Now showing items 15817-15836 of 20719

    • Sage-Grouse Habitat Monitoring: Daubenmire versus Line-Point Intercept

      Thacker, Eric; Messmer, Terry; Burritt, Beth (Society for Range Management, 2015-12-01)
      On the Ground • Evaluation of range/habitat projects for sage-grouse require careful monitoring to measure their impact. • Daubenmire canopy cover and line-point intercept did not yield similar results. • As herbaceous canopy cover increased, the differences between the cover estimates increased. • Adoption of both techniques by both groups may be the only feasible solution since institutional constraints limit either group from changing monitoring techniques.
    • Sagebrush Control with 2,4-D

      Cornelius, D. R.; Graham, C. A. (Society for Range Management, 1958-05-01)
    • Sagebrush Control: At What Canopy Cover Is It Economically Justified?

      Bastian, Christopher T.; Peck, Dannele E.; Smith, Michael A.; Jacobs, James J. (Society for Range Management, 2012-07-01)
      We determine the economic threshold level for big sagebrush control based on 18 yr of forage-response data from an experiment conducted in Carbon County, Wyoming. We analyze the impacts of climatic variables and treatment site characteristics, such as sagebrush abundance levels, precipitation, and understory composition, on forage response and threshold level. We find that sagebrush canopy cover levels, April precipitation, May soil moisture, and understory composition are statistically significant factors in explaining forage response to sagebrush treatment. Forage yield across treated and untreated plots for 10 canopy cover levels, ranging from 4% to 40%, are analyzed via panel data regression techniques. We further investigate the impact of variability in precipitation and understory characteristics on economic outcomes of sagebrush control by analyzing three scenarios. Scenario 1 uses actual forage response data that include all variability from precipitation and understory composition. Scenario 2 uses regression-predicted yields across plots assuming average precipitation and soil moisture conditions. Scenario 3 uses regression-predicted yields assuming average precipitation, soil moisture, and understory characteristics across plots. Net present values based on value of grazing (for estimated yield differences between treated and untreated plots assuming 50% forage utilization) compared to treatment cost across sagebrush cover levels are estimated across these three scenarios. Results indicate that the economic threshold level of sagebrush infestation for the study period was between 8% and 24% for the analyzed scenarios. This indicates variability in precipitation and understory composition impact forage response and the resulting economics of sagebrush control. We conclude that range managers should consider potential control site characteristics and long-range weather forecasts when contemplating sagebrush control./Determinamos el nivel del umbral económico para el control de la artemisa basados en 18 años de datos sobre la respuesta del forraje en un experimento realizado en Carbon County, Wyoming. Analizamos el impacto de variables climáticas y características del sitio tales como niveles de abundancia de artemisa, precipitación y la composición abajo del dosel en la respuesta del forraje y el nivel de umbral. Encontramos que los niveles de cobertura aérea de la artemisa, la precipitación de abril, la humedad del suelo de mayo y la composición son factores estadísticamente significantes para explicar la respuesta del forraje en el tratamiento de la artemisa. El rendimiento de forraje a lo largo de las parcelas tratadas y no tratadas para diez niveles de cubierta aérea fluctuaron del 4% al 40% son analizados por medio de técnicas de regresión de datos panel. Además investigamos el impacto de la variabilidad en precipitación y características debajo del dosel en los resultados económicos del control de la artemisa analizando tres escenarios. En el escenario uno, se usaron los datos de la respuesta actual del forraje la cual incluye toda la variabilidad de la precipitación y composición de abajo del dosel. El escenario dos, usa rendimientos predichos de regresión a lo largo de las parcelas asumiendo precipitación promedio y condiciones de humedad del suelo. El escenario tres usa rendimientos predichos de regresión asumiendo precipitación promedio, humedad del suelo y características de abajo del dosel a través de las parcelas. Valores presentes netos basados en el valor del pastoreo (estimados de las diferencias entre los rendimientos de las parcelas tratadas y no tratadas asumiendo un 50% de utilización del forraje) comparado con el costo del tratamiento a través de los niveles de cobertura de la artemisa son estimados a través de estos tres escenarios. Los resultados indican que el nivel del umbral económico de infestación de artemisa para el periodo de estudio fue entre 8% y 24% de los escenarios analizados. Esto indica que la variabilidad en precipitación y composición abajo del dosel impacta la respuesta del forraje resultando en el control económico de la artemisa. Concluimos que manejadores de pastizales deben considerar las características potenciales de control en el sitio y rangos amplios de pronósticos de tiempo cuando consideren el control de la artemisa.
    • Sagebrush Control—Costs, Results, and Benefits to the Rancher

      Hyatt, S. Wesley (Society for Range Management, 1966-01-01)
    • Sagebrush Conversion to Grassland as Affected by Precipitation, Soil, and Cultural Practices

      Shown, L. M.; Miller, F. A. (Society for Range Management, 1969-09-01)
      The most successful conversions of sagebrush to crested wheatgrass, in areas of the Western United States that receive an average of 8 to 14 inches of precipitation annually, usually occur where the annual precipitation exceeds 10 inches and on soils having medium moisture-holding capacities. Conversion results were intermediate on coarse soils having low moisture-holding capacities and comparatively poor on fine soils having high moisture-holding capacities. Degree of grass establishment varied directly with the big sagebrush vigor-index. Grass production was lower on gravelly sites converted from black sagebrush than on nearby sites converted from big sagebrush. Cheatgrass hindered the establishment of crested wheatgrass in some places. Conversion results were poor on sites where greasewood or shadscale was mixed with sagebrush. These halophytes had usually re-established on the treated sites.
    • Sagebrush Infested by Leaf Defoliating Moth

      Gates, Dillard H. (Society for Range Management, 1964-07-01)
    • Sagebrush ingestion by lambs: Effects of experience and macronutrients

      Burritt, E. A.; Banner, R. E.; Provenza, F. D. (Society for Range Management, 2000-01-01)
      We investigated how experience early in life and macronutrient content of the diet influenced intake of mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana (Rydb.) Beetle) by sheep. In the first part of our study, 2-month-old lambs were exposed as a group for 2 mo to a 70% barley-30% soybean meal ration (300 g/hd/day) that contained increasing amounts sagebrush (1 to 20%). Control lambs received grain without sagebrush. All lambs had access to alfalfa hay and pellets ad libitum. When lambs were tested at 6 months of age, prior exposure had no effect on sagebrush consumption after the first 4 days of the trial. When sagebrush comprised 20% of an alfalfa/barley ration, lambs ate the sagebrush ration readily even when a nutritious alternative was offered indicating the flavor of sagebrush did not prevent lambs from feeding. Increasing the amount of sagebrush in the ration from 50% to 75% resulted in lambs eating less of the barley/sagebrush ration, but daily intake of sagebrush remained constant throughout the 4 day trial, presumably because toxins (terpenes) limited intake of sagebrush. In the second part of our study, lambs experienced with sagebrush were fed 250 g/hd/day of barley, and nutritional status was varied by offering alfalfa pellets at 33% or 80% of ad libitum (1.2 and 2.7 times maintenance, respectively) to determine if dietary energy levels affected intake of sagebrush. Each day lambs received a 50/50 sagebrush/barley supplement ad libitum for 1 hour. Lambs fed at 33% of ad libitum consumed more of the sagebrush/barley supplement than lambs fed at 80% of ad libitum. Thus, additional energy did not enable lambs to consume more sagebrush. In the last trial, lambs in both treatments were fed a basal ration of alfalfa pellets at 50% of ad libitum. Each morning for 1 hour, lambs were offered macronutrient supplements containing either 50% barley/50% sagebrush (high energy) or 25% barley/25% soybean meal/50% sagebrush (high energy and protein). Lambs consumed the same amount of sagebrush regardless of supplement. Thus, supplemental protein did not improve sagebrush consumption. We conclude lambs readily ingested a high-energy ration containing sagebrush, regardless of exposure early in life, suggesting toxins, not flavor, control intake of sagebrush. Further, supplementing lambs with energy or protein failed to improve intake of sagebrush, which suggests these macronutrients did not enhance detoxification of sagebrush.
    • Sagebrush on Relict Ranges in the Sanke River Plains and Northern Great Basin

      Passey, H. B.; Hugie, V. K. (Society for Range Management, 1962-09-01)
    • Sagebrush Rebellion—Another Point of View

      Hyde, Robert M. (Society for Range Management, 1981-12-01)
    • Sagebrush Reinvasion as Affected by some Environmental Influences

      Johnson, J. R.; Payne, G. F. (Society for Range Management, 1968-07-01)
      Five chemically sprayed and 15 plowed and seeded areas in southwestern Montana were examined to determine the influence of several environmental factors on big sagebrush reinvasion. Sagebrush surviving the treatments was found to be the most important factor related to reinvasion. Plowing near or after sagebrush seed maturation resulted in heavy reinfestation of seeded stands. Sagebrush adjacent to treated areas was of no practical importance as a seed source for reinvasion. Non-sagebrush vegetation, slope, erosion, soil texture, and precipitation were seldom related to sagebrush reinvasion. Northwest exposures favored reinvasion.
    • Sagebrush response to ungulate browsing in Yellowstone

      Wambolt, C. L.; Sherwood, H. W. (Society for Range Management, 1999-07-01)
      Big sagebrush (Artemisia tridentata Nutt.) declined from ungulate browsing during the first half of the twentieth century on the Northern Yellowstone Winter Range. It was our objective to compare shrub parameters of Northern Yellowstone Winter Range sagebrush habitat types continually browsed or protected for 32 to 37 years. Measurements were taken in and out of exclosures for 19 environmentally paired, protected, and browsed sites. We found significant differences in development between protected and browsed shrubs. Big sagebrush canopy cover at the 19 sites averaged 19.7% with protection and 6.5% where browsed (P less than or equal to 0.0027), and plants were twice as numerous (P less than or equal to 0.0027) under protection. Winter forage production of individual big sagebrush plants was also greater under protection at 16 of the 19 paired sites (P less than or equal to 0.0027). Subdominant sprouting shrubs generally responded the same as big sagebrush. This ungulate induced decline of shrubs has implications for many Northern Yellowstone Winter Range values. Ultimately many organisms are sacrificed with the loss of quality big sagebrush habitat.
    • Sagebrush Seedling Production as Related to Time of Mechanical Eradication

      Bleak, A. T.; Miller, W. G. (Society for Range Management, 1955-03-01)
    • Sagehen Exclosure: A History of Bitterbrush Reproduction

      Kindschy, Robert R. (Society for Range Management, 1987-06-01)
    • Sahara 03505 sulfide-rich iron meteorite: Evidence for efficient segregation of sulfide-rich metallic melt during high-degree impact melting of an ordinary chondrite

      D'Orazio, M.; Folco, L.; Chaussidon, M.; Rochette, P. (The Meteoritical Society, 2009-01-01)
      The Sahara 03505 meteorite is a 65 g sulfide-rich iron found in an undisclosed locality of the Sahara. It consists of roughly equal volumetric proportion of polycrystalline troilite (crystal size 1.5-7.5 mm) enclosing cellular/dendritic metallic Fe-Ni (width of the dendrite arms, ~100 micrometers). The mineral assemblage is completed by sparse skeletal crystals of chromite, abundant droplets, 5-100 m in size, of anhydrous Fe-, Fe-Na-, and Fe-Mn-Mg-Ca-Na-K-phosphates, tiny crystals of schreibersite, and particles of metallic Cu. The medium- to fine-grained quench texture, and cooling modeling suggest that Sahara 03505 formed through crystallization of a sulfur-rich metallic melt under rapid cooling conditions (1-4 degrees C s^(-1)). The low troilite/metallic Fe-Ni ratio (~0.6 by weight) shows that this liquid was generated at much higher temperatures (1300 degrees C) with respect to the FeS-Fe,Ni cotectic liquids. Based on bulk chemistry and oxygen isotope composition of chromite, we propose that Sahara 03505 formed by extensive impact melting of an ordinary chondrite lithology, followed by the efficient segregation of the immiscible silicate and metallic liquids. The sulfur-rich metallic liquid rapidly cooled either by radiation into space as a small lump, or by conduction to a chondrite country rock as a vein intruded into the walls of an impact crater. Sahara 03505 belongs to a small group of sulfide-rich iron meteorites which are characterized by medium- to fine-grained quench textures and by bulk chemistry that is different from the other iron meteorite groups. We propose here to use the descriptive term sulfide-irons for this meteorite group, by analogy with the stony-irons.
    • 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.
    • Salinity Research

      College of Agriculture, University of Arizona (Tucson, AZ), 1986
    • 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.