A multi-disciplinary evaluation of the invasion and management of Melaleuca quinquenervia

Ecosystem invasion by exotic plant species poses a significant threat to community biodiversity, function, and stability in the Florida Everglades. One of the most problematic invasive species in this ecosystem is Melaleuca quinquenervia (Cav.) Blake. The goal of my dissertation was to use a multi-scale, interdisciplinary approach to evaluate the ecosystem-level consequences of the invasion and management of M. quinquenervia. The results presented include above and belowground storages of nutrients in invaded and non-invaded systems, alterations of soil microbial biomass and function, evaluations of biological and chemical control methods, and plant community response to a native disturbance regime in the context of management.;Overall, both the invasion and management of M. quinquenervia altered basic ecosystem functions of nutrient storage and cycling, plant community diversity, and community response to native disturbance. We found that in the absence of top-down control from herbivory, M. quinquenervia trees were able to create a positive feedback loop to growth whereby increased quality and quantity of above- and below-ground biomass drove higher levels of storage and availability of below-ground resources. In addition, analysis of large-scale research plots in native, invaded, and managed sub-tropical wetland sites revealed that the use of herbicides to control M. quinquenervia invasion may damage long-term ecosystem structure and function. We found that after a seasonal fire plots that had been chemically treated to control M. quinquenervia populations had the lowest storages of critical plant nutrients and the fewest number of mature native trees.;The results of this study will benefit local efforts to manage invasive species. Currently there is a need to develop a better understanding of the ecological consequences of exotic species invasion and methods for countering them. This issue is vital to the restoration of the Everglades because efforts are underway to restore hydrologic systems in Florida's natural areas without a good understanding of ecosystem-level effects of exotic plants, which may ultimately hinder or even prevent restoration. Elucidation of the extent, duration, and impact of the changes caused by exotics will help in developing more effective restoration and management techniques.