Leaf litter thickness, but not plant species, can affect root detection by ground penetrating radar
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Ground penetrating radar (GPR), a nondestructive tool that can detect coarse tree roots, has not yet become a mature technology for use in forests. In this study, we asked two questions concerning this technology: (i) Does the leaf litter layer influence root detection and major indices based on the time interval between zero crossings (T) and the amplitude area (A)? (ii) Can GPR images discriminate roots of different plant species?
Roots buried in a sandy bed, which was covered with different thicknesses of leaf litter, were scanned using a 900 MHz GPR antenna. Roots of four plant species in the bed were also scanned.
Leaf litter decreased root reflections without distorting the shape of the hyperbolas in the radar profile. A values decreased with increasing litter thickness, whereas T was independent of litter thickness. For all species combined, GPR indices were significantly correlated with root diameter.
Leaf litter dramatically decreased root detection, but the influence of the litter could be ignored when the sum of T for all reflection waveforms (ΣT) is adopted to estimate root diameter. To use A values to detect roots, litter should be removed or equalized in thickness. Radar profiles could not reliably differentiate among roots belonging to plants of different species.
KeywordsCoarse roots Leaf litter Nondestructive root detection Phyllostachys pubescens Root diameter
Sum of amplitude areas for all reflection waveforms
- Single Amax
Amplitude area of the maximum reflection waveform
Time interval between zero crossings
Sum of time intervals for all reflection waveforms
- Single Tmax
Time interval for the maximum reflection waveform
Ground penetrating radar
We thank Y. Kanazawa (Kobe University), M. Ishii and T. Igarashi (KANSO Technos), M. Hiraoka (Tokyo University of Agriculture and Technology), and S. Asano, U. Kurokawa, T. Chikaguchi, S. Narayama, M. Tanaka, Y. Shimada, N. Makita, H. Hagino, and the other members of FFPRI for their help with data analysis and the field experiments. We also thank M. Ohashi (University of Hyogo) and Y. Matsuda (Mie University) for providing comments on an early draft of this manuscript. We additionally thank three reviewers for their critical comments on an earlier draft of the manuscript. We are grateful for financial support from Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan (No. 22380090, 25252027). This study was also supported by the Program for Supporting Activities for Female Researchers, which is funded by MEXT’s Special Coordination Fund for Promoting Science and Technology.
- Butnor J, Roth B, Johnsen K (2005) Feasibility of Using Ground-penetrating Radar to Quantify Root Mass in Florida’s Intensively Managed Pine Plantations. FBRC Report #38Google Scholar
- Cheng NF, Tang HWC, Ding XL (2014) A 3D model on tree root system using ground penetrating radar. Sustain Environ Res 24:291–301Google 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
- Groisman PY, Karl TR, Easterling DR, Knight RW, Jamason PF, Hennessy KJ, Suppiah R, Page CM, Wibig J, Fortuniak K, Razuvaev VN, Douglas A, Forland E, Zhai PM (1999) Changes in the probability of heavy precipitation: important indicators of climatic change. Clim Chang 42:243–283. doi: 10.1023/A:1005432803188 CrossRefGoogle Scholar
- IPCC (2012) Summary for Policymakers. In: CB F, Barros V, TF S, Qin D, DJ D, KL E, MD M, KJ M, G-K P, SK A, Tignor M, PM M (eds) Managing the risks of extreme events and disasters to advance climate change adaptation. A special report of working groups I and II of the intergovernmental panel on climate change. Cambridge University Press, Cambridge, pp. 1–19Google Scholar
- Karizumi N (2010) The latest illustrations of tree roots. Seibundo-shinkosha, Tokyo, 937 ppGoogle Scholar
- Preston NJ, Crozier MJ (1999) Resistance to shallow landslide failure through root-derived cohesion in east coast hill country soils, North Island, New Zealand. Earth Surf Process Landf 24:665–675. doi: 10.1002/(SICI)1096-9837(199908)24:8<665::AID-ESP980>3.0.CO;2-B CrossRefGoogle Scholar