Root orientation can affect detection accuracy of ground-penetrating radar
Ground-penetrating radar (GPR) has been applied to detect coarse tree roots. The horizontal angle of a root crossing a scanning line is a factor that affects both root detection and waveform parameter values. The purpose of this study was to quantitatively evaluate the influence of root orientation (x, degree) on two major waveform parameters, amplitude area (A, dB × ns) and time interval between zero crossings (T, ns).
We scanned four diameter classes of dowels in a sandy bed as simulated roots using a 900 MHz antenna from multiple angles to clarify the relationships between the parameters and x.
Angle x strongly affected reflection images and A values. The variation in A(x) fitted a sinusoidal waveform, whereas T was independent of x. The value of A scanning at 90° was estimated by A values of arbitrary x in two orthogonal transects. The sum of T in all reflected waveforms showed a significant linear correlation with dowel diameter.
We clarified that root orientation dramatically affected root detection and A values. The sum of T of all reflected waveforms was a suitable parameter for estimating root diameter. Applying grid transects can overcome the effects of root orientation.
KeywordsCarbon storage Coarse root Grid transect Nondestructive root method Root angle Root diameter
Root angle subtended to the transecting lines
Time interval between zero crossings
Sum of amplitude areas for all of reflection waveforms
Sum of time intervals for all reflection waveforms
- Single Amax
Amplitude area of the maximum reflection waveform
- Single Tmax
Time interval of the maximum reflection waveform
- Butnor JR, Barton C, Day FP, Johnsen KH, Mucciardi AN, Schroeder R, Stover DB (2011) Using ground-penetrating radar to detect tree roots and estimate biomass. In: Mancuso S (ed) Measuring roots, an updated approach. Springer, Berlin, pp 213–245Google Scholar
- Čermák J, Ulrich R, Staněk Z, Koller, Aubrecht L (2006) Electrical measurement of tree root absorbing surfaces by the earth impedance method: 2. Verification based on allometric relationships and root severing experiments. Tree Physiol 26:1113–1121. doi:10.1093/treephys/26.9.1113 PubMedCrossRefGoogle Scholar
- Cox KD, Scherm H, Serman N (2005) Ground-penetrating radar to detect and quantify residual root fragments following peach orchard clearing. Hort Technol 15:600–607Google Scholar
- Government of Japan (2008) Report on Japan’s supplementary information on LULUCF393 activities under article 3, paragraphs 3 and 4 of the Kyoto ProtocolGoogle Scholar
- Guo L, Lin H, Fan B, Cui X, Chen J (2013b) Impact of root water content on root biomass estimation using ground penetrating radar: evidence from forward simulations and field controlled experiments. Plant and Soil: 1–18. Doi:10.1007/s11104-013-1710-4
- Repo T, Cao Y, Raimo C, Silvennoinen R, Ozier-Lafontaine H (2011) Electrical impedance spectroscopy and roots. In: Mancuso S (ed) Measuring roots, an updated approach. Springer, Berlin, pp 25–49Google Scholar
- Stokes A, Fourcaud T, Hruška J, Čermák J, Nadyezdhina N, Nadyezhdin V, Praus L (2002) An evaluation of different methods to investigate root system architecture of urban trees in situ: I. Ground-penetrating radar. J Arboricult 28:2–10Google Scholar