1. Institute of Social Ecology Vienna, Alpen-Adria Universitaet Klagenfurt, Wien, Graz, 1070 Vienna, Austria.
2. Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY 10027, USA.
3. Department of Geography and Environmental Systems, University of Maryland, Baltimore County, Baltimore, MD 21250, USA.
4. Institute for Environmental Studies, VU University, Amsterdam, de Boelelaan 1087, 1081 HV Amsterdam, Netherlands.