Research Note: Observed Symmetry and Force of Plantanus × acerifolia (Ait.) Willd. Roots Occurring Between Foam Layers Under Pavement

Jason C. Grabosky; E. Thomas Smiley; Gregory A. Dahle

doi:10.48044/jauf.2011.006

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Figure 1.
Schematic photograph and drawing of the wood-metal loading jig to impose load onto foam sections. Drawing and dimension details the wooden section. The photo shows the end view of the loading jig with the ball-bearing used to “float” the jig against the travel surface of the upper platen, which produced the load. The ball fit into a recess milled into the metal plate matched to recess centered on the upper platen on the load press.
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Figure 2.
Growth offset as a percentage of root diameter along the distance of the root that was under pavement. Distances for roots A1 and B1 are estimates within 10 cm of true zero.
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Figure 3.
Pressure-penetration curves of foam sections to produce deformations to depths defined by observed multi-year root growth. Three curves generated to 27 mm at 2.25 mm h⁻¹ with a three-hour load, three-hour rest period loading sequence. Two curves generated to 18 mm at 1.5 mm h⁻¹ with three hour load, three-hour rest period loading sequence. Load was later converted to MPa by dividing load by contact surface of the loading jig on the foam.

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Table 1.

Dimension measurement data from four roots growing under concrete sidewalk between two foam protection layers. Offset measurements relative to root pith were measured as radius to edge in horizontal (defined by foam panel interface) and vertical (perpendicular to defined horizontal plane) directions. Left and right horizontal were defined by view from proximal end of the root section toward the distal end of the collected root sample.

TREE label	A		B
ROOT label	1	2	1	2
Section (5 cm) count	35	23	19	28
Mean (S.E.) root vertical diameter (mm)	31 (1.1)	35 (1.4)	31 (0.7)	52 (0.6)
Mean up (+) versus down (−) vertical growth offset as % (S.E.)	−27 (3.7)	−22 (4.6)	−27 (3.3)	−31 (2.7)
Mean (S.E.) root horizontal diameter (mm)	35 (1.4)	45 (2.9)	25 (0.7)	60 (1.7)
Mean left (+) versus right (−) horizontal growth offset as % (S.E.)	8 (5.2)	−13 (6.0)	2 (4.2)	2 (3.3)
Mean (S.E.) vertical-horizontal dia. growth differential (mm)	−3.3 (1.5)	−10.1 (3.0)	5.5 (1.0)	−8.1 (2.0)