Alien species

Nature is characterised by change

Sweden’s flora and fauna are constantly changing. Since the ice sheets began to withdraw from southern Sweden for circa 15 000 years ago different species have dominated the landscape. Initially the climate and the ability of species to spread determined where species existed.  Already at the beginning of the Neolithic age over 6 000 years ago man began to have a large influence on which species were present in the landscape. In terms of horticulture, agriculture and forestry man has promoted, and in certain cases introduced, species of great value. Many of the crops in Sweden originated in southern Europe or the Middle East and during the last three hundred years the prevalence of species from North and South America has increased significantly. Since the middle of the 20th century conifers have been imported from alien provenances and at present there are few forest plants that have a Swedish origin.

New species are discovered every year

Every year numerous new species are discovered in Sweden. This may include species that disperse and enter the country in a natural way, as well as species that have existed here for some time but have only recently been discovered. Common to these new species is that they made their way to Sweden unaided.

What is an alien species?

In addition to the new species discovered every year new alien species, in other words species that have arrived in Sweden due to human invention, are also discovered. Species such as turnip-rooted chervil and signal crayfish have been actively introduced to Sweden for cultivation whilst groundsel, the Spanish slug and the round goby entered as passive stowaways in imported plant material and ballast water from Poland ferries.