1. School of Forestry, Northern Arizona University, 200 East Pine Knoll Drive, Flagstaff, AZ 86011-5018, USA.
2. Warnell School of Forestry and Natural Resources, University of Georgia, 180 East Green Street, Athens, GA 30602-2152, USA.
3. Warner College of Natural Resources, Colorado State University, 1401 Campus Delivery, Fort Collins, CO 80523-1401, USA.