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 | -- |