Hotspots of plant invasion predicted by propagule pressure and ecosystem characteristics
Notwithstanding recent evidence suggesting a link between plant invasiveness and performance-related traits, species that are invasive in one ecosystem will not necessarily be invasive elsewhere. More general predictions that focus on landscape susceptibility to invasion are required, as some habitats are more easily invaded than others.
To develop a method for characterizing invasion risk at the landscape scale that is not species-specific, the Corangamite catchment in Victoria (Australia) has been taken as a study area. Data on occurrence and cover abundance of all exotic species were modeled and analyzed. The expected proportional cover of a species was expressed as a function of the environmental conditions and of specific locations studied. Variables indicating propagule pressure, human impact, abiotic and community characteristics were rated as the top four most influential variables. It appeared that the predicted probability of all exotic species occurrence was the highest in the flat, central region of Victoria where elevation is low and the land is predominantly used for non-irrigated agriculture. The likelihood of an exotic species occurring in a site was lowest in areas of higher elevation such as around the Great Otway National Park and the forested area located at the east of Ballarat. The expected abundance of all exotic species was also highest around towns. Expected abundance was also elevated within 200 m of watercourses and roads. These results enable spatial prioritization of IAP surveillance and control in the areas most susceptible to invasions.
Sources
Catford JA, Vesk PA, White MD, Wintle BA (2011) Hotspots of plant invasion predicted by propagule pressure and ecosystem characteristics. Diversity and Distributions 17, 1099-1110.