• The Effect of Slide and Frequency Observation Numbers on the Precision of Microhistological Analysis

      Holechek, J. L.; Vavra, M. (Society for Range Management, 1981-07-01)
      The number of slides and frequency observations per slide required for microhistological analysis was determined. Slides should be prepared so that at least 20 frequency observations are recorded per slide. When five slides were prepared per sample, reasonable estimations were obtained for species comprising 20% or more of the diet. Minor and trace species in the diet were poorly estimated indicating a large number of slides are needed for adequate precision.
    • The Oxalate, Tannin, Crude Fiber, and Crude Protein Composition of Young Plants of Some Atriplex Species

      Davis, A. M. (Society for Range Management, 1981-07-01)
      Oxalate, tannin, crude fiber, and crude protein contents were determined in 11 introduced Atriplex species and four species native to western North America that might be browsed by wildlife and livestock. Atriplex species of foreign origin resembled domestic species in content of oxalate, tannins, crude fiber, and crude protein, with averages and range similar to those of A. canescens. These foreign species could fit into a range ecosystem to improve the quality and quantity of different browse species.
    • The Productivity and Nutritive Value of Imperata cylindrica (L) Beauv. in the Thai Highlands

      Falvey, J. L.; Hengmichai, P.; Pongpiachan, P. (Society for Range Management, 1981-07-01)
      The rate of dry matter production after the annual pre-wet season burning, the rate of regrowth after cutting at three times during the year and the nitrogen content, phosphorus content and in vitro digestibility of Imperata cylindrica were studied in highlands of north Thailand over a one-year period. Dry matter production was slower than that recorded in more tropical regions and nitrogen content and digestibility correspondingly remained higher for longer. It is suggested that the slower growth rates recorded in this environment, permitted Imperata to remain a useful forage for a longer period than is usually considered possible for this species.
    • Tree Age and Dominance Patterns in Great Basin Pinyon-Juniper Woodlands

      Tausch, R. J.; West, N. E.; Nabi, A. A. (Society for Range Management, 1981-07-01)
      Prior studies of pinyon-juniper woodlands at a few locations have indicated considerable historical expansion of the trees and loss of understory. Whether these changes are a widespread phenomenon and related to pervasive, rather than local, influences was the question asked by this research. An objective sampling of 18 randomly selected mountain ranges in the Great Basin was undertaken. Tree age and dominance in the pinyon-juniper woodlands showed definite geographical, elevational, and historical trends. The oldest, most tree-dominated woodlands were located in areas of intermediate topography where disturbances may have been less frequent. Populations of both tree species [Pinus monophylla (Torr.) and Juniperus osteosperma (Torr. and Frem.)] were progressively younger and less dominant in both upslope and downslope directions from the intermediate elevations. Tree densities have also historically increased within the oldest woodlands. Pinyon density has increased faster than that of juniper. Approximately 40 percent of the sampled plots had their trees establishing during the last 150 years. These changes generally coincide with introduction of heavy livestock grazing, tree utilization by the mining industry, and fire suppression that followed settlement of the region. Associated climatic trends were also investigated. The relative importance of these influences on the changes in tree age and dominance cannot be determined without further research. The loss of understory, coincident with increasing tree dominance, has reduced forage production and made the woodlands progressively less susceptible to fire. Barring some major environmental change or management action, this forage reduction and decreased frequency of burning will continue until trees dominate much more area.
    • Variation in Defecation Rates of Pronghorns Relative to Habitat and Activity Level

      Irby, L. R. (Society for Range Management, 1981-07-01)
      During June through September, 1977, pronghorn antelope (Antilocapra americana) were observed in the National Bison Range, Moiese, Montana, to determine if defecation rates were constant in different habitat types and at different levels of activity. Individuals and groups that were active 50% or more of observation periods were found to have defecation rates approximately 10 times greater than groups or individuals that were active less than 50% of observation periods. Habitat type was much less tightly related to defecation frequency than was activity level.