1. Department of Energy and Environment; Energy Technology; Chalmers University of Technology; SE-412 96 Göteborg Sweden
2. Department of Energy and Environment; Physical Resource Theory; Chalmers University of Technology; SE-412 96 Göteborg Sweden
3. New South Wales Department of Primary Industries/University of New England; Armidale NSW 2351 Australia
4. Department of Forest Ecology and Management; Swedish University of Agricultural Sciences; 901 83 Umeå Sweden
5. Department of Forest Resource Management; Swedish University of Agricultural Sciences; 901 83 Umeå Sweden
6. Research Institute for Environment, Energy and Economics; Appalachian State University; Boone NC 28608 USA
7. Department of Ecology; Swedish University of Agricultural Sciences; 750 07 Uppsala Sweden