• Mineral salt supplementation of cattle grazing tall larkspur-infested rangeland during drought

      Pfister, J. A.; Manners, G. D. (Society for Range Management, 1991-03-01)
      Mineral salt supplements are used in attempts to reduce cattle losses to tall larkspur (Delphinium spp.). We determined the effects of a mineral salt mix on larkspur consumption, ruminal fluid kinetics, and water intake during 4 periods in June, July, and August, 1988 (Trial 1), and during an 18-day grazing period in August, 1989 (Trial 2). In 1988, 12 ruminally cannulated heifers were divided into 3 treatment groups: control with no access to mineral (CONT), 0.5 g mineral (LOW), and 1.0 g mineral kg body weight-1 day-1 (HIGH) dosed intraruminally. In 1989, 10 cows were allocated to either a control group or 0.75 g mineral kg body weight-1 day-1. During Trials 1 and 2, consumption of larkspur peaked at 5 and 7% of cattle diets, respectively; these low levels were attributed to drought. There were no differences (P>0.1) in consumption of total larkspur or larkspur plant parts. Mineral supplement increased water consumption (P<0.05) during Trial 1, but not during Trial 2. The HIGH group averaged 0.1 liters kg body weight-1 day-1 compared to 0.07 liters for the CONT and LOW groups. Ruminal fluid passage rate, turnover time, volume and fluid outflow rate (FOR) did not differ (P>0.05) among treatments during Trial 1, but FOR was increased by mineral treatment in Trial 2. Alkaloid concentration in larkspur deciined with maturity, and was apparently elevated by drought in Trial 2. This study found little indication that mineral salt supplement altered the amount of larkspur consumed by grazing cattle. Increased water intake one summer did not alter rumlnal fluid kinetics. If dietary minerals alter toxicity of larkspur to cattle, other mechanisms than those tested are responsible.
    • Plant community responses to short duration grazing in tallgrass prairie

      Gillen, R. L.; McCollum, F. T.; Hodges, M. E.; Brummer, J. E.; Tate, K. W. (Society for Range Management, 1991-03-01)
      A key to management of short duration grazing systems is maintaining proper rest periods for individual pastures, but information on the necessary length of rest periods for tallgrass prairie is limited. Research hypotheses for this study were that tallgrass prairie plant communities would respond differently to grazing schedules incorporating rest periods of varying lengths and that this response would be dependent on stocking rate. Treatments consisted of 3 grazing schedules (2, 3, or 4 rotation cycles per 152 day grazing season) and 2 stocking rates (1.6 and 2.2 times the moderate continuous rate). Plant frequency, standing crop, species composition, and forage utilization were sampled from 1985 to 1989. Precipitation was above average in 4 of the 5 study years. Grazing schedule did not affect any vegetation parameter over time. Stocking rate did not affect plant frequency or species composition. Standing crop was reduced and forage utilization increased at the higher stocking rate but these effects were consistent over time. Frequency of western ragweed [Ambrosia psilostachya DC.] and the relative species composition of the forb component increased in all grazed pastures compared to ungrazed pastures. The overall lack of major treatment effects was attributed to favorable precipitation, spring burning, and the initial high-seral successional stage of the experimental pastures.
    • Response of cottontail rabbit populations to herbicide and fire applications on cross timbers rangeland

      Lochmiller, R. L.; Boggs, J. F.; McMurry, S. T.; Leslie, D. M.; Engle, D. M. (Society for Range Management, 1991-03-01)
      Knowledge of how resident wildlife populations respond to brush management strategies is especially limited for rangelands in the cross timbers vegetation type of Oklahoma. We examined how cottontail rabbit (Sylvilagus floridanus) density and habitat use were influenced by applications of tebuthiuron or triclopyr, with and without annual burning, on cross timbers rangeland. Line transect flush-counts, mark-recapture livetrapping, and fecal pellet counts were used to evaluate seasonal differences in population density among 5 brush control treatments. Cottontail rabbits (n = 225) were flushed along 362 km of line transects during 5 census periods. Density in winter was consistently lower than summer for all treatments, except for the untreated control in winter 1987. Line transect density estimates varied from 0 to 1.975 rabbits/ha and suggested that herbicide and annual burning treatments had a positive influence on cottontail rabbit populations compared to untreated controls. Mark-recapture density estimates did not differ among treatments. Fecal pellet counts were greater on herbicide-treated pastures than an untreated control in both spring and fall. Prairie-eastern redcedar (Juniperus virginiana L.) and forest-prairie ecotone habitats were utilized greater than expected by cottontail rabbits. Mature hardwood overstory and mixed-brush habitats were avoided. Tebuthiuron and triclopyr effectively deceased hardwood overstory and increased preferred habitats for cottontail rabbits.
    • Vegetational responses of a mixed-grass prairie site following exclusion of prairie dogs and bison

      Cid, M. S.; Detling, J. K.; Whicker, A. D.; Brizuela, M. A. (Society for Range Management, 1991-03-01)
      Combined grazing by black-tailed prairie dogs (Cynomys ludovicianus) and bison (Bison) produces and maintains a series of changes in the vegetation of prairie dog colonies. However, because their grazing patterns differ in frequency and intensity through time, their individual impacts may be different. The objective of this study was to determine the individual and combined influences of these 2 herbivores in maintaining selected vegetation characteristics of a prairie dog colony in a mixed-grass prairie at Wind Cave National Park, S.D. This was assessed by monitoring plant responses during 2 years following exclusion from grazing by 1 or both species. In spite of their different grazing patterns, prairie dogs and bison had similar and independent (i.e., additive) effects in maintaining plant community structure. For example, total above-ground biomass increased 32-36% within 2 years of removal of each species, primarily as a result of increases in accumulation of graminoid biomass. Plant species diversity, equitability, and dominance concentration were similar in all treatments both years, although there were slight decreases in relative abundance of forbs and increases in relative abundance of grominoids in the second year after removal of grazers. Mean graminoid leaf nitrogen concentration (May to September) declined slightly but significantly after removal of prairie dogs (1.49 to 1.38%) in 1985, and after bison exclusion (1.64 to 1.50%) in 1986. We suggest that rate of vegetation change following removal of grazers depends upon weather conditions, plant species composition, and prior intensity and duration of grazing.
    • Water relations and transpiration of honey mesquite on 2 sites in west Texas

      Wan, C.; Sosebee, R. E. (Society for Range Management, 1991-03-01)
      Transpiration rates and internal water relationships of honey mesquite (Prosopis glandulosa) were investigated weekly during May through September 1986 on sandy loam and clay loam, both upland sites in west Texas. Average transpiration rates peaked at approximately 7 mmol m-2 s-1 at 1100 hr during wet periods and reached a plateau between 4 and 5 mmol m-2 s-1 between 1200 and 1400 hr. During dry periods, the average transpiration rates reached their maximum plateau of 2 mmol m-2 s-1 at 1000 hr and declined between 1200 and 1600 hr. The transpiration rates ranged from an average of 3.28 +/- 2.05 mmol m-2 s-1 for trees on a sandy loam site to an average of 3.85 +/- 1.94 mmol m-2 s-1 for those on a clay loam site. Stomatal closure in midsummer caused a substantial increase in leaf temperature. Mesquite has developed other means, such as leaf orientation, wax accumulation, and reduction in canopy development, to avoid drought. Stomatal conductance of mesquite is very responsive to soil water availability and dryness of the air, and is less responsive to internal water status. This research further substantiates that mesquite behaves like a facultative phreatophyte in west Texas.
    • Vegetation changes following brush control in creosotebush communities

      Morton, H. L.; Melgoza, A. (Society for Range Management, 1991-03-01)
      Changes in herbaceous plant density and canopy cover of creosotebush (Larrea tridentata Sesse & Moc. ex DC) and associated shrubs following brush control treatments were measured in Sonoran and Chihuahuan Desert communities. Treatments were applied in 2 successive years st the Santa Rita Experimental range, Arizona, and 3 locations in Chihuahua, Mexico. Across all locations and years 1.5 kg/ha tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N'-dimethylurea) > 1.0 kg/ha tebuthiuron= disking = disking with furrowing >2-way railing >0.5 kg/ha tebuthiuron > land imprinting in reducing canopy cover of creosotebush and associated shrubs. At the Santa Rita Experimental Range annual precipitation was above long-term mean in 1982, 1983, 1984, and 1985; and grass density increased on all treated and untreated plots. Annual precipitation was below long-term mean during 1986 and 1987 and grass density decreased on both treated and untreated plots but did not decrease to pre-treatment densities. Forb densities were less than 3 plants/m2 throughout the study, except in 1987 when Russian thistle (Salsola iberica Sennen & Pau) increased on all plots. At the Chihuahuan locations, grass densities usually increased during the first year of the study, but very low precipitation throughout the study caused subsequent reductions in grass and forb densities. In dry years brush control treatments did not increase herbaceous plant density.
    • Technical Notes: The effect of light on adventitious root formation in blue grama

      Roohi, R.; Jameson, D. A.; Nemati, N. (Society for Range Management, 1991-03-01)
      Formation of adventitious roots in blue grama seedlings requires that the node between the subcoleoptile and the coleoptile be exposed to light at the 3-leaf or later stages of development. Thus, adventitious root formation will occur only at or near the soil surface. With continuous light, the subcoleoptile approximated zero length, but for those developed in darkness the usual length was about 1 cm. Under usual range conditions, the time between germination and the 3-leaf stage of development is such that it is rare that both of these events will occur with moist soil conditions, and seedling survival will be infrequent.
    • President's Address: Rangeland Is—

      Cleary, C. Rex (Society for Range Management, 1991-03-01)
    • Pasture characteristics affecting spatial distribution of utilization by cattle in mixed brush communities

      Owens, M. K.; Launchbaugh, K. L.; Holloway, J. W. (Society for Range Management, 1991-03-01)
      Utilization patterns of cattle were related to pasture characteristics in a nonrandom and complex manner. Six mixed brush pastures on the Rio Grande Plains (244-356 ha) that were topographically flat and homogeneous in soil type and range sites were studied. Two experiments were conducted: the first experiment was conducted when green forage was abundant and the second under conditions of little vegetative regrowth. A total of 340 random points were characterized for amount, frequency, and greenness of both grasses and forbs, brush and shade tree density, and distance to nearest fence, road, and water. These are variables that can be altered with management practices. When green forage was abundant, factor analysis identified 5 orthogonal factors (green herbage availability, grass quantity, brush abundance, remoteness from roads, and water availability) which accounted for 70% of the communal variation. Six factors (brush abundance, grass quantity, green forb frequency, road location, fence proximity, and water availability) accounted for 70% of the communal variation when herbage was limited. Regression analyses predicting percent utilization from the orthogonal factors indicated that when green forage was abundant, utilization was related largely to green herbage availability, grass quantity, brush abundance, and remoteness (R2 = 0.54, RSD = 0.114). Remoteness, brush abundance, green forb frequency, and water availability were the factors associated with utilization when forage was limited (R2 = 0.45, RSD = 0.152). Green herbage availability was less important under conditions of limited forage. In mixed brush communities, the actual amount of grass, brush abundance, and remoteness were the major factors affecting utilization.
    • Economic relationships of brushpiles, forage production, and California quail hunting

      Gorenzel, W. P.; Mastrup, S. A.; Fitzhugh, E. L. (Society for Range Management, 1991-03-01)
      Harvesting trees for firewood in the oak hardwood rangelands of the western Sierra Nevada foothills creates slash that may be burned to improve livestock forage production or piled into brushpiles for wildlife. The economics of these actions are undocumented. We observed a firewood harvest that created 378 brushpiles averaging 13.6 m2 and 1.3 m high, and resulted in a forage loss of 1,807 kg dry weight, equivalent to 4.4 AUM. We projected the present net value of 5 management options concerning the removal or retention of brushpiles during a 15-year period. Inputs included revegetation of burned-brushpile sites, annual forage production on areas with the oak canopy removed, burning and reseeding costs, and income derived from cattle grazing and quail hunting. The options were: (A) burning all brushpiles and reseeding the burned sites; (B) option A without reseeding; (C) burning 235 brushpiles and reseeding, leaving 23 brushpiles/ha for quail; (D) option C without reseeding; (E) leaving all brushpiles. All but option B were economically feasible at a 4% interest rate; at an 8% interest rate, only options C-E were profitable. After 15 years, the accumulated returns per hectare at 4% for options A-E were 11.67, -3.97, 32.43, 22.29, and 23.35, respectively, and at 8%, -17.35, -25.74, 8.58, 3.02, and 17.98, respectively.
    • Emergence of several Triticeae range grasses influenced by depth of seed placement

      Lawrence, T.; Ratzlaff, C. D.; Jefferson, P. G. (Society for Range Management, 1991-03-01)
      Seed of 8 Triticeae species was planted in petri dishes (depth = 0) and 2, 4, 6, and 8 cm deep in soil in the greenhouse. Total emergence at 6 weeks after planting declined significantly with increased depth and the species by depth interaction was significant (P < 0.001). Dahurian wildrye (Elymus dahuricus Turcz. ex Griseb.) and tetraploid Russian wildrye (Psathyrostachys juncea [Fisch.] Nevski) exhibited similar emergence from deep seedlings and were superior to all other species except Altai wild ryegrass (Leymus angustus [Trin.] Pilger). The better emergence of the tetraploid Russian wildrye entry compared to diploid cultivar suggests that the establishment of the tetraploid cultivar will be less affected by poor seed depth control. Newly released cultivars of Dahurian wildrye will be less affected by variable seed depth than several of the species currently recommended for seedling rangelands.
    • Effect of fertilizer on plant biomass distribution and net accumulation rate in an alpine meadow in central Himalaya, India

      Ram, J.; Singh, S. P.; Singh, J. S. (Society for Range Management, 1991-03-01)
      The objective of this study was to observe the effect of nitrogen application on the plant biomass and rate of net aboveground accumulation in an alpine grassland of Central Himalaya, dominated by the grass Danthonia cachemyriana, Jaub. and Spach. Nitrogen was applied in the form of urea at the rate of 250 kg ha-1 in late May 1984 and late April 1985. Aboveground and belowground biomass from both fertilized and control plots were measured from a day before fertilization and at 30-day intervals throughout the growing season in 1984 and 1985. The aboveground net accumulation (ANC) in 1984 was 409 g m-2 for the control and 450 g m-2 for treated plots, and in 1985 it was 382 g m-2 in the control and 458 g m-2 in the treated plots. The differences in ANC between control and fertilized plots were significant at P<0.05 for 1984 and P<0.01 in 1985. The belowground net accumulation (BNA) in 1984 was slightly greater in the treated plots (314 g m-2) compared to the control (207 g m-2), but in 1985 the BNA was significantly (P<0.05) higher (328 g m-2) for the control plots compared to treated plot (222 g m-2). Results indicate that this alpine meadow is less nitrogen limited than the grasslands studied elsewhere. Nitrogen fertilization had more effects on the pattern of biomass allocation than on total production.
    • Effects of cattle trampling and mechanical seedbed preparation on grass seedling emergence

      Winkel, V. K.; Roundy, B. A. (Society for Range Management, 1991-03-01)
      Cattle trampling has been recommended to bury seeds and encourage seedling establishment but has not been compared with traditional seedbed preparation techniques. We compared seedling emergence of broadcast-seeded 'Vaughn' sideoats grams [Bouteloua curtipendula (Michx.) Torr], 'A-130' blue panic (Panicum antidotale Retz.), 'A-68' Lehmann lovegrass (Eragrostis lehmanniana Nees), and 'Cochise' atherstone lovegrass (Eragrostis lehmanniana Nees X E. tricophera Coss and Dur.) on lightly and heavily trampled seedbeds with that on undisturbed, land imprinted, and root-plowed or ripped seedbeds. We seeded and applied the treatments prior to summer rains on a sandy loam soil in southern Arizona for 3 years. In a wet year (1987) when surface soil water was estimated to be available for at least 24 consecutive days, heavy trampling and land imprinting increased emergence of blue panic and land imprinting increased emergence of Cochise lovegrass. In that year, lovegrass emergence was high even on undisturbed plots. In a moderately wet year (1988), surface soil water was available for periods of 6-9 days during seedling emergence and greater disturbance, either by heavy trampling, land imprinting and/or root plowing or ripping produced higher emergence than light trampling and nondisturbance. In a dry year (1989), surface soil water was available for periods of 2-3 days and seedling emergence was low and generally similar for all treatments. Sideoats grama emergence was low all 3 years, but was highest in 1988 when initial thunderstorms were followed closely by subsequent storms. Seedbed disturbance by cattle and mechanical methods may enhance revegetation in the Southwest in years of moderate precipitation but may be unnecessary in wet years or futile in dry years, depending on species and soils.
    • Evaporation from rangeland with and without honey mesquite

      Dugas, W. A.; Mayeux, H. S. (Society for Range Management, 1991-03-01)
      The Bowen ratio/energy balance technique was used to estimate evaporation (E) from honey mesquite (Prosopis glandulosa Torr. var. glandulosa) as the difference in total E (plant and soil) between that of adjacent mesquite-dominated and mesquite-free rangeland areas near Throckmorton, Tex. After treatment with diesel in July 1988 to defoliate the honey mesquite, E from the treated area decreased to a minimum value of about 40% of that from the untreated area. In 1989, seasonal E totals from the untreated and treated areas were, respectively, 190 and 176 mm-a 7% reduction in E due to mesquite defoliation. Total E for the herbaceous and honey mesquite vegetation in 1989 in the untreated area was 117 and 73 mm, respectively. Honey mesquite foliar cover was 15% in the untreated area, but it accounted for 38% of the total E. These honey mesquite E data were supported by independent measurements of sap flow. While honey mesquite used substantial amounts of water, E from the rangeland from which it was removed was just slightly lower due to increased herbaceous evaporation associated with increases in standing crop. Under the circumstances of low grazing intensity and low runoff potential, honey mesquite removal would provide little if any additional water for off-site uses in the short-term and, therefore, the removal of this species for purely hydrological purposes would not be justified. Increases in off-site water availability may, however, result from honey mesquite control under grazing regimes which preclude accumulation of additional herbaceous standing crop or at site with greater runoff potential.
    • Effects of seedbed preparation and cattle trampling on burial of grass seeds

      Winkel, V. K.; Roundy, B. A.; Blough, D. K. (Society for Range Management, 1991-03-01)
      Location of seeds in the seedbed may affect germination and seedling establishment of range grasses. Our objective was to determine the effects of trampling by livestock and mechanical seedbed preparation on burial of grass seed on a sandy loam seedbed. Plots were root plowed or ripped then broadcast seeded, or broadcast seeded then lightly or heavily trampled by cattle or land imprinted before summer rains. Seedbeds were sampled by extracting soil plugs with plastic vials, splitting the plugs, and determining seed location with a dissecting scope. Sampling occurred after treatment, after summer thunderstorms, and after seedling emergence. An average of 75, 42, 17, and 7% of seeds found were buried immediately after heavy trampling, land imprinting, light trampling, and no disturbance, respectively. After summer thunderstorms an average of 78, 72, 63, 40, and 29% of seeds found were buried on plots root plowed or ripped, heavily trampled, imprinted, lightly trampled, and undisturbed, respectively. Although high percentages of seeds were buried on plots heavily trampled, imprinted, and root plowed or ripped, many of these seeds were too deep for seedling emergence. Smaller-seeded blue panic (Panicum antidotale) and the lovegrasses (Eragrostis lehmanniana Nees and Eragrostis lehmanniana Nees XE. trichophera) were buried by treatment and rain better than sideoats grama [Bouteloua curtipendula (Michx) Torr.].
    • Herbage response following control of honey mesquite within single tree lysimeters

      Heitschmidt, R. K.; Dowhower, S. L. (Society for Range Management, 1991-03-01)
      Justification for controlling honey mesquite (Prosopis glandulosa Torr. var. glandulosa) on rangelands has been traditionally related to enhanced livestock production from increased herbage production. More recently, however, it has been hypothesized that control would also increase off-site water yield. The objective of this 3-year study was to quantify the effects of control of individual honey mesquite trees inside nonweighable lysimeters on herbage standing crop, leaf area, and aboveground production. Utilizing frequent harvest techniques, estimated aboveground net primary production (ANPP) in intact tree lysimeters averaged 235 g/m2. Estimated ANPP in the treated lysimeters averaged 349 g/m2. The increased ANPP, following removal of the trees, resulted in significantly greater amounts of herbaceous leaf area and standing crop. The increase in ANPP was relatively uniform regardless of distance from the trunk of removed trees and was the result of increased production by those herbage species present at time of control rather than a shift in species composition. The dominant species in both treatments was Texas wintergrass (Stipa leucothrica Trin. & Rupr.). Sideoats grams [Bouteloua curtipendula (Michx.) Torr.] was a subdominant. The results, in combination with concurrent water yield studies, suggest control of honey mesquite will not enhance water yields dramatically in this region in the absence of livestock grazing.
    • Influence of Spanish goats on vegetation and soils in Arizona chaparral

      Severson, K. E.; DeBano, L. F. (Society for Range Management, 1991-03-01)
      The key to managing Arizona chaparral depends on creating and maintaining brush-free or savanna-like habitats. Brush control using fire, chemicals, and mechanical methods has been tested previously; but limited information is available on goats. This study evaluated the effect of 4 goat-stocking levels in a short duration grazing system and mechanical brush crushing on chaparral shrubs, herbaceous vegetation, litter, and soils. After 4-1/2 years, percent total shrub cover was lower (P<0.05) on paddocks stocked at 1.4, 2.4, and 4.2 Spanish goats/ha (35, 39, and 382, respectively) compared to unstacked controls (51%). Crushing brush increased the effectiveness of goats; mean total shrub cover was lower (P<0.05) on paddocks where brush was crushed vs not crushed (33 and 50% respectively). Shrubs least preferred by goats were not affected, while preferred browse was impacted at all stocking levels. Goat stocking and brush treatments did not affect perennial herbs, while annuals were generally increased by soil disturbance. Less litter (P<0.05) accumulated under shrubs subjected to heavy stocking levels compared to unbrowsed paddocks. Concentrations of N and P in the soil were also affected (P<0.05) under desert ceanothus (Ceanothus greggii Gray) where the soil bulk density was also increased (P<0.05). While goats can reduce total shrub cover, problems may result. Perennial herbaceous vegetation did not respond. Shrubs preferred by goats were also preferred by native deer. Reduced forage diversity and nutritional stress could result if these species were eliminated from the stand. Also, trampling disturbance by goats affected nitrogen accumulation in the litter and soil, but more importantly heavy browsing may eliminate nitrogen-fixing shrubs