• Halogeton grazing management: Historical perspective

      Young, J. A. (Society for Range Management, 2002-05-01)
      Halogeton [Halogeton glomeratus (Bieb.) C. A. Mey], is a fleshy, annual, herbaceous species that was accidentally introduced into the western U.S. during the 20th century. Because it is highly poisonous to sheep (Ovis aries), this rather diminutive herb became the center of attention for biological research on Intermountain rangelands during the 1950s. Grazing management for halogeton involves procedures to prevent accidental poisoning of the grazing animals, and management to encourage the density and vigor of competing perennial vegetation to biologically suppress halogeton. Halogeton became most abundant in salt desert rangelands and the lower elevation portions of the sagebrush (Artemisia)/bunchgrass zone. In the sagebrush zone the introduced perennial crested wheatgrass [Agropyron desertorum (Fisher) Schultes] was widely planted to both suppress halogeton and to provide alternative forage for livestock. In the salt deserts, the management of native chenopod shrubs was the key to suppressing halogeton. The key species in salt deserts was the highly preferred semi-woody species winterfat [Krascheninnikova lanata (Pursh) A. D. J. Meeuse Smit]. In many parts of the Intermountain region, halogeton has declined in importance because of the reduced importance of the range sheep industry and improved range condition. In the south central Great Basin, halogeton is still considered a serious problem.
    • Reproductive losses to poisonous plants: Influence of management strategies

      Panter, K. E.; James, L. F.; Gardner, D. R.; Ralphs, M. H.; Pfister, J. A.; Stegelmeier, B. L.; Lee, S. T. (Society for Range Management, 2002-05-01)
      Poisonous plants that impair normal reproductive functions in livestock include Veratrum californicum Durand, lupines, ponderosa pine (Pinus ponderosa Dougl.), broom snakeweed (Gutierrezia sarothrae (Pursh) Britt. Rusby), locoweeds (Astragalus and Oxytropis spp.), selenium-containing forages, phytoestrogenic plants, endophyte-infected grasses and others. In this review we focus on lupines, locoweeds and ponderosa pine needles to demonstrate the broad and diverse effects that poisonous plants have on reproduction. Certain lupines (Lupinus spp.) contain quinolizidine and piperidine alkaloids that are fetotoxic and when grazed by pregnant cattle during specific stages of gestation induce skeletal birth defects and cleft palate, "crooked calf disease". Poison-hemlock (Conium maculatum) and some Nicotiana spp. contain similar alkaloids and induce identical birth defects in cattle, pigs, goats and sheep when ingested at certain stages of gestation. Locoweeds (species of the Astragalus and Oxytropis genera containing the indolizidine alkaloid swainsonine) interfere with most processes of reproduction when grazed for prolonged periods of time. Animals can recover normal reproductive function if withdrawn from locoweed grazing before severe poisoning occurs. While most animals may recover reproductive function, permanent neurological deficits may preclude normal reproductive behavior. Ponderosa and lodgepole pine needles (Pinus spp.) cause abortion in cattle when grazed during the last trimester of gestation. The specific chemical constituents responsible for the abortions belong to a class of compounds called labdane resin acids, including isocupressic acid (ICA), succinyl ICA, and acetyl ICA. Basic management recommendations to reduce reproductive losses to poisonous plants include: (1) keep good records; (2) know what poisonous plants grow on ranges and understand their effects; (3) develop a management plan to provide for alternate grazing in poisonous plant-free pastures during critical times; (4) provide for balanced nutrition, including protein, energy, minerals and vitamins; (5) maintain a good herd health program; (6) integrate an herbicide treatment program to reduce poisonous plant populations or to maintain clean pastures for alternate grazing; and, (7) manage the range for maximum forage production.
    • Risk management to reduce livestock losses from toxic plants

      Pfister, J. A.; Provenza, F. D.; Panter, K. E.; Stegelmeier, B. L.; Launchbaugh, K. L. (Society for Range Management, 2002-05-01)
      Risk of livestock losses to poisonous plants can be reduced on many ranges through prudent management based on application of existing knowledge. Poisonous plants can be categorized using both acceptability to livestock and a plant's toxic potential. Acceptability encompasses forage qualities such as taste and chemistry (i.e., nutrient and toxin concentrations) and postingestive feedback from an animal's daily and long-term (e.g., body condition) nutritional and toxicological state. Toxic potential reflects aspects of plant chemistry, including seasonal or other changes in concentration or functionality of the toxin(s), and type of toxicity (i.e., acute or chronic). Persistent livestock losses to poisonous plants may indicate that ranges are over-grazed or improperly managed. Aggressive management schemes that employ high stocking rates and grazing intensities may yield greater returns, but may also increase risk if poisonous plants are present. Plants may be ranked according to toxicity and acceptability. Six interrelated categories of plants are discussed: 1) always toxic and acceptable to livestock; 2) always toxic and not acceptable; 3) always toxic and acceptable at certain times; 4) toxic only at certain times and acceptable to livestock; 5) toxic at certain times and unacceptable; and 6) toxic at certain times and acceptable at certain times. Each category involves differing risk and uncertainty. Within this management matrix, strategies for dealing with specific poisonous plants can be customized depending on how much and when the plant is eaten by livestock, and when the plant is most toxic.
    • Ecological relationships between poisonous plants and rangeland condition: A Review

      Ralphs, M. H. (Society for Range Management, 2002-05-01)
      In the past, excessive numbers of livestock on western U.S. rangelands, reoccurring droughts, and lack of management resulted in retrogression of plant communities. Poisonous plants and other less palatable species increased with declining range condition and livestock were forced to eat these poisonous species because of a shortage of desirable forage, resulting in large, catastrophic losses. The level of management on most western rangelands has improved during the last 60 years, resulting in marked improvement in range condition; yet losses to poisonous plants still occur, though not as large and catastrophic as in the past. Some poisonous species are major components of the pristine, pre-European plant communities [tall larkspur (Delphinium barbeyi Huth), Veratrum californicum Durand, water hemlock (Cicuta douglasii (DC.)Coult. Rose), bracken fern (Pteridium aquilinum (L.) Kuhn), chokecherry (Prunus virginiana L.), Ponderosa pine (Pinus ponderosa Lawson), and various oak species (Quercus spp.)]. Although populations of many poisonous seral increaser species have declined with better management, they are still components of plant communities and fluctuate with changing precipitation patterns [locoweed (Astragalus and Oxytropis spp.), lupine (Lupinus spp.), death camas (Zigadenus spp.), snakeweed (Gutierrezia spp.), threadleaf groundsel (Senecio longolobis Benth.), low larkspur (Delphinium nuttallianum Pritz.), timber milkvetch (Astragalus miser Dougl. ex Hook.), redstem peavine (A. emoryanus (Rydb.) Cory), western bitterweed (Hymenoxys odorata D.C.), orange sneezeweed (Helenium hoopesii Gray), twin leaf senna (Cassia roemeriana Schelle), and white snakeroot (Eupatorium rugosum Houtt)]. Many of the alien invader species are poisonous: [Halogeton glomeratus (Bieb.) C.A. Mey, St. Johnswort (Hypericum perforatum L.), poison hemlock (Conium maculatum L.), tansy ragwort (Senecio jacobaea L.), hounds tongue (Cynoglossum officinale L.), leafy spurge (Euphorbia esula L.), yellow star thistle (Centaurea solstitialis L.) and other knapweeds (Centaurea spp.)]. Poisoning occurs when livestock consume these plants because they are either relatively more palatable than the associated forage, or from management mistakes of running short of desirable forage.
    • Snakeweed: Poisonous properties, livestock losses, and management considerations

      McDaniel, K. C.; Ross, T. T. (Society for Range Management, 2002-05-01)
      Snakeweeds (broom, Gutierrezia sarothrae (Pursh) Britt Rusby); and threadleaf, G. microcephala (DC.) Gray) fall into that class of poisonous weeds that seldom cause direct livestock losses because they are highly unpalatable and animals rarely consume large quantities of plant material. However, when snakeweed becomes dominant on rangeland and retards growth of desirable forage, then indirectly it becomes a serious hazard to animal health. Confined and rangeland feeding trials conducted at New Mexico State University with cattle and sheep have failed to elicit reproductive failure with elevated snakeweed dosages. Snakeweed was shown to impair certain reproductive functions such as pituitary responsiveness to luteinizing hormone, and caused mild hepato-renal toxicity. Under rangeland conditions, livestock grazing in areas dominated by snakeweed reportedly have more serious problems, such as abortion. A commonality between confined feeding trials and rangeland grazing trials is that in the presence of snakeweed, animals typically display symptoms associated with a low-plane of nutrition such as lack of gain, emaciation, and occasional death. To reduce snakeweed dominance and improve range condition, management interventions such as herbicide or fire control may be necessary. Complicating the decision regarding snakeweed control is the uncertainty about treatment life and whether this relatively short-lived perennial weed might be eliminated by natural causes. Knowing the snakeweed population pattern in a given area greatly enhances management decisions.
    • Do most livestock losses to poisonous plants result from "poor" range management?

      Holechek, J. L. (Society for Range Management, 2002-05-01)
      In recent years livestock death losses from poisonous plants in the western United States have averaged about 2-3% annually. A review of 36 grazing studies in North America shows poisonous plant availability and death losses of livestock from poisonous plants are closely associated with grazing intensity. Across studies, livestock death losses to poisonous plants average about 2.0% under moderate grazing compared with 4.8% under heavy grazing intensities. Sheep and goat losses from poisonous plants appear to be increased more by heavy stocking than those from cattle. Impacts of poisonous plants on livestock reproductive success are difficult to quantify, but probably reduce calf and lamb crops, even when grazing intensities are conservative. Increased poisonous plant consumption may explain in part why calf and lamb crops average about 7% lower under heavy compared to moderate grazing. With the exception of 1 Texas study, rotation and continuous/season long grazing systems show little differences in livestock death losses under comparable stocking rates. Certain plants, such as locoweeds (Astragalus sp.) and larkspur (Delphinium sp.), can elevate livestock death losses, even when grazing intensities are moderate or conservative. Special management programs that involve careful timing of grazing, aversive conditioning, and creation of locoweed (or larkspur)-free pastures can reduce problems with these plants. Use of adapted livestock is a critical part of minimizing poisonous plant problems. However, on some rangelands, such as those with infestations of locoweed and larkspurs, naive livestock may be less affected by poisonous plants than familiar livestock. Knowledge of poisonous plant identification, conditions of toxicity, and affects on the animal, in conjunction with conservative grazing, will in most cases avoid excessive death and productivity losses from poisonous plants. In some cases livestock can be conditioned or trained to not consume poisonous plants. It can be concluded that most livestock losses from poisonous plants are caused by poor management.
    • Water stress and triclopyr on clopyralid efficacy in honey mesquite

      Roche, A. R.; Bovey, R. W.; Senseman, S. A. (Society for Range Management, 2002-05-01)
      Water stress may affect herbicide efficacy in herbaceous and woody plants. Chamber studies were conducted to evaluate the influence of water stress (-1.3 to -2.8 MPa) and triclopyr on the absorption and translocation of clopyralid in greenhouse-grown honey mesquite (Prosopus glandulosa Torr.). Xylem water potential was determined in honey mesquite at time of herbicide application. Absorption and translocation of clopyralid was determined at low (-1.3 MPa), medium (-2.2 MPa), and high (-2.8 MPa) water stress at 4 h after application for 1.5-mo-old plants, while only translocation was determined at either a low (-1.4 or -1.6 MPa) or a high (-2.4 MPa) water stress treatment at 24 hours after herbicide application for 3-mo-old plants. Water stress did not affect (P < 0.05) absorption or translocation of clopyralid alone in either study. With 1.5-mo-old plants, the addition of triclopyr to clopyralid increased (P < 0.05) clopyralid absorption in leaves at low (63 microgram) and medium (54 microgram) water stress compared to high water stress (33 microgram) but did not affect (P > 0.05) translocation at 4 hours after application. On 3-mo-old plants, triclopyr decreased (P < 0.01) clopyralid translocation 24 hours after treatment at high water stress. The reasons for reduced uptake and 24 hours post-treatment translocation of clopyralid when applied with triclopyr at high water stress are unclear, but have implications for field applications.
    • Irrigation impact on harvest efficiency in grazed Old World bluestem

      Teague, W. R.; Dowhower, S. L. (Society for Range Management, 2002-05-01)
      In 1992 and 1993, pastures of WW-Spar Old World bluestem (Bothriochloa ischaemum L.) were maintained at 2 levels of soil water, rainfall and rainfall plus 25 mm/week of supplementary irrigation. At both moisture levels the grass was maintained at 2 levels of standing crop, averaging 1,548 and 2,154 kg ha(-1), using continuous variable stocking. Measurements were made to determine how different levels of soil moisture interacted with grazing intensity to change leaf area index, leaf-stem and live-dead ratios, tiller density, and the proportion of gross leaf production that was grazed (harvest efficiency). The proportions of live to dead, and leaf and stem biomass, remained constant under the different levels of soil water content. Soil water content alone had no effect on leaf area index, tiller density and the proportion of live or dead, leaf and stem. Winter tiller survival was significantly higher in the pastures with higher soil water content. Increasing soil water content and increasing grazing intensity interacted to reduce the proportion of dead leaf, increase production of new tillers, and increase the proportion of leaf grazed by decreasing leaf that died and was not grazed. This study indicates that if continuously grazed Old World bluestem was maintained at a standing crop of 1,500 kg ha(-1), harvest efficiency would be higher in wet years or under irrigation than if standing crop was higher.
    • Nutritional quality of forages used by elk in northern Idaho

      Alldredge, M. W.; Peek, J. M.; Wall, W. A. (Society for Range Management, 2002-05-01)
      The nutritional quality (digestible energy, crude protein, and minerals) of 7 known elk (Cervus elaphus Linnaeus) forages was assessed at 4 different time periods from May to November. Species evaluated were elk sedge (Carex geyeri Boott), Kentucky bluegrass (Poa pratensis Linnaeus), western goldthread (Coptis occidentalis Nuttall), clover (Trifolium repens Linnaeus), service-berry (Amelanchier alnifolia Nuttall), redstem ceanothus (Ceanothus sanguineus Pursh), and Scouler willow (Salix scouleriana Barratt). Mineral concentrations generally met estimated requirements for elk in all seasons, except sodium remained below requirements in all seasons. Crude protein in most plant species sampled was adequate for adult gravid or lactating cows throughout the year, although concentrations in graminoids fell below requirements during August. Forage provided adequate digestible energy for gravid or lactating cows only during May, indicating potential deficiencies in summer and autumn. Elk must be selective of plant parts, plant taxa, and foraging habitat to gain adequate nutrition. In this area, summer and fall forage quality may be critical to lactating cow elk.
    • White-tailed deer habitats in the central Black Hills

      DePerno, C. S.; Jenks, J. A.; Griffin, S. L.; Rice, L. A.; Higgins, K. F. (Society for Range Management, 2002-05-01)
      White-tailed deer (Odocoileus virginianus dacotensis Zimm.) numbers in the central Black Hills have declined since the middle 1970s. Population status has been documented by a decline in hunter success, deer reproductive success, and fawn survival. Most management agencies believe habitat deterioration is the primary cause of population decline in the Black Hills. We evaluated habitat selection for a white-tailed deer herd in the central Black Hills of South Dakota and Wyoming. From July 1993-July 1996, 73 adult and yearling doe and 12 adult and yearling buck white-tailed deer were radiocollared and visually monitored. Habitat Information was collected at 4,662 white-tailed deer locations and 1,087 random locations. During winter, white-tailed deer selected ponderosa pine- (Pinus ponderosa P. C. Lawson) deciduous and burned pine cover types. Overstory-understory habitats selected included pine/grass-forb, pine/bear-berry (Arctostaphylos uva-ursi (L.) Spreng.), pine/snowberry (Symphoricarpos albus L.), burned pine/grass-forb, and pine/shrub habitats. Structural stages selected included sapling-pole pine stands with 70% canopy cover, burned pine sapling-pole and saw-timber stands with 40% canopy cover. During summer, white-tailed deer selected pine-deciduous, aspen (Populus tremuloides Michx.), aspen-coniferous, spruce (Picea glauca (Moench) Voss), and spruce-deciduous cover types. Overstory-understory habitats selected included pine/juniper Juniperus communis L.), aspen/shrubs, spruce/juniper, and spruce/shrub habitats. Structural stages selected included pine, aspen, and spruce sapling pole stands with all levels (0-40%, 41-70%,71-100%) of canopy cover. Results supported low habitat quality as a factor involved with the decline of the deer population. We recommend that habitat management techniques, such as aspen regeneration and prescribed burns, be used to Improve the habitat base in the central Black Hills.
    • Evaluation of a technique for measuring canopy volume of shrubs

      Thorne, M. S.; Skinner, Q. D.; Smith, M. A.; Rodgers, J. D.; Laycock, W. A.; Cerekci, S. A. (Society for Range Management, 2002-05-01)
      Cover methods quantify vegetative communities in only 2 dimensions. The addition of height measurements to cover data, resulting in canopy volume estimates, provide a more practical level of description for shrub communities. We evaluated a technique to estimate canopy volume of shrubs that used a formula [2/3piH (A/2 x B/2)] derived from the basic ellipsoid volume formula. Objectives of this study were to determine if there were significant differences among means of repeated observations on sample units: (1) among observers; (2) within observers; and (3) between sample periods when using this technique. At 2 locations in Wyoming, 10 planeleaf willow (Salix planifolia var. planifolia Pursh) plants along each of 5 randomly established transects were sampled during 2 consecutive periods by 4 observers. Differences among observers were significant at both sites (P < 0.05). However, within observer variation between sample periods was not significant (P > 0.05) at either site. Mean canopy volume did not vary significantly (P > 0.05) between sample periods when averaged across observers. Estimated sample sizes ranged between 2 and 31 transects depending on the desired sampling precision and confidence level. The average time per transect among all observers decreased from 13 minutes (SD = 3.7) in sample period 1 to 9 minutes (SD = 1.3) in sample period 2. Using this method, managers can better describe and monitor trends in the structural diversity of shrub communities. This canopy volume technique can be applied with minimal training and is precise, efficient, and repeatable.
    • Drought and grazing: II. Effects on runoff and water quality

      Emmerich, W. E.; Heitschmidt, R. K. (Society for Range Management, 2002-05-01)
      Understanding the interacting effects of drought and grazing on runoff, erosion, and nutrient transport is essential for improved rangeland management. Research was conducted at the Fort Keogh Livestock and Range Research Laboratory located near Miles City, Mont. using 12, non-weighing lysimeters for 3 years. During years 1 and 3, no drought treatment was imposed. For year 2, one half of the lysimeters were covered to implement a drought treatment. The 3 grazing treatments were ungrazed, grazed during but not after drought, and grazed during and after drought. Runoff, sediment yield, and an array of nutrients in the runoff water were measured from the lysimeters. First year base line data with no grazing or drought treatments applied indicated no significant differences among lysimeters. Below normal precipitation occurred during year 2, resulting in no runoff from the drought treatment and negated the "non-drought" control. This prevented a direct assessment of the interaction among the drought and grazing treatments for this year. The drought treatment did produce significant reductions in water, sediment, and nutrient yield. No grazing impact was observed during year 2. The third year with more normal precipitation, there was a trend toward increased runoff, sediment, and nutrient yield from the second year drought treatment lysimeters. In the third year, both grazing treatments showed significantly greater runoff, sediment, and nutrient yield than the ungrazed treatment. Runoff and sediment yield tended to increase from the combination of drought and grazing treatments. The observed increases in runoff and sediment and reduced water quality from the drought and grazing treatments were measured against controls and when compared to the natural variability and water quality standards, they were concluded to be minimal.
    • Steer nutritional response to intensive-early stocking on shortgrass rangeland

      Olson, K. C.; Jaeger, J. R.; Brethour, J. R.; Avery, T. B. (Society for Range Management, 2002-05-01)
      Steer nutritional response to vegetation conditions created by 4 grazing treatments was evaluated during the final 2 years (1987-88) of a 9-year grazing trial. Treatments were season-long stocking (treatment 1) at a moderate stocking rate and intensive-early stocking at 3 stocking rates: equal to season-long stocking by using twice as many steers for the first half of the season-long stocking grazing season (double-stocked-intensive-early stocking, treatment 2), and 2 rates greater than season-long stocking made by stocking at 2.5 or 3 times the stocking density or season-long stocking (2.5X- and triple-stocked-intensive-early stocking, treatments 3 and 4). Each treatment was replicated twice in a randomized-complete block. Three esophageally fistulated steers were placed in each pasture to collect diet samples for nutritional analyses, including crude protein and cell wall constituents. Total feces were collected from 3 steers in each pasture to estimate fecal output and calculate forage intake. Diet digestibility was estimated using alkaline-peroxide lignin as an internal marker. Three or 4 sampling periods were conducted during each grazing season. Herbage availability and dietary crude protein were similar among treatments in 1987, but both declined as stocking density increased in 1988. Cell wall constituents generally increased as stocking density increased in 1987, but were similar among treatments in 1988. Digestibility and forage intake were unaffected by grazing treatments in both years. Steer average daily gain declined as stocking density increased in both years. Seasonal changes in diet quality and forage intake reflected the precipitation pattern with improved nutrition whenever precipitation caused growth of the warm-season shortgrasses. Nutrient intake was reduced by stocking rates greater than that employed under season-long stocking, but was generally similar between season-long stocking and double-stocked-intensive-early stocking.
    • Establishment of silver sagebrush in the Northern Mixed Prairie

      Romo, J. T.; Grilz, R. W. (Society for Range Management, 2002-05-01)
      Interest has been expressed in using silver sagebrush (Artemisia cana Pursh ssp. cana) in restoring the Northern Mixed Prairie in Saskatchewan. The objectives of this study were to determine the effects of seedbed manipulation treatments and autumn or spring sowing on establishment of silver sagebrush on sites previously seeded to native, perennial grasses. Seeds (achenes) were sown by broadcasting at 20 pure live seeds m(-2). Seedling emergence ranged from 5 to 6% of seeds sown. Most seedlings emerged in May and June; no seedlings emerged after July or in the second year after planting. Seventy-four to 84% of emerging seedlings survived the first growing season with 96 to 98% of these seedlings establishing. On upland sites, seedling emergence (1.1 seedlings m(-2) SE +/- 0.1) and establishment (0.9 seedlings m(-2) SE +/- 0.1) were similar between autumn and spring sowing and among seedbed manipulation treatments. On lowland sites, seedling emergence (1.4 seedlings m(-2) SE+0.2) and establishment (0.8 seedlings m(-2) SE +/- 0.2) were similar between autumn and spring seeding. Density of seedlings establishing was greatest when the seedbed was tilled. Establishment of silver sagebrush appears primarily limited by low numbers of seedlings emerging, indicating very specific safe site requirements for this shrub. Drastic disturbance of the seedbed is not required to establish silver sagebrush in established stands of perennial grasses. Sowing silver sagebrush in late autumn when temperatures are consistently below 0 degrees C or in early spring immediately after snowmelt is recommended.
    • Response of the mixed prairie to protection from grazing

      Willms, W. D.; Dormaar, J. F.; Adams, B. W.; Douwes, H. E. (Society for Range Management, 2002-05-01)
      The Mixed Prairie plant communities developed with the influences of fire and grazing. Available evidence suggests that removal of these disturbances could cause succession toward a more mesic type with the accumulation or litter or loss in productivity as nutrient turnover is delayed. Exclosures constructed in 1927 in a semiarid Mixed Prairie community provided an opportunity to examine the effects that protection had on vegetation and soils. Fifteen exclosures were selected for detailed examination; of these, 11 were located on Chernozemic soil and 4 on Solonetzic soil. We measured plant and soil variables both inside and outside the exclosures in a test of the hypothesis that protection from grazing will lead to a loss of production potential of the semi-arid. Mixed Prairie communities in the Northern Great Plains of southeastern Alberta. We found little evidence that 70 years of protection from large animal disturbance reduced the production potential of the plant communities. Conversely, most evidence suggested a neutral effect or an improvement as reflected in an increased cover of Pascopyrum smithii Rydb. (Löve) (P = 0.049) and increased annual net primary production (P = 0.047). The effect of protection appeared largely driven by the accumulation of litter mass that primarily benefits soil and plant indices of quality on the Chernozemic soil type. Although protection tended to reduce species diversity (P = 0.097) among native plants on the Chernozemic soil type, evenness and richness were not affected (P > 0.10). The potential effect that reduced diversity might have on reducing production stability appears more than compensated for by increased litter mass.