Mean incremental growth of four shade tree species on the campus of the University of Illinois at Urbana-Champaign, 1987-1991.
| Tree species | Mean dbh1 (cm) | Trench distance2 (m) | Treatment | Mean incremental growth (cm)4 | ||||
|---|---|---|---|---|---|---|---|---|
| 1987 | 1988 | 1989 | 1990 | 1991 | ||||
| Hackberry | 26.2 | 0.5 | T | 1.12 | 0.38a | 0.96a | 0.69a | 0.66a |
| 23.4 | — | C | —3 | 0.74b | 1.72b | 1.32b | 1.12b | |
| Sweetgum | 28.2 | 2.6 | T | 1.73a | 0.61a | 1.45a | 1.83a | 1.04a |
| 28.4 | — | C | 1.96a | 0.91a | 1.55a | 1.83a | 1.34b | |
| Sugar Maple | 29.5 | 0.9 | T | 0.58a | 0.36a | 0.94a | 1.09a | 0.69a |
| 29.0 | — | C | 0.91b | 0.23a | 0.94a | 0.84a | 0.74a | |
| Honeylocust | 44.9 | 1.8 | T | 0.79a | 0.51a | 0.83a | 0.76a | 0.74a |
| (Site#l) 47.7 | — | C | 1.04a | 0.53a | 0.74a | 0.76a | 0.81a | |
| Honeylocust | 36.6 | 3.3 | T | 1.12a | 0.96a | 0.74a | 0.96a | 0.51a |
| (Site #2) 31.8 | — | C | 1.04a | 0.69b | 0.81a | 0.71b | 0.69a | |
↵1. Mean dbh measurements of all four tree species for trenched and control trees taken prior to the 1987 growing season.
↵2. Linear distance from the center of the trunk of the affected tree to the center of the trench.
↵3. No data available due to the replacement of the original control set with a new control set. (Refer to Materials and Methods for details).
↵4. Paired treatment values for each tree species for each growing season followed by the same letter are not significantly different.(p<0.05; Two-Tailed T-test).