• Beef cattle distribution patterns on foothill range

      Pinchak, W. E.; Smith, M. A.; Hart, R. H.; Waggoner, J. W. (Society for Range Management, 1991-05-01)
      A 3-year experiment designed to quantify the spatial and temporal utilization patterns of range sites by beef cattle on summer foothill range was conducted on the Wick Brothers Management Unit of the Wyoming Game and Fish Commission, 8 km w. of Arlington, Wyo. The grazing seasons, in replicate pastures, were from 15 July-9 August, 15 June-26 July, and 15 June-2 August in 1980, 1981, and 1982, respectively. Daily observations were made of radio-telemetry collared cattle (3 per pasture). Cattle dispersion was constrained by the spatial distribution of water and slope. Across 3 seasons, 77% of observed use was within 366 m of water. Approximately 65% of the land area was beyond 723 m from water and sustained only 12% of observed use. Cattle concentrated use (79%) on slopes less than 7%. Consequently 35% of the area, on or surrounded by slopes > 10%, received only 7% of observed use. Loamy, grazable woodland and wetland/subirrigated range sites were most preferred and accounted for over 65% of observed use while occupying less than 35% of the land area. Overall, coarse upland, very shallow and shallow loamy sites were not preferred; however, site preference varied as areas further from water were utilized. Observed use was significantly (P < 0.10) correlated (r 0.41 to 0.69) with standing crop and crude protein standing crop over various growth form characteristics of the forage component. Associated stepwise regression models accounted for 44 to 73% of the variation in observed use over the 1982 grazing season. As the forage complex became more similar, in terms of standing crop and crude protein content, significantly less (P < 0.05) variation in use was accounted for by the forage variables (0-37%).
    • Cattle grazing behavior on a foothill elk winter range in southeastern Wyoming

      Hart, R. H.; Hepworth, K. W.; Smith, M. A.; Waggoner, J. W. (Society for Range Management, 1991-05-01)
      Cattle at a light stocking rate of 0.17 to 0.18 AUM/ha over a 35-day grazing season in summer preferred to graze on lowland range sites, while elk in winter preferred upland range sites. We changed stocking rates on the same pastures to a moderate rate of 0.28 AUM/ha and a very light rate of 0.034 AUM/ha to determine the effects of stocking rate on cattle preference for range sites and possible habitat overlap between cattle and elk. At all stocking rates, cattle spent significantly more time grazing on loamy range sites and less time on other sites than would be expected on the basis of area occupied by the sites. When grazing pressure was increased from light to moderate, cattle grazing time on loamy sites increased. When grazing pressure was decreased from light to very light, cattle grazed only loamy and shallow sites to the complete exclusion of other sites. Cattle grazed farther from water as stocking rate increased and as the grazing season progressed. They also grazed on steeper slopes as stocking rate increased, and as the season progressed under the highest stocking rate. Even at the highest stocking rate studied, there was little habitat overlap between cattle and elk.
    • Comparison of four methods of grassland productivity assessment based on Festuca pallescens phytomass data

      Defossé, G. E.; Bertiller, M. B. (Society for Range Management, 1991-05-01)
      The relative utility of 4 methods for grasslands above-ground net primary productivity (ANPP) assessment were evaluated. These methods, applied to a set of phytomass and litter data collected at about bimonthly intervals for 2 years in a Festuca pallescens (St. Yves) Parodi grassland steppe of southwestern Chubut, Argentina, were: (1) summation of positive increments of green (live) biomass between harvests, (2) summation of positive increments of total phytomass between harvests, (3) summation of positive increments of green biomass between harvests plus correction factors which accounted for the concomitant increases in dry, old dead, and litter, respectively, and (4) mathematical model of simultaneous differential equations which fitted the values of phytomass data obtained in the field. Method 1 gave consistently (p less than or equal to 0.05) the lowest ANPP values in both years. Productivity values obtained with methods 2, 3, and 4 were highly correlated and did not differ significantly (p less than or equal to 0.05) with each other. Their estimates varied from 94.9 to 105.3 g of dry matter per m2 for the first year and from 73.0 to 149.4 g of dry matter per m2 for the second year. These values are within the range of productivity given for other climatologically and physiognomically similar semiarid grasslands of North America. Each method except 1 provided reliable estimations of ANPP for the grassland studied. Methods 2, 3, and 4 can also be used to assess ANPP in any other grassland with similar characteristics. Each one, however, might have particular applications according to the specific objectives pursued.
    • Correcting estimates of net primary production: Are we overestimating plant production in rangelands?

      Biondini, M. E.; Lauenroth, W. K.; Sala, O. E. (Society for Range Management, 1991-05-01)
      This paper addresses the issue of the effect of random errors in field estimates of net primary production (NPP). This is a critical subject in range management because field estimates of plant production are regularly used to determine stocking rates, range condition, and animal consumption. What we show in this paper is that random errors associated with field estimates of NPP can result in a positive bias and thus an overestimation of NPP. Depending on the case, this overestimation has been reported as high as 700%. We present examples with overestimations in the 200% to 400% range. The overestimation in NPP increases with increases in biomass variances, frequency of sampling, and number of taxonomic (species) and tissue (live, dead, etc) components sampled. We (1) outline in nonmathematical terms the reasons behind overestimation in NPP and the analytical solutions designed to correct them; and (2) present applications of the analytical solution for adjustments to concrete cases. The adjustments for overestimation outlined in this paper do not guarantee an accurate estimate of NPP but eliminate an unneeded source of error. A computer program (for IBM(TM) compatible) designed to implement the necessary adjustments is available from the authors free of charge (send a blank diskette).
    • Correlation of environment and root carbohydrate content to picloram translocation in leafy spurge

      Lym, R. G.; Messersmith, C. G. (Society for Range Management, 1991-05-01)
      14C-picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) absorption and translocation in leafy spurge (Euphorbia esula L.) was evaluated over 2 growing seasons and was compared to selected environmental parameters and root carbohydrate content. 14C-picloram absorption was greatest during the vegetative growth stage (52%) and increased directly with relative humidity but was not affected by the temperature at treatment. 14C-picloram translocation to leafy spurge roots generally was influenced more by the plant growth stage than the environment. The greatest translocation to roots occurred during the true-flower and seed-set growth stages. The water-soluble (monosaccharide and disaccharide) and water insoluble carbohydrate content in leafy spurge roots average across the growing season varied by depth with the lowest amount in the 0- to 8-cm depth, 35 and 53 mg/g, and the most in the 16- to 24-cm depth 84 and 221 mg/g, respectively. 14C-picloram translocation to leafy spurge roots was independent of either carbohydrate fraction when evaluated over the entire growing season. However, 14C-picloram content increased when the water-soluble fraction increased during the true-flower growth stage. 14C-picloram translocation to the roots did not increase in the fall, in contrast to the general hypothesis that herbicides move with photosynthates to the roots.
    • Defoliation effects on yield and bud and tiller numbers of two Sandhills grasses

      Mullahey, J. J.; Waller, S. S.; Moser, L. E. (Society for Range Management, 1991-05-01)
      Intensive grazing strategies for the Nebraska Sandhills must be based on time and frequency of defoliation of key warm-season grasses. A 3-year field study was conducted in the Nebraska Sandhills to determine the effects of defoliation on yield and bud and tiller number of sand bluestem [Andropogon gerardli var. paucipilus (ash) Fern.] and prairie sandreed [Calamovilfa longifolia (Hook.) Scribn.]. Defoliation (7 cm) treatments imposed on a 1.5 X 1-m plot were: a single defoliation on 10 June, 10 July, or 10 August; 2 successive defoliations on 10 June and 10 August; or 3 successive defoliations on 10 June, 10 July, and 10 August. All plots were harvested in October to obtain aftermath yield. Control plots were harvested only at the end of the growing season (October). Defoliation treatments were initiated in 1986, 1987, and 1988 on different plots and the effect of year of initiation as well as the effect of 3 successive years of repeated treatment (1986 plots) was evaluated. Annual dry matter (DM) yield, and bud and tiller numbers were measured. Following the initial year of treatment multiple defoliations increased yield of both grasses while bud and tiller numbers were similar to those of the control plants. After 3 years of repeated treatment, annual DM yield of sand bluestem for all defoliation treatments was lower than the control. A single defoliation of sand bluestem in August or a June-July-August defoliation reduced bud number compared to other treatments and the control. A June-August defoliation of prairie sandreed over a 3-year period increased annual DM yield compared to all treatments and the control although defoliation treatments reduced bud number. The optimum time and frequency of defoliation for annual DM yield and bud and tiller number was a single June or July defoliation for sand bluestem and a June-August defoliation for prairie sandreed.
    • Economics of broom snakeweed control on the Southern Plains

      Carpenter, B. D.; Ethridge, D. E.; Sosebee, R. E. (Society for Range Management, 1991-05-01)
      Revenues associated with controlling broom snakeweed (Xanthocephalum sarothrae) on 6 soils with heavy, moderate, and light infestations of snakeweed were estimated. The analysis considered economic returns associated with grass yield response and those from livestock efficiency gains. Results indicate that control of moderate and heavy infestations is generally economically feasible, but treatment of light infestations does not pay. The economic benefits from livestock efficiency gains are generally greater than the value of increased grass production.
    • Effects of revegetation on surficial soil salinity in panspot soils

      Hopkins, D. G.; Sweeney, M. D.; Kirby, D. R.; Richardson, J. L. (Society for Range Management, 1991-05-01)
      Panspots and transition zone panspots (slickspots) from a Leptic/Typic Natriboroll soil complex in western North Dakota were compared to determine the effects of secondary plant succession upon soil properties. Herbage and rooting characteristics were evaluated among panspot, transition zone, and adjacent well-vegetated Belfield soils using point frame data and a modified dry ashing technique. The effects of vegetation upon soil electrical conductivity (EC) were tested using gradient transects aligned perpendicular to boundaries between panspots and transition zones. Transition zones had 40% more total forage and twice the litter found in panspot areas. Thirteen of 17 gradient transects showed an inverse relationship between soil EC and distance into transition zones at the 0 to 5 cm depth. Significantly higher root-mass was obtained in the 0 to 5 cm depth in transition zones compared to panspots. A conceptual model based on subsurface water flow is presented to explain the polygonal cracking that was observed only in transition zone surfaces initiating a series of interactions resulting in natural reclamation of the transition zone soil.
    • Effects of tree canopies on soil characteristics of annual rangeland

      Frost, W. E.; Edinger, S. B. (Society for Range Management, 1991-05-01)
      In the central California region of annual rangeland, herbage production beneath blue oak (Quercus douglasii Hook & Arn.) canopies is greater and production beneath the canopies of interior live oak (Quercus wislizenii DC) and digger pine (Pinus sabiniana Dougl.) is less than that in adjacent open grassland. The objective of this investigation was to assess the impact of these major overstory species on soil-associated characteristics in an effort to explain this tree-herbage production relationship. Greater amounts of organic carbon (OC), greater cation exchange capacity (CEC), lower bulk density, and greater concentrations of some nutrients were found beneath blue oak canopies than in open grassland. This explains, at least in part, the increased herbage production beneath blue oak canopy.
    • Estimation of fecal output with an intra-ruminal continuous release marker device

      Adams, D. C.; Short, R. E.; Borman, M. M.; MacNeil, M. D. (Society for Range Management, 1991-05-01)
      Efficacy of a continuous release marker device (CRD) containing chromium oxide to estimate fecal output was evaluated in two 12-day grazing trials with beef steers (n = 10, trial 1; n = 7, trial 2). Trial 1 was conducted on mature green irrigated tall wheatgrass (Elytrigia pontica [Podp.] Holub) pasture during September. Trial 2 was conducted on dormant native range during December. Fecal output was determined by total fecal collection (TFC) and the CRD for each steer. Fecal output estimates from the CRD were based on a chromium release rate (980 mg/day) provided by the manufacturer. Estimates of daily fecal dry matter output (kg) in trial 1 were 2.70 and 2.69, and in trial 2 were 3.19 and 2.89 from the TFC and CRD, respectively. Differences between TFC and CRD were not significant in trial 1 (P = 0.59) but were significant in trial 2 (P < 0.01). When averaged over days and animals, estimates of daily fecal dry matter from CRD were within 1% of TFC in trial 1 and 10% of TFC in trial 2. Estimates of daily fecal dry matter from CRD were influenced by sampling day and steer (P < 0.01); however, there was no consistent pattern to day or animal variation. Multiple days and animals are required for both TFC and CRD. We conclude that CRD provides an acceptable estimate of daily fecal output. However, to improve accuracy, TFC can be used on a subsample of animals as a double sampling technique to adjust estimates derived from CRD.
    • Factors affecting weeping lovegrass seedling vigor on shinnery oak range

      Matizha, W.; Dahl, B. E. (Society for Range Management, 1991-05-01)
      Low vigor of seedlings and stand failures plague many revegetation efforts in semiarid and arid rangelands. Phototoxicity, sandbur (Cenchrus incertus M.A. Curtis) competition, seedbed preparation (plowing vs. disking), and nitrogen (N) fertilization were studied as reasons for low vigor of Ermelo weeping lovegrass [Eragrostis curvula Schrad.) Nees] seedlings on sand shinnery oak (Quercus havardii Rydb.) range in west Texas. Oak leaf residue and sandbur-dominated grass residue extracts did not affect seed germination and initial shoot growth of lovegrass seedlings. However, these residue extracts reduced root length 92% and 21%, respectively. Survival of weeping lovegrass seedlings was not affected by even 65 sandbur plants/m2. But, herbage yield was reduced 65, 72, and 79% with 30, 45, and 65 sandbur plants/m2. Early in the growing season, unfertilized plowed (P) plots had 5.6 ppm N in the 10-20 cm soil layer compared to a maximum of 3.9 ppm on other seedbed treatments. In the surface 10 cm, the P plots had less N than the disked plots. Surface-applied N fertilizer accumulated in the upper 10 cm of soil and promoted weed growth without improving weeping lovegrass stands or seedling vigor. Weeping lovegrass seedling vigor was greatest on P and least on disked plots. Thus, plowing buried weed seeds better, put resident N more deeply into the soil for better root uptake, removed allelopathic residues from seedling contact better, and provided for much higher seedling vigor than the disked seedbeds.
    • Germination of mechanically scarified neoteric switchgrass seed

      Jensen, N. K.; Boe, A. (Society for Range Management, 1991-05-01)
      Stand establishment from neoteric switchgrass (Panicum virgatum L.) seed can be hindered due to dormancy. The objective of this study was to evaluate the effect of mechanical scarification on germination and seedling emergence of neoteric (1- to 19-month-old) switchgrass seed. Scarification for 15 or 30 seconds in a Forsberg cylinder scarifier significantly increased 14-day germination percentage for 1- to 5-month-old seed of 5 cultivars. The magnitude of increase in seedling emergence due to scarification varied across cultivars. Four-month- and 18-month-old seed lots of 'Sunburst' and a North Dakota ecotype (NDE) exhibited significant increases in germination and seedling emergence after scarification. Scarification increased overall mean germination percentage for 3 lots of Sunburst and 2 lots of NDE by 73%. Field studies are needed to determine the usefulness of mechanical scarification as a preplant treatment for neoteric seed.
    • Grazing behavior and forage preference of sheep with chronic locoweed toxicosis suggest no addiction

      Ralphs, M. H.; Panter, K. E.; James, L. F. (Society for Range Management, 1991-05-01)
      Addiction is commonly cited as a clinical sign of locoweed (Astragalus spp. and Oxytropis spp.) poisoning. In a previous study, ewes progressively poisoned on locoweed ("locoed") in cafeteria trials did not become addicted to locoweed. Following a year of recovery, these ewes were allowed to graze locoweed-infested rangeland to determine if there was any residual preference for, or addiction to, locoweed. Neither the locoed nor control ewes consumed appreciable amounts of locoweed on rangeland where associated forage was succulent and actively growing, and where grazing pressure was sufficiently low to allow selective grazing. There was no residual preference for locoweed in previously locoed ewes. However, locoed ewes often exhibited sudden involuntary seizures when attempting to take a bite of forage. The head would tremble and tuck up under the brisket in a bobbing motion, and eye lids fluttered for a few seconds before the animal was able to proceed in feeding. Biting rate of locoed ewes was about a third less than that of the control ewes (P<.05) , and locoed ewes took fewer bites of grass than the control ewes (P<.01). Physical inhibitiion of feeding caused by the sudden seizures and reduced consumption of coarse forage, which may be more difficult to prehend, may contribute to the persistent emaciated condition and reduced productivity of some locoed animals.
    • Grazing systems, stocking rates, and cattle behavior in southeastern Wyoming

      Hepworth, K. W.; Test, P. S.; Hart, R. H.; Waggoner, J. W.; Smith, M. A. (Society for Range Management, 1991-05-01)
      Grazing systems and stocking rates are used to influence livestock grazing behavior with the intent of improving livestock and vegetation performance. In 1982, a study was initiated to determine effects of continuous, rotationally deferred, and short-duration rotation grazing and moderate and heavy stocking rates on steer gains, range vegetation, and distance traveled by and activity patterns of steers. Steers were observed from dawn to dark on 12 dates during 1983, 1984, and 1985, and activity recorded every 15 minutes. Eight steers per treatment (system X stocking rate combination) per date were observed in 1983 and 1984, and 10 per treatment in 1985. In 1984 and 1985, map locations of all steers were recorded at the same times as activity, and distance traveled summed from distances between successive map locations. In 1984, activity of 3 steers per treatment was electronically monitored during darkness. Steers grazed approximately 8.6 hr per day during daylight and 1.6 hr during darkness. Steers grazed an average of 8.9 hr/day during daylight under moderate vs 8.1 hr under heavy stocking, but stocking rate interacted with date in 1984 and grazing system in 1985. Steers traveled farther under continuous than under short-duration rotation grazing at both stocking rates in 1984, but only at the high stocking rate in 1985. Steers had to travel farther to water in the continuous pastures, and may have had to cover a greater area in an effort to select a more desirable diet, particularly under heavy stocking. These differences were not reflected in differences in gain among stocking rates or grazing systems.
    • Influence of seedbed microsite characteristics on grass seedling emergence

      Winkel, V. K.; Roundy, B. A.; Cox, J. R. (Society for Range Management, 1991-05-01)
      Successful germination and establishment of grass seedlings from surface-sown seeds requires a microsite which provides adequate soil water and temperature conditions, among other species-specific requirements. The microsite where these requirements are met has been termed a "safesite". Safesites may occur naturally as cracks and depressions in the soil surface, gravel, and plant litter, or be prepared by seedbed equipment and livestock trampling. A greenhouse study was conducted to determine the influence of seedbed microsite characteristics and soil water treatments on seedling emergence of 'Vaughn' sideoats grama (Bouteloua curtipendula (Michx.) Torr.), 'A-130' blue panic (Panicum antidotale Retz.), and 'Cochise' Atherstone lovegrass (Eragrostis lehmanniana Nees X E. tricophera Coss and Dur.). Although there were several interactions, in general, emergence of all 3 species was highest from gravel, followed by litter, cracks, and finally the bare soil surface. Bare surface sites decreased in water content more quickly than the other sites. Cochise lovegrass had high emergence in gravel under all water treatments. Small-seeded species such as Cochise lovegrass broadcast on coarse-textured surface soils may establish with minimal seedbed preparation, provided summer precipitation is adequate.
    • Long-term effects of rangeland disking on white-tailed deer browse in south Texas

      Montemayor, E.; Fulbright, T. E.; Brothers, L. W.; Schat, B. J.; Cassels, D. (Society for Range Management, 1991-05-01)
      Brush is an important component of white-tailed deer (Odocoileus virginianus Raf.) habitat. We determined the long-term effects of offset disking on canopy cover, density, and diversity of brush species browsed by white-tailed deer. In 1989, we sampled vegetation in untreated strips and strips disked in 1973 in Jim Hogg County, Texas. Strips disked in 1974-1975 were sampled in Duval County, Texas, in 1985. Brush density was used to calculate species richness, evenness, and Shannon's index. In Jim Hogg County, Texas pricklypear (Opuntia lindheimeri Engelm.) density and canopy cover was greater in disked than in untreated strips. Density of other brush species was similar in disked and untreated strips. In Duval County, agarito (Berberis trifoliata Moric.) was the only brush species with lower density on disked (56 plants/ha) than on untreated (222 plants/ha) strips. Brush species richness and diversity were similar in the untreated and disked strips in both study areas. Landowners should consider disking for managing brush if they want to maintain brush diversity and browse for white-tailed deer.
    • Long-term tebuthiuron content of grasses and shrubs on semiarid rangelands

      Johnsen, T. N.; Morton, H. L. (Society for Range Management, 1991-05-01)
      Perennial plants collected from 5 north-central Arizona semiarid locations were assayed for tebuthiuron [N-5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl-N,N'-dimethylurea] and its metabolites using gas chromatography with flame photometric detection. Tebuthiuron was applied at rates ranging from 0.9 to 6.7 kg active ingredient (a.i.)/ha in 1975 through 1979. Plants were harvested in 1980 through 1986, 2 to 11 years after applications. Tebuthiuron was detected in sideoats [Bouteloua curtipendula (Michx.) Torr.] and blue grama [B. gracilis (H.B.K.) Lag. ex Griffiths] 10 years after application of 6.7 kg/ha. Metabolites of tebuthiuron were detected in blue grama 11 years after applications of 2.2, 4.5, and 6.7 kg/ha. The ratios of tebuthiuron to metabolites varied widely. The highest concentrations of tebuthiuron plus metabolites were 25 microgram/g in blue grama 10 years after application of 4.5 kg/ha, and 21 and 23 microgram/g in sideoats grama 9 and 10 years, respectively, after application of 6.7 kg/ha. Only these 3 samples of 120 samples assayed exceeded the legal limit of 20 microgram/g of tebuthiuron plus metabolites in forage plants. No samples from plots treated with 4.0 or less kg/ha exceeded 10 microgram/g of tebuthiuron plus metabolites, and only 10% of them exceeded 5 microgram/g.
    • Managing range cattle for risk—the STEERISK spreadsheet

      Hart, R. H. (Society for Range Management, 1991-05-01)
      Variable weather, forage production, weed and pest problems, and livestock prices contribute to uncertainty in range livestock production. Because returns from livestock production, in which producers invest money and other resources, are uncertain, these variables are sources of risk. The STEERISK spreadsheet gives producers a tool to estimate the chances of different levels of forage production, test different management and marketing strategies, and estimate returns from them. Examples of STEERISK applications include selecting the most profitable stocking rate and evaluating the profitability of weed and insect control.
    • Monitoring roots of grazed rangeland vegetation with the root periscope/mini-rhizotron technique

      Karl, M. G.; Doescher, P. S. (Society for Range Management, 1991-05-01)
      The root periscope/mini-rhizotron technique has been used most commonly to monitor root growth of field crops in a nondestructive manner. This study introduces a successful application of the technique for monitoring root growth of grazed rangeland vegetation. The relative, root growth response of orchardgrass (Dactylis glomerata L. 'Potomac') to defoliation by cattle was monitored on a conifer plantation in southwest Oregon. Despite stocking densities of about 2.7-4.4 animal unit/ha and 19 days of grazing during 1988, trampling and breakage of mini-rhizotrons on the cattle-grazed area was minimal. Defoliation by cattle had a negative impact on the relative number of roots for grazed orchardgrass in June and July (P < 0.05). Cautions and limitations for the use of the technique on rangelands are presented. The root periscope/mini-rhizotron appears to be a suitable, nondestructive, and affordable (1,000-1,200 per root periscope; 8.50 per mini-rhizotron) technique for monitoring root growth of rangeland vegetation defoliated by livestock and/or native ungulates.