• 1976-1986: Research Assistant and Research Associate, University of Antwerp, Belgium
  • 1987-1988: Visiting Professor, University of Washington, Seattle, USA
  • 1988-1989: Research Scientist, Government Poplar Research Station, Geraardsbergen, Belgium
  • 1989: Visiting Professor, University of Paris-XI, Orsay, France
  • 1990-1999: Research Director of the Fund for Scientific Research-Flanders at the University of Antwerp, Belgium
  • 1999-2019: Full Professor at the Department of Biology, University of Antwerp and Director of Research Group of Plants and Ecosystems
  • 2001-2004: Vice-Chair  of the Department of Biology, University of Antwerp
  • 2004-2006: Chair of the Department of Biology, University of Antwerp
  • 2006-2009: Vice-Dean of the Faculty of Sciences, University of Antwerp
  • 2008-2019: Director, Research Center of Excellence
  • 2013-2019: Visiting Professor, University of Ghent
  • Since 1 Oct. 2019: Emeritus professor, Department of Biology, University of Antwerp and Chair Scientific and Ethical Board, CzechGlobe