1. School of Natural Resources; University of Nebraska-Lincoln; Lincoln Nebraska USA
2. Now at Botany and Plant Sciences; University of California; Riverside California USA
3. Now at Department of Geography; University of North Carolina at Chapel Hill; Chapel Hill North Carolina USA
4. Department of Forestry and Environmental Resources; North Carolina State University at Raleigh; Raleigh North Carolina USA
5. Nicholas School of the Environment; Duke University; Durham North Carolina USA