Integrating complex ecological information to develop a management plan for Chinese tallow (Sapium sebiferum L. Roxb.) in south Georgia

Abstract

Managing pernicious invasive plant species is an essential component of maintaining biodiversity and restoring natural ecosystem structure and function. Chinese tallow (Sapium sebiferum L. Roxb.) is recognized as one of the most aggressive invaders of southeastern US wetland and coastal habitats. However, effective management of S. sebiferum is often obstructed by a lack of scientific information for management strategies, conflicting objectives, and a paucity of funding. The first chapter is a comprehensive management plan for S. sebiferum, and includes a description of the biology and ecology of S. sebiferum and its history in the southeastern US. It provides a comprehensive overview of treatment methods for the species, including each method's advantages and disadvantages, timing, and case studies involving management of S. sebiferum on public lands. In Chapter Two, I analyze the effects of feral hog (Sus scrofa L.) rooting behavior on S. sebiferum seedling recruitment and survivorship in island vs. mainland habitats as a function of hog density. I discuss the implications of tallow population regulation by hogs, and associated challenges to agencies mandated to eliminate both of these deleterious exotic species. My analysis indicates that at high densities of feral hogs such as occur on Ossabaw Island, feral hog rooting significantly increases the mortality of Chinese tallow seedlings; whereas at low densities such as occur in mainland ecosystems, there is little impact. In Chapter Three, I present a scientific approach for prioritizing management objectives through the application of generalized linear models to predict seed crop quality based on morphological seed traits in 16 populations of S. sebiferum in mainland, coastal, and island habitats in south Georgia, USA. Based on analyses of generalized linear models (GLMs), I conclude that the use of such models to accurately predict seed crop quality of S. sebiferum populations is an ineffective tool for assisting land managers in developing priorities for tallow control. However, this technique does appear to be useful in identifying very high- and low-priority populations for management. The goal of this body of research is to merge sound science with judicious management strategies, resulting in effective conservation practices.