Baumtomographie.de
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Table of Contents
About
Recent years have seen the transfer of a range of methods from geophysics to arboriculture, especially hazard tree assessment. Sonic tomography is now widely applied for the assessment of hazard trees, with electrical resistivity tomography (ERT) as a recent addition.
ERT is also used to locate roots, as has been georadar.
This site is about tree tomography and related technology:
- sonic tomography (aka stress wave tomography)
- electrical resistivity tomography (aka electrical resistivity tomography)
- georadar for root detection
Information is mostly focused on non-destructive hazard tree assessment in urban trees. Some applications in tree physiology and pathology are described.
About me
Steffen Rust is a professor of arboriculture in the Faculty of Ressource Management at the University of Applied Science and Art in Göttingen, Germany. His research interests are
-
non-destructive testing of trees, especially
- tomography
- georadar
- electrical resistivity methods
- pulling tests
- tree biomechanics
- tree and stand water relations
Technical background
In 1999, I introduced sonic tomography for trees at the arboricultural conference and trade show in Osnabrück, Germany. The first scientific paper (Rust 2001) was presented at Wood NDT-2000 in Sopron, Hungary.
Also in 1999, colleagues from the University of Applied Science and Art in Göttingen, Germany, published their successfull tests with electrical resistivity tomography.
Stem tomography
Sonic tomography
Sonic tomography for trees uses many sonic sensors around the circumference of the tree recording the transmission time of sonic signals simultaneously. Tomograms are reconstructed from relative sonic velocities rather than trying to find an absolute velocity trigger level that would determine whether wood is sound or defective. Analysis of tomograms is done based the ability of the wood to transmit sonic waves rather than velocity or density maps.
Electrical resistivity tomography
While sonic tomography is based on biomechanical properties of wood, electrical resistivity tomography mainly visualises chemical properties. The instrument uses point-like electrodes at the boundary of the object. At two of these a current is injected. The resulting electric field depends on the resistivity distribution and is measured by using the other electrodes pair-wise to obtain a potential difference. Data collection is followed by the tomographic re-construction of the resistivity distribution.
Root detection
Ground penetrating radar (GPR) is an indirect method for the investigation of subsurface features. Its ability to detect tree roots has been shown by several studies. Another geophysical method which has been successful applied to study different aspects of tree roots is electrical resistivity tomography (ERT).
As a continuation of earlier approaches we have been using both techniques to study the spatial root architecture of urban trees.
Tree care
The main application of stem tomography is in non-invasive hazard tree assessment. The extent of decay in the cross-section is used to estimate the risk of breakage, e. g. (Gilbert and Smiley 2004).
GPR is used to locate roots in advance of construction works and to evaluate fungal decay in roots without excavation.
Tree physiology
ERT can be used to measure the active xylem area, e. g. in studies on sap flow in trees (Bieker and Rust 2010). In some species, very subtle differences in wood chemistry will be detected (Bieker and Rust 2010a).
Tree pathology
ERT can detect very early stages of decay (Bieker 2010). To show up in sonic tomograms, decay has to be more advanced (Deflorio2008).
Publications
My publications can be found here.
Links
Date: 2011-06-14 12:31:05
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