Jianbang Gan
Friday, October 17, 2008 - 3:30-4:00
Chinese tallowtree (Triadica sebifera L.) currently occupies 450,000 acres of forest land in the Southern U.S., mostly in the Coastal Plain Province. This acreage estimate came from plot data surveyed on all forest lands by the USDA Forest Service R&D in partnership with State forestry agencies (FIA database). This coverage makes tallowtree the most pervading, stand replacing, alien tree species in the region; and a significant threat to forest ecosystem sustainability, productivity, and health. In 2001, the potential range of tallowtree was predicted using the CLIMEX model by Pattison, Mack, and Black at Washington State University to be as far north as Illinois and New Jersey. Our current research aims to predict the progressive occupation and impacts using a developed analytical framework and models to yield testable mitigation strategies. Several databases have been combined including the FIA database. Logit regressions relate current and future occupation to elevation and slope, proximities to water and roads, forest stand age and diversity, site productivity, forest ownership, and natural and human disturbances. Parallel analyses have found no statistical evidence for negative impacts of tallowtree density on southern pine growth rate, suggesting that gradual stand replacement is the major affect on forest productivity, as also reported for prairies. A conceptual model based on optimal control theory is under development for determining an optimal mitigation strategy. These findings should help guide future early detection, monitoring and mitigation efforts for Chinese tallowtree in the region; while our analytical approaches will be applicable to other invasive species.
Keywords: CHINESE TALLOWTREE, TRIADICA SEBIFERA, SAPIUM SEBIFERUM, PLANT INVASION, CONTROL, U.S. SOUTH