Litterature review: How to assess interactions between non-native species

This is the conclusion of a report from the Norwegian Scientific Committee for Food and Environment (VKM).

“This is important for ensuring improved management of biodiversity and for meeting the requirements of the Nature Diversity Act concerning holistic environmental assessments,” says Gaute Velle. He is the chair of VKM’s Panel on Biodiversity and led the project group for this scientific work.

Background

Climate change, global trade, and human land use all lead to the establishment of species in new environments where they do not naturally belong—so-called ‘alien’ species. This poses challenges for biodiversity, as these species may compete with native species, introduce diseases, and alter food webs.

“Management of alien species in Norway has so far focused mainly on the risks posed by individual species. However, several alien species often occur together in the same area. Interactions among these species may result in cumulative effects that are either greater or smaller than the sum of their individual impacts,” Velle explains.

What is known about cumulative effects

VKM has investigated how cumulative effects can be better assessed.

Non-native species may influence one another in several ways—for example through competition, predation, disease transmission, or indirectly through changes in habitat or food web structure. Certain areas in Norway are particularly vulnerable, such as agricultural landscapes, transport corridors, riparian zones, ports and marine areas, and islands.

The way forward

In the report, VKM proposes how existing methods for risk assessment of individual alien species can be expanded to include interactions among multiple alien species. Qualitative assessments may be used where data is lacking, and both short- and long-term climate perspectives should be incorporated.

The project is self initiated, and the assessment has been approved by VKM’s Panel on Biodiversity.