• Identification of Subspecies of Big Sagebrush by Ultraviolet Spectrophotometry

      Shumar, M. L.; Anderson, J. E.; Reynolds, T. D. (Society for Range Management, 1982-01-01)
      The three subspecies of big sagebrush (Artemisia tridentata) are dominant shrubs over much of the Intermountain West. Because the subspecies differ in palatability and habitat requirements, researchers and resource managers have become increasingly concerned with their identification. Subspecies have been identified by leaf morphology, ultraviolet (UV) fluorescence, or chromatography. Fluorescence of leaf extracts under short-wave UV light provides a convenient technique for distinguishing between A.t. vaseyana and the other two subspecies, but this technique will not distinguish between A.t. tridentata and A.t. wyomingensis. Chromatographic techniques can differentiate between all of the subspecies, but the methods are tedious. We describe a technique for distinguishing all three subspecies by UV spectrophotometry. Alcohol leaf extracts of the three subspecies produce relative absorbance graphs that differ markedly from one another between 230 and 280 nm.
    • Response of Small Mammals to Livestock Grazing in Southcentral Idaho

      Johnson, M. K. (Society for Range Management, 1982-01-01)
      The effects of livestock grazing on populations of wildlife have been addressed in two recent studies on the INEL Site. However, studies were performed by measuring indices of abundance among areas where different practices had occurred prior to initiation of study. There is no proof that differences detected among the areas actually resulted from the land use practices. Studies should be conducted with replication and strict controls before correlated data can be accepted as indicators of cause and effect relationships. The large variation in the occurrence and densities of small mammals among areas with the same or similar uses suggests the need for further studies to resolve conflicting conclusions.
    • Summer Grazing of Sagebrush-Grass Range by Sheep

      Harniss, R. O.; Wright, H. A. (Society for Range Management, 1982-01-01)
      Sagebrush-grass range normally grazed in the spring and fall can be grazed in the summer to provide a maintenance ration for ewes if their lambs are weaned early. Moderate grazing (57-99 sheep days/ha) in early or late summer did not change vegetative composition or yields. Heavy grazing (185-198 sheep days/ha) in the early summer decreased yields of grasses and the cushion-forb Hoods phlox. Late summer grazing did not change the grass or forb yields. Sagebrush yields increased in the sagebrush subtype where balsamroot was abundant under early summer grazing.