1. Swiss Federal Institute for Forest Snow and Landscape Research WSL Birmensdorf Switzerland
2. Centre for Invasion Biology, Department of Botany and Zoology Stellenbosch University Stellenbosch South Africa
3. Institute of Geography and Sustainability University of Lausanne Lausanne Switzerland
4. Department of Biology, Unit Ecology and Evolution University of Fribourg Fribourg Switzerland
5. Department of Invasion Ecology Institute of Botany, Czech Academy of Sciences Průhonice Czech Republic