Species, number of study trees and control trees, location, average diameters and percent of crown left after topping.
| Species | Study area | Number of topped trees | Number of control trees | Average diam. of topped trees | Average diam. of controls | Percent of crown left after topping |
|---|---|---|---|---|---|---|
| cm | cm | |||||
| Beech, American | Maryland | 30 | 30 | 19.6 | 23.9 | 50.4 |
| Hickory | Maryland | 28 | 28 | 20.5 | 16.9 | 69.2 |
| Oak, chestnut | Pennsylvania | 30 | 30 | 30.5 | 30.0 | 52.4 |
| Oak, northern red | Pennsylvania | 30 | 30 | 37.4 | 38.9 | 57.2 |
| Oak, white | Maryland | 30 | 30 | 24.3 | 21.3 | 48.3 |
| Pine, Virginia | Maryland | 30 | 30 | 18.4 | 18.0 | 62.7 |
| Sweetgum | Maryland | 24 | 24 | 19.7 | 26.2 | 39.3 |
| Sycamore | Maryland | 7 | 7 | 43.2 | 52.7 | 36.1 |
| Yellow-poplar | Pennsylvania | 30 | 30 | 34.5 | 29.0 | 45.3 |