1. Department of Forestry, Ahar Faculty of Agriculture and Natural Resources, University of Tabriz, Tabriz 53548-54517, Iran
2. Department of Food and Resource Economics, Faculty of Science, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg, Denmark
3. Forest Researches Division, Research Institute of Forests and Rangelands, Agricultural Research, Education and Extension Organization, Tehran 13185-116, Iran
4. School of Environment and Sustainability, University of Michigan, Ann Arbor, MI 48109, USA