Okun, A.; Brazee, N.J.; Clark, J.R.; Cunningham-Minnick, M.J.; Burcham, D.C.; Kane, B. Assessing the Likelihood of Failure Due to Stem Decay Using Different Assessment Techniques. Forests2023, 14, 1043.
Okun, A.; Brazee, N.J.; Clark, J.R.; Cunningham-Minnick, M.J.; Burcham, D.C.; Kane, B. Assessing the Likelihood of Failure Due to Stem Decay Using Different Assessment Techniques. Forests 2023, 14, 1043.
Okun, A.; Brazee, N.J.; Clark, J.R.; Cunningham-Minnick, M.J.; Burcham, D.C.; Kane, B. Assessing the Likelihood of Failure Due to Stem Decay Using Different Assessment Techniques. Forests2023, 14, 1043.
Okun, A.; Brazee, N.J.; Clark, J.R.; Cunningham-Minnick, M.J.; Burcham, D.C.; Kane, B. Assessing the Likelihood of Failure Due to Stem Decay Using Different Assessment Techniques. Forests 2023, 14, 1043.
Abstract
Arborists commonly investigate the extent of stem decay to assess the likelihood of stem failure when conducting tree risk assessments. Studies have shown that (i) arborists can sometimes judge the extent of internal decay based on external signs; (ii) sophisticated tools can reliably illustrate the extent of internal decay; and (iii) assessing components of tree risk can be highly subjective. We recruited 18 experienced tree risk assessors who held the International Society of Arboriculture’s Tree Risk Assessment Qualification (TRAQ) to assess the likelihood of stem failure due to decay after each of 5 consecutive assessments on 30 individuals of 2 genera. Five assessment techniques, in stepwise order, were 1) visual, 2) sounding the trunk with a mallet, 3) viewing a scaled diagram of the cross-section that revealed sound and decayed wood ascertained from resistance drilling, 4) viewing sonic and electrical resistance tomograms, and 5) consulting with a peer. For each technique, assessors assigned two or more likelihood of failure ratings (LoFRs) for at least 83% of trees, which were proportionally greatest after assessors viewed tomograms; the proportions did not differ among the other four assessment techniques. Covariates that influenced the distribution of LoFRs included percent of the cross-section that was decayed, and assessors’ experience using resistance drilling devices and tomography in regular practice. Practitioners should be aware that disagreement on the likelihood of tree failure exists even among experienced arborists.
Keywords
tree risk assessment; decay; resistance drilling; tomography; tree risk assessment qualification; tree stem
Subject
Biology and Life Sciences, Forestry
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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