Chinese Tallow Invasion On A South Carolina Barrier Island: A Study Of Current Distribution Following Herbicide Treatments

At roughly 5,000 acres in size along the coast of South Carolina, Bulls Island is Cape Romain National Wildlife Refuge’s largest island. The island is comprised of habitats ranging from maritime forest and beaches to salt marshes and brackish wetlands. Live oak trees (Quercus virginiana) and loblolly pines (Pinus taeda) have historically dominated the island. Natural disturbance events such as hurricanes have affected island dynamics in recent decades. Additionally, management practices including controlled burns have been carried out to mimic the ecosystem effects of historic fire occurrence. The exotic tree Chinese tallow (Triadica sebifera), an ornamental species historically used for economic purposes, is quickly spreading across the Southeastern United States and has now reached invasive levels becoming one of the most prevalent tree species on the island. Extremely salt, water, and light tolerant, Chinese tallow is currently threatening the unique habitat mosaics of the island. With each new disturbance event, Chinese tallow is quickly able to invade vulnerable habitats, with water sources serving as easy vectors for seed dispersal, creating thick tree stands and smothering native vegetation. Between 2006 and 2012, substantial portions of the island underwent herbicide treatments of Chinese tallow. Since these treatment events, no new data have been collected to determine the success of treatments or current distribution of Chinese tallow. Field work conducted during the summer of 2017 aimed to fill this gap in knowledge. Distribution data of Chinese tallow was collected at 160 study plots in 8 sections (two untreated and six treated) on the island and further analyzed to determine habitat variables contributing to Chinese tallow presence and abundance in both treated and untreated sections. This research will go on to further aid invasive species management on the island