EPPO Global Database

EPPO Reporting Service no. 11 - 2013 Num. article: 2013/253

Understanding misunderstandings in invasion science: why it is difficult to reach an agreement on common concepts and risk assessments

Understanding the diverging opinions of academic experts, stakeholders and the public on invasive alien species is important for effective conservation management. This is especially so when a consensus is needed for action to minimize future risks but the knowledge upon which to base this action is uncertain or missing.
To characterize experts’ understanding and valuation of alien and invasive species, structured qualitative interviews were performed on 26 academic experts, 13 of whom were invasion biologists and 13 landscape experts. Within both groups, thinking varied widely, not only about basic concepts (e.g., what is meant by non-native or alien, by invasive), but also about their valuation of effects of invasive species. The divergent opinions among experts, regarding both the overall severity of the problem in Europe and its importance for ecosystem services, contrasted strongly with the apparent consensus that emerges from scientific synthesis articles and policy documents. The authors postulate that the observed heterogeneity of expert judgments is related to 3 major factors:
  • Diverging conceptual understanding (i.e. on the definitions of alien and invasive species);
  • Lack of empirical information and high scientific uncertainty due to complexities and contingencies of invasion processes, and;
  • Deliberation of values necessary.
The notion of an invasive alien species is therefore interpreted as a ‘boundary object’, i.e. a concept that has a similar but not identical meaning to different groups of experts and stakeholders. As a consequence, the sometimes vigorous conflicts between social and natural scientists related to the invasive alien species issue may have arisen from a failure to recognize that they were using the same term to mean different things. Social scientists, accustomed to deliberations about the cultural connotations of terms like alien or non-native, accuse invasion biologists of being xenophobic, though biologists use the term in a very different context and usually without any cultural connotations.
An alternative to seeking consensus on exact definitions and risk assessments would be for invasive alien species experts to acknowledge uncertainties and engage transparently with stakeholders and the public in deliberations about conflicting opinions, taking the role of providers of policy alternatives rather than being advocates of certain issues.


Humair F, Edwards PJ, Siegrist M ; Kueffer C (2013) Understanding misunderstandings in invasion science: why experts don’t agree on common concepts and risk assessments. Neobiota (in press).
Franziska Humair, ETH Zürich, Switzerland, E-mail: fhumair@ethz.ch