• Effect of Jointworms on the Growth and Reproduction of Four Native Range Grasses of Idaho

      Spears, B. M.; Barr, W. F. (Society for Range Management, 1985-01-01)
      A study of jointworm larvae (Tetramesa Walk.) feeding in 4 native range grasses of Idaho was conducted to determine effects on their hosts. These insects were responsible for a decrease in the length of reproductive culms of red threeawn (Aristida longiseta Steud.), bottlebrush squirreltail (Sitanion hystrix (Nutt.) J.G. Smith), sand dropseed (Sporobolus cryptandrus (Torr.) A. Gray), and needleandthread (Stipa comata Trin. and Rupr.) Jointworms caused a decrease in the number of spikelets produced per inflorescence in bottlebush squirreltail and needleandthread, and a decrease in the inflorescence length of sand dropseed. They caused a decrease in seed weight, percentage germination, and germination rate of all 4 grasses. By adversely affecting native grasses, these insects contribute significantly to the degradation of valuable rangelands, and their control may be desirable.
    • Mechanical renovation of shortgrass prairie for increased herbage production

      Griffith, L. W.; Schuman, G. E.; Rauzi, F.; Baumgartner, R. E. (Society for Range Management, 1985-01-01)
      A study to determine the effects of single ripping, double ripping, and contour furrowing treatments was conducted on shortgrass rangeland in southeastern Wyoming from 1979-1982. The mechanical treatments changed species composition and increased total forage production over the control. Western wheatgrass (Agropyron smithii Rydb.) exhibited increased production on the treated areas compared to the control. Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Griffiths] production was significantly lower on the double ripping (1981 and 1982) and the contour furrow (1981) treatments than on the control. Needle-and-thread (Stipa comata Trin. & Rupr.) exhibited an increasing trend on the single and double ripping treatment over the control treatment all 4 years. Forbs also showed his trend in 1979, 1980 and 1981 on all renovation treatments, however little difference in forb production was evident in 1982. Total production differences were the greatest in the first year of renovation (1979) and in 1980 when the annual precipitation was below the long-term average. Increased livestock carrying capacities would result in payback of the renovation costs in 4 years.
    • Nutritional and Physical Attributes of Seeds of Some Common Sagebrush-steppe Plants: Some Implications for Ecological Theory and Management

      Kelrick, M. R.; MacMahon, J. A. (Society for Range Management, 1985-01-01)
      A study was conducted to identify seed attributes which might influence granivore preferences. Physical and chemical characteristics were estimated for seeds of 7 common sagebrush-steppe species (Artemisia tridentata, Bromus tectorum, Oryzopsis hymenoides, Pascopyrum smithii, Purshia tridentata, Stipa comata and Stipa viridula) and 1 sacrifice food species (Panicum miliaceum). Seed weights and caloric contents were determined, as well as % composition contributed by 5 organic, 3 inorganic and 5 synthetically defined fractions (including crude protein, solvent extract, structural and soluble carbohydrates and lignin). Results indicate that % soluble carbohydrate may be a good predictor of granivore seed preference. The generality of this or any other predictor is unknown, since sufficiently detailed seed attribute data are unavailable for most species. For management scenarios involving seeds subject to predation, such data would help effectively translate ecological understanding of granivory into more efficient management practices.