An assessment of control methods for cape ivy in coastal riparian ecosystems

Jennifer Stern, California State University, Monterey Bay

Thesis (M.S.) Division of Science and Environmental Policy


The goals of this research were to quantify the achievable outcomes and associated costs of controlling Cape ivy (Delairea odorata), a non-native invasive plant. Current gaps in the knowledge-base limit decision makers from assigning appropriate costs, and therefore funding, for invasive species control (D’Antonio and Chambers 2006). Towards these goals, I measured and compared the success and cost-effectiveness of three control methods on Cape ivy in riparian areas along the Central Coast region of California. The control methods used in this study included hand removal, herbicide application (glyphosate), and a combination of these two methods. Control methods were applied to Cape ivy infestations at three research sites; two within Santa Cruz County and one in Monterey County, beginning July 2008 and concluding September 2009. Success of each control method was measured by comparison of pre and post-treatment vegetation sampling. The costs associated with each method (labor, herbicides, materials) were also recorded for each method. After twelve months, the hand removal method achieved the highest reduction of Cape ivy cover and resulted in the highest native plant cover. However, the most cost-effective method (per dollar) for the first twelve months of Cape ivy control was the herbicide only method. The results of this study will be provided to staff at California State Parks, the Land Trust of Santa Cruz County, and the Big Sur Land Trust to inform future management of Cape ivy on their properties. Additionally, this research will contribute to needed guidelines for restoration of Cape-ivy infested riparian ecosystems, and serve as a resource for researchers interested in control of invasive plants and restoration of disturbed areas.