• A Research Program for and the Process of Building and Testing Grassland Ecosystem Models

      Van Dyne, G. M.; Anway, J. C. (Society for Range Management, 1976-03-01)
      This paper reports on the organization and operation of the U.S. International Biological Program's Grassland Biome study. The study has involved in the past 8 years a large number of scientists from many disciplines working in an integrated and data-sharing mode. Field studies have been conducted on 11 western grassland sites to obtain data to drive and to validate mathematical simulation models and to provide cross-site comparative information. The models are based upon data from field studies, the literature, and rate process studies, often conducted in the laboratory. A multiple-flow, ecosystem level model called "ELM" which can be adapted to various sites by changing parameters is described. The types and sources of scientific outputs from the program are described.
    • An Optimum Sampling Strategy for Plant Species Frequencies

      Bonham, C. D. (Society for Range Management, 1976-03-01)
      An optimum sampling strategy was developed for predicting frequency values for all plant species occurring in an area. The approach uses both multistage and double-sampling procedures to predict the frequency of occurrence of all species. The application of these procedures to one grassland area resulted in an average saving of 26% in the number of sample quadrats required to determine the frequency of all species.
    • Control of Aspen Poplar , Balsam Poplar, and Prickly Rose by Picloram Alone and in Mixtures with 2,4-D

      Bowes, G. (Society for Range Management, 1976-03-01)
      Picloram alone and in combination with 2,4-D was evaluated for the control of aspen poplar (Populus tremuloides Michx.), balsam poplar (Populus balsamifera L.), and prickly rose (Rosa acicularis Lindl.) on rangeland in Saskatchewan which had alfalfa (Medicago sativa L.) as an important grazing component. The addition of picloram at 0.5 lb/acre to 2,4-D amine at 2 lb or less per acre did not improve the control of aspen poplar when compared to the presently recommended treatment in Saskatchewan of 2 lb/acre of 2,4-D ester. However, there was some evidence that the addition of 1 lb/acre of picloram to 2 lb/acre of 2,4-D amine may improve control. Picloram applied at 1 lb/acre alone or in combination with 2 lb/acre of 2,4-D amine provided effective control of balsam poplar. There was excellent control of prickly rose for 4 to 5 years following the application of 0.5 lb/acre of picloram with or without the addition of 2,4-D. The herbicide rates that were necessary for the control of any of the woody species, almost completely removed alfalfa from the rangeland. The significance of alfalfa on rangeland and the potential loss of grazing from using or not using herbicides is discussed.
    • Control of Pinyon Saplings with Picloram or Karbutilate

      Young, J. A.; Evans, R. A. (Society for Range Management, 1976-03-01)
      The herbicides picloram or karbutilate were used to kill one-leaf pinyon saplings that form dense stands in areas that were previously chained to remove large trees. The granular herbicides were applied to the soil beneath the crown spread of the saplings by pouring the herbicide on top of the trees and allowing it to trickle down through the branches. Both materials were effective at low rates. If desirable shrubs or herbaceous species were not rooted directly beneath the tree canopies, minimum damage resulted from the herbicide application. Herbage production was not significantly increased or decreased by removal of the pinyon saplings with herbicides. Cutting the saplings and shrubs by hand and removing them from the plot increased herbage production.
    • Controlling Sixweeks Fescue on Shortgrass Range

      Houston, W. R.; Hyder, D. N. (Society for Range Management, 1976-03-01)
      Sixweeks fescue is an unpalatable annual grass that, when abundant, may seriously reduce grazing on associated species, limiting livestock gains and causing spot overgrazing. In this study, abundance was affected more by seasonal precipitation patterns than grazing or nitrogen fertilization. Either atrazine and simazine herbicides, applied at 1.1 kg/ha in either fall or spring, effectively controlled sixweeks fescue.
    • Deer Forage and Overstory Dynamics in a Loblolly Pine Plantation

      Blair, R. M.; Enghardt, H. G. (Society for Range Management, 1976-03-01)
      In a loblolly pine plantation in central Louisiana, forage growth was basically governed by the development of pine crowns and the corresponding reduction of light in the understory. In young stands ready for initial thinning at age 20 years, growth of herbaceous and woody vegetation was virtually precluded by the dense pine canopy. Hardwood trees, shrubs, and woody vines increased as stands were thinned every 5 years. By plantation age 30 years, a multilayered midstory was developing as hardwoods and some shrubs grew beyond the deer feeding zone. Midstory density increased directly with the intensity of pine removal, and by stand age 35 it was the principal deterrent to growth of deer forage. Herbage was not abundant.
    • Effect of Weed Control on Forage Production in the Nebraska sandhills

      Morrow, L. A.; McCarty, M. K. (Society for Range Management, 1976-03-01)
      Plots for the control of broadleaf weeds and for the determination of forage loss due to broadleaf weeds were established in the Nebraska sandhills. Herbicides were applied in the first year, the first and second years, the first, second and third years, and the first and third years in a four-year study. Forty lb/acre of N (40-N) were applied the fourth year. Herbicide treatments included 2,4-D amine, 2,4-D ester, 2,4,5-T, and silvex at 1 and 3 lb/acre; dicamba at 1/8 or 1/4 lb/acre in combination with 2 or 1 lb/acre 2,4-D amine, respectively; and picloram at 1/16 or 1/8 lb/acre in combination with 2 or 1 lb/acre 2,4-D amine, respectively. Control of broadleaf weeds with herbicide increased forage production up to 330 lb/acre when used without N. N applied following applications of dicamba at 1/4 lb/acre combined with 1 lb/acre 2,4-D amine increased forage production up to 660 lb/acre. Total herbage production increased when N was applied, but broadleaf weed production increased when weeds were not controlled. Herbicides and fertilizer can be effectively utilized to increase forage production, but they will not correct the mismanagement that results in weedy grazing lands.
    • Effects of Water Stress and Temperature on Germination of True Mountainmahogany

      Piatt, J. R. (Society for Range Management, 1976-03-01)
      The effects of five levels of available water and four constant temperature regimes upon the germination of two ecotypic collections of true mountainmahogany (Cercocarpus montanus Raf.) were investigated. Results indicate that moisture stress significantly decreases both the rate and final amount of germination in this species. The amount of moisture stress required to cause these decreases was found to be dependent upon both the seed source and the temperature. Temperature was found to be more important in determining the rate than the amount of germination.
    • Growth and Tillering of Sand Bluestem as Affected by Exogenous Growth Regulators

      Stubbendieck, J.; McCully, W. G. (Society for Range Management, 1976-03-01)
      Two plant growth regulators that were reported to inhibit auxin transport were exogenously applied to sand bluestem seedlings. DPX-1840 and Ethrel were shown to change tillering patterns, dry matter production, and plant form. When applied at relatively low concentrations, tillering was accelerated. Larger numbers of tillers developed on plants treated at the three-leaf stage as compared with those treated at the six-leaf stage. Exogenously applied plant growth regulators often reduced tiller length, plant height, and dry matter production. DPX-1840 caused plants to have an open or spreading appearance. In addition, laminas often remained rolled and were chlorotic.
    • Herbicide Nomenclature and Related Terminology

      Scifres, C. J. (Society for Range Management, 1976-03-01)
    • Improved Technique for Estimating Milk Production from Range Cows

      Bluntzer, J. S.; Sims, P. L. (Society for Range Management, 1976-03-01)
      Calf weaners, commonly called "blabs," were found to be useful devices to aid in collection of milk consumption data in range animal nutrition research. Inserting a blab in the calf's nostril prevents the calf from nursing when cow and calf are turned out to graze. Calves are then weighed, allowed to nurse, and then reweighed. The difference in the two weighings was considered to be the amount of milk consumed by the calf or produced by the cow for that time interval. This procedure is an improvement over that suggested by other investigators, as both the cow and calf remain together and graze more normally, as opposed to the calves' being penned for 12 hours.
    • Influence of Temperatures, Water Stress, and Nitrogen Treatments on Chlorophyll and Dry Matter of Western Wheatgrass

      Bokhari, U. G. (Society for Range Management, 1976-03-01)
      Western wheatgrass (Agropyron smithii Rydb.) raised from seeds was given four treatments under three temperature regimes in environment controlled growth chambers. Dry matter and chlorophyll (a + b) were determined in the shoots of these plants at 20-day intervals for 100 days. Dry matter and chlorophyll production was greater from irrigated and irrigated-plus-fertilized plants under each temperature regime than it was from control or fertilized plants. This response was more pronounced at the intermediate temperature regime (24/13 degrees C) than that at the lower (13/7 degrees C) or the higher temperature regimes (30/18 degrees C). The maximum chlorophyll increase of irrigated and irrigated-plus-fertilized plants was 350% and 395% at 24/13 degrees C while in the control and fertilized plants the increase was 251% and 176%, respectively. A positive linear relationship was found between dry matter and chlorophyll of all the plants under the three temperature regimes.
    • Morpa weeping lovegrass produces more beef

      Shoop, M.; McIlvain, E. H.; Voigt, P. W. (Society for Range Management, 1976-03-01)
      Morpa, a new variety of weeping lovegrass (Eragrostis curvula (Schrad.) Nees), increased yearly gain per steer 33 lb, or 12%, in a 3-year grazing comparison with Common weeping lovegrass at Woodward, Oklahoma. Because steer gains were greater, Morpa produced $12.00, or 170%, more profit per acre. Also, Morpa had the same high carrying capacity as Common; was equally adapted to withstand drouth; and required the same high level of cultural and grazing management. Morpa was slightly less winterhardy than Common.
    • Poisoning in Sheep from Emory Milkvetch and Nitro Compounds

      Williams, M. C.; James, L. F. (Society for Range Management, 1976-03-01)
      Sheep were fed nitro-containing Emory milkvetch (Astragalus emoryanus) and infused intravenouslv with 3-nitro--1-propanol and 3-nitropropanoic acid. Emory milkvetch and the nitro compounds produced similar clinical syndromes. Nitro compounds, therefore, appear to be the principal toxic constituent in Emory milkvetch.
    • Predation on domestic sheep in northeastern Nevada

      Klebenow, D. A.; McAdoo, K. (Society for Range Management, 1976-03-01)
      A northern Nevada range band of sheep was studied in order to verify the extent of losses to predation and to other causes. Daily searches were made for losses and carcasses were autopsied. During lambing, predator losses varied on the two operations studied, 1 loss per 14 days in one case and 1 loss per day in the other. Losses from other causes were high at that time. Predation increased in late summer and continued to be high into the fall. Predation was the major cause of loss at that time. Winter losses were variable. In one short period, 38 head of sheep were lost to halogeton (Halogeton glomeratus). In one annual production cycle 9% of the band was the total verified loss. The verified predator loss was 4% of the band. The coyote (Canis latrans) accounted for 91% of the total predation.
    • Rainfall Interception by Cool-desert Shrubs

      West, N. E.; Gifford, G. F. (Society for Range Management, 1976-03-01)
      Interception patterns of big sagebrush (Artemisia tridentata Nutt.) and shadscale (Atriplex confertifolia (Torr.) Wats.) were measured under two simulated rainfall intensities during three different seasons. Mean rainfall interception rate of individual plants of both species was 0.15 cm when averaged over all sampling dates and rainfall intensities. Interception during individual storms of at least 0.15 cm size by entire plant communities, based on measured vegetal cover, was calculated at 0.028 cm or less. On the average, about 4% of the total annual rainfall (not snowfall) would be intercepted by these plant communities.
    • Red Meat Production on U.S. Rangelands

      Mitchell, John E. (Society for Range Management, 1976-03-01)
    • Response of Switchgrass (Panicum virgatum L.) to Clipping Frequency

      Beaty, E. R.; Powell, J. D. (Society for Range Management, 1976-03-01)
      The native grasses are not widely grown for cultivated pastures in the South but are important forage producers in the United States. Their responses to frequency of clipping are not widely known and appear to be significantly different from that of the introduced cultivars, Bermudagrass (Cynodon dactylon) and Bahiagrass (Paspalum notatum). The introduced species, however, are slow to initiate growth in the spring, and it appears that the forage program in the South could be improved significantly by grazing switchgrass before the summer perennials initiate growth. Haying at flowering and grazing following frost could utilize the switchgrass later in the summer. Pangburn switchgrass (Panicum virgatum L.), a native species, tolerated one clipping during the season with little or no reduction in forage production, clonal survival, tiller number per clone, or tiller height. However, two or more clippings per season reduced all of the above. Over-utilization of switchgrass at the start of the season decreased the number of tillers and clones per plot and resulted in a serious weed problem.
    • Responses of Andropogon Pumilus Roxb. to Various Heights and Intervals of Clipping

      Singh, V. P.; Mall, L. P. (Society for Range Management, 1976-03-01)
      Andropogon pumilus Roxb. produced most dry matter (above ground and underground) when it was clipped at an interval of 45 days and at height of 15 cm. The average seed output at this clipping was maximum.