Invasive alien species in Switzerland - Schweizer ...

Résumé 23
in this report on the basis of the available knowledge, which reflects difficulties in
monitoring and taxonomy and also the importance of the different groups.
The taxonomic groups chosen, i.e. vertebrates, insects, crustaceans, arachnids, molluscs,
other animals, plants and fungi, are the basis of separate chapters presenting lists
of alien species and additional information about them, Fact Sheets for the invasive
species, and finally an evaluation of the status, impacts, pathways, control options and
recommendations for the alien species of each group. The Fact Sheets summarize
information on the invasive species under the headings taxonomy, description, ecology,
origin, introduction, distribution, impact, management and references. A special focus
is given to information on impacts of the species on the environment and economy to
indicate their detrimental nature and the importance of managing them. This information
is often difficult to find but crucial to show the true potential threat to Switzerland
without being hysterical about it.
All signatories to the Convention on Biological Diversity (CBD), including Switzerland,
are obliged to prevent the introduction of, control or eradicate those alien species
which threaten ecosystems, habitats or species. There are other international instruments,
ratified by Switzerland, calling for management of invasive species, e.g. the
Convention on the Conservation of Migratory Species of Wild Animals and the Convention
on the Conservation of European Wildlife and Natural Habitats. This report
can also be used in response to the call from the CBD Secretariat for countries to
produce lists of alien species and can provide information for a national strategy on
IAS.
The importance of IAS is increasingly recognized in Central Europe, indicated by the
recently published book Neobiota in Österreich (Essl and Rabitsch, 2002) and the very
recently produced Gebietsfremde Arten; Positionspapier des Bundesamtes für Naturschutz
in Germany (Klingenstein et al., 2005).
The following sections of this chapter explain the definitions used in the report, then
present a predominantly global perspective of the IAS issue, with examples from
Switzerland. Evaluations of pathways, origins of the species, number of alien species in
comparison to native species, their impacts, management options and other trends are
given in the chapters on the taxonomic groups. An overall evaluation of these factors
was attempted, but it became obvious that that was not a constructive exercise, since
the clear trends in some taxonomic groups were diluted and combining groups with
very different knowledge bases made it difficult to compare the results. However,
within the groups, trends are often very obvious and for these readers are referred to
the chapters on the taxonomic groups.
1.1 Definitions
Definitions used in relation to IAS are as varied as the species themselves. The term
‘invasive’, for instance, is used in one extreme, to describe a population that is expand-