Thousands of alien species could invade the Arctic

Species that are not native to an area can displace species that already live there. 

The Intergovernmental Panel on Nature (IPBES) considers this to be one of the greatest threats to species diversity on our planet.

Researchers have now catalogued which alien plants may pose a threat to plants in the Arctic. 

The results are concerning, particularly at a time when it has probably never been easier for alien species to spread.

“We found a total of 2,554 species that would find a suitable climatic niche in today’s Arctic,” says Kristine Bakke Westergaard, an associate professor at the NTNU University Museum's Department of Natural History.

This means that these plants have a chance of making it in the Arctic if they manage to find a way there. They can do so, for example, by hitchhiking with humans.

“Our results show that alien species from virtually all over the world can find a niche in the Arctic. And with all the human activity in the Arctic now, there are lots of opportunities to get there,” the researcher says.

Data from more than 51 million occurrences

Together with colleagues from the Department of Natural History and the University of Liverpool, Westergaard carried out a so-called ‘horizon scan.’

“We looked at roughly 14,000 known alien plant species that can spread to places where they do not originally belong,” she says.

The researchers used data from over 51 million known occurrences of these species. They found this information in the GBIF – the Global Biodiversity Information Facility, in large databases, and in scientific literature.

Tor Henrik Ulsted began the work as a master’s student at the NTNU University Museum until 2024. He has since worked to get the article published.

Norway is a high-risk country

The researchers used the data to create a map that provides an overview of the most threatened areas.

“Our map shows hotspot areas in the Arctic where many alien species can tolerate the climate. The highest number of species are found in the north of Norway,” Ulsted says.

While Norway is among the high-risk areas, few – if any – places in the Arctic are completely safe. Not even Svalbard.

“Even in Svalbard, 86 alien species can find a climatic niche,” says Westergaard, who has personally found and studied alien species there.

Conditions in the north are changing rapidly. In recent years, it has generally become warmer in the Arctic, meaning that more and more alien species can find a possible niche where they can thrive.

Tools for those assessing the threat

Expert committees are often appointed to assess the risk of alien species in different areas. The Norwegian Biodiversity Information Centre's committees do this for Norway and Svalbard.

“These committees have long found it to be very laborious, almost impossible, to make a list of relevant species that should be assessed as possible new alien species,” says Westergaard.

Experts on these committees can now use the new methodology as a tool. They can review the species lists from this work and assess the ecological risk of each species.

“Our long-term goal is to help identify alien species before they become invasive and problematic,” Ulsted says.

It's far more effective to identify and manage such species as early as possible rather than waiting until they are well established, he adds.

Westergaard says this approach also aligns with target number six of the Kunming-Montreal Global Biodiversity Framework.

The goal is to reduce the threat from alien species, including by halving the introduction and establishment of alien species by 2030.

Reference:

Ulsted et al. Horizon scanning of potential new alien vascular plant species and their climatic niche space across the Arctic,  NeoBiota, 2025. DOI: 10.3897/neobiota.104.165054

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Read the Norwegian version of this article on forskning.no

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