Plant and Soil

, Volume 395, Issue 1–2, pp 289–305 | Cite as

Calibrating the impact of root orientation on root quantification using ground-penetrating radar

  • Li Guo
  • Yuan Wu
  • Jin Chen
  • Yasuhiro Hirano
  • Toko Tanikawa
  • Wentao Li
  • Xihong Cui
Regular Article


Background and aims

Ground-penetrating radar (GPR) has provided a non-invasive means for field root investigation. However, the horizontal cross angle (x) of root orientation intersecting a survey line considerably impacts the amplitude area (A) reflected from a root and impairs the accuracy of GPR-based root quantification. Prediction of A(90°) (the value of A scanning at x = 90°) from multiple A(x) measurements could correct such impact. Previous method of A(90°) prediction focused on target roots at field point scale. The aim of this study is to develop a method to predict A(90°) at field plot scale.


A(90°) was predicted by a pair of A(x) measured at two arbitrary scanning lines together with an estimated soil background amplitude area. Three independent datasets were employed to test the proposed method. The field experiment included radar data collected for six roots of Caragana microphylla in a sandy-clay soil at four cross angles (30°, 45°, 60°, and 90°). The sand box experiment included radar data for 12 dowels at 13 cross angles (0° to 180°, in 15° steps). The simulation experiment included A(x) of 46 simulated roots at 13 cross angles (0° to 180°, in 15° steps).


For all experiments, A(90°) was accurately estimated. Root orientation could also be determined. After correcting the impact of cross angle, the accuracy of root diameter estimation improved. Correlation coefficient between actual and estimated root diameters increased from 0.77 to 0.81, with RMSE declining from 9.53 to 7.05 mm.


A method of correcting the influence of root orientation on root GPR signal at the field plot scale has been established. This method enhances root quantification using GPR.


Coarse root Field plot scale Nondestructive root method Root angle Root diameter Root biomass 



Ground-penetrating radar


Root angle subtended to the transecting line


Amplitude area


Sum of the amplitude areas for all reflection waveforms

Single Amax

Amplitude area of the maximum reflection waveform


Amplitude area of the soil background




Root mean square error

Supplementary material

11104_2015_2563_MOESM1_ESM.docx (16 kb)
ESM 1(DOCX 16 kb)


  1. Barton CVM, Montagu KD (2004) Detection of tree roots and determination of root diameters by ground penetrating radar under optimal conditions. Tree Physiol 24:1323–1331. doi:10.1093/treephs/24.12.1323 CrossRefPubMedGoogle Scholar
  2. Bassuk N, Grabosky J, Mucciardi A, Raffel G (2011) Ground-penetrating radar accurately locates tree roots in two soil media under pavement. Arboric Urban For 37:160–166Google Scholar
  3. Borden KA, Isaac ME, Thevathasan NV, Gordon AM, Thomas SC (2014) Estimating coarse root biomass with ground-penetrating radar in a tree-based intercropping system. Agroforest Syst 88:657–669. doi:10.1007/s10457-014-9722-5 CrossRefGoogle Scholar
  4. Butnor JR, Doolittle JA, Kress L, Cohen S, Johnsen KH (2001) Use of ground-penetrating radar to study tree roots in the southeastern United States. Tree Physiol 21:1269–1278. doi:10.1093/treephys/21.17.1269 CrossRefPubMedGoogle Scholar
  5. Butnor JR, Barton CVM, 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
  6. Čermák J, Hruška J, Martinková M, Prax A (2000) Urban tree root systems and their survival near houses analyzed using ground penetrating radar and sap flow techniques. Plant Soil 219:103–116CrossRefGoogle Scholar
  7. Cui X, Chen J, Shen J, Cao X, Chen X, Zhu X (2011) Modeling tree root diameter and biomass by ground-penetrating radar. Sci China Earth Sci 54:711–719. doi:10.1007/s11430-010-4103-z CrossRefGoogle Scholar
  8. Cui X, Guo L, Chen J, Chen X, Zhu X (2013) Estimating tree-root biomass in different depths by ground-penetrating radar: evidences from a controlled experiment. IEEE TGRS 51:3410–3423. doi:10.1109/TGRS.2012.2224351 Google Scholar
  9. Dannoura M, Hirano Y, Igarashi T, Ishii M, Aono K, Yamase K, Kanazawa Y (2008) Detection of Cryptomeria japonica roots with ground penetrating radar. Plant Biosyst 142:375–380. doi:10.1080/11263500802150951 CrossRefGoogle Scholar
  10. Giannopoulos A (2005) Modelling ground penetrating radar by GprMax. Constr Build Mater 19:755–762. doi:10.1016/j.conbuildmat.2005.06.007 CrossRefGoogle Scholar
  11. Gregory PJ (2006) Plant roots: growth, activity and interactions with the soil. Blackwell Science, OxfordCrossRefGoogle Scholar
  12. Guo L, Chen J, Cui X, Fan B, Lin H (2013a) Application of ground penetrating radar for coarse root detection and quantification: a review. Plant Soil 362:1–23. doi:10.1007/s11104-012-1455-5 CrossRefGoogle Scholar
  13. 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 Soil 371:503–520. doi:10.1007/s11104-013-1710-4 CrossRefGoogle Scholar
  14. Guo L, Lin H, Fan B, Cui X, Chen J (2013c) Forward simulation of root’s ground penetrating radar signal: simulator development and validation. Plant Soil 372:487–505. doi:10.1007/s11104-013-1710-4 CrossRefGoogle Scholar
  15. Hirano Y, Dannoura M, Aono K, Igarashi T, Ishii M, Yamase K, Makita N, Kanazawa Y (2009) Limiting factors in the detection of tree roots using ground-penetrating radar. Plant Soil 319:15–24. doi:10.1007/s11104-008-9845-4 CrossRefGoogle Scholar
  16. Hirano Y, Yamamoto R, Dannoura M, Aono K, Igarashi T, Ishii M, Yamase K, Makita N, Kanazawa Y (2012) Detection frequency of Pinus thunbergii roots by ground-penetrating radar is related to root biomass. Plant Soil 360:363–373. doi:10.1007/s11104-012-1252-1 CrossRefGoogle Scholar
  17. Hruška J, Čermák J, Sustek S (1999) Mapping tree root systems with ground-penetrating radar. Tree Physiol 19:125–130Google Scholar
  18. Isaac ME, Anglaaere LCN (2013) An in situ approach to detect tree root ecology: linking ground-penetrating radar imaging to isotope-derived water acquisition zones. Ecol Evol 3:1330–1339. doi:10.1002/ece3.543 PubMedCentralCrossRefPubMedGoogle Scholar
  19. Jackson RB, Canadell J, Ehleringer JR, Mooney HA, Sala OE, Schulze ED (1996) A global analysis of root distributions for terrestrial biomass. Oecologia 108:389–411. doi:10.1007/BF00333714 CrossRefGoogle Scholar
  20. Jol H (2009) Ground penetrating radar, theory and applications. Elsevier, AmsterdamGoogle Scholar
  21. Nadezhdina N, Čermák J (2003) Instrumental methods for studies of structure and function of root systems of large trees. J Exp Bot 54:1511–1521. doi:10.1093/jxb/erg154 CrossRefPubMedGoogle Scholar
  22. Stokes A, Fourcaud T, Hruška J, Čermák J, Nadezhdina N, Nadyezhdin V, Praus L (2002) An evaluation of different methods to investigate root system architecture of urban trees in situ: 1. Ground-penetrating radar. J Arboriculture 28:2–10Google Scholar
  23. Stover DB, Day FP, Butnor JR, Drake BG (2007) Effect of elevated CO2 on coarse-root biomass in Florida scrub detected by ground-penetrating radar. Ecology 88:1328–1334. doi:10.1890/06-0989 CrossRefPubMedGoogle Scholar
  24. Tanikawa T, Hirano Y, Dannoura M, Yamase K, Aono K, Ishii M, Igarashi T, Ikeno H, Kanazawa Y (2013) Root orientation can affect detection accuracy of ground-penetrating radar. Plant Soil 373:317–327. doi:10.1007/s11104-013-1798-6 CrossRefGoogle Scholar
  25. Tanikawa T, Dannoura M, Yamase K, Ikeno H, Hirano Y (2014) Reply to: “Comment on root orientation can affect detection accuracy of ground-penetrating radar. Plant Soil 380:445–450. doi:10.1007/s11104-014-2136-3 CrossRefGoogle Scholar
  26. Waisel Y, Eshel A, Kafkafi U (2002) Pland roots: the hidden half, 3rd edn. Marcel Dekker, New YorkGoogle Scholar
  27. Wu Y, Guo L, Cui XH, Chen J, Cao X, Lin H (2014a) Ground-penetrating radar-based automatic reconstruction of three-dimensional coarse root system architecture. Plant Soil 383:155–172. doi:10.1007/s11104-014-2139-0 CrossRefGoogle Scholar
  28. Wu Y, Guo L, Li W, Cui XH, Chen J (2014b) Comment on: “root orientation can affect detection accuracy of ground-penetrating radar. Plant Soil 380:441–444. doi:10.1007/s11104-014-2124-7 CrossRefGoogle Scholar
  29. Zenone T, Morelli G, Teobaldelli M, Fischanger F, Matteucci M, Sordini M, Armani A, Ferrè C, Chiti T, Seufert G (2008) Preliminary use of ground-penetrating radar and electrical resistivity tomography to study tree roots in pine forests and poplar plantations. Funct Plant Biol 35:1047–1058. doi:10.1071/FP08062 CrossRefGoogle Scholar
  30. Zhu S, Huang C, Su Y, Sato M (2014) 3D ground penetrating radar to detect tree roots and estimate root biomass in the field. Remote Sens 6:5754–5773. doi:10.3390/rs6065754 CrossRefGoogle Scholar

Copyright information

© Springer International Publishing Switzerland 2015

Authors and Affiliations

  • Li Guo
    • 1
    • 2
  • Yuan Wu
    • 3
  • Jin Chen
    • 1
    • 2
  • Yasuhiro Hirano
    • 4
  • Toko Tanikawa
    • 5
  • Wentao Li
    • 3
  • Xihong Cui
    • 3
  1. 1.College of Global Change and Earth System ScienceBeijing Normal UniversityBeijingChina
  2. 2.Joint Center for Global Change StudiesBeijingChina
  3. 3.State Key Laboratory of Earth Surface Processes and Resource EcologyBeijing Normal UniversityBeijingChina
  4. 4.Graduate School of Environment StudiesNagoya UniversityNagoyaJapan
  5. 5.Kansai Research Center, Forestry and Forest Products Research InstituteKyotoJapan

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