1. a Department of Ecosystem Biology , University of South Bohemia, České Budějovice , Czech Republic
2. b Institute of Botany of ASCR, Třeboň , Czech Republic
3. c Administration of the Šumava National Park and Protected Landscape Area , Kašperské , Hory , Czech Republic
4. d Peatland Ecology Group, Department of Forest Sciences , University of Helsinki , Finland
5. e University of Eastern Finland, School of Forest Sciences , Joensuu , Finland