• Sahelian rangeland development; a catastrophe?

      Rietkerk, M.; Ketner, P.; Stroosnijder, L.; Prins, H. H. T. (Society for Range Management, 1996-11-01)
      This paper sets out that the dynamics of the Sahelian rangeland vegetation can be interpreted as a cusp catastrophe and that this interpretation offers a promising basis for the description and analysis of this ecosystem. Firstly, an existing scheme of the dynamics of Sahelian herbaceous vegetation is translated into the state-and-transition formulation. Secondly, the application of the cusp catastrophe is explored by studying the behaviour of the Sahelian rangeland ecosystem under changing effective rainfall and grazing intensity, using the transitions from the state-and-transition formulation as vectors along the cusp manifold. This conceptual cusp catastrophe model subsequently results in the identification of hypotheses and the detection of 5 catastrophic properties of this ecosystem (bimodality, inaccessibility, sudden jumps, divergence and hysteresis) that have important management implications. The continuous and the discontinuous processes occurring in the Sahelian rangeland ecosystem can both be captured in a unified conceptual model by applying the cusp catastrophe theory. Testing the hypotheses generated by the conceptual model and searching for additional catastrophic properties, such as divergence of linear response and critical slowing down, is a useful direction for future research.
    • Sainfoin Shows Promise in New Mexico

      Glover, Charles R. (Society for Range Management, 1980-04-01)
    • Salinity affects development, growth, and photosynthesis in cheatgrass

      Rasmuson, K. E.; Anderson, J. E. (Society for Range Management, 2002-01-01)
      The effects of salt stress on growth and development of cheatgrass (Bromus tectorum L.) were investigated in 2 greenhouse studies. The first study assessed developmental and physiological responses of this grass to 4 salinity levels. Salinity stunted growth through reduced leaf initiation and expansion, and reduced photosynthetic rates. Reduction of photosynthetic rates appeared to be primarily due to stomatal limitation. Salinity also reduced carbon isotope discrimination, indicating long-term effects on conductance and carbon gain. Root growth was severely inhibited by high salinity, resulting in a shift in the root to shoot allocation pattern. The second study investigated growth patterns of cheatgrass in relation to intraspecific variation in salt tolerance using plants grown from seeds collected at non-saline and saline sites. Salinity reduced growth of plants from both environments. However, plants from the saline site accumulated leaf and root area at nearly twice the rate as those from the non-saline site, even in the control group. Because plants were grown in a common environment, growth differences between populations were genetically based. Thus, the potential for rapid growth may enable plants from the saline site to rely on shallow, less saline moisture reserves available early in the growing season.
    • Salinity effects on forage quality of Russian thistle

      Fowler, J. L.; Hageman, J. H.; Moore, K. J.; Suzukida, M.; Assadian, H.; Valenzuela, M. (Society for Range Management, 1992-11-01)
      Russian thistle (Salsola iberica Sennen and Pau), a common weed found on overgrazed rangelands, abandoned farmlands, and other disturbed sites in the western United States, is often grazed by livestock and in times of drought has been extensively harvested for hay. Much of the land where Russian thistle grows in the western United States has a salinity hazard. The purpose of this study was to determine the effects of salinity stress on forage quality of Russian thistle. Russian thistle plants were grown in a greenhouse in sand culture irrigated with salinized nutrient solutions (electrical conductivities of 1.3, 10.6, 19.5, 26.8, and 33.9 dS/m) prepared with NaCl and CaCl2 (2:1 molar ratio). Chemical indices of forage quality (total N, neutral detergent fiber, acid detergent fiber, acid detergent lignin, nitrate, and oxalates) at 2 growth stages (early flower and full flower) were determined. Forage quality of Russian thistle, as measured by total N and fiber constituents, improved with increasing salinity. Mineral ash content increased with salinity stress at both growth stages but was reduced slightly by increasing maturity. Nitrate levels increased at early flower but decreased at full flower with increasing salinity, whereas oxalate-levels at both growth stages were reduced by salinity. Neither component was of sufficient magnitude to be toxic to ruminants. These results indicate that salinity stress is not detrimental to forage quality of Russian thistle but tends to improve it.
    • Salivary Contamination of Forage Selected by Esophageal Fistulated Steers Grazing Sandhill Grassland

      Wallace, J. D.; Hyder, D. N.; Van Dyne, G. M. (Society for Range Management, 1972-05-01)
      The effect of saliva contamination on chemical composition of forage collected from esophageal fistulated steers grazing sandhill grassland was studied over four different seasons. Salivary contamination of grazed forage significantly increased the ash component but did not change other chemical constituents calculated on an organic matter basis. The increase in ash attributed to saliva varied with species of plants and season of grazing.
    • Salt and Meal-Salt Help Distribute Cattle Use on Semidesert Range

      Martin, S. C.; Ward, D. E. (Society for Range Management, 1973-03-01)
      Cows on semidesert grass-shrub range ate less than 1/2 lb/day of 3:1 meal-salt mix when it was fed 1 to 2 1/2 miles from water. No injury to cattle due to either inadequate or excessive salt intake was observed. Compared to feeding at water, placing salt or meal-salt 1 to 2 1/2 miles from water increased average utilization of perennial grasses where use was usually light, but it did not materially decrease use near water.
    • Salt and Oxalic Acid Content of Leaves of the Saltbush Atriplex halimus in the Northern Negev

      Ellern, S. J.; Samish, Y. B.; Lachover, D. (Society for Range Management, 1974-07-01)
      Saltbush (Atriplex halimus L.) in the semiarid south of Israel was analyzed for leaf sodium, chlorine, and oxalic acid in order to identify and propagate low-salt bushes likely to be browsed more readily by range cattle and sheep. No correlation was found between leaf chlorine and growth habit factors like bush size and leafiness, or between chlorine and sodium. High-chlorine bushes had a lower Na/Cl ratio, and probably a substantial proportion of the Na+ and Cl- ions are not linked as NaCl. Leaf oxalic acid was lower in high-chlorine bushes. The data suggest that moisture streess sharply reduced insoluble leaf oxalate. Values found are unlikely to cause toxicity problems in livestock.
    • Salt and Specific Ion Effects on Germination of Four Grasses

      Ryan, J.; Miyamoto, S.; Stroehlein, J. L. (Society for Range Management, 1975-01-01)
      The effects of NaCl, CaCl2, MgCl2, NaSO4, CaSO4-2H2O, and MgSO4-7H2O at concentrations of 50, 100, 150, and 200 meq/l were studied on germination of the following range grasses: blue panicgrass (Panicum antidotale Retz.), Lehmann lovegrass (Eragrostis lehmanniana Nees.), Wilman lovegrass (E. superba Peyr.), and weeping lovegrass (E. curvula (Schrad.) Nees.). Increasing salt concentrations decreased germination. The extent of the decrease varied with the species and the type of salt. Inhibition was greatest with Mg and least with Ca salts. When MgSO4-7H2O was used, the effect was less than the equivalent concentration of MgCl2. At equal osmotic pressures the effect of specific ions varied. Wilman and weeping lovegrasses were found to be relatively salt tolerant.
    • Salt Consumption by Breeding Cows on Native Range in the Northern Great Plains

      Houston, W. R. (Society for Range Management, 1963-01-01)
    • Salt Tolerance and Cation Interaction in Alkali Sacaton at Germination

      Hyder, S. Z.; Yasmin, S. (Society for Range Management, 1972-09-01)
      Salt tolerance and cation interaction in alkali sacaton (Sporobolus airoides Torr.) was studied during the germination stage. Germination was inhibited at a concentration of 275 meq/liter of sodium chloride. Mannitol and other salts at iso-osmotic pressure restricted germination in the following decreasing order: MgCl2, KCl, CaCl2, NaCl, and mannitol. Inhibitory effects of magnesium on germination were partially counteracted by calcium and sodium. Greater recovery in germination was noted by addition of calcium than sodium in seeds previously treated with a high concentration of magnesium chloride. The role of sodium and calcium in counteracting magnesium effects has been discussed. It is also concluded that specific effects of salts are more important than osmotic effects on the seed germination of this species.
    • Salt Tolerance of Five Varieties of Wheatgrass during Seedling Growth

      Moxley, M. G.; Berg, W. A.; Barrau, E. M. (Society for Range Management, 1978-01-01)
      The salt tolerance of five relatively recently released varieties of wheatgrass was evaluated in a 6-week greenhouse study. Barton western wheatgrass (Agropyron smithii Rydb.) tended to be more sensitive to salinity than Arriba or Rosana western wheatgrass. Critana thickspike wheatgrass (A. dasystachyum [Hook.] Scribn.) tended to be more salt tolerant than the western wheatgrasses but was not as salt tolerant as Jose tall wheatgrass (A. elongatum [Host] Beauv.).
    • Salt Tolerance of Two Saltbush Species Grown in Processed Oil Shale

      Richardson, S. G.; McKell, C. M. (Society for Range Management, 1980-11-01)
      The tolerance of fourwing saltbush (Atriplex canescens) and cuneate saltbush (Atriplex cuneata) to the salts in processed oil shale was studied in a greenhouse experiment over an Ece range of 4 to 38 mmho/cm. Growth responses differed, depending on the species and the particular salt or salts in the soil solution. Cuneate saltbush was more salt tolerant than fourwing saltbush, but both species survived and grew at salinities as high as 38 mmho/cm. Because of their high salt tolerance these saltbush species may be very important for use in the rehabilitation of processed oil shale disposal sites.
    • Salt-Lick-Induced Soil Disturbance in the Teton Wilderness, USA

      Walters, D. K.; DeLuca, T. H. (Society for Range Management, 2007-11-01)
      Manmade salt licks on public lands throughout the Rocky Mountain West have been created to attract large game for hunting purposes. This practice is both illegal and controversial, but is of particular importance in otherwise pristine wilderness landscapes. The impact of widespread saltlicks on public lands has never been quantified. This study was undertaken to examine the degree of change in soil physical and chemical properties caused by approximately 10-60 years of salt application in the Teton Wilderness of Wyoming, USA. A total of 27 sites were identified, surveyed, and paired with non-salt-affected control areas. Three replicate sampling points were located within each salt site and in each of the paired control areas. Soil samples from each site were analyzed for soil bulk density, soil salinity as electrical conductance (EC), pH, organic matter content, sodium absorption ratio (SAR), and exchangeable concentrations of sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+). Salt-treated site centers were found to have elevated EC, bulk density, pH, SAR, and Na+ concentration compared to the no-salt controls. Salt-affected sites also contained decreased organic matter contents and decreased concentrations of Ca2+ and Mg2+. Observed differences were due to the addition of Na+ to the soil solum as well as direct effects of ungulates. Soil compaction appears to have a greater impact on plant establishment than the actual presence of NaCl. Salt licks established in wilderness areas habituate animals to localized zones causing extensive soil trampling and consumption of surface soils by grazing ungulates. 
    • Saltcedar Control

      Stevens, Richard; Walker, Scott C. (Society for Range Management, 1998-08-01)
    • Saltcedar recovery after herbicide-burn and mechanical clearing practices

      McDaniel, K. C.; Taylor, J. P. (Society for Range Management, 2003-09-01)
      Mechanical clearing and herbicide-burn treatments were compared to evaluate saltcedar (Tamarix chinensis Lour.) control and recovery along the Rio Grande on the Bosque del Apache National Wildlife Refuge, Socorro, N.M. The herbicide-burn treatment included an aerial application of imazapyr (+)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-pyridinecarboxylic acid] + glyphosate [N-(phosphono-methyl)glycine] (0.6 + 0.6 kg ai ha-1 rate) followed 3 years later by a prescription broadcast fire that eliminated > 99% of the standing dead stems. Six years after initial herbicide application, saltcedar mortality was 93%. Mechanical saltcedar clearing entailed removing aerial (trunks and stems) growth by blading, stacking and burning debris, followed by removal of underground plant portions (root crowns) by plowing, raking, and burning stacked material. Saltcedar mortality 3 years after mechanical clearing averaged 70%, which was deemed unsatisfactory. Thus, root plowing, raking, and pile burning was repeated. Three years later, after the second mechanical clearing, saltcedar mortality was 97%. Costs for the herbicide-burn treatment averaged 283 ha-1, whereas mechanical control costs were 884 ha-1 for the first surface and root clearing and an additional 585 ha-1 for the second root clearing. Riparian managers should consider environmental conditions and restoration strategies prior to selecting a saltcedar control approach. Although control costs were significantly lower for the herbicide-burn treatment compared to mechanical clearing in this study, the choice of methods should always consider alternative control strategies for saltcedar. Frequently, combinations of methods result in more efficient, cost-effective results.
    • Saltcedar Water Use: Realistic and Unrealistic Expectations

      Owens, M. Keith; Moore, Georgianne W. (Society for Range Management, 2007-09-01)
      Saltcedar (Tamarix spp.) is a widespread invasive plant found in riparian corridors and floodplains in 16 western states. In addition to being associated with such problems as increased soil salinity and decreased plant diversity, saltcedar has been reported to be a prolific water user. Popular press articles widely report that each individual saltcedar tree can use as much as 757 L (200 gallons) per day. Consequently massive control and removal efforts are underway to reduce transpirational water loss and increase water salvage for arid and semiarid environments. Although the potential economic benefits of these control efforts are touted, it has not been proven whether such water savings are possible on a stream level. The original citation for the 757-L estimate does not list the experimental design or techniques used to arrive at this value. We use three lines of evidence— peer-reviewed scientific literature, sap flux rates and sap wood area, and potential evaporation rates—to demonstrate the improbability that saltcedar, or any other woody species, can use this much water per tree on a daily basis. A more realistic estimate of maximum tree-level daily water use derived from sap flux measurements would be <122 L d-1 (32.2 gallons). Estimates of water salvage would be grossly overestimated using the popular water use value (757 L d-1), and economic benefits from saltcedar control based solely on water salvage are questionable. 
    • Sample numbers for microhistological estimation of fecal vizcacha diets

      Bontti, E. E.; Bóo, R. M. (Society for Range Management, 2002-09-01)
      Precise estimates of diet composition are useful to assess herbivores impact on rangelands and to make management decisions. Since the variability within- and between-samples affect precision of estimates on diet studies, we studied this variability in diets of the rodent vizcacha (Lagostomus maximus Blainv.). We analyzed fecal pellets using a microhistological technique and we estimated the number of samples and subsamples required to achieve given confidence levels. Diets of this herbivore, which is thought to compete with cattle for forage, were studied in November 1994, May, July, and October 1995 in a mixed shrub-grassland community of the southern caldénal in central Argentina. Most grasses, the main components of the diets (> 80%), were estimated with high precision (confidence interval: CI = 10%, p = 0.05) by observing 14 samples and 5 slides per sample. Forbs (5-6%) and shrubs (12%) were estimated with this same number of samples and slides, but yielded a lower level of precision (CI = 20%, p = 0.10). Although our results may not be directly applicable to other vegetation or herbivores, the procedures may be used in other situations to improve precision of diet estimates through microhistological analysis of feces.
    • Sample Preparation Techniques for Microhistological Analysis

      Holechek, J. L. (Society for Range Management, 1982-03-01)
      A study was conducted to determine the influence of sample preparation procedures on the ratio of identifiable to nonidentifiable fragments in diet samples analyzed by microhistological analysis. The number of identifiable fragments on slides was significantly higher when samples were soaked in either bleach or sodium hydroxide in conjunction with use of Hertwig's clearing solution compared to the control, which involved the use of only Hertwig's clearing solution. The percentages by weight of grasses, forbs, and shrubs in two prepared diet samples were more accurately estimated when either sodium hydroxide or bleach was applied in comparison with the control. However, some plant species or plant parts may be destroyed by bleach or sodium hydroxide. Therefore, diet materials should also be examined through standard procedures before the decision is made to apply one of these treatments.
    • Sampling Big Sagebrush for Phytomass

      Uresk, D. W.; Gilbert, R. O.; Rickard, W. H. (Society for Range Management, 1977-07-01)
      A double sampling procedure was employed for obtaining more reliable weight estimates for leaves, flowering stalks, live wood, dead wood, various combinations of the preceding, and total phytomass of sagebrush shrubs. Easily obtained dimension measurements were related to harvest categories using regression analyses. Volume (length × width × height) and length measurements were the most highly correlated to phytomass. Double sampling reduced the variance of the mean phytomass estimates ranging from 33% to 80% for the various categories assuming optimum allocation. The precision achieved by combining dimension measurements with harvesting is significantly higher than by harvests without supporting dimensional measurements.
    • Sampling Herbaceous Native Vegetation with an Electronic Capacitance Instrument

      Neal, D. L.; Currie, P. O.; Morris, M. J. (Society for Range Management, 1976-01-01)
      Dry matter yields of herbaceous native vegetation were effectively estimated with electronic herbage meters. Yields were estimated on vegetation types varying from a low-elevation annual type to a high-elevation alpine type. Phenology, dead organic matter, plant stature, composition, and meter placement within the vegetation affected efficiency of yield estimates. Double sampling techniques are necessary. Optimum sample size for either a fixed-cost or fixed-variance estimate should be determined for each vegetation type.