Native ranges of Utah are extremely heterogeneous. Pronounced variations exist in soil, seasonal rainfall, temperatures, and altitude on most grazing areas. Rough topography and micro-climates on even individual grazing allotments present variable vegetation types and site conditions. Such variations account for the comparatively large number of species and variable nutritive content found in range forage.
Cook, C. Wayne and Harris, Lorin E., "Bulletin No. 344 - The Nutritive Value of Range Forage as Affected by Vegetation Type, Site, and State of Maturity" (1950). UAES Bulletins. Paper 305.