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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  • Livestock Grazing Impacts on Desert Vegetation, Khirthar National Park, Pakistan

    Enright, Neal J.; Miller, Ben P. (Society for Range Management, 2007-11-01)
    The impact of livestock grazing on desert vegetation in Khirthar National Park, Pakistan, was investigated by comparing dry and wet season plant species composition, richness, cover, and a grazing index for quadrats outside (‘‘open’’) and inside (‘‘exclosed’’) native mammal breeding enclosures that had excluded livestock for 6 years. A total of 93 plant species were recorded in the dry season, 88 species in exclosed quadrats and 50 in open quadrats. While only 5 species were unique to open quadrats, 43 species were found only in the exclosed quadrats. Species richness was higher in the exclosures because of the presence of more grass and herb species, while grazing was higher in the open. After rain, species richness and cover were significantly higher than in the dry season because of the growth of summer ephemeral herbs and grasses, but richness was no longer different between the exclosure and open treatments. Although some herbaceous species may have been adversely affected by livestock grazing, overall species richness suggests strong ecosystem resilience to grazing, with levels no different after seasonal rains regardless of grazing level. Many grass and herb species absent from open sites during the dry season reappeared after rain, which suggests that livestock grazing may eliminate them as the dry season proceeds, but that a soil seed or bud bank persists. 
  • 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. 
  • Hydrologic Impacts of Mechanical Seeding Treatments on Sagebrush Rangelands

    Pierson, Frederick B.; Blackburn, Wilbert H.; Van Vactor, Steven S. (Society for Range Management, 2007-11-01)
    In and around the Great Basin, United States, restoration of shrub steppe vegetation is needed where rangelands are transitioning to annual grasslands. Mechanical seedbed preparation can aid native species recovery by reducing annual grass competition. This study was designed to investigate the nature and persistence of hydrologic and erosion impacts caused by different mechanical rangeland seeding treatments and to identify interactions between such impacts and related soil and vegetation properties. A cheatgrass (Bromus tectorum L.)-dominated site was burned and seeded with native grasses and shrubs in the fall of the year. An Amazon-drill and a disk-chain seeder were used to provide varying levels of surface soil disturbance. An undisturbed broadcast seeding was used as a control. Simulated rainfall was applied to 6 large (32.5-m2) plots per treatment over 3 growing seasons at a rate of 63.5 mm h-1. Rainfall was applied for 60 minutes under dry antecedent moisture conditions and for 30 minutes, 24 hours later under wet antecedent moisture conditions. The disk-chain created the largest reduction in infiltration and increase in sediment yield, which lasted for 3 growing seasons posttreatment. The Amazon-drill had a lesser impact, which was insignificant after the second growing season posttreatment. Surface soil properties showed little correlation with treatment-induced hydrologic and erosion impacts. Hydrologic recovery was strongly correlated with litter dynamics. The seeding treatments were unsuccessful at establishing seeded plant species, and the site once again became dominated by cheatgrass. A continuous upward trend in biomass production and surface litter cover was observed for all treatments between the beginning and end of the study because of cheatgrass invasion. Although the initial goal of using mechanical seeding treatments to enhance recovery of native grass species failed, cheatgrass production provided sufficient biomass to rapidly replenish surface litter cover necessary for rapid hydrologic stability of the site. 
  • Effects of Grazing Intensity, Precipitation, and Temperature on Forage Production

    Patton, Bob D.; Dong, Xuejun; Nyren, Paul E.; Nyren, Anne (Society for Range Management, 2007-11-01)
    Questions have been raised about whether herbaceous productivity declines linearly with grazing or whether low levels of grazing can increase productivity. This paper reports the response of forage production to cattle grazing on prairie dominated by Kentucky bluegrass (Poa pratensis L.) in south-central North Dakota through the growing season at 5 grazing intensities: no grazing, light grazing (1.3 +/- 0.7 animal unit months [AUM] ha-1), moderate grazing (2.7 +/- 1.0 AUM ha-1), heavy grazing (4.4 +/- 1.2 AUM ha-1), and extreme grazing (6.9 +/- 2.1 AUM ha-1; mean +/- SD). Annual herbage production data were collected on silty and overflow range sites from 1989 to 2005. Precipitation and sod temperature were used as covariates in the analysis. On silty range sites, the light treatment produced the most herbage (3 410 kg ha-1), and production was reduced as the grazing intensity increased. Average total production for the season was 545 kg ha-1 less on the ungrazed treatment and 909 kg ha-1 less on the extreme treatment than on the light treatment. On overflow range sites, there were no significant differences between the light (4 131 kg ha-1), moderate (4 360 kg ha-1), and heavy treatments (4 362 kg ha-1; P > 0.05). Total production on overflow range sites interacted with precipitation, and production on the grazed treatments was greater than on the ungrazed treatment when precipitation (from the end of the growing season in the previous year to the end of the grazing season in the current year) was greater than 267.0, 248.4, 262.4, or 531.5 mm on the light, moderate, heavy, and extreme treatments, respectively. However, production on the extreme treatment was less than on the ungrazed treatment if precipitation was less than 315.2 mm. We conclude that low to moderate levels of grazing can increase production over no grazing, but that the level of grazing that maximizes production depends upon the growing conditions of the current year. 
  • Nutrient Availability in Rangeland Soils: Influence of Prescribed Burning, Herbaceous Vegetation Removal, Overseeding with Bromus tectorum, Season, and Elevation

    Blank, R. R.; Chambers, J.; Roundy, B.; Whittaker, A. (Society for Range Management, 2007-11-01)
    Soil nutrient availability influences plant invasions. Resin capsules were used to examine soil nutrient bioavailability along 2 sagebrush-grassland elevation transects in the east Tintic Range (Utah) and Shoshone Range (Nevada). In the fall of 2001, treatments were applied to 3 replicate plots at each site, which included prescribed burning, herbaceous vegetation removal, and controls. Cheatgrass (Bromus tectorum L.) was overseeded in small subplots within each treatment. Following treatments in each plot, resin capsules were installed at 15-cm depth in a shrub interspace and a B. tectorum-overseeded area. Nutrient availability was integrated during late fall to spring and spring to late fall for 2 years. Herbaceous vegetation removal increased availability of nitrate (Nevada and Utah) and Ca and Mg (Nevada only) but only during the second sampling period (growing season). Availability of K and ortho-P (Nevada and Utah) and nitrate (Nevada only) was greater on prescribed burned plots. For Utah, availability of ortho-P, K, Ca, Mg, and Fe generally increased with increasing elevation. Availability of Ca, Mg, K, and Fe was greatest during late fall to spring integration periods for Nevada. Overseeding with B. tectorum interacted with the burn treatment to influence availability of Ca, Mg, and Fe (Nevada sites only). Patterns of nutrient availability can be explained by a combination of decreased root uptake in relation to mineralization, differences in soil water content with season and elevation, and nutrient release from vegetation and soil as a consequence of prescribed burning. Herbaceous vegetation removal and burning can raise nitrate availability and increase risk of invasion by nitrophilic species such as B. tectorum. Nutrient availability can be out of phase with plant growth; plants capable of taking up nutrients during cold periods may have a competitive advantage. Resin capsules have utility in quantifying the effects of treatments on the availability of many soil nutrients. 
  • The Effects of Forest Residual Debris Disposal on Perennial Grass Emergence, Growth, and Survival in a Ponderosa Pine Ecotone

    Law, Darin J.; Kolb, Peter F. (Society for Range Management, 2007-11-01)
    Soil surface conditions can have profound effects on plant seedling emergence and subsequent seedling survival. To test the hypothesis that different soil-surface treatments with logging residue affect range grass seedling emergence and survival, 6 alternative forest-residual treatments were established in the summer of 1998 following thinning of mature trees from approximately 500 to 133 trees ha-1. The treatments included 1) whole logging debris, hand-piled; 2) whole logging-debris piles that were burned; 3) whole logging-debris piles that were chipped; 4) whole logging-debris piles that were chipped and burned; 5) scattered debris followed by a broadcast burn; and 6) zero debris, not burned. The influences of the debris treatments on grass seedling emergence and survival were tested by seeding with native and exotic perennial grass species. Three plots per treatment were seeded with a mix of 4 native grass species, and another 3 plots per treatment were seeded with a mix of 4 exotic grass species. Two plots per treatment were left unseeded. Subsequent grass emergence, growth, and establishment were measured as seedling emergence, cover, density, height, and biomass for 3 growing seasons. Grass cover, density height, and biomass increased on the burn treatments during the study. Less-significant results were obtained for the nonburned woody- debris treatments. In addition, important abiotic factors, such as soil moisture and soil surface temperature, were not adversely affected by the woody debris disposal practices tested in this study. Results indicate that scattered woody debris that is broadcast burned is the best mechanism for disposing of woody debris, increasing grass emergence and survival, and preventing ponderosa pine recruitment and exotic invasion.
  • Influence of Grassland Gap on Seedling Establishment of Leymus chinensis (Trin.) Tzvel

    Liu, G. X.; Han, J. G. (Society for Range Management, 2007-11-01)
    A field study was conducted to investigate the effects of existing adult neighbors and gap size on the process of seedling establishment in Leymus chinensis. Seeds of L. chinensis were added to artificially created gaps in a degraded steppe in North China. Neighbor root exclusion was accomplished using polyvinyl chloride tubes sunk in the soil of gaps. Seedling emergence and survivorship was greater in gaps than in control areas, but growth performance was higher only in larger gaps (20 cm and 40 cm in diameter) with neighboring roots present and in all gaps without neighboring roots present. Seedlings produced no tillers in the control and few tillers in 10-cm- and 20-cm-diameter gaps. Seedlings had more tillers in the largest gaps (40 cm) without root exclusion and in all sizes of gaps with root exclusion. Differences between gaps in light levels can explain the patterns of emergence. However, root exclusion was the major factor that increased seedling growth performance. These results confirm that L. chinensis is a gap-enhanced species and suggest that restoration of degraded grassland needs to ensure that large light gaps and low belowground competition are regularly maintained to maximize successful seedling recruitment. 
  • Prediction of Cheatgrass Field Germination Potential Using Wet Thermal Accumulation

    Roundy, Bruce A.; Hardegree, Stuart P.; Chambers, Jeanne C.; Whittaker, Alison (Society for Range Management, 2007-11-01)
    Invasion and dominance of weedy species is facilitated or constrained by environmental and ecological factors that affect resource availability during critical life stages. We compared the relative effects of season, annual weather, site, and disturbance on potential cheatgrass (Bromus tectorum L.) germination in big sagebrush (Artemisia tridentata Nutt.) communities. Soil water status and temperature in the seedbed were measured continuously for 4 years on 9 big sagebrush sites in Nevada and Utah. Field plots at lower-, middle-, and upper-elevation sites were either undisturbed, or were burned, sprayed with herbicide, or both sprayed and burned. Spraying removed perennial herbaceous vegetation, whereas burning removed sagebrush. We used thermal-germination data from laboratory incubation studies of 18 cheatgrass seedlots and field soil moisture and temperature measurements to model and predict potential germination in the field plots for periods when seedbeds were continuously wet (above –0.5, –1, or –1.5 MPa) and across intermittent wet and dry periods. Season had the greatest effect on potential cheatgrass germination, followed by annual weather, and site variables (elevation and location); the effects of disturbance were minimal. Potential germination was predicted for most sites and years in spring, a majority of sites and years in fall, and few sites or years in winter. Even though disturbance has limited effects on potential germination, it can increase cheatgrass invasion and dominance by reducing perennial herbaceous species resource use and allowing increased cheatgrass growth and reproduction. 
  • Establishment of Native Species in Soils From Russian Knapweed (Acroptilon repens) Invasions

    Tyrer, Sarah J.; Hild, Ann L.; Mealor, Brian A.; Munn, Larry C. (Society for Range Management, 2007-11-01)
    Russian knapweed (Acroptilon repens [L.] DC.), an exotic perennial forb, has invaded many native ecosystems in western North America. Russian knapweed’s success is attributed to allelopathy, extensive tap rooting, zinc accumulation in soils, and a lack of North American predators. Revegetation following chemical control slows exotic reestablishment, but the impacts of Russian knapweed-invaded soils on the establishment of native forbs and shrubs have not been determined. In a greenhouse experiment, we monitored the establishment of two native forbs, Indian blanketflower (Gaillardia aristata Pursh) and purple prairie clover (Dalea purpurea Vent.) and two native shrubs, winterfat (Krascheninnikovia lanata [Pursh] A.D.J. Meeuse Smit syn. Ceratoides lanata) and Wyoming big sagebrush (Artemisia tridentata Nutt. subsp. wyomingensis [Hook.] Nutt.) in soils obtained from three Russian knapweed invasions and adjacent noninvaded areas. We analyzed soils collected near Greybull and Riverton, Wyoming, and Greeley, Colorado, for cation exchange capacity, organic matter, electroconductivity, pH, and total nitrogen, carbon, and plant-available potassium, zinc, manganese, copper, and phosphate. We documented seedling emergence of the four natives and Russian knapweed every two days for 14-17 weeks, harvested seedlings biweekly to assess their growth, and determined their zinc accumulation. All species established in invaded soil and seedlings were larger in invaded than in noninvaded soils. Invaded rangeland soils had greater organic matter (8.6% and 1.1% in invaded vs. 2.5% and 0.4% in noninvaded soils) and lower pH (7.4 in invaded versus 8.0 noninvaded soils). Zinc concentrations in invaded soils (from 0.15 to 6.56 mg kg-1) were not high enough to limit plant growth. Reports that Russian knapweed is a hyper-accumulator of zinc are not supported by our seedling data, which suggests that previously invaded soils may not limit native seedlings. 
  • Effects of Fire and Neighboring Trees on Ashe Juniper

    Noel, Jill M.; Fowler, Norma L. (Society for Range Management, 2007-11-01)
    The survival of Ashe juniper (Juniperus ashei Buchh.) plants of all sizes was compared between paired burned and unburned plots in four savanna sites on the eastern Edwards Plateau. Smaller plants were less likely to survive a fire than larger plants, over the entire range of plant sizes. Overall fire survival rates varied from <45% (0- to 50-cm-tall plants) to <92% (> 2-m-tall plants). The high rate of survival of small plants indicates that fires like those typically used in this region are not likely to control even the early stages of the encroachment of Ashe juniper. If fire is to be used to maintain savannas in this region, multiple burns, more intense fires, or supplementary mechanical removal will probably be needed. Junipers 0 to 200 cm tall were significantly more likely to be growing under the canopy of a tree (defined as a plant > 2 m tall of any species) than in the open. Small (0 to 50 cm tall) junipers under a tree canopy were significantly more likely to be alive than plants in the same size class growing in the open, suggesting facilitation of small Ashe juniper by neighboring trees. There was, however, no significant effect of neighboring trees on the rate at which small Ashe juniper survived fire, contrary to our initial expectation. 
  • Effects of Supplementation on Juniper Intake by Goats

    Campbell, Erika S.; Taylor, Charles A.; Walker, John W.; Lupton, Christopher J.; Waldron, Dan F.; Landau, S. Y. (Society for Range Management, 2007-11-01)
    The potential for winter supplementation to increase juniper intake by goats on rangelands in the Edwards Plateau region of Texas was assessed in two experiments. The first experiment evaluated the effect on juniper intake of either no supplementation (negative control) or supplementation with corn, alfalfa, or cottonseed meal fed at an isonitrogenous protein level of 1.5 g kg body weight-1 for 12 days. Redberry juniper (Juniperus pinchotii Sudw.) consumption by individually penned Spanish, Boer 3 Spanish, Spanish 3 Angora, and Angora goats was measured on days 11 and 12. Each goat received each supplement in a complete 4 X 4 Latin square design. Juniper intake increased for goats supplemented with alfalfa and cottonseed meal (P = 0.001), but not for those supplemented with corn (P = 0.944). Boer 3 Spanish goats did not differ in levels of consumption (P = 0.085) from the other breeds. A second study investigated the effect of either no supplementation or soybean meal supplementation on juniper consumption by free grazing Angora and Boer 3 Spanish goats. Forty goats were assigned to four pasture groups by breed and previous juniper intake, and randomly allocated to either the treatment (supplementation) or control (no supplementation) regime in a complete block design. After 4 days of grazing and supplementation, fecal samples were collected to estimate percent of juniper in the diet using near-infrared spectroscopy. Goats were then rotated to another pasture. Juniper intake was highest for goats supplemented with soybean meal (P = 0.034). Breed of goat did not affect intake (P = 0.240). Goats previously categorized as high juniper consumers based upon prior measurements of juniper intake ate more juniper (P = 0.003) than those classified as low consumers. This research indicates that the effectiveness of goats for biological control of juniper can be improved with a high protein, low starch supplement. 
  • Effects of Weaning Date and Prepartum Protein Supplementation on Cow Performance and Calf Growth

    Stalker, L. Aaron; Ciminski, Lane A.; Adams, Don C.; Klopfenstein, Terry J.; Clark, Richard T. (Society for Range Management, 2007-11-01)
    Two experiments evaluated effects of weaning date on cow body condition score (BCS) and calf growth. In Experiment 1, 134 March-calving cows were used in a four-year experiment. Calves were weaned 18 August or 7 November and cows were fed 0 or 0.45 kg protein supplement (42% crude protein) three days per week from 1 December to 28 February while grazing upland range in a 2 by 2 factorial arrangement of treatments. In Experiment 2, spring calving cows (year 1, n = 97; year 2, n = 104) were assigned randomly to one of eight weaning dates at 2-week intervals from 19 August to 25 November. In Experiment 1, weaning in August increased cow BCS precalving (P < 0.001) and prebreeding (P < 0.001), but not pregnancy rates (P = 0.56). Cows fed supplemental protein had greater BCS precalving (P<0.001) and prebreeding (P=0.001) than nonsupplemented cows, but pregnancy rates were similar (P=0.27). Calves born to cows fed supplemental protein prepartum had greater weaning weight than calves born to nonsupplemented cows regardless of whether weaning occurred in August (P = 0.001) or November (P < 0.001). Effects of weaning date on feedlot performance interacted with supplementation treatment. Calves born to cows fed supplement that were weaned in November generated the greatest net returns. In Experiment 2, BCS decreased linearly (P<0.001) as date of weaning was delayed from August to November. Nursing calf gain increased cubically (P < 0.0004) and weaned calf gain from August to November increased quadratically (P < 0.002). Protein supplementation did not affect cow pregnancy rate, but calves born to cows fed protein supplement had greater pre- and postweaning gains. Cow BCS decreased as weaning date was moved later in the year but cow pregnancy rate was not affected by weaning date. 
  • The Potential for Horses to Disperse Alien Plants Along Recreational Trails

    Wells, Floye H.; Lauenroth, William K. (Society for Range Management, 2007-11-01)
    Plant invasions are rapidly becoming an important threat to the conservation of wildlands. Understanding how potentially invasive plants are dispersed to new habitats is a critical step in the process of understanding such invasions. Our objective was to characterize the potential for long-distance transport of plant species in the digestive tract of horses along recreational trails. We sampled horse dung along the first 4 000 m of the Lower Piney River trail in the White River Forest of western Colorado. We evaluated the seed content of each sample by applying standard methods for soil seed bank analysis. We found 20 species and 564 seedlings. Twelve of the species were graminoids, 6 were forbs, 1 was a shrub, and 1 was a tree. The species were evenly divided between natives and aliens, but 85% of the seedlings were aliens. An average of 47 seedlings emerged per sample, but the range was from 4 to 192. Our results make it clear that horses, and very likely all pack stock used on recreational trails, represent a potentially important dispersal vector for alien plants into western wildlands. 
  • Initial Effects of Brush Cutting and Shoot Removal on Willow Browse Quality

    Rea, Roy V.; Gillingham, Michael P. (Society for Range Management, 2007-11-01)
    We examined the initial effects of brush cutting (removal of all aboveground biomass), as well as clipping (removal of current annual shoots) and ungulate browsing (collectively referred to as shoot removal) on the morphology and nutrient quality of Scouler’s willow (Salix scouleriana J. Barratt ex Hook.) for ungulates on sites 2 and 4 years after brush cutting. We specifically assessed changes in the biomass, tannin content, digestible energy, and digestible protein of shoots from brush-cut willows relative to shoots of uncut willows to determine how browse plants respond to this form of vegetation management. In winter, the resprouted current annual shoots of willows that had been brush cut were larger in mass and lower in digestible protein than shoots of uncut willows for at least 4 years after brush cutting. Shoots of brush-cut willows were also lower in tannin and digestible energy than the shoots of uncut plants for two winters after brush cutting. In the second winter after brush cutting, shoot biomass decreased and tannin content increased with increasing shoot removal during the previous winter. In the fourth winter after brush cutting, shoot mass increased and digestible energy decreased in shoots with greater shoot removal. Nutrient quality was otherwise unaffected by the amount of shoot removal during the previous winter. Because of the occasional importance of site effects in this study, we recommend that long-term studies maximize the number of sampled sites. Because brush cutting alters the quality of regenerating browse and can affect how ungulates utilize such browse for several years after brush cutting, we further recommend that forest vegetation managers consider potential impacts of brush cutting on ungulate winter range. 
  • Chukar Watering Patterns and Water Site Selection

    Larsen, Randy T.; Flinders, Jerran T.; Mitchell, Dean L.; Perkins, Ernest R.; Whiting, David G. (Society for Range Management, 2007-11-01)
    We evaluated chukar (Alectoris chukar) watering patterns as well as habitat variables influencing water site selection in western Utah. Motion-sensing cameras and chukar dropping counts were primary techniques to evaluate watering patterns. We took vegetative and other habitat measurements at each water source (n = 43) to discriminate use from nonuse sites using logistic regression. Chukars watered during daylight hours with a modal hour from 1200 hours to 1300 hours daylight savings time. Annual patterns suggest limited use of water sources from November to May with first observed visits occurring in June and last observed visits in October. Shrub canopy cover was the only variable to discriminate between site types (P<0.01). Cross validation showed a predictive success rate of 84%. Significant differences were found between use and nonuse sites in terms of security cover (P < 0.01), but not total cover (P > 0.05). Chukars seem to have a loose shrub canopy threshold near 11% that is likely due to predation risk. Water sources meeting this threshold received use, whereas those not meeting this threshold did not. Increasing shrub canopy cover above 11% did not translate into increased water source use. Managers might want to consider annual patterns when setting hunt season timing and structure as well as judging sites for new water developments based on shrub canopy cover. More generally, these results suggest a behavioral constraint on the use of water sources as a function of predation risk—we should expect other species to demonstrate similar behavioral constraints. These constraints must be considered in any effort to determine benefits or impacts of water developments. 
  • 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. 
  • Digital Photography: Reduced Investigator Variation in Visual Obstruction Measurements for Southern Tallgrass Prairie

    Limb, Ryan F.; Hickman, Karen R.; Engle, David M.; Norland, Jack E.; Fuhlendorf, Samuel D. (Society for Range Management, 2007-09-01)
    Landscapes with structural heterogeneity or patchiness can support diverse and stable wildlife populations. Visual obstruction methods (i.e., Robel pole and Nudd’s coverboard) are common and useful techniques for quantifying vegetation structure; however, both rely on ocular estimations, which can be highly variable between observers. Our objectives were to 1) compare measurement and observer variation for visual obstruction among the two standard methods and the digital image method we developed using a digital camera; and 2) compare the performance of the Robel pole and digital image to estimate standing crop. The mean variation across the five observers using the digital image method (6.8%) was significantly lower (P < 0.05) than both the Nudds’ coverboard (32.1%) and the Robel pole (52.2). There were no significant differences among locations for the digital image method; however, there were for both the Robel pole and Nudds’ cover board (P<0.05). The digital image method provided a better estimate of standing crop (r2 = 0.89) compared to the Robel pole (r2 = 0.68), accounting for 21% more of the observed variation in biomass. Long-term research programs that utilize seasonal field technicians to quantify habitat structure with a visual obstruction method could benefit from implementing use of the digital image method we developed. The low measurement error observed with this technique relative to the more traditional methods compared in this study might limit year- to-year and within-year variability of habitat structure data collected by numerous technicians with a high annual turnover. 
  • Extent of Stem Dieback in Trembling Aspen (Populus tremuloides) as an Indicator of Time-Since Simulated Browsing

    Carson, Allan W.; Rea, Roy V.; Fredeen, Arthur L. (Society for Range Management, 2007-09-01)
    Simulated browsing treatments were imposed on an important browse species of the North American moose (Alces alces L.) to see if the development and extent of subsequent stem dieback in trembling aspen (Populus tremuloides Michx.) could be used to determine the time of browsing during the growing season. Two hundred naturally growing aspen saplings of similar size and form were randomly selected in a 20-ha area near the endowment lands of the University of Northern British Columbia, Prince George, British Columbia, Canada. Plants were randomly assigned to treatment categories so that the apical meristems of 50 plants each were assigned to a control or were clipped on one of the following dates 6 weeks apart: 1 June, 16 July, and 30 August 2005. The leader of each aspen was clipped and dieback was left to progress until the onset of winter dormancy. Our results showed that the earlier the simulated browsing occurs in the growing season, the greater the length of stem dieback, up to the maximum of the subapical axillary node below the point of clipping. The average rate at which dieback progressed varied between treatments and decreased throughout the growing season. Our results suggest that the ratio of the actual length of stem dieback to the overall length of stem between the clip point and the subapical axillary node serves as a good indicator for estimating the time at which aspen meristems have been browsed during the growing season. 
  • Influence of Fire on Black-Tailed Prairie Dog Colony Expansion in Shortgrass Steppe

    Augustine, David J.; Cully, Jack F.; Johnson, Tammi L. (Society for Range Management, 2007-09-01)
    Factors influencing the distribution and abundance of black-tailed prairie dog (Cynomys ludovicianus) colonies are of interest to rangeland managers because of the significant influence prairie dogs can exert on both livestock and biodiversity. We examined the influence of 4 prescribed burns and one wildfire on the rate and direction of prairie dog colony expansion in shortgrass steppe of southeastern Colorado. Our study was conducted during 2 years with below-average precipitation, when prairie dog colonies were expanding throughout the study area. Under these dry conditions, the rate of black-tailed prairie dog colony expansion into burned grassland (X ̄ 5 2.6 ha 100-m perimeter-1 y-1; range = 0.8-5.9 ha 100-m perimeter-1 y-1; N = 5 colonies) was marginally greater than the expansion rate into unburned grassland (X ̄ 5 1.3 ha 100-m perimeter-1 y-1; range = 0.2-4.9 ha 100-m perimeter-1 y-1; N = 23 colonies; P = 0.066). For 3 colonies that were burned on only a portion of their perimeter, we documented consistently high rates of expansion into the adjacent burned grassland (38%-42% of available burned habitat colonized) but variable expansion rates into the adjacent unburned grassland (2%-39% of available unburned habitat colonized). While our results provide evidence that burning can increase colony expansion rate even under conditions of low vegetative structure, this effect was minor at the scale of the overall colony complex because some unburned colonies were also able to expand at high rates. This result highlights the need to evaluate effects of fire on colony expansion during above- average rainfall years, when expansion into unburned grassland may be considerably lower. 
  • Will Molasses or Conditioning Increase Consumption of Spotted Knapweed by Sheep?

    Whitney, Travis R.; Olson, Bret E. (Society for Range Management, 2007-09-01)
    The spread of the invasive, Eurasian spotted knapweed (Centaurea maculosa Lam.) across the northwestern United States would be reduced if livestock regularly consumed it. We determined if white-face yearling ewes (n = 36) conditioned for 12 days to fresh-cut spotted knapweed, with or without molasses, would increase their use of it during a 5-day field trial and/or a 4-day drylot trial. Ewes were assigned to one of three treatments: ewes not conditioned to spotted knapweed or molasses (NC), ewes conditioned to spotted knapweed (SK), or ewes conditioned to spotted knapweed sprayed with liquid beet molasses (SKM). During conditioning, all groups consumed high amounts of their feed. Nonconditioned ewes (NC) consumed less than ewes conditioned to spotted knapweed (SK, SKM), indicating spotted knapweed did not inhibit initial consumption. In the field, SKM ewes spent more time grazing spotted knapweed and other forbs than SK ewes. In a drylot, time spent eating and intake of spotted knapweed and bromegrass (Bromus inermis Leyss.) varied through time. Conditioning yearling ewes to spotted knapweed, with or without molasses, did not increase consumption of this invasive plant, possibly because sheep inherently graze spotted knapweed only to a certain extent, or we did not use enough spotted knapweed during conditioning. 

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