Abstract
Conservation of natural habitats is a pressing issue in Florida and measures are taken to understand the dynamics of invasive exotic species, such as Melaleuca quinquenervia (Cav.) Blake, in these systems. Melaleuca quinquenervia, one of Florida’s most problematic invasive exotic species, is present on the campus of Florida Gulf Coast University (FGCU), located on 308 ha in Lee County, Florida. Over 162 ha of the campus were naturally wetland or upland preserves that have been undergoing restoration by removal of invasive exotic species. Restoration approaches include hand removal, mechanical removal, herbicide treatment, biological control agents (snout weevil, Oxyops vitiosa; psyllid fly, Boreioglycaspis melaleucae), and replanting of native vegetation. In May 2004, a wildfire burned approximately 121 ha in the southern half of the FGCU campus. To investigate the affects of fire on M. quinquenervia-invaded lands, four transects were established in the burned areas: (1) a restored wetland/upland ecotone with low infestation; (2) a restored wetland with previously high infestation, replanted with natives following exotic removal; (3) a wetland with high infestation; and (4) a restored wetland/upland ecotone with mature native vegetation remaining after exotic removal. In this thesis I report on: (1) the degree that M. quinquenervia infestation, relative to the fire, influences native mortality, (2) the responses of M. quinquenervia to wildfire in south Florida, and (3) the dynamics of post-fire recovery of M. quinquenervia. The results of this study suggest that greater M. quinquenervia infestations in burned areas significantly increase native plant mortality but also result in significant M. quinquenervia mortality. Mortality of smaller stem sizes of M. quinquenervia trees was significantly greater than that of larger stem sizes in burned areas. Biological control agents survived this fire and readily re-invaded M. quinquenervia-infested areas. This wildfire in combination with biological control agents present appeared to effectively decrease the number of M. quinquenervia. The implication of this work supports the suggestion that introduced invasive exotic species change the historical role that fire has played in south Florida. Fire as a land management tool holds promise to help control M. quinquenervia, but demands more study on our altered landscapes.