• Fire Temperatures and Physical Characteristics of a Controlled Burn in the Upper Sonoran Desert

      Patten, D. T.; Cave, G. H. (Society for Range Management, 1984-05-01)
      Fire temperatures at 4 vertical locations within 3 desert microhabitats were measured during a controlled burn using both temperature pellets and thermocouples. Examples of maximum air temperatures (30 cm) during the fire were 138 degrees C in open interspaces, 352 degrees C within a shrub, and 442 degrees C under a palo verde tree. Fire temperatures among other levels and microhabitats varied considerably. Environmental conditions during the fire were monitored. Soil water repellency at 4 vertical locations within 3 microhabitats showed minimal changes after burning. Soil surface albedo increased by 5% following the fire resulting from 70% perennial plant cover removal and subsequent white ash release. Soil and air temperatures did not vary significantly after the fire when compared to an unburned control.
    • Horses and Cattle Grazing in the Wyoming Red Desert. II. Dietary Quality

      Krysi, L. J.; Sowell, B. F.; Hubbert, M. E.; Plumb, G. E.; Jewett, T. K.; Smith, M. A.; Waggoner, J. W. (Society for Range Management, 1984-05-01)
      Botanical composition of horse and cattle diets from fecal analysis and nutrient quality of hand-harvested forages used by these herbivores were evaluated to assess dietary quality during the summer and winter seasons of 1981 in the Wyoming Red Desert. Dietary crude protein estimates averaged 7.5 +/- 0.1% and 9.0 +/- 0.5% during the summer for horses and cattle, respectively. Dietary crude protein estimates in the winter were lower, averaging 6.1 +/- 0% and 6.0 +/- 0% for horses and cattle, respectively. Estimated dietary calcium levels for both herbivores were high through the summer and winter, while dietary phosphorus levels appear to be deficient during both seasons. Average in vitro dry matter disappearance coefficients for horses and cattle during the summer were 52 +/- 2% and 52 +/- 2%, respectively. During the winter these values dropped to 39 +/- 1% and 40 +/- 1% for horses and cattle, respectively.
    • Vegetation Change after 13 Years of Live-Stock Grazing Exclusion on Sagebrush Semidesert in West Central Utah

      West, N. E.; Provenza, F. D.; Johnson, P. S.; Owens, M. K. (Society for Range Management, 1984-05-01)
      Range managers often assume that release of vegetation from livestock grazing pressure will automatically result in a trend toward the pristine condition. The pathways and time scales for recovery are also sometimes assumed to be the same as for retrogression. These assumptions were examined via monitoring of plant community composition and forage production in five large paddocks of sagebrush semi-desert vegetation in west central Utah over a 13-year interval. No significant increases in native perennial grasses were noted over this period despite a trend toward more favorable precipitation in recent years. Thus, the present brush-dominated plant community is probably successionally stable. A return to vegetation similar to the original sagebrush-native grass mixture is unlikely. The possibility of a successional deflection via fire is enhanced by the increase of annual grass. Improvement of forage production in this vegetation will not necessarily follow after livestock exclusion. Direction manipulations are mandatory if rapid returns to perennial grass dominants are desired in such environments.