Application and comparison of three tomographic techniques for detection of decay in trees

This paper reports application of electric, ultrasonic, and georadar tomography for detection of decay in trees and their comparison with the traditional penetrometer. Their feasibility in arboriculture is also evaluated, critically considering some "open problems." The experiments were carried out in an urban environment on two plane (Platanus hybrida Brot.) trees. Both trees, after felling, showed extensive white rot in the central cylinder. The electric tomography revealed low resistivity zones roughly centered in the trunk. A comparison with the successively cut sections showed a fine correspondence to decayed areas and a strong correspondence between high moisture zones and low resistivity zones. Ultrasonic tomography demonstrated to be a very effective tool for the detection of internal decay, accurately locating the position of the anomalies and estimating their size, shape, and characteristic in terms of mechanical properties. With the georadar technique, the high contrast of electromagnetic impedance measured between the inner decayed section and the outside sound section allowed the detection of the interface between the sound and decayed section of the tree, using radar acquisition in reflection modality. The penetrometer profiles detected the low-resistance areas inside the two trunks.

[1]  W. Wilcox,et al.  Detection of early stages of wood decay with ultrasonic pulse velocity , 1988 .

[2]  Voichita Bucur,et al.  Acoustics of Wood , 1995 .

[3]  R. Barker,et al.  Rapid least-squared inversion of apparent resisitivity pseudosections by a quasi-Newton method , 1996 .

[4]  L. Socco,et al.  ULTRASONIC TOMOGRAPHY FOR WOOD DECAYS DIAGNOSIS. , 2000 .

[5]  Y. Tomikawa,et al.  Nondestructive Inspection of a Wooden Pole Using Ultrasonic Computed Tomography , 1986, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[6]  S. Guddanti,et al.  Replicating sawmill sawing with TOPSAW using CT images of a full-length hardwood log , 1998 .

[7]  Helge Breloer,et al.  FIELD GUIDE FOR VISUAL TREE ASSESSMENT (VTA) , 1994 .

[8]  Johan Oja.  X-ray measurement of properties of saw logs , 1999 .

[9]  Elena Comino,et al.  FEASIBILITY OF ULTRASONIC TOMOGRAPHY FOR NONDESTRUCTIVE TESTING OF DECAY ON LIVING TREES , 2004 .

[10]  Grigoriy I. Torgovnikov,et al.  Dielectric Properties of Wood and Wood-Based Materials , 1993, Springer Series in Wood Science.

[11]  S. Rust.  Comparison of three methods for determining the conductive xylem area of Scots pine (Pinus sylvestris) , 1999 .

[12]  G. Kilbertus,et al.  Technique Ultrasonore de Caractérisation du Degré d'Altération des Bois de Hêtre et de Pin Soumis à l'Attaque de Différents Champignons , 1991 .

[13]  Walter C. Shortle.  Electrical Properties and Rate of Decay in Spruce and Fir Wood , 1987 .

[14]  Voichita Bucur,et al.  Dynamic elastic anisotropy and nonlinearity in wood and rock , 1998 .

[15]  T. Carpenter,et al.  Water distribution in fungal lesions in the wood of sycamore, Acer pseudoplatanus, determined gravimetrically and using nuclear magnetic resonance imaging , 1997 .

[16]  Giovanni Nicolotti,et al.  USING HIGH-TECHNOLOGY INSTRUMENTS TO ASSESS DEFECTS IN TREES , 1998 .

[17]  C. G. Gardner,et al.  High dielectric constant microwave probes for sensing soil moisture , 1974 .

[18]  T. Tattar,et al.  Relationship Between the Degree of Resistance to a Pulsed Electric Current and Wood in Progressive Stages of Discoloration and Decay in Living Trees , 1972 .

[19]  C. Skaar.  Wood-Water Relations , 1988, Springer Series in Wood Science.

[20]  M. Worthington,et al.  An introduction to geophysical tomography , 1984 .

[21]  Patricia K. Lebow,et al.  The relationship between stress wave transmission characteristics and the compressive strength of biologically degraded wood , 1997 .

[22]  Guust Nolet,et al.  Seismic tomography : with applications in global seismology and exploration geophysics , 1987 .

[23]  H. Berndt,et al.  High-resolution ultrasonic imaging of wood , 1999, Wood Science and Technology.

[24]  T. Tattar,et al.  Comparison of Electrical Resistance and Impedance Measurements in Wood in Progressive Stages of Discoloration and Decay , 1973 .