• Wyoming big sagebrush control with metsulfuron and 2,4-D in northern New Mexico

      McDaniel, K. C.; Anderson, D. L.; Balliette, J. F. (Society for Range Management, 1991-11-01)
      Field experiments conducted between 1982 to 1988 compared 2,4-D [(2,4-dichlorophenoxy)acetic acid] and metsulfuron [2-[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl) amino)carbonyl]amino]sulfonyl]benzoic acid) for control of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis Beetle and Young) in northern New Mexico. Precipitation was near or above normal during years of herbicide applications. Broadcast sprays of 2,4-D at 2.2 kg/ha were most efficacious during rapid shoot elongation, but mortality averaged less than 38% from treatments applied over 4 separate years. Wyoming big sagebrush shoot growth was greatest in April and May compared to other months, but growth was highly variable among shrubs and probably reduced effectiveness of 2,4-D sprays. The optimum application timing for metsulfuron was during the late-flower growth and fruiting stages. Fall-applied metsulfuron at 0.035 kg/ha provided 65% Wyoming big sagebrush mortality compared to 27% when spring-applied. When metsulfuron was fall-applied at 0.07 kg/ha or higher, control averaged 88% following 3 annual applications. Combining metsulfuron at .0175 kg/ha plus 2,4-D at 1.1 kg/ha was comparable to or more effective than either herbicide applied alone in spring or fall. Total standing crop of grasses increased by nearly 300% after 1 or 2 growing seasons when Wyoming big sagebrush canopy cover was reduced by at least 75% following herbicide treatments.
    • Utilization of larkspur by sheep

      Ralphs, M. H.; Bowns, J. E.; Manners, G. D. (Society for Range Management, 1991-11-01)
      Sheep are more resistent to larkspur (Delphinium spp.) poisoning than are cattle, and may be used as a biological tool to graze larkspur prior to cattle turn-in to reduce the risk of cattle poisoning. Sheep utilization of 3 species of larkspur was measured at 3 phenological growth states (vegetative, bud, and flower) at 5 locations. Utilization of waxy larkspur (D. glaucescens Wats), varied among years at Ruby, Mont. Use of duncecap larkspur (D. occidentals. Wats) at Oakley, Ida., was uniformly higher in all 3 growth stages due to closed herding practices. Use of tall larkspur (D. barbeyi Huth) increased as it matured. Trailing sheep through larkspur patches, or bedding them in patches greatly increased trampling of larkspur stalks and utilization of heads and leaves.
    • Use of ornamental lilac and honeysuckle phenophases as indicators of rangeland grasshopper development

      Kemp, W. P.; Berry, J. S.; Caprio, J. M. (Society for Range Management, 1991-11-01)
      Comparisons were made between phenological phase dates of 2 common ornamental shrubs, purple common lilac (Syringa vulgaris L.) and Zabeli honeysuckle (Lonicera krolkowii Stapf, var. Zabelii (Rehd. Rehder)), and rangeland grasshopper (composite of 6 common species) development for 3 years at 9 sites throughout Montana. Results indicated that spring hatch (75% instar 1) occurred about 10 days after the begin bloom phase of purple common lilac. Peak occurrence of grasshoppers for instar 2 coincided, on average, with the end bloom phase of Zabeli honeysuckle, whereas peak instar 3 occurred about 10 days later. On average, peak instar 4 preceded the first red berry phase of Zabeli honeysuckle by about 8 days, and 75% adult stage occurred about 14 days after red berries first appeared. Our results provide rangeland managers and ranchers with a simple method for the improved timing of assessment and control of rangeland grasshoppers.
    • The grass seedling: When is it established?

      Ries, R. E.; Svejcar, T. J. (Society for Range Management, 1991-11-01)
      Adventitious roots of sufficient length and diameter must develop to assure that the photosynthetic surfaces receive sufficient water and nutrients before grass seedlings can be considered established. We evaluated development of crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.] and blue grama [Bouteloua gracilis (H.B.K.) Lag.] seedlings in the field to decide when they were established. Blue grams and crested wheatgrass seedlings, under the environmental conditions of this study, were considered established 21 days after emergence. At this time, crested wheatgrass seedlings had 4 leaves, 2 adventitious roots penetrating to a depth of at least 80 mm into the soil, and 1 tiller per plant. Blue grama seedlings had about 6 leaves, 2 adventitious roots penetrating to a depth of at least 100 mm into the soil, and 2 tillers per plant. Most seedlings that reached this stage by the end of the first growing season overwintered and survived the following growing season and provided adequate stands for both species.
    • Technical Note: Surgical establishment of esophageal fistulae in suckling calves

      Adams, D. C.; Short, R. E.; Pfister, J. A.; Peterson, K. R.; Hudson, D. B. (Society for Range Management, 1991-11-01)
      Esophageal fistulae were established in five 34-day-old suckling calves by a modified surgical procedure used previously for sheep and goats. After skin incision, the esophagus was exposed by separating the brachiocephalicus and sternocephalicus muscles. A cannula was inserted into the esophagus after a longitudinal incision was made into the lumen of the esophagus. Sutures were not used in the esophagus. The calves recovered quickly with moderate post-operative swelling. We concluded that the surgical procedure was satisfactory and that diets were collected readily and without fistulae shrinkage.
    • Sward and steer variables affecting feasibility of electronic intake measurement of grazers

      Forwood, J. R.; Da Silva, A. M. B.; Paterson, J. A. (Society for Range Management, 1991-11-01)
      Forage intake is perhaps the most critical parameter in understanding performance of ruminants on pasture. The Thermal Conductivity Cannula (TCC) is an animal-carried device that measures forage intake without disturbing normal grazing patterns by counting the number of boli swallowed over time. To evaluate its accuracy, studies of the effects of animal size, forage availability, quality, and species differences were conducted. In a grazing study, bolus weights of heavy (533 kg) and light (360 kg) esophageally fistulated steers were monitored on 2 different grazing systems [tall fescue (Festuca arundinacea Shreb) + red clover (Trifolium sp.) season-long vs. tall fescue + red clover in spring and fall and bit bluestem (Andropogon gerardi Vit; cv. Kaw) in summer]. Boli weight differences between steer weights indicated that TCC intake estimation will require calibration for steer weight or use of uniform steers. Boli weights of heavy steers varied (P < 0.05) within (9.0 to 19.4 g) and among (19.4 to 30.2 g) forage species. That did not occur with light steers (average = 6.25). Analysis of data on a metabolic weight basis indicated that size of the oral cavity and the 'critical mass' needed to stimulate swallowing may be a factor as well as weight. Sward characteristics and quality parameters were poorly correlated with bolus weight. An indoor study using 3 steer weights (heavy-546 kg, medium-486 kg, and light-220 kg) fed orchardgrass (100%), alfalfa (100%), and orchardgrass X alfalfa hay (50/50) indicated that heavier steers always produced heavier boli but that the weight differences between steers had to be greater than 86 kg to be significantly different. Light steers produced most consistent boli weights over all feeds.
    • Spatial components of plant-herbivore interactions in pastoral, ranching, and native ungulate ecosystems

      Coughenour, M. B. (Society for Range Management, 1991-11-01)
      The spatial component of herbivory remains enigmatic although it is a central aspect of domestic and native ungulate ecosystems. The effects of ungulate movement on plants have not been clearly established in either range or wildlife management. While livestock movement systems have been implemented to cope with increases in livestock density, restrictions on movement, and overgrazing, a large number of studies have disputed the effectiveness of different livestock movement patterns. Traditional pastoralism, particularly nomadism, has been perceived as irrational and even destructive, but many studies have documented features of traditional pastoral land use that would promote sustainability. Disruptions of wild ungulate movements have been blamed for wildlife overgrazing and population declines, but actual patterns and mechanisms of disrupted movement and population responses have been poorly documented. Models that integrate plant growth, ungulate movement, and foraging are suggested as a way to improve analyses of spatial plant-herbivore systems. Models must give due attention to nonforage constraints on herbivore distribution, such as topography. Models should assess the significance of movement as a means of coping with local climatic variation (patchy rainfall). Models that distribute an aggregate population over a landscape in relation to the distribution of habitat features deemphasize aspects of ungulate movements and population responses that inevitably cause nonideal distributions, particularly in natural ecosystems. Individual based models describe movement and foraging processes more accurately, but these models are difficult to apply over large areas. Both top-down and bottom-up approaches to spatial herbivory are needed. To model plant responses to movement, it is important to account for small scale phenomena such as tiller defoliation patterns, patch grazing, and grazing lawns as well as large scale patterns such as rotation and migration. Herbivory patterns at these different scales are interrelated.
    • Plant-plant interactions affecting plant establishment and persistence on revegetated rangeland

      Pyke, D. A.; Archer, S. (Society for Range Management, 1991-11-01)
      Restoration and revegetation of rangeland ecosystems is based on knowledge of abiotic and biotic interactions that affect plant establishment. Once plants become autotrophic, interactions within and between plant species may occur and then interactions may range from antagonistic to mutualistic. This full range of potential interactions needs to be considered to ensure successful revegetation. At the intraspecific level, we propose the development and use of density-yield diagrams for rangeland species. These diagrams would be based on the self-thinning principle, that aboveground biomass is related to plant density and to the dynamic process of density-dependent mortality. The proposed approach would be used to determine optimum seeding rates, and to predict future biomass of revegetated rangeland. At the interspecific level, competitive relationships of species used to reseed rangelands need to be identified to enhance the probability that species will coexist and thereby facilitate greater species diversity on the site. A diversity of species and growth forms may provide a more stable cover and productivity than a monoculture on sites characterized by environmental variability while potentially enhancing nutrient status for the site.
    • Plant-animal interactions affecting plant establishment and persistence on revegetated rangeland

      Archer, S.; Pyke, D. A. (Society for Range Management, 1991-11-01)
      The role of ungulate grazing in shaping rangeland ecosystems is well known relative to other important plant-animal interactions such as pollination, seed dispersal, granivory, and belowground herbivory. Successful rangeland revegetation may be enhanced by strategies that favor certain groups of animals and discourage others. Many perennial forbs and shrubs require animals for successful pollination, reproduction, and subsequent maintenance of species on a site; however, pollination biology of many rangeland plants and pollinator abundances at potential revegetation sites are largely unknown. Granivory may be significant in some locations and planning and design of revegetation areas may be improved by implementing principles of seed escape mechanisms, such as predator satiation, seed escape in space (low perimeter-to-area ratio for revegetation site), and seed escape in time (synchronous or staggered timing for nearby revegetation sites). Seedling establishment may be associated with invertebrate population levels which need to be considered in future revegetation projects. Timing and site preparation are important in limiting belowground herbivory. Animals can serve as dispersal agents of seeds. Livestock dosed with desirable seeds can disperse them in their dung across the landscape, thereby creating patches of desirable plants. If revegetation sites will be grazed by livestock, then managers should choose plant species that tolerate rather than avoid grazing and should apply adequate management to establish and maintain plant populations. Seeds inoculated with mutualistic species such as mycorrhizae, nitrogen-fixing bacteria, or actinomycetes may enhance establishment, productivity, and nutrient quality of rangeland species while increasing rates of succession.
    • Perspectives and processes in revegetation of arid and semiarid rangelands

      Call, C. A.; Roundy, B. A. (Society for Range Management, 1991-11-01)
      Range revegetation research has been dominated by empirical studies that provide some information about what works or does not work under a given set of conditions, but tell us little or nothing about the underlying ecological processes. Research has emphasized the establishment of vigorous exotic grasses on specific sites rather than the establishment of persistent, biologically diverse plant communities. A more mechanistic research approach is needed to better understand factors governing germination, seedling establishment, and plant community development in natural and synthetic systems to guide revegetation toward biological diversity. This paper evaluates selected aspects of the present knowledge of revegetation science on arid and semiarid lands, and attempts to identify areas for future research direction. Specific concepts and aspects of succession and plant community development, such as seedbed ecology, temporal and spatial patterns of resource availability and use, species life history traits, and species interactions are important areas of research. Continuous measurement of detailed environmental and biological data at the appropriate scale (down to the size of small seeds) will allow development of mechanistic models which can be used to predict plant establishment and community development for different environmental conditions.
    • Nutrient intake of cattle on rotational and continuous grazing treatments

      McKown, C. D.; Walker, J. W.; Stuth, J. W.; Heitschmidt, R. K. (Society for Range Management, 1991-11-01)
      Many benefits have been obtained from rotational grazing, including management flexibility and livestock distribution, but long-term positive effects on plant and animal production have been inconsistent. The purpose of this cast study was to investigate nutrient intake of animals in 2 production scale grazing, treatments. The study site was the Texas Experimental Ranch located in Throckmorton County, in the eastern portion of the Rolling Plains of Texas. Treatments were a 465-ha, 16-paddock, 1-herd, cell designed rotational grazing system (RG) stocked at a heavy rate (3.7 ha cow-1 yr-1) and a 248-ha continuously grazed (CG) treatment stocked at a moderate rate (6.2 ha cow-1 yr-1). Size of RG paddocks was varied to create different livestock densities to simulate rotational grazing at a 14 and 42 paddock level. Comparisons were made to determine the effect of type of grazing system (RG vs. CG) and the effect of livestock density within the RG system on nutrient intake. Nutrient intake of esophageally fistulated steers was determined by daily dosing them with ytterbium nitrate-labeled forage and collection of fecal samples plus collection of fistula extrusa samples for crude protein and in vitro organic matter digestibility determinations. The only difference caused by different livestock densities was a higher (P < 0.001) intake of forage crude protein in the simulated 42 paddock system. Nutrient intake of steers in the CG treatment was greater (P < 0.001) than those in the RG treatment. Differences between treatment were attributed primarily to differences in stocking rate rather than grazing system.
    • Light reflectance characteristics and video remote sensing of pricklypear

      Everitt, J. H.; Escobar, D. E.; Alaniz, M. A.; Davis, M. R. (Society for Range Management, 1991-11-01)
      This paper describes the use of a black-and-white visible-infrared (0.4-2.4 micromoles) sensitive video camera, filtered to record radiation in the 1.45-2.0 micromoles mid-infrared (MIR) spectral region, for distinguishing the succulent plant species pricklypear (Opuntia lindheimeri Engelm.) on rangelands in southern Texas. Ground-based spectroradiometric plant canopy measurements at 5 sampling dates revealed that pricklypear had significantly lower (p = 0.05) reflectance than that of associated plant species and soil over the 1.50-1.75 micromoles MIR water absorption spectral region. Airborne MIR video imagery of rangeland areas indicated that pricklypear populations could be differentiated from other landscape features. The optimum time for distinguishing the evergreen pricklypear was in January-February because most of the associated woody plant species were deciduous and lost their foliage during this period. Computer-based image analyses of MIR video imagery showed that pricklypear populations could be quantified, indicating that MIR video imagery may be useful for distinguishing and mapping pricklypear populations over large and inaccessible rangeland areas.
    • Leaf and whole plant transpiration in honey mesquite following severing of lateral roots

      Ansley, R. J.; Jacoby, P. W.; Hicks, R. A. (Society for Range Management, 1991-11-01)
      This study examined water loss by fully grown honey mesquite (Prosopis glandulosa var. glandulosa Torr.) trees at 2 levels of resolution, the whole plant (canopy) and the individual leaf. Trees were manipulated by severing lateral roots during winter dormancy. Leaf transpiration and photosynthesis were measured in root-severed and unsevered (control) trees for 2 growing seasons following treatment. An empirical model which integrated leaf transpiration, whole plant leaf area, and influence of shading within the canopy on leaf transpiration was used to calculate daily water loss from individual trees. During the first growing season leaf abscision occurred on root-severed, but not control trees, in early July, resulting in a 50% reduction in whole plant leaf area. Following abscission, transpiration and photosynthesis of remaining leaves on root-severed trees were significantly greater than on control trees from July through September. Because of increased transpiration of remaining leaves on root-severed trees, daily water loss per tree was not significantly different between root-severed and similar-size control trees before or after leaf abscission. No differences in leaf or canopy transpiration were found between root-severed or unsevered honey mesquite during the second growing season. Daily water loss per tree ranged from 30 to 75 liters during the study. These responses illustrate that water loss from mesquite may be regulated by various combinations of stomatal control and adjustment of transpirational surface area.
    • Instantaneous intake rates of 9 browse species by white-tailed deer

      Koerth, B. H.; Stuth, J. W. (Society for Range Management, 1991-11-01)
      Instantaneous intake rate (IIR) and instantaneous nutrient intake rate (INIR) by tame white-tailed deer (Odocoileus virginianus) of 9 common browse species in south Texas were studied to determine if morphological properties of the plants were associated with intake rate, and if IIR and INIR correlated to preference ratings derived from percent time spent foraging a particular species and with total foliage consumed. Mean leaf mass showed a significant (P < 0.05) positive correlation to IIR (r = 0.75), INIR of neutral detergent fiber (r = 0.73), acid detergent fiber (r = 0.73), and acid detergent fiber nitrogen (r = 0.68). Mean leaf length showed a significant (P < 0.05) positive correlation to INIR of crude protein (r = 0.67). Thorn density showed no significant (P > 0.05) correlations to IIR or INIR. Leaf weight/stem weight ratio showed a significant (P < 0.05) positive-correlation to IIR (r = 0.65) and INIR of acid detergent fiber nitrogen (r = 0.81). Rankings of IIR and INIR did not agree with preference indices based on weight of forage removed or amount of time spent browsing. Significant (P < 0.05) positive correlations for all trials between preference indices based on weight removal and time spent browsing (r = 0.73 for new leaf development, r = 0.87 for stem elongation, and r = 0.70 for full leaf development) indicated these 2 techniques closely agreed on species rank.
    • Economic feasibility and management considerations in range revegetation

      Workman, J. P.; Tanaka, J. A. (Society for Range Management, 1991-11-01)
      Although range researchers and managers involved in range revegetation often have little economics training, economic analysis is usually a crucial step in range revegetation decisions. This synthesis paper is intended to provide a useful background in economic analysis for teachers, students, and natural resource professionals who deal with range revegetation. First, 3 economic standards by which all revegetation projects must be judged are described and interpreted: (1) economic feasibility, (2) economic efficiency, and/or (3) cost effectiveness. Next, the information required for economic analysis and the analytical procedures used to evaluate range revegetation projects are described. A detailed reseeding example is then used to describe the following information requirements: project costs, benefits, value of benefits, interest rate (including real vs. nominal rates), risk, project life (including life extension and grazing deferment), and range site selected for revegetation. Last, procedures for determining optimal vegetation conversion and use are reviewed, emphasizing the vegetation response function as the key to balancing the 3 determinants of long-term net returns: initial vegetation conversion, grazing intensity, and project life.
    • Digestibility of guajillo for white-tailed deer

      Barnes, T. G.; Blankenship, L. H.; Varner, L. W.; Gallagher, J. F. (Society for Range Management, 1991-11-01)
      A study was conducted from May 1986 to June 1987 with white-tailed deer (Odocoileus virginianus) to determine seasonal nutritive value and nutrient digestibilities of guajillo (Acacia berlandieri) and a pelleted diet. In vivo dry matter digestibility (DMD) of guajillo varied seasonally from 35.2 to 48.1% and was inversely correlated to levels of condensed tannins in the forage. Apparent protein digestibility varied seasonally from 13.7 to 45.8% and was a highly dependent function R2 = 0.97) of the amount of neutral detergent fiber nitrogen (NDFN) digested and the negative impact of condensed tannins. Cellulose and hemicellulose digestibilities also varied seasonally (0.6 to 13.5% and 52.3 to 71.1%, respectively). Nutrient digestibilities of the pelleted diet did not vary by season, sex, or age. Dry matter digestibility of the pelleted diet was 75.6% +/- 0.9 and true protein digestibility was 95.0 +/- 0.04. Results suggest summer is a stressful period for south Texas deer due to low protein and energy digestibility and high levels of condensed tannins.
    • Dependence of standing crop on range condition rating in New Mexico

      Tiedeman, J. A.; Beck, R.; Ecret, R. V. (Society for Range Management, 1991-11-01)
      The Sandy Ridge Site of southern New Mexico was studied to determine the dependance of total standing crop and components of standing crop on range condition rating. Total standing crop which included mesquite (Prosopis glandulosa Torr.) decreased, but total standing crop minus mesquite increased as range condition rating increased. These relationships were found to be highly significant (P less than or equal to 0.01) by regression analysis. Very low R-square values for these models indicate that the often assumed positive linear relationship of standing crop to range condition rating is not reliable. Prediction of standing crop from range condition ratings using linear or quadratic models was found to be unreliable for the Sandy Range Site in southern New Mexico.
    • Bias in aging feral horses

      Garrott, R. A. (Society for Range Management, 1991-11-01)
      Several investigators studying feral horses (Equus caballus) in the western U.S. have noted anomalies in the age distribution of captured horses that raised concern about the accuracy of aging technique. Possible biases in the aging technique were investigated by assembling records for 60,116 horses removed from public lands in Nevada, Oregon, and Wyoming between 1975 and 1987. Records were consolidated for each state and the resulting age distributions were compared to an expected distribution derived from a population model based on published demographic parameters. These comparisons revealed a tendency for 5-year-olds to be under represented while 6- and 7-year-olds were over represented. There were also higher than expected numbers of horses aged as 15 and 20 years. These apparent anomalies were consistent among states and also among years within each state. The pervasiveness of the trends demonstrates that several biases exist in the current aging technique. Given these uncertainties, it is recommended that development of age-specific demographic variables based on yearly increments beyond age 3 or 4 be avoided, instead lumping data into broad age classes whenever possible.