Alien species in Norway: Results from quantitative ecological impact assessments

• Published in: Ecological Solutions and Evidence
• Main Authors: Hanno Sandvik, Olga Hilmo, Snorre Henriksen, Reidar Elven, Per Arvid Åsen, Hanne Hegre, Oddvar Pedersen, Per Anker Pedersen, Heidi Solstad, Vigdis Vandvik, Kristine B. Westergaard, Frode Ødegaard, Sandra Åström, Hallvard Elven, Anders Endrestøl, Øivind Gammelmo, Bjørn Arild Hatteland, Halvor Solheim, Björn Nordén, Leif Sundheim, Venche Talgø, Tone Falkenhaug, Bjørn Gulliksen, Anders Jelmert, Eivind Oug, Jan Sundet, Elisabet Forsgren, Anders Finstad, Trygve Hesthagen, Kjell Nedreaas, Rupert Wienerroither, Vivian Husa, Stein Fredriksen, Kjersti Sjøtun, Henning Steen, Haakon Hansen, Inger S. Hamnes, Egil Karlsbakk, Christer Magnusson, Bjørnar Ytrehus, Hans Christian Pedersen, Jon E. Swenson, Per Ole Syvertsen, Bård Gunnar Stokke, Jan Ove Gjershaug, Dag Dolmen, Gaute Kjærstad, Stein Ivar Johnsen, Thomas C. Jensen, Kristian Hassel
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2020
• Subjects: door‐knocker species; ecological effect; ecological impact; evidence‐based management; genetic contamination; invasion potential; Environmental sciences; GE1-350; Ecology; QH540-549.5; Arctic; Jan Mayen; Norway; Svalbard; Arctic Archipelago
• Online Access: https://doi.org/10.1002/2688-8319.12006; https://doaj.org/article/7c5452d8c1ce4492b38ca84d2eecb27e

Abstract 1. Due to globalisation, trade and transport, the spread of alien species is increasing dramatically. Some alien species become ecologically harmful by threatening native biota. This can lead to irreversible changes in local biodiversity and ecosystem functioning, and, ultimately, to biotic homogenisation. 2. We risk‐assessed all alien plants, animals, fungi and algae, within certain delimitations, that are known to reproduce in Norway. Mainland Norway and the Arctic archipelago of Svalbard plus Jan Mayen were treated as separate assessment areas. Assessments followed the Generic Ecological Impact Assessment of Alien Species (GEIAA) protocol, which uses a fully quantitative set of criteria. 3. A total of 1,519 species were risk‐assessed, of which 1,183 were species reproducing in mainland Norway. Among these, 9% were assessed to have a severe impact, 7% high impact, 7% potentially high impact, and 49% low impact, whereas 29% had no known impact. In Svalbard, 16 alien species were reproducing, one of which with a severe impact. 4. The impact assessments also covered 319 so‐called door‐knockers, that is, species that are likely to establish in Norway within 50 years, and 12 regionally alien species. Of the door‐knockers, 8% and 10% were assessed to have a severe and high impact, respectively. 5. The impact category of most species was driven by negative interactions with native species, transformation of threatened ecosystems, or genetic contamination. The proportion of alien species with high or severe impact varied significantly across the different pathways of introduction, taxonomic groups, time of introduction and the environments colonised, but not across continents of origin. 6. Given the large number of alien species reproducing in Norway and the preponderance of species with low impact, it is neither realistic nor necessary to eradicate all of them. Our results can guide management authorities in two ways. First, the use of quantitative assessment criteria facilitates the prioritisation of ...