• Using the Green and Ampt infiltration equation on native and plowed rangeland soils

      Hutten, N. C.; Gifford, G. F. (Society for Range Management, 1988-03-01)
      Soil textural relationships were used on 3 soil series on both plowed and native rangeland to predict Green and Ampt infiltration equation parameters. Infiltration rates predicted from the Green and Ampt soil texture relationships were regressed against field infiltration rates. Good predictability was found on only 4 of 94 plots, all of which were in the agricultural area. Results indicate that current soil texture relationships developed for estimating infiltration rates may not be sufficient for use in either agricultural or rangeland semiarid environments. At this point in time, if infiltration values are important, then they should be measured (not estimated) using appropriate methodologies.
    • Use of leader lengths and diameters to estimate production and utilization of Cercocarpus breviflorus

      Mahgoub, E. F.; Pieper, R. D.; Ortiz, M. (Society for Range Management, 1988-03-01)
      Weight relations for twig lengths and diameters were determined for hairy mountain mahogany plants in southern New Mexico. Both twig lengths and twig diameters were related linearly to twig weights. Twig length and twig diameters explained more than 80% of the variation in twig weight. The equation ŷ(g) = -0.68 + 0.3 (length) + 6.33 (diameter) resulted in the highest r2 (0.88) value compared to either length or diameter alone. Thus, twig length and diameter measurements could be used to determined production and utilization of hairy mountain mahogany. These relationships probably, however, vary with environmental context.
    • Trace element intake via soil ingestion in pronghorns and in black-tailed jackrabbits

      Arthur, W. J.; Gates, R. J. (Society for Range Management, 1988-03-01)
      Soil ingestion ratios were estimated for 2 primary herbivore species utilizing a sagebrush ecosystem in southeastern Idaho to determine the relative importance of soil and vegetation pathways in trace element ingestion and to make predictions of the importance of these pathways for toxic and radioactive elemental intake. The mean (mean and 95% CI) soil intake rates for pronghorns (Antilocapra americana) and black-tailed jackrabbits (Lepus californicus) were 48.7 (45.0-52.7) and 9.7 (9.0-10.6) g/day, respectively, with seasonal peaks occurring in spring (March-May) and in fall (August-October). We did not determine whether soil intake resulted from direct soil ingestion or soil attachment to ingested forage. Soil comprised 5.4% and 6.3%, respectively, of the pronghorn and jackrabbit total dry matter intake. Relating trace element concentrations in soil and vegetation to the daily soil and forage intake rates permitted an estimate of the importance of these 2 ingestion pathways. For both pronghorn and jackrabbits, the estimated percentage of elemental intake attributable to soil was 75% (Na, Fe, V, and F) and 10-50% (Mn, Cr, Mg, Ni, K and Zn).
    • The influence of climate and soils on the distribution of four African grasses

      Cox, J. R.; Martin-R., M. H.; Ibarra-F., F. A.; Fourie, J. H.; Rethman, N. F. G.; Wilcox, D. G. (Society for Range Management, 1988-03-01)
      Around 1900 temperate and semidesert grassland productivity declined, soil erosion increased, and drought destabilized the livestock industry in the northern and southern hemispheres. As government leaders throughout the world began to recognize the importance of grassland productivity and soil conservation, a massive experiment began to evolve. Government and private individuals collected seed from every continent, and planted seed at experimental stations and ranches in their respective countries. Hundreds of individuals who conducted thousands of seeding trials observed that buffelgrass (Cenchrus ciliaris L.), weeping lovegrass [Eragrostis curvula (Schrad.) Nees], kleingrass (Panicum coloratum L.), and lovegrass (Eragrostis lehmanniana Nees) plants from seed collected in Africa were easier to establish and persisted longer than other grasses. Between 1930 and 1986 scientists in many countries evaluated the establishment and persistence of these grasses, but no attempt was made to synthesize the data base and determine the effects of climate and soil on plant establishment and persistence. Our objective was to: (1) determine the climatic and edaphic characteristics of areas where the seed of each grass was collected in Africa, and where each grass has been successfully established in both hemispheres, and (2) identify characteristics which influence long-term persistence. Where buffelgrass predominates and spreads, summer rainfall varies from 150 to 550 mm, winter rainfall is less than 400 mm, mean miminum winter temperatures rarely fall below 5 degrees C, and soil texture is loamy. Weeping lovegrass can be established and plants persist when spring, summer, and fall rainfall varies from 400 to 1,000 mm on deep sandy soil and mean minimum winter temperatures rarely fall below -5 degrees C. The invasion of adjacent nonplanted sites occurs only in Africa where growing season rainfall infrequently cycles between 750 and 1,000 mm and soils remain wet in mid-summer. Kleingrass can be established where mean maximum daily summer temperatures are above 30 degrees C, mean minimum daily winter temperatures rarely fall below 0 degrees C, summer growing season rainfall varies from 400 to 990 mm, and soils are clayey or silty. Kleingrass, like weeping lovegrass, spreads to nonplanted sites only in Africa where a mid-summer drought does not occur. Lehmann lovegrass predominates and spreads only in southern Africa, southeastern Arizona, and northern Mexico when summer rainfall in 30 to 40 days exceeds 150 mm, and soil textures are sandy or sandy loam.
    • Successional patterns in bitterbrush habitat types in north-central Washington

      Youtie, B. A.; Griffith, B.; Peek, J. M. (Society for Range Management, 1988-03-01)
      Twenty-five plant communities were classified within 3 bitterbrush (Purshia tridentata) habitat types along the Columbia River in north-central Washington. Topography, indicator species, and soils data were used to assign stands to habitat type. Ordination across 3 habitat types reflected a moisture gradient: bitterbrush/Idaho fescue (Festuca idahoensis) communities occupied the moist end, bitterbrush/needle-and-thread (Stipa comata) communities the xeric end, and bitterbrush/bluebunch wheatgrass (Agropyron spicatum) an intermediate position. Solar radiation index and elevation accounted for 76% of the variation in the major axis. Ordinations of communities within habitat types described the sere. High-seral communities were not present on the study area. Mid-seral communities had greater perennial grass cover and lower bitterbrush density than low-seral communities.
    • Some vegetation responses to selected livestock grazing strategies, Edwards Plateau, Texas

      Thurow, T. L.; Blackburn, W. H.; Taylor, C. A. (Society for Range Management, 1988-03-01)
      Understanding the temporal response of vegetation to selected livestock grazing strategies is necessary for the continued maintenance or increased productivity of rangelands. Vegetation cover and above-ground biomass were sampled bimonthly from 1978-1984 on pastures grazed continuously (MCG) and moderately stocked (8.1 ha AU-1); continuously (HCG) and heavily stocked (4.6 ha AU-1); high-intensity, low-frequency (HILF) and moderately stocked (8-1; 17:119 day stocked at 8.1 ha AU-1); short-duration grazing (SDG) and heavily stocked (14-1; 4:50 day, stocked at 4.6 ha AU-1); and livestock exclusion (LEX). Prior grazing history, vegetation cover, soils, and slope were similar among pastures. Midgrass cover was eliminated in the HCG pasture, and declined in the heavily stocked SDG pasture. Midgrass cover was maintained under the moderately stocked HILF grazing strategy and increased under MCG or LEX. During 1984, sideoats grama (Bouteloua curtipendula (Michx.) Torr.) basal diameter in the MCG and LEX pastures was significantly greater than in the SDG pasture. By the end of the study, total organic cover and total aboveground biomass in the MCG or LEX pastures were significantly greater than in the SDG and HCG pastures. The heavy grazing intensity used in this study, regardless of the grazing strategy, does not appear suited for long-term maintenance of midgrass species.
    • Simple pivot balance for measuring phytomass in quadrats

      Johnson, D. E.; Borman, M. M.; Ben Ali, M. (Society for Range Management, 1988-03-01)
      An inexpensive, easily constructed balance was made to measure plant phytomass from clipped quadrats. It can be fabricated from materials generally available in developing countries and, within the designed range, it is accurate enough to provide reliable estimates of standing crop. Since balances are easily and inexpensively constructed they can be made in quantity and distributed to local extension agents and farmers.
    • Plant distribution surrounding Rocky Mountain pinyon pine and oneseed juniper in south-central New Mexico

      Armentrout, S. M.; Pieper, R. D. (Society for Range Management, 1988-03-01)
      Within the pinyon-juniper type, trees and understory vegetation are interspersed with open areas forming a mosaic of vegetational patterns. The objective of this research was to define and describe vegetational zones surrounding Rocky Mountain pinyon (Pinus edulis Engelm.) and oneseed juniper (Juniperus monosperma [Engelm.] Sarg.). Transects consisting of contiguous frames were laid out from the base of the tree and continued into the interspace area (outside the canopy) for each cardinal direction. Potential zone boundaries were located by calculating a squared Euclidean distance utilizing basal cover estimates of each frame. Zone boundaries were verified by discriminant analysis. Vegetation associated with both pinyon pine and oneseed juniper exhibited 3 zones. Zone 1 consisted of vegetation associated with the tree bole. Zone 2 was, for the most part, located beneath the tree canopy. Zone 3, consisting primarily of interspace, contained mostly perennial grasses and forbs. Mean basal cover of vegetation surrounding oneseed juniper increased from <1% in zone 1, to approximately 7% in zone 2, to about 12% in zone 3. Mean basal cover estimates of vegetation associated with pinyon pine increased from approximately 4% in zone 1, to 10 and 11% in zones 2 and 3, respectively. Differences in species composition among zones between tree species were apparent.
    • Mule deer-induced mortality of mountain big sagebrush

      McArthur, E. D.; Blauer, A. C.; Sanderson, S. C. (Society for Range Management, 1988-03-01)
      A fence line contrast was provided by a deer fence that bisected a mountain big sagebrush (Artemisia tridentata ssp. vaseyana) community. The sagebrush community was located on an exposed, west-facing slope that was generally swept free of snow during the severe winters of 1982-83 and 1983-84. On the freeway side of the fence, the site was essentially free of browsing animals, while above the fence, the shrubs were exposed to concentrations of mule deer (Odocoileus hemionus). Considerable big sagebrush mortality was evident after the 2 successive winters of heavy snowfall. Big sagebrush mortality and partial dieback of portions of the canopy were significantly (P<0.05) higher in the portion of the community exposed to browsing. Herbaceous species composition also differed between the protected and browsed areas with a higher portion of annual species found in the browsed community. A large number of big sagebrush seedlings germinated in 1984, but failed to establish by 1986. Excessive use of native plants by native large herbivores can have lasting effects on plant communities.
    • Longevity of harvester ant colonies in southern Idaho

      Porter, S. D.; Jorgensen, C. D. (Society for Range Management, 1988-03-01)
      Harvester ant colonies (Pogonomyrmex owyheei Cole) in southern Idaho were monitored periodically for 9 years. Mortality rates indicate that established colonies live 14-30 years (mean = 17). Mounds were commonly reactivated after the death of an old colony; consequently, some may be utilized for many decades. Clearings with active mounds showed almost no change after 9 years of observations while those without active mounds were rapidly filled by annual herbs and then gradually by perennial shrubs. Harvester ants are clearly a very persistent component of cold desert shrub communities.
    • Influence of forest site on total nonstructural carbohydrate levels of pinegrass, elk sedge, and snowberry

      Krueger, J. K.; Bedunah, D. J. (Society for Range Management, 1988-03-01)
      Seasonal trends in total nonstructural carbohydrates (TNC) were studied in pinegrass (Calamagrostis rubescens Buckl.), elk sedge (Carex geyeri Boott), and snowberry (Symphoricarpos albus (L.) Blake) in western Montana in 1983 and 1984. Plants were collected from 4 forest sites at approximate 2-week intervals throughout the growing season. The sites were a clearcut and forested area in 2 different habitat types. Total nonstructrual carbohydrates were determined using an enzyme digestion technique and acid hydrolysis. Total nonstructural carbohydrates in pinegrass rhizomes exhibited a U-shaped curve with reduced levels during growth initiation in the spring and increased levels after growth cessation in late summer. Snowberry root crown TNC exhibited a V-shaped curve with rapid drawdown caused by spring growth followed by rapid replenishment of TNC levels. Elk sedge, an evergreen, did not have a stage of development which resulted in large fluctuations in TNC content of roots or root crowns. In general, TNC levels in elk sedge roots and root crowns and snowberry root crowns were greater on forested sites than clearcuts while the opposite was found in pinegrass rhizomes. Phenological development of plants growing under the forest canopy was delayed by 2 to 3 weeks compared to plants growing in the clearcuts. The influence of clipping pinegrass and elk sedge to a 5-cm or 10-cm stubble height in late May and late June was also studied. Elk sedge TNC levels were least affected when plants were clipped to a 10-cm height in late May and most affected when clipped to a 5-cm height in either May or June. Pinegrass rhizome TNC levels were lower than controls 2 weeks after clipping to 5-cm stubble heights in late May and late June, but after 4 weeks TNC levels of 5-cm clipped plants were not different from controls. Clipping to a 10-cm stubble height in late May did not cause a reduction in TNC levels. The 10-cm clipping treatment reduced pinegrass rhizome TNC levels compared to the control 2 weeks after clipping in late June. The replenishment of TNC reserves of elk sedge and pinegrass to moderate foliage removal during the spring suggests that these species may be moderately grazed in early spring when they are more palatable to livestock.
    • Germination responses of desert saltgrass to temperature and osmotic potential

      Cluff, G. J.; Roundy, B. A. (Society for Range Management, 1988-03-01)
      Desert saltgrass [Distichlis spicata var. stricta (Torr.) Beetle] is the dominant herbaceous forage on many saline rangelands. The ability to direct-seed this grass would permit revegetation of disturbed saline soils. Seeding guidelines must be based on an understanding of germination requirements in relation to seedbed conditions. Germination responses to alternating temperatures in relation to sodium chloride (NaCl)-reduced osmotic potentials were studied in the laboratory and seedbed salinity and water potentials were measured in a typical saltgrass stand in Nevada. Optimum conditions for saltgrass germination were at -0.1 MPa osmotic potential and a 20 degrees C differential in cold and warm period temperatures with warm period temperatures above 30 degrees C. Decreasing osmotic potentials from 0 to -2 MPa decreased the rate of germination from 4.5 to 0.3 and total germination from 60 to 9% across all temperature regimes. Water potentials in the lower topographical positions of a typical saltgrass stand after an unusually wet winter were high enough for germination (>-2MPa) in June when temperatures were optimum for germination. In most years and on xeric sites, optimum temperature and moisture conditions would not overlap to result in high germination. Some germination occurs at cooler than optimum temperatures and low osmotic potentials. Some seeds may eventually germinate in saline seedbeds under these conditions but highest germination would be expected when unusually high precipitation or topographic position results in high seedbed water potentials during late spring and early summer when temperatures are optimum. Consequently, irrigation during late spring and summer should produce the best stands of saltgrass from direct seeding. Where irrigation is not possible, saltgrass should be seeded in the fall to permit germination during early spring when temperatures are suboptimum but the seedbed is still moist. Success of nonirrigated seedings will be highly dependent on seedbed salinity and moisture conditions in the spring.
    • Economic optimum big sagebrush control for increasing crested wheatgrass production

      Tanaka, J. A.; Workman, J. P. (Society for Range Management, 1988-03-01)
      An approach was developed for estimating the economic optimum rate of initial overstory kill for increasing seasonal forage availability. The model was formulated using: (1) a biological production function relating understory production to initial kill percentage, (2) a derived demand function for seasonal forage value, and (3) a cost of overstory kill function for each control method. The specific optimum solution will vary with the situation; however, the general model may be applied to any ranching situation where understory forage production is constrained by undesirable overstory vegetation. The model was illustrated using the big sagebrush-crested wheatgrass vegetation type on a Utah cow-calf-yearling operation with prescribed burning, 2,4-D spraying, and tebuthiuron application as control methods. For the ranch analyzed, a big sagebrush kill rate between 92 and 100% is optimal depending on the derived demand and cost-of-kill functions used. Kill rates that differ from the optimum caused significant opportunity costs to be incurred.
    • Collecting, drying, and preserving feces for chemical and microhistological analysis

      Hinnant, R. T.; Kothmann, M. M. (Society for Range Management, 1988-03-01)
      Chemical and botanical analyses of feces provide information on diet quality and composition that is not easily collected directly from a grazing animal. However, fecal excreta is readily available in the pastures the animals are grazing. This study was conducted to determine the feasibility of collecting fecal samples from the pasture for chemical (nitrogen) and botanical analysis. Two experiments were conducted to determine the effects of method of drying (oven-dried vs. freeze-dried) and duration of fecal pat exposure on chemical and microhistological analyses. Concentration of nitrogen was not affected by method of drying or by duration of exposure in the field. Samples <72 hours during the winter and <24 hours during the summer may be used for nitrogen analysis. However, we recommend that samples be collected as soon as possible following defecation to reduce possible negative effects of precipitation, insect damage, and trampling. Method of drying had no significant (P<0.05) effect on percentage of identifiable fragments or subsequent forage class determination. Bleach, as a blending medium reduced pigment masking of epidermal fragments resulting in an increase in the percentage of identifiable epidermal fragments. Duration of exposure did not affect identification of most of the forage classes. The proportion of identifiable fragments, was lower during winter than summer.
    • Cattle grazing tall larkspur on Utah mountain rangeland

      Pfister, J. A.; Ralphs, M. H.; Manners, G. D. (Society for Range Management, 1988-03-01)
      Ingestion of tall larkspur (Delphinium barbeyi L. Huth) is a major cause of cattle death on ranges where the plant occurs. The amount and timing of tall larkspur ingestion by grazing cattle was studied from 30 July to 2 September 1986 on high mountain rangeland in central Utah. Forbs dominated the vegetation and were also the major dietary item selected by cattle (>70% of total bites). There was a negative relationship (r=-0.62) between standing crop of other forbs and tall larkspur consumption. Cattle began eating substantial quantities (>10% of bites) of tall larkspur about 10 August, and consumption had increased to 20% when the study ended. Tall larkspur leaves and pods were the major parts selected. At the time of major consumption, leaves were relatively low and declining in total alkaloid concentration (TAC) (1.0-0.6%) while pods were approximately 1.0% TAC and increasing when the study ended. Time spent per feeding station (TFS) was influenced by the vegetation area where animals foraged. TFS in the grass-forb, currant (Ribes spp.), and larkspur areas were 11.2, 25.9, and 22.0 s, respectively. Cattle grazed most efficiently (bite rate:step rate) in the grass-forb areas, and least efficiently in the current areas. Cattle ate large quantities of tall larkspur during the study with no deaths, probably due to the low alkaloid levels in the tall larkspur. Larkspur consumption was not correlated with previous 12- or 24-h precipitation totals. However, cattle did begin major consumption of tall larkspur after 2 rain showers fell following a several week dry period.
    • Arthropod predation of black grass bugs (Hemiptera: Miridae) in Utah ranges

      Araya, J. E.; Haws, B. A. (Society for Range Management, 1988-03-01)
      The predation by selected arthropod predators on immature and adult black grass bugs (BGB), Labops hesperius and Irbisia brachycera, on Utah ranges was investigated. Adult Nabis alternatus was found to be the most important predator of BGB; this species is particularly abundant in early spring and was observed preying on BGB both in the field and in laboratory feeding tests. Immature nabids consumed the bugs but preyed mostly on leafhoppers, smaller plant bug nymphs, and other immature nabids. Nabis vanduzeei showed potential as a predator of adult BGB in the laboratory feeding tests. Spiders were important predators of BGB. Based on predation of BGB in field and laboratory studies, the spiders observed were ranked as follows from greatest to least importance as predators: Xysticus cunctator, Misumenops lepidus, Tibellus sp. (Thomisidae), Castianeira sp. (Clubionidae), and Tetragnatha sp. (Araneidae). Spiders attacked any prey of a size similar to themselves, but they also preyed on beneficial arthropods, including nabids and other spiders.
    • Analysis of Russian thistle (Salsola species) selections for factors affecting forage nutritional value

      Hageman, J. H.; Fowler, J. L.; Suzukida, M.; Salas, V.; Lecaptain, R. (Society for Range Management, 1988-03-01)
      The need for forage plants that are productive in, and adapted to, semiarid conditions prompted us to examine the range and independence of assortment of nutritional qualities of wild stands of Russian thistle (Salsola species). Seventy selections from a 5-state area of the southwestern United States were planted in observational plots and analyzed for crude protein, acid detergent fiber, lignin, nitrate, water-soluble oxalate, in vitro digestibility, and ash content at 2 stages of maturity. Values on a dry matter basis of crude protein (5.4 to 22.3%), acid detergent fiber (20.1 to 48.8%), acid detergent lignin (3.1 to 10.4%), nitrate (0.1 to 5.1%), water-soluble oxalate (0.2 to 9.1%), plant height (40 to 180 cm at second harvest), stage of development (midbloom to complete seed development at second harvest), and degree of prickliness (soft to extremely prickly at second harvest) were determined for each of the 70 selections at 2 harvest times. The color, branch density, and degree of leafiness were examined at the second harvest only. Values for in vitro digestibility (45.1 to 66.3% organic matter disappearance) and ash (12.7 to 30.5% of dry wt) were determined for a subset of 22 samples. About 10% of the selections had a composite of properties which would suggest they they would make moderate to good forages.
    • An economic assessment of risk and returns from prescribed burning on tallgrass prairie

      Bernardo, D. J.; Engle, D. M.; McCollum, E. T. (Society for Range Management, 1988-03-01)
      A stochastic (Monte Carlo) simulation model was developed to evaluate the influence of prescribed burning on the expected value and variability of net returns from a representative stocker cattle enterprise. The model was applied to both shallow prairie and eroded prairie range sites in eastern Oklahoma. Prescribed burning is shown to be an economically feasible means of improving the productivity of eastern redcedar infested rangeland. Implementation of an annual burning program resulted in a $69.00 and $4.80 per hectare increase in the net present value of the 10-year return stream generated from stocker cattle production on shallow prairie and eroded prairie range sites, respectively. Prescribed burning does not increase the variability of annual income from stocker cattle production. However, when risk is measured in terms of relative variability (coefficient of variation) or the probability of annual returns below zero, prescribed burning is determined to be a risk-reducing practice.