Invasive species have been a growing concern over the last few decades. Current research focuses almost entirely on non-native species invasion, with many arguing that origin of a species is a primary factor in determining management status. In the face of wide-spread, dramatic anthropogenic change, however, native species have been found to experience swift range expansion and have many of the same undesirable impacts on the systems in which they originate; thus, some argue for impact assessment as the driver of species management. In this thesis, I aim first to find a theoretical middle ground that utilizes both origin and impact in determining the appropriateness of species management. I then focus on a native Western Australian tree Allocasuarina huegeliana invading into adjacent heathlands. This study was guided by previous work and management concerns that the invasion, thought to be caused by shifting fire regimes, is decreasing heathland diversity. I quantified the strength of the relationships between the invasion, shifted fire regimes, and biodiversity through observational study of A. huegeliana densities, time since last fire, and species loss in eleven individual heath patches. I found a strong relationship between the invasion and species loss, supporting the hypothesis that A. huegeliana is a driver of ecological change in invaded systems. I then used simulation modeling to examine the effect of fire and other management tactics on A. huegeliana population spread. I found that fire-based management is potentially a viable control method, though current return intervals are inadequate.
|Publication status||Unpublished - 2012|