IPBES just published a new report on invasive species assessment (media release - report). In it, they estimate that invasive species are a contributing factor in 60% of species extinctions worldwide with being the sole driver in about 16% of those extinctions. On islands, 90% of extinctions can be contributed mainly to invasive species. Yikes! Invasive vertebrates seem to have the most devastating impacts in this regard. I think this demonstrates again the value in documenting “feral” instances of introduced species.
According to the report, there are over 37,000 alien species recorded worldwide, with over 3,500 being invasive, so that’s about a 1 in 10 ratio for alien species turning invasive. They also provide some helpful definitions on page 3 of the report. I know this has come up in discussions before so here’s what they are operating with:
Native species - A species (animal, plant or other organism) within its natural range including shifting its range, without human involvement.
Alien species - A species whose presence in a region is attributable to human activities that have enabled it to overcome its barriers that define its natural range.
Established alien species - A subset of alien species that have produced a viable, self-sustaining population and may have spread.
Invasive alien species - A subset of established alien species that spread and have a negative impact on biodiversity, local ecosystems and species. Many invasive alien species also have impacts on nature’s contributions to people (embodying different concepts, such as ecosystem goods and services and nature’s gifts) and good quality of life.
They also comment on strategies to combat alien invasions. Under C18, it specifically mentions citizen science as a surveillance strategy that can help with early detection and enable rapid intervention. This is where it ties in with iNaturalist. In fact, appendix III lists iNaturalist on top of the tools suggested for identification. I also found appendix II listing knowledge and data gaps interesting as well.
I know it’s a long report to read but it might be worth a look. Apparently it is the first report looking at this in such a global context. I’m curious what others are finding the most new or interesting about it. For example, I was surprised by some of their top contenders for invasives with negative impacts, such as lantana which always seemed like a fairly innocuous garden plant to me. I may have to rethink my “probably planted” attitude on that one.