For the purposes of this study, impacts were assessed in terms of the potential role Coralita was having on the environment of the islands, in terms of directly affecting local plant species, and affecting plant communities and their characteristics. An assessment of the direct socio-economic consequences of Coralita was not in the scope of this research.
Luke used three key data sources. Firstly, vegetation maps detailing the types of species and their abundance were used to establish the extent of Coralita (and other plant species) on the islands. Although this information was not recent (from the early 1990s), it represented the most comprehensive means to describe where Coralita could be found and to assess how Coralita was affecting other plant species. Important to note was that this information concerned only part of the surface area of the islands; more urban areas were not included within this prior research, which has corresponding implications as to the impact that Coralita might be having. A second key data source was an online database maintained by the IUCN detailing invasive species and the types of impacts that they had been identified as having. Coralita could thus be compared to these species and parallels could potentially be drawn between the circumstances on the islands and the documented impacts for other species in similar circumstances. Finally, information regarding the characteristics (traits) of Coralita, other species identified on the islands and those invasive plant species identified as having an impact was requested from the TRY plant trait database. This information could be used to explore how unusual Coralita was compared to other local species, and inferences could be drawn as to the changes occurring at the plant community level due to the spread of Coralita. This data was analysed using a variety of statistical techniques.
Overall, the impact of Coralita on individual species and plant communities was classed as moderate. This reflected potential impacts on biodiversity, whereby the number of species in the area where Coralita was most prevalent appeared to be less, the likely impacts as a result of comparison with other invasive species and some limited evidence of competitive exclusion of some species in some areas. Trait-based evidence appears to show that Coralita has more in common with other invasive species than island species, and as such is likely to impact the structure of communities where it is found (i.e. changing the average characteristics of the community, such as plant height, or leaf area), with corresponding implications for the ecosystem function. On the contrary, analysis associated with traits and levels of abundance used for this study suggest that Coralita is not currently having a substantial impact across the areas that it is found in a general sense. Although different to local species, the level of abundance of Coralita is insufficient across all locations where it is found to change community average values for characteristics in statistically significant sense.
These somewhat conflicting findings, together with a lack of certainty in relation to these findings more generally, means that further research would be recommended to build sufficient confidence that Coralita is having a major impact. In particular, research into the implications of Coralita extent in more urban areas, where disturbance is a key driver of Coralita spread, is recommended by Luke.
You can read the details of his research in his thesis, and of course, send us whatever questions you may have!