Citation: Sandvik, H., O. Hilmo, A. G. Finstad, H. Hegre, T. L. Moen, T. Rafoss, O. Skarpaas, R. Elven, H. Sandmark, L. Gederaas (2019) Generic Ecological Impact Assessment of Alien Species (GEIAA): the third generation of assessments in Norway. Biological Invasions, 21, 2803–2810.

Key words: Ecological effect, interaction with native species, invasion potential, invasive species, quantitative set of criteria, risk assessment.

GEIAA's ecological impact matrixAbstract: The Generic Ecological Impact Assessment of Alien Species (GEIAA) is described. It comprises a set of criteria and an assessment procedure. The set of criteria consists of three criteria that quantify invasion potential, and six criteria that capture the ecological effects of alien species. The threshold values for all criteria are numerically defined, rendering the set of criteria fully quantitative. Genericity is ensured by using criteria that are applicable to all taxonomic groups and in all habitats. In being generic, quantitative, ecological and normatively neutral, the criteria were inspired by the international Red List criteria. Capturing both invasion potential and effect, GEIAA can be regarded as a full ecological impact assessment. The assessment procedure contains guidelines on documentation, the collection of background information, the handling of uncertainty, and quality assurance. GEIAA represents the second revision, and thus the third generation, of assessment methodology in Norway. It has recently been used to carry out more than 2500 impact assessments of alien species in Norway and Sweden.

Full text: © 2019 The Authors. If you accept (i) the conditions specified in the Creative Commons "Attribution" 4.0 licence, and (ii) that printouts have to be made on recycled paper, you may download the article here (pdf, 0.2 MB).

Supplementary material: Online Resource 1 of this article (GEIAA’s set of criteria – rationale, changes, estimation and documentation) is available here (pdf, 0.1 MB).

Related publications:

  1. GEIAA’s criterion B, expansion speed, has been described in more detail elsewhere.
  2. GEIAA has been applied to alien species in Norway.
  3. GEIAA has been applied to alien species in Sweden (in Swedish with English summary).
  4. GEIAA is a revised version of an earlier scheme that has been used in Norway.
  5. The quantitative nature of GEIAA’s criteria has a number of advantages.


[back / tilbake]