1. Institute of Forestry and Rural Engineering; Estonian University of Life Sciences; Kreutzwaldi 5 51014 Tartu Estonia
2. Department of Forest Resources; University of Minnesota; 115 Green Hall 1530 Cleveland Avenue North St Paul Minnesota 55108 USA
3. Center for Forest Disturbance Science; USDA Forest Service; 320 Green Street Athens Georgia 30602 USA
4. Latvian State Forest Research Institute “Silava”; Rigas 111 2169 Salaspils Latvia
5. Department of Forest Sciences; University of Helsinki; Latokartanonkaari 7 00014 Helsinki Finland
6. Faculty of Forestry and Ecology; Institute of Environment and Ecology; Aleksandras Stulginskis University; Studentu 11 Akademija 53361 Kaunas District Lithuania