1. Department of Forest Ecology; Faculty of Forestry and Wood science; Czech University of Life Sciences; Kamýcká 1176 CZ-16521 Praha Czech Republic
2. Department of Nonlinear Modeling; Institute of Computer Science; Academy of Sciences of the Czech Republic; Pod Vodárenskou věží 2 CZ-18207 Prague 8 Czech Republic
3. Department of Forestry and Renewable Forest Resources; University of Ljubljana; Vecna Pot 83 SI-1000 Ljubljana Slovenia
4. Swedish University of Agricultural Sciences - SLU; Southern Swedish Forest Research Centre; Box 49 230 53 Alnarp Sweden