1. Experimental Plant Ecology Institute of Botany and Landscape Ecology University of Greifswald Greifswald Germany
2. Plant Ecology Albrecht von Haller Institute for Plant Sciences University of Goettingen Goettingen Germany
3. Department of Silviculture and Genetics of Forest Trees Forest Research Institute Raszyn Poland
4. Landscape Ecology and Ecosystem Dynamics Institute of Botany and Landscape Ecology University of Greifswald Greifswald Germany