A professor of Environmental Sciences who studies terrestrial and wetland ecosystems and their functioning in a changing world (land use change, water management, global change). His key expertise is in eco-hydrology, landscape ecology, biogeochemical cycles, biodiversity and nature conservation. He has given > 200 presentations, convened a number of top class symposia and conferences and has published > 180 peer reviewed articles in refereed journals. He was head of the research group Environmental Sciences (2000-2023) and was head of the Copernicus Institute of Sustainable Development (2007-2016) at the Faculty of Geosciences, Utrecht University. He acts as a member of external review commissions (Dutch National Research Council (NWO), EU, external academic research assessments) and he is a regular reviewer of manuscripts for high impact journals. He is member of the Editorial Board of the Journal of Water and land Development. He was awarded with a honorary medal by the Institute for Land Reclamation and Grassland Farming, IMUZ, Poland (2005) and in 2007 and 2024 he received a honorary award of Warsaw University of Life Sciences, SGGW, Poland. He is active in several advisory commissions and committees on nature protection, nature restoration, biodiversity and land use in the Netherlands. He is chairing the European Bison Re-introduction Project, National Park Zuid Kennemerland and is member of the Advisory Committee National Parks for the minister of Agriculture, Nature and Food supply (NL) and is a member of the Dutch Ecological Authority. He was vice-president of the board of Vereniging Natuurmonumenten (2007-2015), an influential NGO for nature protection in the Netherlands with c. 900.000 members.