1. Center for Agroforestry, School of Natural Resources, University of Missouri-Columbia, Columbia, MO, USA
2. USDA Forest Service, Northern Research Station, Rhinelander, WI, USA
3. Institute of Lowland Forestry and Environment, University of Novi Sad, Novi Sad, Serbia
4. Indian Head Research Farm, Agriculture and Agri-Food Canada, Indian Head, Saskatchewan, Canada