1. Department of Agroecology and Crop Production, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 165 21 Prague 6, Suchdol, Czech Republic
2. Institute of Forest Ecology, Slovak Academy of Sciences, Ľ. Štúra 2, 96053 Zvolen, Slovakia; E-mail:
3. Institute of Landscape Ecology, Slovak Academy of Sciences, Nitra Branch, Akademická 2, 94901 Nitra, Slovakia