Article Figures & Data
Figures
- Figure 1.
Box plots for species exhibiting a significant relationship between root depth and crown vigor rating (1 = vigorous, 7 = replacement needed).
Tables
- Table 1.
Root depth and indicators of tree performance were recorded on street trees from three locations. A visual rating system was used for crown vigor. Where insufficient trees were available for some species, data is reported by genus. A trunk condition rating system was also used as a measure of performance at the North Carolina site because of a history of Phytophthora basal lesions.
Genus/species N Trunk diam. (cm) Avg. (SE). Average root depthz (cm) Avg. (SE) Roots > 8 cm deep (%) Root depthz range (cm) Median crown vigor rating (scale 1–7) Median trunk condition rating (scale 0–4) Low High Greensboro, NC – July 2008 Acer rubrum 50 16.6 (0.6) 6.5 (1.6) 8 −26.0 31.0 3 1 Snoqualmie, WA – November 2007 Quercus rubra 50 15.8 (0.4) −3.1 (1.5) 40 >-20.0y 15.0 2 -- Tilia cordata 50 11.4 (0.3) −3.3 (1.5) 24 >-20.0 15.0 3 -- Fraxinus oxycarpa 50 8.9 (0.2) −11.1 (1.2) 60 >-20.0 5.0 3 -- Glen Ellyn, IL – June/July 2007 Fraxinus sp.x 21 12.4 (1.5) −0.6 (1.5) 19 −13.5 12.5 1 -- Malus 17 7.7 (0.8) −2.9 (1.5) 18 −19.5 6.5 2 -- Quercus bicolor 26 8.8 (0.8) −1.2 (1.6) 23 −20.0 10.5 3 -- Quercus sp. 22 9.5 (0.8) −1.8 (1.2) 23 −15.0 14.5 3 -- Ulmus hybridw 25 10.2 (1.2) 1.9 (1.3) 8 −12.0 12.0 3 -- Tilia cordata 8 4.5 (2.3) −10.3 (2.2) 63 −19.0 −2.5 4 -- Gleditsia triacanthos 18 8.9 (1.2) 1.0 (0.8) 0 −4.5 9.0 2 -- Acer × freemanii 18 9.5 (1.9) 1.3 (2.1) 25 −18.0 17.0 2 -- Taxodium distichum 10 11.6 (2.0) 1.2 (1.8) 10 −10.5 8.0 2 -- Gymnocladus dioica 11 13.0 (2.8) −4.5 (3.4) 36 −24.0 9.0 1 -- - Table 2.
Regression analysis was used to determine the relationship between root depth and tree performance, with depth as the independent variable and crown vigor or trunk diameter (only on sites where trees of uniform size from the same source were all planted at the same time) as the dependent variable. Logistic regression was used for crown vigor and trunk condition ratings. Linear regression was used for trunk diameter measurements. Where insufficient trees were available for some species, data is reported by genus.
Genus/species Crown vigor Trunk diameter Trunk condition Sommers’D P (χ2) r2 P Sommers’D P (χ2) Greensboro, NC – July 2008 Acer rubrum 0.306 0.050 0.042 0.153 0.306 0.017 Snoqualmie, WA – November 2007 Quercus rubra 0.005 0.712 0.020 0.326 -- -- Tilia cordata −0.048 0.936 0.081 0.045 -- -- Fraxinus oxycarpa 0.107 0.559 0.130 0.010 -- -- Glen Ellyn, IL – June/July 2007 Fraxinus sp.z 0.229 0.231 -- -- -- -- Malus 0.283 0.088 -- -- -- -- Quercus bicolor 0.481 0.002 -- -- -- -- Quercus sp. 0.202 0.166 -- -- -- -- Ulmus hybridy 0.081 0.763 -- -- -- -- Tilia cordata 0.571 0.118 -- -- -- -- Gleditsia triacanthos 0.153 0.386 -- -- -- -- Acer × freemanii 0.229 0.428 -- -- -- -- Taxodium distichum 0.429 0.478 -- -- -- -- Gymnocladus dioica 0.556 0.096 -- -- -- --
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