D Carl Freeman1, E Durant McArthur2, K T Harper3, A C Blauer2. 1. Department of Biological Sciences, Wayne State University, Detroit, Michigan, 48202. 2. USDA-Forest Service, Intermountain Forest and Range Experiment Station, Shurb Sciences Laboratory, Provo, Utah, 84601. 3. Department of Botany and Range Science, Brigham Young University, Provo, Utah, 84602.