Rising human activity in the Arctic, combined with a warming climate, increases the probability of the introduction and establishment of alien plant species. While settlements are known hotspots for persistent populations, little is known about colonization of particularly susceptible natural habitats. Systematic monitoring is lacking and available survey methods vary greatly.

Here we present the most comprehensive survey of alien vascular plant species in the high-Arctic archipelago of Svalbard to date, aimed at: i) providing a status within settlements; ii) surveying high-risk habitats such as those with high visitor numbers and nutrient enrichment from sea bird colonies; iii) presenting a systematic monitoring method that can be implemented in future work on alien plant species in Arctic environments; and iv) discuss possibilities for mapping alien plant habitats using Unmanned Arial Vehicles (UAVs).

The systematic grid survey, covering 1.7km² over three settlements and six bird cliffs, detected 36 alien plant species. Alien plant species were exclusively found in areas of human activity, particularly areas associated with current, or historic animal husbandry. The survey identified the successful eradication of Anthricus sylvestris in Barentsburg, as well as the rapid expansion of Taraxacum sect. Ruderalia over the last few decades.

As there is currently no consistent method for monitoring alien plant species tailored to polar environments, we propose a systematic methodology that could be implemented within a structured monitoring regime as part of an adaptive monitoring strategy towards alien species in the Arctic.