[Invasive-species] criteria for a list ofinvasive species

Etienne Branquart ebranquart at gmail.com
Mon Feb 13 17:00:13 CET 2006

Hi Luc,

I produced a new version of black/watch lists according to criteria
described in the attached document (environmental hazard x naturalization
level), trying to take into account most of the suggestions provided by
forum members.

I also attached a work file including non native vertebrate species that
have been introduced in Belgium. For each species, naturalization level,
impact type (according to literature and studies in neighbour countries),
introduction date and pathway as well as black list category are specified.
At first sight, it is striking to note that most of the introductions have
been more or less deliberate and that a high proportion of acclimatised
species seems to produce environmental impacts (except for birds, nearly
half of the species are considered at high risk for biodiversity).

I think this file could be used as a good basis for preparing graphs, etc.
for the 9th March speech. Please feel free to complete it with additional

Some questions:

1. Will you take the continuation in hand ?
2. Have you already a draft text for the abstract ? (deadline is coming
3. Any ideas for the distribution maps ?

Best regards,


2006/2/9, DE BRUYN, Luc <Luc.DEBRUYN at inbo.be>:
> Hello,
> Sorry for my late response. I think we have to stick as much as possible
> to scientific, well defined definitions. My definitions (which I try to
> follow in the Flemish Nature Reports) are (very) simple:
> Alien species: all (with emphasis on all) species that occur on our
> territory and arrived here due through human intervention. This is in
> agreement with the definition used in the Netherlands and many other
> countries which had severe problems (e.g. New Zealand, Australia). For
> most species this is simple because it is known they arrived here by
> boat, airplane, ... I hve to admit it is not so clear for other species.
> Some fish species could arrive here because (new) canals form corridors
> between river catchments which were not connected earlier. Most (all?)
> people consider them as aliens. But what about man made changes that
> occurred much longer ago, and or are more gradual. For example, take
> species like the pigeon Streptopelia decaocto or ferns that grow on
> (city) walls. These species arrived in Belgium on there own power, but
> only because we changed the environment.
> Invasive alien species: species that colonise(d) (semi)natural habitats
> and some of these invasive species can have detrimental effects. The
> problem with the discrimination of both categories is that there is a
> lack of sound scientific studies. Most of the time it is based on
> subjective "gut feeling", coincidental observations or superficial
> correlative research.
> I think "assimilated" or "archeophyta" species are not a good terms in
> the scope of alien species. They are too arbitrary. First some of these
> species might become invasive/detrimental in the future (see also
> further). Second, some of these species are indeed detrimental or at
> least have important impact on our natural ecosystems. The rabbit
> changes the environment and species composition through grazing.
> Pheasants are supposed to be detrimental for our indigenous herpetofauna
> (although I do not know a scientific paper that actually proofs this,
> maybe somebody can point me to one?). We only learned to live with that
> (or we do/did not care).
> I also think it should be emphasised that all alien species are
> potential time bombs. It has been shown that species can be present for
> a long time and suddenly become invasive/detrimental due to adaptation
> of the species in question and/or changes in the environment. For
> instance, many species now confined to urban environments may become
> invasive due to climate change. It is also very important to point out
> that it is far more important to prevent the introduction of new alien
> species, than to start eradication and/or control programs for the
> (invasive) aliens present.
> Best wishes,
> Luc
> --------------------------------
> Luc De Bruyn
> Instituut voor Natuur- en bosonderzoek (INBO)
> Research Institute for Nature and Forest
> Kliniekstraat 25
> 1070 Brussel
> tel.: ++32(0)494/89.99.50
> web: www.nara.be
>      www.natuurindicatoren.be
> --------------------------------
> _______________________________________________
> Invasive-species mailing list
> Invasive-species at biodiversity.be
> http://www.biodiversity.be/cgi-bin/mailman/listinfo/invasive-species
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