and Montagu 2004;al Hagrey 2007). But, at present, the accuracy and resolution of GPRs are not enough for fine roots (root diameter\1 mm), and more advanced GPRs are needed.…”

Detection of Tree Roots in an Urban Area with the Use of Ground Penetrating Radar

“…Ground penetrating radars successfully provide detection of different subsurface objects: abandoned storage tanks, disturbed soil, buried pipes, artifacts, caves and land mines. Ground penetrating radar has also been used to detect tree roots and map root systems (Hruška et al, 1999;Čermák et al, 2000;Wielopolski et al, 2000) and to determine root biomass (Butnor et al, 2001(Butnor et al, , 2003. Because the radar probing method is a technique non-invasive and non-destructive, GPR allows repeated measurements that allow follow the temporal assessment of root system development.…”