1. University of Alberta, Dept. Renewable Resources, 442 Earth Sciences Bldg., Edmonton, AB, Canada
2. Instituto de Recursos Biológicos, Centro de Investigación de Recursos Naturales, Instituto Nacional de Tecnología Agropecuaria, CP 1686 Hurlingham, Buenos Aires, Argentina
3. The University of British Columbia, Dept. Forest and Conservation Sciences, Vancouver, BC, Canada