Article Figures & Data
Figures
- Figure 1.
Method used to compare predictions by evaluators with the actual extent and distribution of decay in cross-sections of the 10 study laurel oaks.
- Figure 2.
Deviation of predicted proportion of decay from actual, and predicted proportional strength loss from actual, for each of the 10 evaluators (A: Gainesville city arborist; B, C, D: assistant tree surgeons; E: consulting forester; F: botany professor; G: plant ecology graduate student; H, I: utility foresters; J: horticulturalist).
- Figure 3.
Deviation of predicted and actual proportion of decay plotted against the deviation of predicted and actual proportional strength loss of all evaluators.
- Figure 4.
Mean deviation of predicted and actual decay areas of 7 evaluators who participated in a preliminary study (3 trees; solid squares) and the final study (10 trees, solid circles). (A: Gainesville city arborist; B, C, D: assistant tree surgeons; E: consulting forester; F: botany professor; G: plant ecology graduate student.) Dotted line indicates a mean deviation of zero between predicted and actual decay. Means > 0 overpredicted decay areas; means < 0 underpredicated decay areas.
Tables
- Table 1.
Equations used to evaluate strength loss associated with wood decay, adapted from (5).
Source Equation Strength loss threshold Strength loss calculated for section A (below) Strength loss calculated for section B (below) Comments Coder
(1989)(d/D)*100 220–44% caution > 50% hazard 13% 4% Does not account for asymmetric decay Wagener
(1963)(d/D)*100 33% 22% 9% Does not account for asymmetric decay Smiley & Freadrich
(1992)(d + r[D-d])/D * 100 33% 22% 14% Accounts for lateral decay, but underestimates strength if internal decay is larger than indicated by external cavity opening Mattheck, et al. (1992) t/R <0.30 0.45 n/a Formula is not applicable to trees with open cavities. For these trees, the strength loss threshold is a cavity occupying >120 degrees of the stem circumference Percent loss in I I decay / 1 trunk * 100 see comment 12% 28% No failure criteria. Accounts for irregularly shaped decay Percent area of a/A * 100 35% 18% Does not account for asymmetric decay Where:
d = diameter of decayed wood
D = diameter of trunk
t = width of sound wood
r = size of cavity opening/circumference of trunk
R = radius of trunk
I = second moment of area a =
area of decay
A = area of trunk
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