The projected risk of plant invasions on the peri‐Antarctic islands under climate change

The peri‐Antarctic islands have largely been shielded from alien plant species due to low human pressure, limited introduction pathways, and local harsh climates. However, climate change is expected to lower these barriers. We assess the vulnerability of 12 peri‐Antarctic islands to invasion by 2220 plant species invasive in at least one region of the globe by projecting their climatic suitability under recent climate (1981–2010) and three future (2071–2100) climate change scenarios, ranging from mild to severe. We use three general circulation models (GCMs) and predictor sets, and account for widespread non‐analog climatic conditions by excluding projections outside the clamping mask. Our results reveal that eight islands are already climatically suitable for at least 100 invasive species. Climate change will generally increase climatic suitability for alien plants, particularly under moderate (+39% species on average across GCMs and islands) and severe climate change (+36% species). Nevertheless, under one GCM, suitability declines (−9.3% species) on eight islands under the most severe scenario. Currently, forbs and graminoids dominate native and alien plant communities, with woody species largely absent from colder islands. Our projections suggest that, if introduced, more woody alien species could establish, with all islands becoming suitable for at least one alien tree species even under moderate climate change. The greatest increases in alien species richness averaged across all scenarios and GCMs are projected for the Kerguelen (206 species) and Falkland Islands (175 species), whereas Signy (31 species), King George (72 species), and the Prince Edward Islands (54 species) will remain relatively resistant to plant invasion, despite strong proportional increases. These findings highlight an increasing vulnerability of the peri‐Antarctic island ecosystems to plant invasions and the need for strong biosecurity measures to limit further propagule introductions. Proactive management strategies are essential to mitigate risks and preserve the ecological integrity of these unique ecosystems.