Alien species – Worst list: Threatens Norwegian nature

Alien species are considered one of the biggest threats to natural diversity both in Norway and in the rest of the world.

– Certain species are considered to have a potentially large effect on particularly threatened species or habitat types, explains Jørgen Rosvold of the Norwegian Institute for Natural Research (NINA) to Dagbladet.

When asked which species are the worst, Rosvold cites these examples:

• Wrinkle rosacea
• White medlar
• Hedge lupine
• Plantain salary
• Signalkreps
• Canada goose
• Japanese drive pliers
• Sitka spruce
• King crab
• Mink

– These are some of the “worst things”, which have been assessed as having both great spreading potential and a great effect on species and nature in Norway, says Rosvold to Dagbladet.

He is head of research at the department for terrestrial biodiversity at NINA.

Planteimport

These species are classified as very high risk i Alien species list to the Artsdata Bank, and Rosvold describes them as “very problematic”.

– There is a constant supply of foreign species to Norway, so the problem is expected to increase in the future, says the researcher.

He points out that plant imports are one of the main routes for the spread of foreign species into Norway.

A number of stowaways are also included in the load. In the soil of the plants there can be, among other things, seeds, insects, spiders and other animals.

Over the past 20 years, the importation of plants into Norway has increased significantly, and since 2014, NINA, commissioned by the Norwegian Environment Agency, has developed the monitoring of alien species that accompany imported plants.

So far, well over 200 alien species and over 1 million individuals have been discovered.

“Most problematic”

Senior researcher Olga Hilmo, subject manager for alien species in the Species Data Bank, also points out garden lupine among examples of species in the Artdatabank’s “very high risk” category.

Other species she mentions are;

• Parkslirekne
• Alpine golden rain
• Japanese sea urchin, “harbour vomit”
• Pacific oysters
• King crab
• Brown forest snail

– A species that has perhaps gone a little under the radar, considering the ecological consequences it has, is red elderberry. It can also be mentioned as one of the most problematic alien species, she says.

Hilmo tells Dagbladet that most of the alien species come from areas with a warmer climate than we have in Norway.

A warmer climate threatens

– A large proportion of alien species come from Europe, but many also come from other parts of the world, particularly Asia and North America, says Hilmo.

According to Hilmo, the ongoing climate changes will mean that more and more of the foreigners will be able to survive outdoors in Norway. A warmer climate will favor both the establishment and spread of more heat-loving species.

– This also includes disease-causing parasitic species that can attack native species. Examples here are species in the genus Phytophthora, which belong to spore fungi. These are found in soil on imported plants.

Many of the Phytophthora species attack trees and cause extensive forest damage. It has already happened in this country. An example is the attack on trees along both Akerselva and Glomma, explains Hilmo.

Several species in the genus are to be risk assessed in the Alien Species List 2023.

Can cross the threshold

– With climate change, some of the alien species that currently only manage indoors will also be able to establish themselves outdoors, explains Hilmo.

An example is insects that currently live indoors, but can cross the doorstep and establish themselves outside when the climate changes.

In the Alien Species List 2023, the Species Data Bank focuses on species that have not yet become established in the wild, but which are likely to become so in the long term, partly due to climate change. These are called threshold species.

– When the risk assessment has been completed, we will know more about which doorstep species may become problematic in the future, and the authorities can therefore take measures before the species have time to spread into the wild, says Hilmo.

Wants to move outdoors

The garden plants also form a large group of alien species that can take the leap into nature when the climate changes.

– Many garden plants are already well established in nature, but with increased temperatures and a longer growing season, more will follow.

Almost every year, one or more foreign vascular plants that have never previously been shown to reproduce are found with their first reproductive populations in Norway.

– An example is Vaccinium corymbosumoften called American blueberry, which has only recently been observed in the wild, she explains.

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