• The Impact of Experimental Design on the Application of Grazing Research Results: An Exposition

      Brown, M. A.; Waller, S. S. (Society for Range Management, 1986-05-01)
      Funding limitations often restrict pasture replication in grazing research on rangeland. Consequently, subsample error has been used to estimate treatment effects or characterize populations. Assumptions associated with experimental designs which utilize subsample error to make inferences are discussed and an example evaluated. The appropriate experimental unit for inferential grazing research is the pasture. Animals or vegetation sampling within pastures must be considered as subsamples in inferential grazing research. Pasture replication must be used in intensive grazing trials to establish treatment differences or provide adequate characterization. Following intensive trials, extensive, unreplicated trials implemented by private producers can be effective in establishing broad-based applicability. Unreplicated pasture trials may also be used for screening several treatments.
    • The Distribution of Halogeton in North America

      Pemberton, R. W. (Society for Range Management, 1986-05-01)
      Halogeton [Halogeton glomeratus (Stephen ex Bieb.) C.A. Mey.], a livestock-poisoning plant from central Asia, occurred in most Great Basin states in 1954. Current distribution of the species was studied by surveying botanists, weed scientists and other specialists in 1980. The survey indicated that halogeton had spread into additional counties in all states occupied in 1954 and into southern California, New Mexico, and east of the Rocky Mountains to Nebraska. The largest infestations continue to be in the Great Basin and Wyoming.
    • Technical Notes: Evaluation of the Dry-Weight-Rank Method for Determining Species Composition in Tallgrass Prairie

      Gillen, R. L.; Smith, E. L. (Society for Range Management, 1986-05-01)
      The dry-weight-rank (DWR) method for determining species composition of tallgrass prairie vegetation was compared to hand clipping. Species composition estimates for the 2 methods were similar in 3 of 4 trials when true ranking and previously published multipliers were used. Weighting the DWR estimates by plot total weight did not consistently improve the accuracy of the method. Observer errors reduced the accuracy of DWR, emphasizing the need for observer training. DWR estimates were generally less precise than hand clipped estimates for a given sample size but the speed of DWR would allow more samples to be taken resulting in more precise estimates in practice.
    • Population Recovery of Black-tailed Prairie Dogs Following Control with Zinc Phosphide

      Knowles, C. J. (Society for Range Management, 1986-05-01)
      This study evaluated the efficacy of 2% zinc phosphide grain bait as a control agent for black-tailed prairie dogs (Cynomys ludovicianus) and the rate at which prairie dogs returned to treated areas. Visual counts of prairie dogs closely corresponded to actual population trends and were chosen as the technique to evaluate changes of prairie dog numbers. Treatment of all of 2, and portions of 5, prairie dog colonies with zinc phosphide grain bait between 30 July and 25 August 1978 resulted in an average of 85% (range 65 to 95%) reduction in prairie dog numbers. Best results were obtained in the 2 colonies treated totally. The 2 colonies treated along the perimeter had the lowest percentage decrease in numbers of prairie dogs and were among the treatment types with the fastest population recovery. Prairie dogs returned to pretreatment levels within 1 year posttreatment at 1 colony. After 2 years posttreatment, 3 other colonies were approaching pretreatment population levels. Three to 5 years posttreatment appeared to be needed to obtain pretreatment numbers in the 2 colonies treated totally.
    • Heterogeneity of Data: Implications for a Variable Federal Grazing Fee

      Fowler, J. M.; Blake, M.; Torell, L. A. (Society for Range Management, 1986-05-01)
      Average grazing lease prices as tabulated in the 1985 federal grazing fee review and evaluation study were found to be significantly different between some pricing regions of the study. Comparing the federal study with a New Mexico state land grazing fee study indicated that lease prices were not homogeneous, even within pricing regions. This heterogeneity of data indicates that a variable federal grazing fee structure should be established if welfare of public land ranchers and collecting full market value of public land forage is important. Other factors, such as ease of fee administration and strong political support have been important considerations in setting the current single uniform fee. The current single-fee formula that sets one uniform grazing fee for all western states cannot be statistically defended. If grazing fees were significantly increased using the current single-fee formula, or any other single-fee formula, an inequitable distribution of impacts upon public land ranchers would arise; some would be subsidized while others would likely be damaged.
    • Habitat Use by Federal Horses in the Northern Sagebrush Steppe

      Ganskopp, D.; Vavra, M. (Society for Range Management, 1986-05-01)
      Distribution patterns of feral horses (Equus caballus) relative to plant communities, herbaceous production, and perennial water sources were studied from April 1979 to March 1981 in Oregon's Owyhee Breaks. Repeated observations of radio-collared and easily identified horses allowed estimation of home range sizes and documentation of the plant communities utilized. A map of plant communities was constructed, and composition and herbaceous production of key communities sampled. Time-lapse cameras monitored the daylight watering patterns of horses. One hundred thirty-three horses were initially censused and identified on the study area with the total population subsequently increasing at an annual rate of 13%. Home ranges averaged 12 km2 with the minimum convex polygon procedure and 27 km2 with the 90% confidence ellipse method. No seasonal shifts in home ranges occurred, and no correlations were detected between home range size and number of horses per band, densities of perennial water sources, or levels of forage production within home ranges. Six distinct herds were identified on the area. Only one band of horses moved from one herd to another during the 2-year study. Animals in each herd made greatest use of the most prevalent plant community, with no community being universally preferred to over another. Watering activities were most intense during the first and last periods of daylight. Horses rapidly vacated the watering areas after drinking. A seasonal trend was observed in which horses remained slightly closer to perennial water sources during warm, dry summer months than during spring periods when additional seasonal sources were available. Seasonal differences were not statistically significant, however.
    • Genetic Progress Through Hybridization of Induced and Natural Tetraploids in Crested Wheatgrass

      Asay, K. H.; Dewey, D. R.; Gomm, F. B.; Horton, W. H.; Jensen, K. B. (Society for Range Management, 1986-05-01)
      Because of restrictions imposed by crossing barriers, crested wheatgrass breeders have usually limited themselves to selection and hybridization within ploidy levels i.e., diploid (2n=14), tetraploid (2n=28), or hexaploid (2n=42) populations. Several procedures have now been devised and evaluated to transfer genetic traits among ploidy levels, and interploidy breeding appears to be a feasible approach in the crested wheatgrass complex. Plant scientists with the USDA-ARS at Utah State University have developed a superior breeding population by hybridizing induced tetraploid Agropyron cristatum (L.) Gaertn. with natural tetraploid A. desertorum (Fisch. ex Link) Schult. The cultivar 'Hycrest' was released from this germplasm base in 1984. Chromosome number of the Hycrest breeding population ranged from 2n=28 to 32 and averaged 30. Chromosome pairing relationships were similar to those observed in natural tetraploids and the cultivar was as fertile as the parental species. Hycrest produced significantly more seeds per spike than 'Nordan,' and ample genetic variability for seed set existed in the population to make additional improvement through selection. Hycrest produced significantly (P<0.05) more forage than Nordan and Fairway in 9 of 12 comparisons at 5 semiarid range sites. The superiority of the cultivar was most noteworthy during and immediately after stand establishment on harsh sites. The need to expand the genetic base of the present population with selected parental materials is recognized.
    • Forage Yield and Quality of Warm- and Cool-Season Grasses

      White, L. M. (Society for Range Management, 1986-05-01)
      High quality forage is needed in the northern Great Plains during the summer when major growth of cool-season grasses has ceased and quality of standing forage is low. The objective of this study was to compare forage yield, nutritional quality, and water use of 2 warm-season grasses {P-15584 little bluestem [Schizachyrium scoparium (Michx.) Nash] and 'Pierre' sideoats grama [Bouteloua curtipendula (Michx.) Torr.]} and 2 cool-season grasses {'Nordan' crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult.] and 'Mayak' Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski]} harvested from 1979 through 1982 at anthesis or when drought stopped further plant growth. Forage was harvested from established stands seeded in rows 53-cm apart growing on a silty range site (Typic Haploborolls) near Sidney, Mont. Plots were 8 by 23 m replicated 5 times in randomized complete blocks. Forage yield averaged 0.84, 0.98, 1.75, and 2.52 t/ha (S-mean=0.17); in vitro organic matter digestibility averaged 56.4, 67.3, 62.0, and 62.3% (S-mean=1.1)$, crude protein averaged 8.0, 10.3 8.6, and 12.8% (S-mean=0.4); phosphorus averaged 0.14, 0.16, 0.15, and 0.16% (S-mean=0.01) over a 4-year period for little bluestem, sideoats grama, crested wheatgrass, and Russian wildrye, respectively. Regression showed that in vitro organic matter digestibility and crude protein concentration were negatively correlated with forage yield. Forage yield and phosphorus concentration were positively correlated with evapotranspiration. The study showed that Russian wildrye would provide the highest quality forage during June and sideoats grama during July. Livestock need both cool- and warm-season forages to provide the highest forage quality.
    • Forage Quality of Winterhardy Lovegrasses

      Voigt, P. W.; Croy, L. I.; Horn, F. P. (Society for Range Management, 1986-05-01)
      Germplasm of Eragrostis curvula and E. lehmanniana was evaluated for in vitro dry matter disappearance (IVDMD), palatability (animal preference among genotypes), and forage vigor (weight/-plant). Our objective was to determine if sufficient genetic variation was present among relatively winterhardy genotypes to develop new lovegrass varieties with improved forage quality. The germplasm was divided into 4 types: curvula, conferta, short chloromelas (SC), and cold-hardy lehmann (CLE). Differences among types were significant for all characteristics studied. Differences within types were found also. The average IVDMD of the more stemmy CLE and SC types was higher than that of the more leafy curvula and conferta types. However, both CLE and SC types were less productive generally than curvula and conferta types and the palatability of CLE types was frequently lower than that of the other types. The more vigorous CLE types tended to be lower in IVDMD and palatability than less productive selections of that type. Chances of selecting an improved lovegrass variety directly from this germplasm are unlikely because few selections were superior to the weeping lovegrass controls. The best CLE and SC selections might be useful in a breeding program for improved forage quality if stemmyness can be decreased in their offspring while IVDMD is increased. Selections of the CLE type should not be widely planted until grazing evaluation proves them to be useful for animal production.
    • Forage Establishment: Weather Effects on Stubble vs. Fallow And Fall vs. Spring Seedling

      Hart, R. H.; Dean, J. G. (Society for Range Management, 1986-05-01)
      Improved pastures are a valuable forage resource in the Central Great Plains, but ranchers need to know which seeding techniques provide the best chance of successful establishment of such pastures. We compared late fall vs. spring seedings of 5 grasses and 2 legumes in barley stubble or fallow. Four directions of stubble rows were compared for snow catchment and effect on forage establishment. Stubble rows in any direction had little effect on snow catch or establishment, and there was little difference between stubble and fallow. Spring seeding gave better stands than fall seeding in the kind of weather most often encountered in the Central Great Plains. Days from seeding to emergence were controlled by soil temperature and timing and amount of precipitation. Stands were negatively correlated with the time required for emergence.
    • Floral Changes Following Mechanical Brush Removal in Central Texas

      Rollins, D.; Bryant, F. C. (Society for Range Management, 1986-05-01)
      A field study was initiated in May 1981 to monitor the effectiveness of mechanical brush control (chaining) as a method of reclaiming Ashe juniper (Juniperus asheii)-oak (Quercus spp.) dominated rangelands in central Texas. Brush was cleared from 4 sites by double-chaining and the resultant slash was burned. Brush canopy reduction and herbaceous standing crop were monitored for 2 growing seasons following treatment. Total brush canopy at 1 year post-treatment was 80% less than untreated brush stands. Chaining was more effective for Ashe juniper (93% reduction) than for oaks (64-75% reduction). Grass and forb standing crop at 22 months post-treatment was 55% higher on chained sites during all collection months.
    • Fertilization Effects on the Phosphorus Content of Browse Species

      Everitt, J. H.; Gausman, H. W. (Society for Range Management, 1986-05-01)
      A study was conducted in Hidalgo County, southern Texas, to determine the effects of inorganic nitrogen (N) and phosphorus (P) fertilization on the P content of 5 deer browse species. Treatments were 2 rates of N-112 and 224 kg N/ha; 2 rates of P-56 and 112 kg P/ha; 1 fertilizer combination of 224 kg N/ha + 112 kg P/ha; and a nonfertilized control. Plant samples were collected and assayed for P on 5 dates: May, September, and December 1981, and May and October 1982. Neither P or N fertilization influenced P browse content. Results indicated that P deficiencies in the browse plant species studied could not be alleviated by P fertilization.
    • Exposition on the Selection of Appropriate Experimental Design and Statistical Analysis for Pasture Improvement Research

      Stroup, W. W.; Waller, S. S.; Gates, R. N. (Society for Range Management, 1986-05-01)
      Selection of appropriate treatment and experiment designs are essential elements in research. However, the expense and variability associated with pasture renovation studies creates unique problems in the application of standard statistical techniques. Pasture-size renovation studies are restricted by expense, requiring the use of grazing exclosures (subsamples). Treatment design must include an adequate control for treatment comparison. Controls for pasture renovation practices cannot be limited to untreated areas within a grazing exclosure. The true measure response is found in the difference between treated areas and a typical grazed pasture situation. Criteria for exclosure selection (homogeneity) and heterogeneity of the grazed pasture may result in unequal variances or nonnormal error distributions, thus restricting the use of an analysis of variance. The experiment design must recognize the requirements for making reliable inferences. Pasture-to-pasture variability generally demands that pastures should be replicated in renovation studies to allow general inferences. Within pasture variability would support the need for multiple exclosures within each pasture. Costs associated with this kind of research limit the utility of idealized experimental designs. Several alternative experimental designs are discussed. Limitations in interpretation and risks of drawing erroneous or weak conclusions are reviewed.
    • Effects of Short-Duration and Continuous Grazing on Bobwhite and Wild Turkey Nesting

      Bareiss, L. J.; Schulkz, P.; Guthery, F. S. (Society for Range Management, 1986-05-01)
      We compared effects of short-duration and continuous grazing on nesting cover and success of bobwhites and wild turkeys in south Texas during 1984. Coverage, density, and dispersion of suitable nest sites and loss rates of artificial nests were not affected by grazing treatment.
    • Effects of Cattle Grazing on Passerine Birds Nesting in Riparian Habitat

      Taylor, D. M. (Society for Range Management, 1986-05-01)
      Nine transects, in areas with different histories of cattle grazing, were established along the Blitzen River in Oregon. Counts of birds and measurements of vegetation were made in the summers of 1981 and 1982. Increased frequency of grazing on an annual basis correlated significantly with decreases in bird abundance, shrub volume, and shrub heights. The longer the time since a transect was last grazed correlated significantly with increases in bird abundance, shrub volume, and shrub heights. Bird abundance increased significantly with increased shrub volume and taller shrub heights. Bird species richness decreased with increased grazing. Bird counts were 5 to 7 times higher on an area ungrazed since 1940 than on 2 areas grazed annually until 1980, and 11 to 13 times higher than on a transect severely disturbed by extensive grazing and dredging activities. Disturbances from camper activities also appeared to reduce bird populations.
    • Effects of Brush Control and Game-bird Management on Nongame Birds

      Gruver, B. J.; Guthery, F. S. (Society for Range Management, 1986-05-01)
      We observed the responses of nongame birds to brush suppression and habitat management for game birds in the Rolling Plains of Texas during 1981-1983. Data from line transects were used to describe density, species diversity, species richness, and equitability. We observed no difference in these variables between untreated sites and sites late sprayed with herbicides in 1969. The density of northern mockingbirds (Mimus polyglottos) was lower on treated than untreated areas, but no other species were affected. Habitat management to favor mourning doves (Zenaida macroura) and bobwhites (Colinus virginianus) was associated with a 54% increase in combined density of nongame birds and a reduction in equitability. Species diversity and species richness were similar on managed and unmanaged sites. On our study area, past herbicide treatment of mesquite (Prosopis glandulosa) and habitat management for game birds were compatible with nongame birds.
    • Effect of Grazing Stubble Height and Season on Establishment, Persistence, and Quality of Creeping Bluestem

      Kalmbacher, R. S.; Martin, F. G.; Pitman, W. D. (Society for Range Management, 1986-05-01)
      Creeping bluestem (Schizachyrium stoloniferum) was grazed every 60-days to 15 or 30-cm stubble heights during the following 4 periods (seasons): (1) June, Aug., Oct. (JAO); (2) Oct., Dec., Feb. (ODF); (3) Feb., Apr., June (FAJ); (4) year-long (YL). Average diameter (37 cm) of plants grazed in JAO and YL to 15-cm stubble was less (P<0.05) than plants (43 cm) grazed to 30 cm. There was no difference in diameter of plants grazed to 15 and 30-cm stubble in ODF and FAJ (45 cm). Tiller density was influenced by stubble height only in 1982 and 1983 when density for the 15 cm stubble averaged 111/m2 vs. 142/m2 for the 30-cm stubble. Tiller density in 1980, 1982, and 1983 was less (P<0.05) in JAO and YL treatments (109/m2) than in ODF and FAJ (167/m2). Forage dry matter yield in 1979-80 and 1982-83 depended on stubble height and seasons. Average yield at 15-cm height was greater for the FAJ treatment (1,700 kg/ha), similar for JAO (910 kg/ha) and ODF (910 kg/ha) and lowest for YL (660 kg/ha), but yield was similar at all seasons (510 kg/ha) at 30-cm stubble. Crude protein and IVOMD were influenced more by grazing time within a season than by seasons or stubble height. Poorest quality forage was at the beginning of the seasons (especially ODF and FAJ treatments). Best quality came from regrowth. Winter or spring grazing resulted in better stands of creeping bluestem than summer or year-long grazing.
    • Douglas-Fir Encroachment into Mountain Grasslands in Southwestern Montana

      Arno, S. F.; Gruell, G. E. (Society for Range Management, 1986-05-01)
      A study of plant succession in relation to disturbance history was conducted in Douglas-fir [Pseudotsuga menziesii var. glauca (Beissn.) Franco] forest and fescue (Festuca L. spp.) grassland communities along the eastern slope of the Continental Divide in Montana. The objective was to obtain ecological information needed for assessing management alternatives aimed at enhancing big game habitat and livestock forage. Fire history was reconstructed through analysis of fire scars and age classes of trees. Sizes and ages were inventoried in sapling stage, pole stage, and mature forest stands. Results indicate that prior to 1890 fires occurring every few decades favored grassland and confined tree growth to rocky or topographically moist sites. Since 1890 fires have been rare as a result of livestock grazing (which removes fine fuels), fire suppression, and cessation of ignitions by Native Americans. Lack of fire allowed extensive areas of Douglas-fir "invasion" now of pole size to become established in former grasslands between 1890 and 1915. Widespread invasion of sapling size trees occurred between 1941 and 1955, when seed crops apparently coincided with unusually favorable moisture conditions. For management of these areas, we recommend use of prescribed fire in conjunction with timber harvesting to enhance declining forage productivity for big game and livestock.
    • Diets and Liveweight Changes of Cattle Grazing Burned Gulf Cordgrass

      Angell, R. F.; Stuth, J. W.; Drawe, D. L. (Society for Range Management, 1986-05-01)
      We investigated effects of fall burning of gulf cordgrass (Spartina spartinae) rangeland on winter diets and liveweight gains of cattle on the Texas Coastal Prairie during 1979-1981. Gulf cordgrass dominated steer diets (21-76%) regardless of burning treatment. However, Texas wintergrass (Stipa leucotricha) on adjacent upland sites accounted for 13 to 36% of animal diets during winter growth periods. Burning increased dietary crude protein content from January to March in all years and increased in vitro organic matter digestibility during February and March. Cattle gained or maintained weights on burned pastures but maintained or lost weight on unburned pastures. Weight gains of animals with access to burned gulf cordgrass, but not Texas wintergrass, equaled gains of animals grazing unburned gulf cordgrass and Texas wintergrass. Burned gulf cordgrass can provide alternative green forage that will improve diet quality of cattle when cool-season species are absent.