The Fraser Island World Heritage Area is internationally renowned for its significant natural features; however, invasive weed species may threaten the island’sunique biodiversity. Asparagus aethiopicus is a highly invasive, bird dispersed perennial shrubfrom South Africa identified as requiring urgent control to limit its spread on Fraser Island. In this study, the potential invasion dynamics of A. aethiopicus on Fraser Island were predicted through a combination of spatial and metapopulation models. The results showed that whilst only a small part of the island is currently occupied by A. aethiopicus, a large part of the island could be potentially invaded by the species. Analysis of field data showed that the species currently has a relatively patchy distribution with low abundance, indicating an early stage of colonisation. The field data were used to parameterise and develop stage-structured stochastic models for each metapopulation of A. aethiopicus on Fraser Island, and a subsequent examination of their population dynamics under various scenarios. The model predictions indicate that populations of A. aethiopicus are likely to rapidly increase expand their distribution range dramatically in the next few years if no management action is taken. Based on the model predictions and current conditions, future management efforts would have to involve the removal of more than 90% of individuals in all stage classes (seedling, juvenile, small adult and large adult) from all populations, with follow-up control every two years to effectively delay the invasion of A. aethiopicus on Fraser Island.
Relation
4th Biennial Great Sandy Conference, Brisbane, Australia 29 July 2011
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