Moving out of town? The status of alien plants in high-Arctic Svalbard, and a method for monitoring of alien flora in high-risk, polar environments

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.