Arboriculture & Urban Forestry 34(1): January 2008 3 Figure 2. Comparison of acoustic tomograph and photo- graph of the cross-section for red oak tree No. 123. visual inspection and single-path stress wave testing to screen for defect followed by acoustic tomography to identify the location and approximate magnitude of defects. Because the tomography only reflects the acoustic properties of the cross-section tested and is not an actual representation of the internal condition, carefully placed resistance microdrilling tests guided by infor- mation provided by the tomographs are needed to differentiate between decayed wood and crack-induced acoustic shadows. Laboratory examination of the tested trees confirmed that the screening tests correctly identified a general problem but without specificity, the tomography accurately revealed the general lo- cation and magnitude of the defects, but microresistance drilling was required to locate the defects and differentiate between de- cayed wood and crack-induced acoustic shadows. LITERATURE CITED Allison, R.B. 2005. Capitol Park Tree Structural Stability Study. Final report submitted to Wisconsin Department of Administration, Divi- sion of Building and Police, Madison, WI. 308 pp. Argus Electronic Gmbh. 2006. Picus Sonic Tomograph Manual. Ros- tock, Germany. 66 pp. Figure 1. Comparison of acoustic tomographs and photo- graphs of corresponding cross-sections for red oak tree No. 307. were larger than the true decay areas present in the cross- sections. Examination of the cross-sections revealed that internal cracks (“star” crack, “snake” crack, lateral crack, and so on) were also the dominating defects in these two red oak trees. These cracks, mostly present in the radial direction and extended up and down in vertical planes within the trunk, effectively cut off linear propagation of the acoustic waves diverting them to a much longer travel path. The direct result of this was that, even without decay present, the software produced a wide light- colored zone in the tomographs that resembled the influence of extensive heartwood decay. This observation was consistent with the warning provided in the operating manual (Argus Electronic Gmbh 2006). Tomographs generated using the Picus software were the composite effects of both decay and cracks. Only through carefully directed resistance microdrilling can the to- mography displays be interpreted as representing decay versus crack-induced acoustic shadows. This study of two mature red oaks demonstrates the effective- ness of a trunk decay detection protocol using a combination of Gilbert, E.A., and E.T. Smiley. 2004. Picus sonic tomography for the quantification of decay in white oak (Quercus alba) and hickory (Carya spp.). Journal of Arboriculture 30:277–280. Hayes, E. 2001. Evaluating Tree Defects, 2nd ed. Safetrees, Rochester, MN. 34 pp. Luley, C.L. 2005. Wood Decay Fungi Common to Living Urban Trees in the Northeast and Central United States. Urban Forestry LLC, Naples, NY. 61 pp. Matheny, N.P., and J.R. Clark. 1994. Evaluation of Hazard Trees in Urban Areas, 2nd ed. International Society of Arboriculture, Savoy, IL. 85 pp. Mattheck, C.G., and K.A. Bethge. 1993. Detection of decay in trees with the Metriguard Stress Wave Timer. Journal of Arboriculture. 19: 374–378. Mattheck, C.G., and H. Breloer. 1994. The Body Language of Trees: A Handbook of Failure Analysis. Her Majesty’s Stationery Office, Lon- don, UK. 240 pp. McCracken, F.I. 1985. Using sound to detect decay in standing hard- wood trees, pp. 281–287. In Proceedings, 5th Symposium on Non- destructive Testing of Wood, 9–11 September 1985. Washington State University, Pullman, WA. Nicolotti, G., L.V. Socco, R. Martinis, A. Godio, and L. Sambuelli. 2003. Application and comparison of three tomographic techniques for detection of decay in trees. Journal of Arboriculture 29:66–78. Pokorny, J. 2003. Urban Tree Risks Management: A Community Guide to Program Design and Implementation. NA-TP-03-03. USDA Forest ©2008 International Society of Arboriculture
January 2008
| Title Name |
Pages |
Delete |
Url |
| Empty |
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success. You will be contacted by Washington Gas with follow-up information regarding your request.
This process might take longer please wait
