Great Basin Naturalist


In 1981, 20 sediment-collecting tanks and troughs were installed on range and timbered sites of the Caribou National Forest. Measured erosion losses from the first year of study were contrasted to Universal Soil Loss Equation (USLE) estimates utilizing three different vegetative factors. State of Idaho C factors, National Rangeland C factors, and the Vegetative Management (VM) factors were studied. The erosion estimates of all three USLE tests were significantly different than measured soil losses. All equations overestimated the measured mean soil loss, 0.52 megagrams/ha/yr (0.23 tons/ac/yr), by 33, 3,000, and 2,000 percent, respectively. The soil erodibility factor (K), Rangeland C, and VM showed significant relationships to soil loss. The K and VM factors accounted for 88 percent of the variability in sediment loss in multiple regression models. Erosion equations suitable for use on this study area are presented.