Now showing items 1-20 of 23

    • Water Balance Calculations and Net Production of Perennial Vegetation in the Northern Mojave Desert

      Lane, L. J.; Romney, E. M.; Hakonson, T. E. (Society for Range Management, 1984-01-01)
      Measurements obtained between 1968 and 1976 indicate the influence of climatic factors and soil characteristics upon soil moisture and production of perennial vegetation in the northern Mojave Desert. Seasonal distribution patterns of precipitation are shown to have a strong effect on plant-available soil moisture, and these patterns are, in turn, reflected in net production of perennial vegetation. Available climatic data and soil characteristics were used as input to a continuous simulation model to calculate the water balance for a unit area watershed. Computed and measured soil moisture agreed quite well over a range of values from close to the wilting point to near field capacity. We used computed evapotranspiration rates to estimate water use by perennial vegetation. Computed water use was multiplied by a water use efficiency factor to estimate net production of perennial vegetation. Estimated net production exhibited year-to-year variability comparable with measured values, and agreed quite closely with available observations. This paper briefly describes soil-water-plant relationships in the northern Mojave Desert and illustrates an application of a continuous simulation model to predict soil moisture and net production of perennial vegetation. Based on our analysis, the simulation model would appear to have potential for estimating the water balance and above ground net primary production on arid and semiarid rangelands.
    • Vegetation and Litter Changes of a Nebraska Sandhills Prairie Protected from Grazing

      Potvin, M. A.; Harrison, A. T. (Society for Range Management, 1984-01-01)
      End of season components of biomass and litter were measured on a Nebraska Sandhills prairie site to follow vegetation changes during the first 4 years following the cessation of intense livestock grazing. The 1977-1980 mean annual end of season biomass at Arapaho Prairie, a Sandhills prairie site, was 109 g/m2. Summer grazing on Arapaho Prairie was terminated in 1977, and as a result, significant increases in the biomass of the deep-rooted, palatable warm-season (C4) grasses, sand bluestem, little bluestem and switchgrass, have occurred since then. The biomass of the shallowly rooted C4 grama grasses for the 4-year period was significantly correlated with growing season precipitation. Significant decreases in end of season biomass of the cool-season (C3) grasses during the same 4-year period were highly correlated with yearly decreases in May precipitation. Following the removal of grazing, litter increased from 40 to 127 g/m2 from 1977 to 1980. A nonsignificant yearly increase in litter production occurred in the third year after grazing as a steady state of litter production and decomposition was approached.
    • Using Weather Records with a Forge Production Model to Forecast Range Forage Production

      Wight, J. R.; Hanson, C. L.; Whitmer, D. (Society for Range Management, 1984-01-01)
      This paper describes a method for calculating site specific forecast yields and their associated probabilities of occurrence. A physically based range forage model, which utilizes beginning soil water content and daily precipitation, mean air temperature, and solar radiation as inputs, calculates the ratio of actual transpiration (T) to potential transpiration (Tp) as a yield index. Annual yield is calculated by the relationship: yield = potential site yield (yield when water is nonlimiting) × T/Tp. By using the current year's beginning soil water content and weather data for a number of years, a population of yields is generated (one yield for each year of weather data). From the population of yields, a mean and various confidence intervals around the mean can be calculated as the forcast yield and its associated confidence intervals. The forecast procedure was tested using 55 years (1917-1971) of weather records and 12 years (1967-1978) of actual yield and soil water data for an upland range site in eastern Montana. An expected two thirds of the field measured yields were within a standard deviation of the forecasted yields for the April, May, and June forecasts.
    • The Effect of Shade and Planting Depth on the Emergence of Fourwing Saltbush

      Hennessy, J. T.; Gibbens, R. P.; Cardenas, M. (Society for Range Management, 1984-01-01)
      Planting trials in southern New Mexico with fourwing saltbush seeds on mesquite dunes and on shaded and nonshaded interdune areas during 3 successive years revealed that seedling emergence was always greater on shaded areas. Planting depth (2 and 5 cm) did not appear to be a critical factor in seedling emergence. The shade provided by mesquite canopy explains, in part, why fourwing saltbush occurs with much higher frequency on dunes than on interdune areas.
    • Seasonal Mineral Concentration in Diets of Esophageally Fistulated Steers on Three Range Areas

      Kalmbacher, R. S.; Long, K. R.; Martin, F. G. (Society for Range Management, 1984-01-01)
      Past analyses of Florida range plants have been hand-plucked, whole-plant samples and have been limited to a few major species sampled at a few times during the year. The objective of this study was to determine if mineral concentrations in hand-plucked samples and the boluses of esophageally fistulated steers: changed from summer to winter; changed on different range areas; could be improved by more frequent grazing. Concentration of P and K in diets collected from steers grazing pine-palmetto, transition, and pond areas were not significantly different, but Ca, Mg, and Mn were usually lower on the pond areas. Concentration of Zn was similar in diets from the 3 areas in summer, but was lower on pine-palmetto and transition areas in winter. Concentration of Fe in diets was greater on pond areas than on pine-palmetto areas, while transition areas were intermediate. Concentrations of P, K, Mg, and Mn in diets of fistulated steers declined from summer to winter. Concentrations of P, K, Fe, and Zn were not different between pastures regrazed in winter and grazed only in winter. Most hand-plucked forages declined in mineral concentration from summer to winter. Florida range must be supplemented with complete minerals regardless of season, range site grazed, or grazing management.
    • Seasonal Changes in Carbon Content, and Dehydrogenase, Phosphatase, and Urease Activities in Mixed Prairie and Fescue Grassland Ah Horizons

      Dormaar, J. F.; Johnston, A.; Smoliak, S. (Society for Range Management, 1984-01-01)
      Total C, water-soluble C, and 3 soil enzymes associated with Ah horizons under ungrazed mixed prairie and fescue grassland ranges were assessed over a 23-month period. Generally, total C was higher in samples from heavily grazed sites than in those from ungrazed sites and was higher over the winter months than during the summer. Water-soluble C was generally higher in soil from mixed prairie than in soil from fescue grassland except for short periods during the winter. Enzymatic activities are highest in samples from the fescue grassland site regardless of grazing intensity. Enzymatic activities of both sites increased during the winter months. Grazing intensity affected enzymatic activities differently at the 2 sites. A working hypothesis is proposed to account for organic matter breakdown during the winter and spring months.
    • Nonstructural Carbohydrates and Root Development in Blue Grama Seedlings

      Wilson, A. M. (Society for Range Management, 1984-01-01)
      The objective of this study was to determine relationships between total nonstructural carbohydrates (TNC) and adventitious root development in blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Steud.] seedlings. Levels of TNC were altered by use of shade and recovery treatments in full light. Seedling growth characteristics and TNC, N, and P concentrations were investigated in 5-week-old seedlings during a 3-day root growth test. Leaf mass, crown mass, total N, and total P were not significantly associated with production of adventitious roots. A decrease in amount of TNC in shoots and an increase in root mass indicated that 13% of the root mass was derived from TNC that had accumulated before the test. The percentages of leaf TNC and crown TNC utilized for growth of adventitious roots were 14 and 30, respectively. This study indicates that blue grama seedlings should be managed to maintain adequate levels of TNC. Utilization of TNC for rapid root growth could be an advantage where the soil surface dries rapidly after precipitation.
    • Nitrogen Fixation Estimates for Some Native and Introduced Legumes, Forbs, and Shrubs

      Baltensperger, A. A.; Smith, M. A. (Society for Range Management, 1984-01-01)
      Seedling plants of 16 legume, forb, and shrub species were compared with 2 alfalfa cultivars (Medicago sativa) for growth and survival in a nitrogen-free sand culture in the greenhouse. All seed accessions were inoculated with the same inoculum mixture. After 11 weeks all surviving plants were harvested and evaluated for top and root growth, percent nitrogen in roots and tops, and acetylene reduction rate of the root mass. All nonlegumes and several legumes died before the experiment was terminated at 11 weeks. Severe chlorosis and subsequent death appeared to be caused primarily from nitrogen deficiency. Six of the legume species-sainfoin (Onobrychis viciaefolia), black medic (Medicago lupulina), Medicago media, Phaseolus metcalfei, Vicia calcarata, and mesquite (Prosopus juliflora)-lived for 11 weeks and produced sufficient top and root growth and accumulated total nitrogen, indicating nitrogen was fixed in the root nodules. There were no differences among accessions for acetylene reduction rates in this experiment. Black medic produced as much or more top and root growth than the other species and merits additional study.
    • Locoweed Poisoning in a Northern New Mexico Elk Herd

      Wolfe, G. J.; Lance, W. R. (Society for Range Management, 1984-01-01)
      Locoweed (Oxytropis sericea) poisoning was confirmed in 16 free-ranging elk (Cervus elaphus nelsoni) from northern New Mexico over a 5-year period, 1977-81. Clinical signs consistently seen were emaciation, weakness, incoordination, muscular trembling, posterior ataxia, lethargy, and visual impairment. Gross morphologic changes included hydrothorax, hydroperitoneum, hydropericardium, meningeal edema, serous atrophy of fat deposits, and anemia. Consistent histological changes were widespread cytoplasmic vacuolation in the parenchyma of most major organ systems. This outbreak of locoweed poisoning coincided with poor range condition exacerbated by subnormal precipitation, and was not considered to be a significant mortality factor in the elk herd. However, locoweed poisoning may significantly affect population dynamics of elk herds restricted to ranges severely infested by locoweed.
    • Horses and Cattle Grazing in the Wyoming Red Desert. I. Food Habits and Dietary Overlap

      Krysl, L. J.; Hubbert, M. E.; Sowell, B. F.; Plumb, G. E.; Jewett, T. K.; Smith, M. A.; Waggoner, J. W. (Society for Range Management, 1984-01-01)
      The sagebrush-grass range in southcentral Wyoming presently supports large numbers of feral horses and domestic livestock. Diets of feral horses and cattle during summer and winter grazing were evaluated using fecal analysis under 2 stocking levels in small pastures. Horses and cattle consumed primarily grasses during the summer and winter. However, shrubs and forbs were also important dietary components. Needleandthread, Sandberg bluegrass, thickspike wheatgrass, Indian ricegrass, gray horsebrush, and winterfat were the major foods of horses and cattle during the summer and winter. Dietary overlap between horses and cattle during the summer averaged 72% and increased to 84% during the winter. Horses and cattle selected foods in a similar order.
    • Germination of Seeds of 'Paloma' and 'Nezpar' Indian Ricegrass

      Young, J. A.; Evans, R. A. (Society for Range Management, 1984-01-01)
      Seedlots of the cultivars 'Paloma' and 'Nezpar' Indian ricegrass [Oryzopsis hymenoides (R. & S). Ricker] were classified as to seed type, germination, and germination in response to the additive enhancement treatments of removing the lemma and palea by dissection, enriching the germination substrate with gibberellin (GA3), and cool-moist stratification at 2 degrees C for 2 weeks. The seedlots contained different proportions of polymorphic seed size, color, and covering types. Seedlots of 'Paloma' were dominated by big black seeds while lots of 'Nezpar' contained roughly equal propertions of big and small black seeds. The various seed types had different germination characteristics both under control and enhancement treatments. The initial germination of untreated seeds of either cultivar was very low; however, maximum germination with enhancement did not exceed 50%.
    • Forage Quality Responses of Selected Grasses to Tebuthiuron

      Masters, R. A.; Scifres, C. J. (Society for Range Management, 1984-01-01)
      Tebuthiuron pellets (20% active ingredient [a.i.]) applied at 0.6, 1.1 or 2.2 kg/ha (a.i.) to native stands of little bluestem and at 1.1 or 2.2 kg/ha to 1-year-old seeded stands of Bahiagrass, Bell rhodesgrass, green sprangletop, and little bluestem did not significantly alter the in vitro digestible organic matter concentrations of grass leaves. Leaf water concentrations of Bahiagrass, green sprangletop, and little bluestem were not consistently altered by application of tebuthiuron. However, application of 1.1 or 2.2 kg/ha of tebuthiuron pellets to seeded stands or to native little bluestem increased foliar crude protein concentrations. Application of 0.125, 0.188, or 0.25 ppm of tebuthiuron in aqueous solutions to pots containing grasses in the greenhouse significantly increased foliar crude protein concentrations, compared to that of untreated plants. Crude protein concentrations were increased only during the growing season of application in the native stand of little bluestem. These results suggest application of tebuthiuron for brush control may enhance rangeland forage crude protein concentrations while not affecting in vitro digestible organic matter.
    • Fire Intensity Effects on the Understory in Ponderosa Pine Forests

      Armour, C. D.; Bunting, S. C.; Neuenschwander, L. F. (Society for Range Management, 1984-01-01)
      The effect of fire intensity on understory vegetation on seral stands of ponderosa pine are presented. Vegetational recovery for 2 burn intensities and unburned sites were compared. The results suggest a change in the understory dominance structure following underburning is related to the amount of duff consumed by the fire and independent of fire line intensity and flame length. A significantly greater proportion of duff was removed on high fire intensity sites (80%) than on low intensity sites (40%). However, the variation in fire line intensity was great, with some overlap. Fire line intensity ranged from 30 to 3,034 kcal/m-s on high intensity sites and from 25 to 194 kcal/m-s on low intensity sites. Flame length ranged from 0.1 to 1.7 m on both high and low intensity sites. Graminoid canopy coverage was lowest on high intensity sites. The reduction was apparently the result of prolonged smoldering of the duff layer. There was no significant difference in coverage among treatments for shrubs or forbs. A significant change in frequency among treatments was noted for 11 of 54 species sampled.
    • Emergence and Seedling Survival of Two Warm-Season Grasses as Influenced by the Timing of Precipitation: A Greenhouse Study

      Frasier, G. W.; Woolhiser, D. A.; Cox, J. R. (Society for Range Management, 1984-01-01)
      A greenhouse study was conducted to determine seedling survival probabilities of sideoats grama (Bouteloua curtipendula (Mich x.) Torr.) and cochise lovegrass (Eragrostis lehmanniana Nees × Eragrostis trichophora Coss & Dur.) for selected combinations of initial wet-day and dry-day sequences. Three separate 14-day experiments were conducted using 1, 2, 3, 4, and 5 days wet followed with 5 days dry. The number of emerging seedlings growing from 10 seeds placed in a sand media in small plastic cones were counted daily. A total of 50 to 70% of the sideoats grama seeds emerged in the initial wet period, but over 50% of the seedlings died in the following 5-day dry period, resulting in less than a 35% survival rate. The cochise lovegrass was slower to germinate and less susceptible to the effect of the 5-day dry period, which resulted in 40 to 60% seedling survival. With the 1- and 2-day wet sequences, the maximum cochise lovegrass plant count was not achieved until the final rewet period. With the exception of 5 days wet, the length of the initial wet period did not significantly affect the number of surviving lovegrass seedlings. This information offers the possibility of incorporating the probablistic aspects of precipitation and soil water relations into a description of the seedling environment.
    • Effects of Herbicides on Germination and Seedling Development of Three Native Grasses

      Huffman, A. H.; Jacoby, P. W. (Society for Range Management, 1984-01-01)
      Two experiments conducted in growth chambers examined influences of 2,4,5-T [(2,4,5-trichlorophenoxy) acetic acid], chlopyralid (3,6-dichloropicolinic acid), picloram (4-amino-3,5,6-trichloropicolinic acid), and triclopyr {[3,5,6-trichloro-2-pyridinyl)-oxy]acetic acid} on germination and early seedling development of buffalograss [Buchloe dactyloides (Nutt.) Engelm.], blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Griffiths], and sideoats grama [Bouteloua curtipendula (Michx.) Torr.]. Germination and plumule growth were largely unaffected chlopyralid but were significantly reduced by 2,4,5-T, picloram, and triclopyr, especially at rates greater than 1.1 kg/ha. Blue grama was less affected by herbicides than either buffalograss or sideoats grama.
    • Economics of Controlling Serrated Tussock in the Southeastern Australian Rangelands

      Vere, D. T.; Campbell, M. H. (Society for Range Management, 1984-01-01)
      Serrated tussock (Nassella trichotoma), a grass native to South America, has been a major economic problem in the rangelands of southeastern Australia since 1950. It currently infests 680,000 ha in southeastern New South Wales, drastically reducing animal production. Controlling serrated tussock was profitable in most situations favourable for pasture improvement but only marginally profitable or unprofitable in areas with low to moderate soil fertility/rainfall indices. Internal rates of return ranged between 49.1% and 7.5% and the benefit-cost ratios between 1.83:1 and 0.88:1. Public intervention was considered to be necessary to expedite control in areas less favorable for pasture improvement. Public rates of return (273.1% to 132.7%) and benefit-cost ratios (32.3:1 to 11.2:1) to control were very high under a system of subsidized finance to private landholders. Various forms of potential public intervention were discussed.
    • Does Summer Range Quality Influence Sex Ratios among Mule Deer Fawns in Utah?

      Pederson, J. C.; Harper, K. T. (Society for Range Management, 1984-01-01)
      Larger ratios of males to females were found among fawns from herd units where forage production on the summer ranges was low and the forage base was dominated by browse. Summer ranges where forage production was high and dominated by forbs produced even or female dominated sex ratios. The number of deer harvested per unit area was correlated with sex ratio of the fawn crop: harvests were lower where males were significantly overrepresented in the fawn crop and higher where sex ratios were even or female biased.
    • Diets of Ungulates Using Winter Ranges in Northcentral Montana

      Kasworm, W. F.; Irby, L. R.; Ihslepac, H. B. (Society for Range Management, 1984-01-01)
      Dietary comparisons based on fecal analysis of mule deer, elk, bighorn sheep, and cattle using mule deer winter ranges along the east slope of the Rocky Mountains indicated that elk, bighorn, and cattle diets were much more similar to each other than to mule deer diets. The greatest overlap between elk, bighorns, and mule deer occurred during late winter when creeping juniper became an important dietary item for all 3 species. Rank-order comparisons indicate that rankings of items in the graminoid and forb forage classes for diets of the 4 ungulate species were significantly correlated with availability of these items. Correlations between availability and diet rank-order were poor for items in the woody forage class. Differences in the diets of the 4 ungulate species were more pronounced at the forage class level than at the plant species/genus level.
    • Diets of Black-tailed Jack Rabbits in Relation to Population Density and Vegetation

      Johnson, R. D.; Anderson, J. E. (Society for Range Management, 1984-01-01)
      Diets of black-tailed jack rabbits (Lepus californicus) and composition of plant communities were compared among habitats that supported different densities of jack rabbits in sagebrush (Artemisia tridentata)/perennial grass communities on the Idaho National Engineering Laboratory (INEL) in southeastern Idaho. Diets were more similar than vegetation among areas, indicating that jack rabbits feed selectively; winterfat (Ceratoides lanata) and perennial grasses were staple foods, comprising about 80% of the diet in all areas. Jack rabbit densities were higher in areas having higher proportions of grass cover. Similarity between diet and vegetation was positively correlated with jack rabbit density and with the amount of grass cover in the habitat. Jack rabbits selected grass-dominated areas for feeding at night and then fed as generalists on the grass species present.