Risk assessment of alien plants in the Southern Ocean - Using distribution modelling approaches to predict potential future invaders

Abstract

As invasive species continue to spread, they increasingly threaten indigenous biodiversity. In isolated island systems, alien invasions particularly pose a risk to native species. The remote Southern Ocean Islands (SOIs. are minimally influenced by human development and disturbance; nevertheless, substantial numbers of alien species have reached the SOIs. To mitigate future invasions, predicting the potential for new invasions to the SOIs is thus essential. Since prevention of introductions of new species is widely recognised as the most cost-effective measure in combatting the threats posed by new and emerging invasive species, we performed a risk assessment of global invaders to the SOIs. Because people travel to the SOIs from across the world, a potentially wide-ranging pool of propagules could be introduced to the region. However, this large potential source pool can be narrowed by only considering species that are climatically suited to survive on SOIs. For this purpose, climate-matching provides a useful first prediction of potential invaders to a region. Therefore, we used a climate-matching approach to predict which global plant invaders have the potential to establish on the SOIs if introduced, and which islands are most prone to invasions. A list of over 13000 global plant invaders, i.e. species with a known history of invasion, was compiled, and occurrence data for these species assembled. Species distribution models were then run for 8564 of these species to establish whether the climate envelopes of the global invaders overlap with the climate conditions of the SOIs. We also examined how invasion risk is expected to change under a climate change scenario. Despite their isolation and relatively cold climates, SOIs are vulnerable to invasive species establishment, and this risk will be worsened under future climate change. It is imperative that biosecurity measures for the region remain strict. - Abstract as displayed in the - Abstract booklet. The presentation on the day may differ from the - Abstract.