Comparative seed dispersal, seedling establishment and growth of exotic, invasive Ailanthus altissima (Mill.) Swingle and native Liriodendron tulipifera (L.)

Ailanthus altissima (Mill.) Swingle (tree of heaven) is an exotic species from China that was intentionally introduced as an urban ornamental species but has since become naturalized throughout much of the U.S. This pioneer species appears poised to invade rural areas as current rates of human-induced forest disturbance lower dispersal barriers and increase available habitat, especially in eastern forests, where it will compete with pioneer native trees such as Liriodendron tulipifera (L.) (yellow poplar). To compare the invasion potential of exotic A. altissima and native L. tulipifera, my research focused on two objectives. First, I investigated characteristics that influence dispersal distance of the species' wind-dispersed samaras, and developed long distance seed dispersal curves from a forest edge into an open field. The second objective addressed the response of seed germination and seedling growth of the two species to three levels of timber harvest on north and south-facing aspects. (Abstract shortened by UMI.)...