When a plant is introduced to a new region, it only becomes naturalized, and later, invasive, if able to overcome certain barriers. Studies indicate that only about 10 per cent of introduced plant species naturalize, and of these, only a tenth become invasive.
In order to identify parameters influencing successful transitions on the introduced—invasive continuum, this study focussed on India, home for 11 per cent of the world's plant diversity and three major biodiversity hotspots, collecting data for 715 alien plant species in the country.
For each species, the authors determined 13 variables including level of establishment, the size of native and naturalized ranges, introduction pathways, and relevant functional traits, relying on GBIF-mediated occurrence data to infer climatic preferences, land use classes and the time since introduction.
Overall, the study found that invasive alien plants had larger naturalized ranges, a greater number of uses and higher specific leaf area than their naturalized and casual counterparts. In addition to range sizes, path analyses showed that growth form directly influenced naturalization success, whereas time since introduction directly influenced invasion success, further affected by number of native congeners.
The authors emphasized inclusion of trading regulations on alien plants while promoting native species in national policy frameworks. With time having a direct impact on invasion success, alien plants already naturalized should be prioritized for early detection and removal.