1. a Department of Plant Biology and Forest Genetics , Swedish University of Agricultural Sciences , PO Box 7080, SE-750 07, Uppsala, Sweden
2. b Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park , SE-751 83, Uppsala, Sweden
3. c Reindeer Husbandry Unit , Swedish University of Agricultural Sciences , SE-750 07, Uppsala, Sweden
4. d Skogforsk (The Forestry Research Institute of Sweden) , SE-918 21, Sävar, Sweden
5. e Department of Forest Ecology and Management , Swedish University of Agricultural Sciences , SE-901 83, Umeå, Sweden