A resource induced shift in growth strategy and rhizome morphology in a non-native clonal plant species

In recent years, a non-native plant, Aralia elata, has emerged as an invasive plant species in the eastern United States. Introduced in New York in the 1830s, A. elata has since spread, via avian dispersal, across much of the mid-Atlantic region. The large scale windthrow and resulting canopy gaps created by the storms of 2011 and 2012 produced the disturbed habitat preferred by A. elata. Clonal growth is a life history trait common among invasive plant species, including A. elata, affording the genet the benefit of improving its fitness through the production of an exploratory rhizome system capable of foraging to acquire limited resources. I hypothesized that the amount of canopy cover will affect rhizome growth dynamics and main stem size over the first three years of invasion. Rhizome dimension data of 150 individual genets were collected and plotted against the percent open canopy. Results indicate that rhizome size and structure are significantly affected by the percent of open canopy. Plants occupying higher light locations had larger main stems, more rhizomes with more branching points, and were shorter in total length than plants growing in low light, indicating investment by the genet into its current location. Unexpectedly, plant growing in low light conditions possessed the longer, less branching rhizome morphology often observed in foraging plants, suggesting that they were attempting to escape the lower light location.M.S.Includes bibliographical referencesby Joshua D. Echol