Introduced to Norway before or after 1800?
Alien species that became established in Norway, after 1800, are to be risk-assessed. This also applies to species introduced before 1800 but which for different reasons did not become established until after 1800. Established species are those which can produce viable offspring, outdoors, without human intervention.
Regionally alien species
Alien species do not necessarily come from far away. In the Norwegian Biodiversity Information Centre's new risk assessment 12 native species are also considered to be alien but only in certain parts of the country.
Alien species can influence the nature on Svalbard
Arctic environments like Svalbard are especially vulnerable, and alien species that gain a foothold can have severe consequences for native habitats. In 2018 an increasing number of alien species were risk-assessed for Svalbard. The majority of these are door knocker species.