Huebner, Cynthia .
Competitive ability of Ailanthus altissima vs. Rhus typhina and Betula alleghaniensis.
Both intra- and interspecific competition were studied in a controlled greenhouse setting for Ailanthus altissima, a potential forest invader. Ailanthus altissima was planted at densities of 10, 20, 50, and 100 seeds per plot and grown in both high light (~860 umol/m2/s) and low light (~130 umol/m2/s) in vermiculite with ample water and nutrients for 2 months. Negative density effects were noted only in low light at the highest density in which case fewer seeds germinated, and all low light individuals had significantly lower root to shoot ratios. Ailanthus altissima was also grown with Rhus typhina and Betula alleghaniensis with ample water and nutrients at a total density of 100 seeds per plot in both high light and low light treatments. Allelopathic effects were controlled using activated carbon and none were found. While R. typhina had significantly fewer germinants in both high and low light treatments, its root to shoot ratio per individual and average height were significantly greater than that of A. altissima in both light levels. Ailanthus altissima appeared to benefit from its negative density effects in low light with regards to competition with R. typhina; the fewer germinants competed better, showing greater internode lengths. These results indicate that R. typhina may be a better competitor than A. altissima, but this advantage decreases somewhat in shaded environments. In contrast, B. alleghaniensis performed much more poorly than A. altissima in both high and low light and may be considered a poor competitor. However, R. typhina seeds require cold stratification and acid scarification for germination, while A. alttissima seeds have few conditions for germination. Similar experiments are being conducted with the shade-tolerant Acer rubrum and field tests for all species are planned.
1 - NE Research Station, USDA Forest Service, 180 Canfield St., Morgantown, West Virginia, 26505, USA
Presentation Type: Paper
Location: Wasatch (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 8:15 AM