1. a Land and Water , CSIRO , GPO Box 1666, Canberra , ACT , 2601 , Australia E-mail:
2. b Land and Water , CSIRO , GPO Box 1666, Canberra , ACT , 2601 , Australia
3. c Forestry and Forest Products , CSIRO , PO Box E4008, Kingston , ACT , 2604 , Australia
4. d Queensland Department of Natural Resources , Resource Sciences Centre , 80 Meiers Road, Indooroopilly , Q , 4068 , Australia