An inventory of alien species and their threat to biodiversity and economy in Switzerland
This report is a compilation of information on Invasive Alien Species in Switzerland, based on scientific publications and advice from experts. Information on emerging biological invasions is also provided. For vertebrates, crustaceans, insects, arachnids, molluscs and other animals, fungi and plants, the report includes a general discussion, a list of non-indigenous species, datasheets and an assessment of status, impact, pathways of introduction, management methods and general recommendations.
For plants, the report provides a list of 362 alien species present in Switzerland, which represent 12.6% of the flora of Switzerland. The origins of alien, naturalized and invasive plants are analysed and raise interesting questions. Out of these 362 alien species, 102 species (28.2%) are naturalized and 20 (5.5%) have become invasive. Out of the 20 species considered invasive, 40% originate from North America and Asia. From the 20 invasive species in Switzerland, 15 (75%) have been deliberately introduced, usually as ornamentals.
Woody and geophytic plants account for 70% of invasive species in Switzerland, contrasting with the proportions of each life group in alien, naturalized and invasive species. With respect to plant life form, the composition of the ecological plant groups of the alien flora differs from the native one and it changes during the process of naturalization and invasion. Ruderal and pioneer species represent 60% of all invasive species, however, 40% of invasive species belong to either the forest, aquatic or marsh ecological plant groups.
A list of plants declared invasive or potentially invasive in Austria, France, Germany, Hungary, Italy, Portugal, Scotland and Spain, and present in Switzerland is also part of the report. Fact Sheets have been prepared for 48 plant species: 19 invasive species, 11 “Watch species” and another 18 to which special attention should be paid.
The review stresses the importance of establishing the biological and ecological characteristics of the naturalized flora to determine the potential invasiveness of alien species in Switzerland. The analysis of the invasive flora of several European countries shows that more than 130 alien plants are of concern in Europe. The status of alien plants in Europe should be one aspect to consider when developing a dynamic “Watch List” of alien plants in Switzerland.
Sources
Wittenberg R (ed.) (2005) An inventory of alien species and their threat to biodiversity and economy in Switzerland. CABI Bioscience Switzerland Centre report to the Swiss Agency for Environment, Forests and Landscape.
Swiss Commission for Wild Plant Conservation CPS/SKEW