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About BFIS

The Belgian Forum on Invasive Species

The Belgian Forum on Invasive Species (BFIS) is an informal structure animated by the Belgian Biodiversity Platform where in scientists interested in biological invasions are involved. It encourages interdisciplinary cooperation among scientists and favours information exchange and dissemination as a support to develop measures dedicated to the prevention and the mitigation of the impacts of invasive species. The BFIS is responsible for preparing and updating the reference list of alien species invading terrestrial, freshwater and marine ecosystems in Belgium, with a focus on organisms causing a strong detrimental impact on native biodiversity.

The BFIS is the national node of the IUCN Invasive Species Specialist Group. It supports activities of the Belgian contact group on invasive species.

The invasion process

Though definitions on invasive alien species (IAS) are multiple, they are always built using various combinations of four main criteria : species origin, ability to reproduce in the wild, spatial dispersion and environmental impact. Definitions agreed by forum members are based on the different steps of the invasion process and the barriers theory developed by David Richardson et al. (2000) (figure 1).

Figure 1 - Alien species have to overcome geographic, environmental, reproductive and dispersal barriers before becoming invasive.

The term alien species is used in reference to the origin criterion, as a synonymous of exotic or non native. It refers to an organism whose presence in a given area is due to intentional or accidental introduction by man (= introduction by man outside its natural range and dispersal potential). Note that natural extension of geographic range induced by global warming is not considered here.

An alien species can be considered as acclimatised if it is able to survive for a long period of time in its new environment. It is considered as naturalised as soon as it is able to reproduce consistently in the wild and sustain populations over several life-cycles without direct intervention by man (= self-perpetuating populations).

Finally, an alien species is considered as invasive when it is naturalised and able to increase population size, to disperse widely in the environment and to colonise semi-natural habitats. This definition doesn’t take potential impact on native biodiversity into account; some invasive species can be considered as 'benign invaders' because no adverse impact on biodiversity is known.

The Harmonia information system

Harmonia is an interoperable database dedicated to alien species introduced by man on the Belgian territory or in neighbour areas after 1500. It includes:

  • exotic species naturalised in Belgium, with a focus on those that actively colonize semi-natural ecosystems and can be detrimental to the environment (black and watch list species)
  • exotic species that aren't yet observed in Belgium but are invasive in neighbour countries where they are considered as highly detrimental to biodiversity (alert list species)

New species are regularly appended to this database by Belgian scientists after being assessed through the ISEIA protocol (see hereafter). Before being published on the Web, data are reviewed for accreditation by a scientific committee.

Alert, black and watch lists of invasive species in Belgium

The environmental impact of non-native species is assessed in a standard, objective and transparent way through a simplified protocol developed by the Forum, the Invasive Species Environmental Impact Assessment (ISEIA) protocol. It consists of four sections matching the last steps of the invasion process, i.e. the potential for spreading and colonising natural habitats as well as the adverse impacts on native species and ecosystems. Scores for each section are assessed based on organism’s history of impact in neighbour areas together with their ecological profiles. More information about this protocol can be downloaded from here.

Figure 2 - List system adopted by the BFIS to identify exotic species that make a threat for native biodiversity.
Legal notice & citation

The following disclaimer applies to all Web pages managed by the Belgian Forum on Invasive Species (BFIS) unless otherwise noted.


The BFIS provides free and open access to data, information and knowledge related to invasive species in Belgium, namely through the Harmonia information system. Users of this information are expected to comply with terms of use.

While the content of many BFIS web pages is in the public domain, some pages contain pics and material that are copyrighted by others and used by BFIS with permission. You may download, display, print and copy information or material from this site only for scientific and non-commerical use. You should obtain permission from the copyright owner for other uses. Information source has to be cited based on the guidelines developed hereafter


The BFIS makes every effort to ensure the quality of the information available on this website and updates the information regularly. Data from the Harmonia database are submitted by Belgian scientists on the basis of literature information and best expert judgement before being reviewed for accreditation. The name and contact address of the scientists taking the responsibility for the information published on the Web are specified for each species included in the database together with references to the scientific literature.

Though strict criteria and definitions are used to standardise information, it is open to modifications as new species are added and/or scientific knowledge advances. This can also lead to updates of alert, black and watch lists of invasive species in Belgium and, possibly, species shift from one list to another one.

These data and information are provided with the understanding that they are not guaranteed to be correct or complete. Users are cautioned to consider carefully the provisional nature of these data and information before using them for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Conclusions drawn from, or actions undertaken on the basis of, such data and information are the sole responsibility of the user.


Cite one record of the Harmonia database as:

<name of authors (= contibutors)>, <year>, Harmonia database: <species name>. Harmonia version 1.2, Belgian Forum on Invasive Species, accessed on <day + month + year> from: http://ias.biodiversity.be

Cite whole Harmonia database as:

Harmonia database <year>, Belgian Forum on Invasive Species, accessed on <day + month + year>from: http://ias.biodiversity.be.

Cite alert, black and watch lists as follows:

E. Branquart (Ed.) <year>, Alert, black and watch lists of invasive species in Belgium. Harmonia version 1.2, Belgian Forum on Invasive species, accessed on <day + month + year> from: http://ias.biodiversity.be.

Cite the ISEIA protocol as:

E. Branquart (Ed.) <2007>, Guidelines for environmental impact assessment and list classification of non-native organisms in Belgium.

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