Journal of Range Management, Volume 51 (1998)
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Welcome to the Rangeland Ecology & Management archives. The journal Rangeland Ecology & Management (RE&M; v58, 2005-present) is the successor to the Journal of Range Management (JRM; v. 1-57, 1948-2004.) The archives provide public access, in a "rolling window" agreement with the Society for Range Management, to both titles (JRM and RE&M), from v.1 up to five years from the present year.
The most recent years of RE&M are available through membership in the Society for Range Management (SRM). Membership in SRM is a means to access current information and dialogue on rangeland management.
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Print ISSN: 0022-409x
Online ISSN: 1550-7424
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Journal of Range Management, Volume 51, Number 6 (November 1998)Society for Range Management, 1998-11-01
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Journal of Range Management, Volume 51, Number 3 (May 1998)Society for Range Management, 1998-05-01
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Journal of Range Management, Volume 51, Number 5 (September 1998)Society for Range Management, 1998-09-01
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Journal of Range Management, Volume 51, Number 4 (July 1998)Society for Range Management, 1998-07-01
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Journal of Range Management, Volume 51, Number 2 (March 1998)Society for Range Management, 1998-03-01
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Journal of Range Management, Volume 51, Number 1 (January 1998)Society for Range Management, 1998-01-01
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Viewpoint: The present status and future prospects of squirreltail researchSquirreltail's [Elymus elymoides (Raf.) Swezey + Sitanion hystrix (Nutt.) J.G. Smith] ready germination, rapid reproductive maturity, capacity for cool-temperature growth, self-pollinated mating system, excellent seed dispersal mechanisms, fire tolerance, and genetic diversity make it a promising candidate for assisting ecological restoration of rangelands dominated by exotic weedy annual grasses such as medusahead wildrye [Taeniatherum caput-medusae (L.) Nevski] and cheatgrass (Bromus tectorum L.). Squirreltail is a short-lived perennial and generally early seral in successional status. It comprises a complex of several subspecies whose ecological amplitudes are poorly understood. Wildfire or prescribed burning may provide opportunities for seeding squirreltail or augmenting existing populations. Grazing deferment is important for a successful transition from an annual to a perennial-dominated grassland. Reduction in frequency of annuals may facilitate natural or artificial establishment of desirable mid- or late-seral grasses, forbs, and shrubs. Currently, squirreltail seed supplies originate from wildland harvests. Reduced cost, dependable supply, and improved quality of seed will require development of efficient commercial seed production practices. Experience in restoration may reveal the suitability of squirreltail plant material for assisted succession as well as expose its weaknesses. Such information will allow researchers to improve plant materials and methods for increased future success.
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Viewpoint: Sustainability of piñon-juniper ecosystems—a unifying perspective of soil erosion thresholdsMany piñon-juniper ecosystems in the western U.S. are subject to accelerated erosion while others are undergoing little or no erosion. Controversy has developed over whether invading or encroaching piñon and juniper species are inherently harmful to rangeland ecosystems. We developed a conceptual model of soil erosion in piñon-juniper ecosystems that is consistent with both sides of the controversy and suggests that the diverse perspectives on this issue arise from threshold effects operating under very different site conditions. Soil erosion rate can be viewed as a function of (1) site erosion potential (SEP), determined by climate, geomorphology and soil erodibility; and (2) ground cover. Site erosion potential and cover act synergistically to determine soil erosion rates, as evident even from simple USLE predictions of erosion. In piñon-juniper ecosystems with high SEP, the erosion rate is highly sensitive to ground cover and can cross a threshold so that erosion increases dramatically in response to a small decrease in cover. The sensitivity of erosion rate to SEP and cover can be visualized as a cusp catastrophe surface on which changes may occur rapidly and irreversibly. The mechanisms associated with a rapid shift from low to high erosion rate can be illustrated using percolation theory to incorporate spatial, temporal, and scale-dependent patterns of water storage capacity on a hillslope. Percolation theory demonstrates how hillslope runoff can undergo a threshold response to a minor change in storage capacity. Our conceptual model suggests that piñon and juniper contribute to accelerated erosion only under a limited range of site conditions which, however, may exist over large areas.
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Viewpoint: Applying riparian buffers to Great Plains rangelandsBetter management of riparian areas has been promoted by public agencies for almost 2 decades. Recently, however, efforts have been intensified because serious conservation concerns remain. To achieve mandated conservation goals for water quality and wildlife will require widespread acceptance and application of recommended riparian practices. Success of riparian programs in the Great Plains will require recognition of differences between the interests of public agencies and those of private landowners and the development of an approach to riparian management that can accommodate both.
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Viewpoint on objectives, boundaries, and rangeland carrying capacityThis paper de-analyses a recent paper by Roe (1997, J. Range Manage., 50:467-472) entitled Viewpoint: On Rangeland Carrying Capacity. This response to that paper: (1) examines and demonstrates the importance of defining objectives and boundaries in management, science, management science and art, (2), reaffirms an earlier, objective-based concept of carrying capacity applicable to general systems and to models of them, and (3) implores minimal use of unnecessary jargon in range management science.
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Viability of weed seeds in feed pellet processingFederal and state agencies in several western states now require the use of noxious weed-free or noxious weed seed-free forage to hinder the spread of noxious weeds. Forage can be certified as noxious weed-free through state administered programs. Processed feeds such as pellets or cubes made from noncertified hay and uncleaned grain are some of the forage products that may be potential sources of weed infestations. This study was conducted to determine levels of weed seed contamination in alfalfa hay/grain feed pellets manufactured with commercial-grade equipment. Seeds of whitetop [Cardaria draba (L.) Hand.], spotted knapweed (Centaurea maculosa Lam.), Canada thistle [Cirsium arvense (L.) Scop.], leafy spurge (Euphorbia esula L.), and common yellow sweetclover [Melilotus officinalis (L.) Lam.] were added in known quantities to alfalfa/grass mixed hay and to barley. The hay was ground in a hammermill through a screen with 7.9-mm diameter perforations, and the barley was ground to pass through a 2.4-mm screen. In a second experiment, uncertified 'Ladak 65' alfalfa (Medicago sativa L.) seeds were ground with alfalfa/grass mixed hay in a hammermill and extruded through a pellet die before being ground in another hammermill with barley grain followed by extrusion through a pellet die. The Montana Department of Agriculture collected pelleted feed from various manufacturers in the state during 1993 and 1994 to estimate potential weed contamination frequency. Grinding of weed seeds with alfalfa hay or barley grain reduced emergence by 98 to 100%. Grinding and pelleting reduced emergence of alfalfa seed by over 99%. Weed seedlings emerged from 11% of random feed pellet samples collected from Montana manufacturers. Rigorous processing such as occurs when manufacturing hay/grain pellets reduces the risk of disseminating weed seeds from pelleted feed.
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Using a grazing pressure index to predict cattle damage of regenerating tree seedlingsThis research investigated the potential for using cattle grazing pressure (AU Mg-1 ha-1) and stocking rate (Animal Unit Days ha-1) for predicting basal scarring and browsing of lodgepole pine (Pinus contorta Dougl.) seedlings on cutblocks in southern British Columbia from 1989 to 1992. Cattle browsing on lodgepole pine seedlings occurred almost exclusively during the first 2 years of grazing. Browsing increased (P < 0.05; r2=0.71) with increasing stocking rate only during the first year of grazing. Browsing increased with increasing grazing pressure in 1989 (P < 0.05; r2= 0.38) and 1990 (P < 0.05; r2 = 0.39). Basal scarring peaked during the second year of grazing, but was correlated (P < 0.05; r2 = 0.79) with stocking rate only during the first year of grazing. Increasing grazing pressure was associated with higher (P < 0.05) basal scarring during all 4 years of the study, and likely better predicts trampling damage than does stocking rate, particularly during the first year of grazing. Basal scarring during 1989 generally increased to > 10% of sample trees when grazing pressure exceeded 12.0 AU Mg-1 ha-1. This threshold grazing pressure value of 12.0 AU Mg-1 ha-1, however, cannot likely be extrapolated directly to other sites. Grazing pressure values and associated basal scarring are unquestionably influenced by many factors (e.g., pasture size, kind of grazing animal, forage species, tree height, water availability, topography, and weather patterns during the grazing period). Nonetheless, our work provides evidence that grazing pressure provides a useful index for predicting the potential for trampling damage of lodgepole pine seedlings by cattle.
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Using a grazing pressure index to predict cattle damage of regenerating tree seedlingsThis research investigated the potential for using cattle grazing pressure (AU Mg-1 ha-1) and stocking rate (Animal Unit Days ha-1) for predicting basal scarring and browsing of lodgepole pine (Pinus contorta Dougl.) seedlings on cutblocks in southern British Columbia from 1989 to 1992. Cattle browsing on lodgepole pine seedlings occurred almost exclusively during the first 2 years of grazing. Browsing increased (P < 0.05; r2 = 0.71) with increasing stocking rate only during the first year of grazing. Browsing increased with increasing grazing pressure in 1989 (P < 0.05; r2 = 0.38) and 1990 (P < 0.05; r2 = 0.39). Basal scarring peaked during the second year of grazing, but was correlated (P < 0.05; r2 = 0.79) with stocking rate only during the first year of grazing. Increasing grazing pressure was associated with higher (P < 0.05) basal scarring during all 4 years of the study, and likely better predicts trampling damage than does stocking rate, particularly during the first year of grazing. Basal scarring during 1989 generally increased to > 10% of sample trees when grazing pressure exceeded 12.0 AU Mg-1 ha-1. This threshold grazing pressure value of 12.0 AU Mg-1 ha-1, however, cannot likely be extrapolated directly to other sites. Grazing pressure values and associated basal scarring are unquestionably influenced by many factors (e.g., pasture size, kind of grazing animal, forage species, tree height, water availability, topography, and weather patterns during the grazing period). Nonetheless, our work provides evidence that grazing pressure provides a useful index for predicting the potential for trampling damage of lodgepole pine seedlings by cattle.
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Understory plant response to site preparation and fertilization of loblolly and shortleaf pine forestsIn developing an improved understanding of the dynamics of understory plant composition and productivity in Coastal Plain forest ecosystems, we examined the influence of site preparation and phosphorus fertilization on the successional trends of shrubs and herbaceous plants growing on lands of widely ranging subsoil texture in Arkansas, Louisiana, and Texas which are managed for southern pine production. Burn-inject, chop-burn, chop-burn-disk, double-chop, shear-burn, shear-windrow, and shear-windrow-disk site preparation methods were applied in a completely randomized split-plot design to sites with subsoil textures consisting of loam, gravelly-clay, silt, silty-clay, and clay, both fertilized with 73.4 kg P/ha and unfertilized. Site preparation method, subsoil texture, and fertilization influenced production of paspalums and other forbs the first growing season following treatment, but no treatment combination affected plant groups in subsequent years. Total herbaceous production increased 24 to 35-fold over pretreatment levels the first growing season after treatment. While site preparation methods had little influence on herbaceous biomass, subsoil texture affected herbaceous production the first year after treatment, with loam subsoils being most productive. Although annual composites were the most abundant herbaceous group the first year after treatment, they were largely replaced by perennial grasses by the third post-treatment growing season. By the seventh growing season following treatment, herbaceous production declined on all subsoil textures with composition and yield approximating pretreatment estimates. Subsoil texture influenced shrub density only in the first and third growing seasons after treatment. During the first few years after site preparation, herbaceous production appeared inversely related to shrub density. In the first and third post-treatment growing seasons, fertilization significantly increased total herbaceous production and biomass of composites and legumes. But 7 years after application, total herbaceous production and biomass of bluestems, other grasses, and sedges was greater on unfertilized areas. The absence of differences among treatments by the seventh post-treatment growing season indicates an overall long-term similarity in the degree of disturbance caused by application of each method in this ecosystem.
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Thurber needlegrass: Seasonal defoliation effects on forage quantity and qualityAlthough Thurber needlegrass (Stipa thurberiana Piper) is an important component of Palouse, sagebrush:steppe, and pine:forest rangelands, little is known of its qualitative and quantitative responses to defoliation. At 14-day intervals one of 7 cohorts of Thurber needlegrass plants was defoliated to a 2.5-cm stubble to describe initial growth rates, determine defoliation effects on subsequent regrowth accumulations, relate regrowth potential to available soil moisture, and determine the nutritional value of initial growth and regrowth for livestock. The study was conducted in 1985 and 1986 with a different group of plants used each year. Although crop-year precipitation for the 1985-86 treatment years was 77 and 111%, respectively, of the long term mean (25.2 cm), growth rates of tussocks were similar between years (P > 0.05). Seasonal yield of regrowth varied between years, however, and was well correlated (r2 = 0.76 to 0.80 P < 0.05) with soil moisture content when treatments were applied. Among 7 defoliation dates (24 April-17 July) only the first 5 yielded regrowth in 1985, and all produced regrowth in 1986. Among treatments regrowth averaged 22% of total herbage yield in 1985 and 50% of total yield in 1986. In both years total herbage accumulations were most suppressed (47-63% reduction) by defoliation during the early-boot stage of phenology. In 1985 when conditions were drier, any defoliation before mid-June depressed (P < 0.05) total herbage yield. Crude protein (CP) of needlegrass herbage was high (19-22%) when growth began in April but declined (P < 0.05) to marginal levels for cattle (6.7-7.7%) by mid-July. Regrowth harvested on 31 July ranged from 7 to 9% CP for the earliest (24 April) treatments and as high as 17% for the latest (17 July). Although Thurber needlegrass can produce highly nutritious regrowth for late-season use, managers face diminishing levels of regrowth as the initial cropping date is delayed later into the growing season. Managers contemplating 2-crop grazing regimes for Thurber needlegrass should base scheduling on plant phenology, soil moisture considerations and historic use rather than specific calendar dates. Further work is needed, however, to definitively determine Thurber needlegrass responses to long-term manipulative grazing regimes.
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The deterioration of tall wheatgrass pastures on saline sodic soilsThe deterioration of sown tall wheatgrass (Elytrigia elongata) growing on 3 sodic saline soils was investigated in the Laprida basin, in the center of the Buenos Aires province of Argentina. These soils are known to have poor drainage and high saline levels and support different species associations. On each soil type the native grassland was compared to sown wheatgrass, in terms of plant density and cover and soil physical and chemical characteristics. The 3 soil types reacted differently to tillage. Tillage had little impact on soil type A (typic Natraquoll), a poorly drained soil with a loamy A horizon (14 cm) overlying a silty clay loam. Soil type B (typic Natraquaf), a wet texture contrast soil with bleached horizons has characteristics that are likely to severely limit plant growth. The sowing of wheatgrass increased ground cover by live vegetation on this soil type. This contrasted with soil type C (typic Natralboll), a saline soil with an organic matter-rich but thin (8 cm) A horizon. In this soil, the plant density declined and other components such as pasture cover also declined with time. This pasture deterioration was attributed to several soil factors including decreased organic matter content and increased soil bulk density. It was concluded that the varied performance of wheatgrass sown pastures was a function of the different inherent characteristics of the soils.
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Temperature effects on regrowth of 3 rough fescue speciesThree species of rough fescue, alpine rough fescue (Festuca altaica Trin.), mountain rough fescue (F. campestris Rydb.), and plains rough fescue (F. hallii (Vasey) Piper) were grown for 12 weeks under 5 temperature regimes — 7:3, 12:8, 17:13, 22:18, and 27:23 degrees C — and defoliated 3 times to 3.5 cm at 4-weekly intervals in a growth cabinet study. Final plant dry mass and harvestable biomass production were greatest at 17:13 degrees C for alpine rough fescue and plains rough fescue, and at 12:8 degrees C for mountain rough fescue. Harvestable biomass plateaued or declined at the final harvest in all species for temperatures above 12:8 degrees C. Tiller numbers increased at successive harvests. Biomass per tiller declined markedly at the final harvest of alpine rough fescue at all temperatures. Regrowth in alpine rough fescue was markedly reduced at temperatures either above or below the optimum. The results indicate that mountain rough fescue and plains rough fescue are better able to regrow following defoliation at temperatures below or equal to their optima, than at temperatures above their optima. This provides greater understanding of field responses in both species where frequent defoliations are more deleterious after the April/May period when temperatures are above optimal.
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Technical Note: Stream temperatures as related to subsurface waterflows originating from irrigationContinuous stream temperature data were collected from adjacent reaches of a third-order stream in eastern Oregon. The upstream reach was located within a non-irrigated meadow and the downstream reach was located within an irrigated meadow. Sensors were placed in the stream above a head-ditch irrigation diversion, in the irrigation ditch, in the subsurface (interflow) groundwater, and in the stream reach within the irrigated meadow. Daily maximum stream temperature in the reach located within the irrigated meadow was found to be 1 to 3 degrees C cooler than the non-irrigated reach. Daily minimum stream temperatures exhibited the opposite relationship with the reach within the irrigated meadow ranging from 0.5 to 1.7 degrees C warmer than the non-irrigated meadow reach.
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Technical note: Predicting the components of aerial biomass of fourwing saltbush from shrub height and volumeShrub height and crown diameter are useful non-destructive measures of shrub growth, but precise yields of aerial biomass require destructive methods which are unsatisfactory in studies on perennial shrubs. We developed simple regression models to predict components of aerial biomass from the height, crown diameter and volume of 27 unbrowsed shrubs of fourwing saltbush (Atriplex canescens). The shrubs, ranging in height from 15 to 110 cm, were cut at ground level and manually separated into forage (leaves) and woody material. Samples were oven-dried. Shrub height and volume were sufficiently precise for predicting components of aerial biomass using exponential and linear regression models, respectively. The precision of these non-destructive measures applied under field conditions to unbrowsed shrubs should be confirmed on browsed shrubs.
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Technical Note: Measuring moisture content of small seedsAn accurate determination of moisture content in hydrated or partially hydrated seeds is fundamental to understanding early physiological processes in seeds, and the associated environmental interactions that affect seedling vigor, establishment, and survival. One difficulty encountered while measuring the moisture content of imbibed seeds is that water evaporates from the seed during weighing. This is particularly significant for small seeds because they have a large surface area to volume ratio. We developed a procedure using a standard tin capsule and microbalance which was simple, inexpensive, facilitated precise measurement of moisture in hydrated seeds, and provided reliable results with a minimal amount of seeds. The method is recommended as a means for increasing the accuracy of seed weight and seed moisture measurements.