Reproducibility of Stress Wave and Electrical Resistivity Tomography for Tree Assessment (original) (raw)
Non-Destructive Assessment of Living Trees by using Electric Resistive Tomography
2020
Electric Resistive Tomography is one of the latest procedures in the assessment of living trees. There is a growing interest regarding this measurement method yet despite the presence of such measuring devices on the market, this method, unlike acoustic assessment techniques for trees, is far from being fully developed. The devices available on the market analyze only the nature of resistivity of the device, but do not take into account the phase character of the measurements. In addition to measurement information, this paper presents several results regarding fixed impedance tomography. The experience gained here is to be used for further research. Key-Words: non-destructive assessment of materials, assessment of living trees, Electrical Impedance Tomography
Combining Sonic and Electrical Impedance Tomography for the Non-destructive Testing of Trees
2008
For the non-destructive testing of standing trees sonic tomography is currently the “state-of-the-art” in many parts of the world. The most significant step forward in this technology in the recent years is the reduction in hardware requirements – by using an electronic hammer the number of sensors can be halved. Especially in large trees this increases the accuracy of the measurements. Although in the majority of cases the results are correct and easy to interpret, some limits remain. To overcome the limits of sonic tomography our research group has been adapting electrical impedance tomography (EIT) from geoelectrics to be used for trees since 1998 [4]. Among other properties, the system allows the detection of early stages of decay, wet wood and different types of heartwood [9]. Since 2004 new reconstruction algorithms for the electric impedance tomography have improved the results by using the exact shape of the measured cross-section of the tree. To achieve this, modern inversi...
A new tomographic device for the non - destructive testing of trees
A new device allows the non - destructive inspection of standing trees for cracks, cavities, and rot. It is based on the simultaneous measurement of the time of transmission of stress waves by several sensors arranged around the stem. The system was extensively tested by comparison of the tomogram with either the cross - section of the tree cut after the measurement, or with data from penetrometers or increment cores obtained in the same plane. The border of cavities is identified to the nearest cm, whereas the with of cracks in the tomogram depends on the position of the sensors around the stem. Rots are identified as soon as the wood is sufficiently deteriorated to reduce the velocity of sound. This system may become a valuable tool for hazard tree inspection, evaluation, and management.
Adapted VTA and SIA method in tree static assessment with use of resistography
Periodicum Biologorum
Background and Purpose: This paper introduces a method for assessment of static safety by using the combination of adapted VTA and SIA methods and a resistograph. The aim is to assess the static as reliably as possible and without the need for expensive equipment. The purpose of this paper is to propose amethod for the static assessment which could be applied in practice in the future. Materials and Methods: Seven trees in the Botanical Garden of the Faculty of Science (University of Zagreb) were selected for the assessment of vitality and static safety. It has been detected that those trees were affected by possible indicators of decreased vitality, such as fungi fruiting bodies on the root collar or trunk, dead branches, growthmalformations, burrs, dead bark etc. The selected trees were: Fagus sylvatica L. »Purpurea Tricolor«, Fraxinus pennsylvanica Marshall, Acer pseudoplatanus L. »Leopoldii«, Fagus grandifolia Ehrh., Quercus petraea L., Quercus phellos L. and Salix alba L. The s...
2020
Baragur Neelappa Divakara, Chitradurga Umesh Nikhitha, Anil Kumar Sethy Institute of Wood Science and Technology, Indian Council of Fares fly Research and Education, Bengaluru, India (bndsira@gmail.com; thoshitha.cu@gmail. cam; sethyanil@gmail.com) Accurate, cost-effective and non-destructive method of diagnostic technique for quantifying the heartwood content in Tectona grandis Linn. f.is indispensable as it helps in selection of trees with more heartwood for further genetic improvement. Tree Tronic tomograms like Electrical Resistivity Tomography (ERT) are one among the advanced non-destructive method aiding for tree inspection. This method gives high resolution with more precision in measuring the sapwood, heartwood, stress and decay in the living trees. In this study, main aim is to explore the possibility of using Electrical Resistivity Tomography (ERT) to determine the sapwood-heartwood (SW-HW) boundary in terms of electrical resistivity. The instrument used to measure electri...
Science of The Total Environment
Inter-individual variability of tree drought responses within a stand has received little attention. Here we explore whether the spatial variations in soil/subsoil properties assessed through electrical resistivity tomography (ERT) could explain variations in drought response traits among trees. We used ERT to compute the percent variation in resistivity (PVR) between dry and wet conditions as an indicator of spatial variability in total available water content. PVR was computed in two different depth ranges (0-2 and 2-5 m) for eleven Quercus ilex stools in a Mediterranean forest stand. PVR values were compared to biological traits, including tree water status (predawn water potential (Ψ)), leaf traits (δ 13 C, leaf mass area (LMA)), and canopy defoliation measured after intense drought. We found significant correlations between PVR and biological variables. For Ψ , the nature and strength of the correlations vary according to the level of drought intensity. The correlation between Ψ and PVR was positive during well-watered conditions in the upper layer (0-2 m) and during water-limited conditions in the deeper layer (2-5 m). During most severe droughts, however, the Ψ was negatively correlated with PVR in the upper layer. Trees with lower PVR in the upper layer were also associated with water use efficiency (higher δ 13 C), higher LMA, and a lower level of defoliation after extreme drought. Overall, our results indicate that local differences in soil/subsoil properties affect tree response to drought and suggest that less favorable soil/subsoil conditions (lower PVR) can lead to lower water stress during the driest period and to lower defoliation after extreme drought. Plausible explanations for this better acclimation include higher stomatal regulation and improved deep soil and subsoil water exploration by trees located in more adverse conditions. We encourage the development of ERT in ecological studies to further explore the interrelated relationships between soil/subsoil, climate, and tree functioning.
Silva Fennica, 2012
The proportions of sapwood and heartwood of trees have significant impacts on various uses. Electric resistivity tomography (ERT) and corresponding electrical resistance (ER) value maps were examined in Japanese cedar (Cryptomeria japonica D. Don), Taiwania (Taiwania cryptomerioides Hayata), and Luanta fir (Cunninghamia konishii Hayata) trees. The position of the sapwood-heartwood demarcation was measured on incremental cores from living trees and the corresponding ER of the sapwood-heartwood boundary was acquired from the ER map. A positive significant relationship was found between the maximum ER plus minimum ER values (ERmax + ERmin) and ER of the sapwood-heartwood demarcation from the tomographic data. The position of the sapwood-heartwood demarcation was determined by corresponding ER, and the critical ER can be established by the ERmax + ERmin value of the tomographic data. The results from this study indicate that ERT technique can be used to determine the position of the sapwood-heartwood boundary and can serve as a methodology in undamaged living trees of Gymnosperm species.
Nondestructive evaluation of standing trees with a stress wave method
2001
The primary objective of this study was to investigate the usefulness of a stress wave technique for evaluating wood strength and stiffness of young-growth western hemlock and Sitka spruce in standing trees. A secondary objective was to determine if the effects of silvicultural practices on wood quality can be identified using this technique. Stress wave measurements were conducted on 168 younggrowth western hemlock and Sitka spruce trees. After in situ measurements, a 0.61-m-long bole section in the test span was taken from 56 felled trees to obtain small, clear wood specimens. Stress wave and static bending tests were then performed on these specimens to determine strength and stiffness. Results of this study indicate that in situ stress wave measurements could provide relatively accurate and reliable information that would enable nondestructive evaluation of wood properties in standing trees. The mean values of stress wave speed and dynamic modulus of elasticity for trees agreed with those determined from small, clear wood specimens. Statistical regression analyses revealed good correlations between stress wave properties of trees and static bending properties of small, clear wood specimens obtained from the trees. Regression models showed statistical significance at the 0.01 confidence level. Results of this study also demonstrate that the effect of silvicultural practices on wood properties can be identified with the stress wave properties of trees. This indicates that this nondestructive stress wave technique can be used to track property changes in trees and help determine how forests could be managed to meet desired wood and fiber qualities.
Annals of Forest Science, 2021
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