Article Figures & Data
Figures
- Figure 1.
Diagrammatic representation of the pull-testing setup.
- Figure 2.
Linear cuts were made with a stump grinder starting at a distance equal to five times the trunk diameter. The trencher was moved closer to the trunk in distance increments equal to the trunk diameter ending with a cut tangential to the trunk.
- Figure 3.
Roots in Group 3 trees were severed one at a time starting opposite the pull line and alternating right and left until all of the roots on 50% of the circumference were severed and a section removed.
- Figure 4.
Correlation between the force required to pull the trunk to an angle of 1° and the force required to pull the tree to the point of failure (FFailure = 4.35[F1] + 27; r2 = 0.76.
- Figure 5.
Standardized force to move the trunk 1° compared with the distance from the trunk of the linear root cuts. Each point is an average of 11 pull tests with the exception of the 5× diameter at breast height (dbh), which is the average of three pull tests. Asterisk indicates that a significant difference exists (P = 0.05) with the 4× dbh value using paired sample t-tests.
- Figure 6.
Comparison of the percentage of buttress roots cut (Rcut/RTotal × 100) and the standardized force (FStd = peak force to move the trunk 1° after root cutting divided by the peak force before cutting roots multiplied by 100) to move the trunk 1°. FStd = 1.99 + 0.59(Rcut/RTotal × 100), r2 = 0.80.
- Figure 7.
The sum of diameters of all roots that were severed divided by dbh (∑Rcut dia/dbh × 100) compared with the standardized force (FStd = peak force to move the trunk 1° after root cutting divided by the peak force before cutting roots multiplied by 100) to move the trunk 1°. FStd = 6.49 + 15 (∑Rcut dia/dbh × 100), r2 = 0.64. dbh = diameter at breast height.
Tables
Parameter Group 1 Group 2 Group 3 Pulled to failure Linear root cut Individual cuts Mean Standard deviation Mean Standard deviation Mean Standard deviation dbh at 1.4 m (4.6 ft) 12.6 cm (5 in) 1.2 12.2 cm (4.9 in) 1.9 13.6 cm (5.4 in) 1.4 Caliper at 15 cm (6 in) 16.5 cm (6.6 in) 1.3 15.8 cm (6.3 in) 2.1 17.9 cm (7.2 in) 1.8 Height 7.3 m (24.1 ft) 0.8 7.2 m (23.8 ft) 0.4 6.8 m (22.4 ft) 0.6 Branch spread 4.6 m (15.2 ft) 0.5 4.9 m (16.2 ft) 0.5 4.5 m (14.9 ft) 0.6 Number of trees 8 11 10 dbh = diameter at breast height.
- Table 2.
Mean reduction in pull force compared with linear root cutting at different distances from the trunk.
Distance Regression r2 No cuts F1 = 75 (dbh) −710 0.78 Four F1 = 65 (dbh) −580 0.76 Three F1 = 80 (dbh) −790 0.81 Two F1 = 80 (dbh) −820 0.84 One F1 = 66 (dbh) −660 0.84 Zero F1 = 75 (dbh) −800 0.81 dbh multiples where F1 = force to pull trunk 1° in kilograms and dbh = diameter at 1.4 m (4.6 ft) in centimeters.
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