• The effect of clipping on the growth and miserotoxin content of Columbia milkvetch

      Majak, W.; Quinton, D. A.; Douwes, H. E.; Hall, J. W.; Muir, A. D. (Society for Range Management, 1988-01-01)
      The growth and miserotoxin content of Columbia milkvetch (Astragalus miser Dougl. var. serotinus (Gray) Barneby) were examined in clipping trials at 2 rangeland sites in southern British Columbia during 1984 and 1986. Growth was determined by measuring the freeze-dried weight of each plant and miserotoxin levels were estimated by a rapid screening method that simplified sample preparation for spectrophotometric determination. In both years and at both sites, growth and toxicity were substantially reduced in response to early clipping in the spring. In comparison to untreated plants, the aboveground biomass of clipped plants was reduced by at least 50% during a 6-wk period of regrowth. A similar reduction was also observed in the miserotoxin content of clipped plants. The results indicate that early grazing may reduce the potential hazard of timber milkvetch to livestock.
    • Temperature requirements for mountain rye, Hycrest crested wheatgrass, and downy brome germination

      Buman, R. A.; Abernethy, R. H. (Society for Range Management, 1988-01-01)
      In this study we determined that mountain rye (Secale montanum), crested wheatgrass (Agropyron cristatum × desertorum 'Hycrest'), and downy brome (Bromus tectorum) have similar germination temperature requirements and thus have the potential to germinate under similar soil temperature regimes, a feature which could be advantageous for subsequent seedling competition of mountain rye or crested wheatgrass against downy brome. Germination temperature profiles were compared using a thermogradient germination plate. Fifty-six different day/night temperature regimes were utilized for the comparisons. The bivariate spline model was found to be the best model for predicting germination-temperature response of the 3 species. Mountain rye and downy brome produced high germination under widely fluctuating (20-30 degrees C, 16 hr day/5-10 degrees C, 8 hr night) temperature regimes with crested wheatgrass demonstrating an optimum germination temperature over a 10-20 degrees C day/25 degrees C night regime. One of the 2 downy brome sources evaluated exhibited a much broader optimum germination temperature range. However, the differences in germination temperature profiles obtained were not of a magnitude likely to be biologically or ecologically significant due to the relatively high germination obtained over a wide range of fluctuating day/night temperatures for all 3 species.
    • Technical Notes: Secar bluebunch wheatgrass as a competitor to medusahead

      Goebel, C. J.; Tazi, M.; Harris, G. A. (Society for Range Management, 1988-01-01)
      A search continues for native perennial range grasses which will compete successfully with introducted annual grasses. Secar blue-bunch wheatgrass (Agropyron spicatum) is a recently released cultivar selected for seedling vigor. Medusahead (Taeniatherum asperum) seeds germinated in about one third the time, were less inhibited by cold temperatures typical of range conditions, and seedlings grew more than twice as fast as Secar in a 30-day trial. Indications are that even this new cultivar will not compete successfully with vigorous medusahead seedlings without initial weed control.
    • Soil nitrogen accumulation in fertilized pastures of the Southern Plains

      Berg, W. A. (Society for Range Management, 1988-01-01)
      Marginal farmlands seeded to grasses in the Southern Great Plains usually have been depleted in N by cropping, cultivation, and erosion. This study measured soil N accumulation over 20 to 22 years in N fertilized weeping lovegrass (Eragrostis curvula) or Old World bluestem (Bothriochloa caucasica) pastures seeded into old fields as compared to adjacent unfertilized old field pastures dominated by sand dropseed (Sporobolus cryptandrus). Significantly more (P<0.05) total N was found in the surface 5 cm of soil from the fertilized pastures. Total N was not significantly different between the old field and N fertilized pastures at greater depths. Two different samplings resulted in an estimated 8 and 5 kg N ha-1 yr-1 (standard error of the mean difference 2.4, n=4 and 2.0, n=10, respectively) greater N accumulation in the N fertilized pastures as compared to the old field pastures. Nitrogen input into the N fertilized pastures as fertilizer and protein supplement was 45 kg N ha-1 yr-1 greater than into the old field pastures. Thus, a relatively small proportion of the N input into the N fertilized pasture was accounted for as increased soil N. The N accumulation rate in the N fertilized pastures appears to be considerably slower than the N depletion rate under past farming practices.
    • Seedling competition between mountain rye, 'Hycrest' crested wheatgrass, and downy brome

      Buman, R. A.; Monsen, S. B.; Abernethy, R. H. (Society for Range Management, 1988-01-01)
      For comparison of seedling growth competitive responses in a controlled environment, monocultures (intraspecific) and 2 species mixtures (interspecific) of mountain rye (Secale montanum), crested wheatgrass (Agropyron cristatum × desertorum 'Hycrest'), and downy brome (Bromus tectorum) were established. Seedling dry root and shoot weights, shoot area, and maximum root length were compared at 1, 2, 3, and 6 weeks of growth in shoot roots boxes under a growth chamber environment (16 hr @ 14 degres C, 1,000 micro-E m-2 sec-1; 8 hr @ 10 degrees C, dark). Soil moisture depletion was monitored gravimetrically. Dry root and shoot weight, shoot area, and root length of mountain rye was greater than that of both downy brome and Hycrest crested wheatgrass at every sampling period over the 6-week study when grown in two-species mixtures. No difference was obtained for these seedling growth characters between downy brome and Hycrest mixtures, except for a 6.4 cm vs. 4.8 cm maximum root length at 1 week of growth. Similarly, in monoculture, mountain rye generally produced greater seedling growth than the other 2 species, although exceptions occurred for root weight, shoot area, and root length by 6 weeks of growth. Mountain rye depleted soil moisture in the growth boxes more rapidly and to a lower potential than the other 2 species. The results of this study indicate mountain rye provide vigorous competition as a seedlling.
    • Seasonal stocking of tobosa managed under continuous and rotation grazing

      Anderson, D. M. (Society for Range Management, 1988-01-01)
      Tobosa (Hilaria mutica [Buckl.] Benth.) was seasonally grazed with cattle under high-density (2.1 to 5.1 animal unit/hectare [AU/ha]) rotation and low-density (0.33 and 0.39 AU/ha) continuous stocking in 1980 and 1981, respectively. Tobosa leaf and culm color were used to evaluate forage quality. At the end of the 1980-81 growing seasons, crude protein was highest in green tobosa (8.4%) and lowest in gray tobosa from the previous seasons (4.7%). Grazing strategies did not influence the proportion of green tobosa within the standing crop; however, flexible rotation produced a more uniform use of green tobosa within the cell when compared to grazing with fixed intervals between rotations. Grazing patterns result from improper utilization of green tobosa which in future years will senesce into gray colored tobosa that composed 46-91% of the standing crop. In this study, flexible rotation of cattle among paddocks, based on a 30-35% reduction of tobosa standing crop height, reduced gray tobosa within the standing crop more than did continuous stocking. Total heifer liveweight gain per ha in 1980 and 1981, respectively, was 43 and 24% less under continuous stocking compared to rotation grazing management.
    • Seasonal burning and mowing impacts on Sporobolus wrightii grasslands

      Cox, J. R. (Society for Range Management, 1988-01-01)
      Land managers have recommended burning or mowing big sacaton (Sporobolus wrightii) grassland in either fall or winter for 100 years. The greatest potential for natural fire would have occurred when lightning strike frequency peaked in summer. The objective of this study was to determine how burning and mowing in fall (October), summer (July) and winter (February) influences big sacaton forage quantity and quality. Plants defoliated in fall produced leaves within 215 to 245 days, those defoliated in summer within 3 days, and those in winter within 20 days. Green and dead forage that accumulated after the burning and mowing in the same seasons were similar, but differences occurred among seasons. Green and dead forage following summer treatments were similar to that on untreated areas within 2 or 3 summer growing seasons, but were reduced on fall and winter treatments. Crude protein in green forage was 3 to 5% greater in treated plants than in untreated plants for 6 weeks after treatment, but forage quality increases were temporary. Burning or mowing at any season removes green forage available to livestock and reduces the amount of green forage that may accumulate for at least 2 summer growing seasons.
    • Root containerization for physiological studies of shrubs and trees on rangeland

      Ansley, R. J.; Jacoby, P. W.; Lawrence, B. K. (Society for Range Management, 1988-01-01)
      The use of metal and plastic barriers to contain root systems of woody plants is presented as a method to study water relations and other physiological responses of field-grown shrubs. This method has permitted the study of plant dependence on lateral root systems and provides a convenient method to isolate plant roots in an equal volume of soil for replicated studies of large plants under field conditions.
    • Response of three shrub communities in southeastern Idaho to spring-applied tebuthiuron

      Murray, R. B. (Society for Range Management, 1988-01-01)
      Tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-61]-N,N′-dimethylurea) pellets containing 20 and 40% active ingredient were applied at 0.6 and 1.1 kg ha-1 during May 1979 to range sites dominated by mountain big sagebrush (Artemisia tridentata subsp. vaseyana Nutt.), threetip sagebrush (A. tripartita Rydb.), and gray horsebrush (Tetradymia canescens DC) to determine effectiveness for shrub control and response of associated grasses and forbs. Sagebrush densities were significantly less (P is lesser than or equal to .05) in 1984 on all herbicide treated sites compared to the untreated sites. The 1.1 kg ha-1 (20P) treatment reduced the densities of all shrubs more than other treatments at all sites. Grass production was significantly (P is lesser than or equal to .05) greater on plots treated at 1.1 kg ha-1 (40P) at the mountain big sagebrush and threetip sagebrush sites. Forb production did not respond to tebuthiuron treatments. Grass production was not increased or decreased significantly by any treatment at the gray horsebrush site. For sites with similar soil and environmental conditions, the 1.1 kg ha-1 (40P) treatment should give sufficient control of sagebrush to allow for significant increases in total grass and forb production.
    • Response of false broomweed and associated herbaceous species to fire

      Mayeux, H. S.; Hamilton, W. T. (Society for Range Management, 1988-01-01)
      Foliar cover of the shrub false broomweed (Ericameria austrotexana M.C. Johnston) was reduced 45 to 65% at the end of the first post-burn growing season and by an average of 29% at 4 years after controlled burning in August. False broomweed's response to February burns was more variable, ranging from 36 to 77% canopy reduction after the first growing season and 3 to 54% after 4 years. Burning in August or February temporarily decreased standing crop of the most common bunchgrasses, pink pappusgrass (Pappophorum bicolor Fourn.) and whiplash pappusgrass (P. mucronulatum Nees.), without influencing frequency of occurrence, indicating that fire reduced vigor of these grasses. Total end-of-season standing crop reflected reductions in pappusgrass production. Fire tended to favor or had no effect on other bunchgrasses, and generally suppressed frequency and standing crop of undesirable grasses such as red grama (Bouteloua trifida Thurb.). Burning in either season had little effect on common curlymesquite [Hilaria berlangeri (Steud.) Nash].
    • Predicting biomass of five shrub species in northeastern California

      Vora, R. S. (Society for Range Management, 1988-01-01)
      Volume, crown diameter, and number of twigs were all highly correlated with biomass of individual shrubs of bitterbrush (Purshia tridentata (Pursh) DC), greenleaf manzanita (Arctostaphylos patula Greene), big sagebrush (Artemisia tridentata Nutt.), snowbrush (Ceanothus velutinus Doug. ex. Hook), and gray rabbitbrush (Chrysothamnus nauseosus (Pall.) Britton). These variables were used to develop equations to predict above-ground dry weight; R2 values varied from 0.76 to 0.98. Oven-dry weights were 39 to 71% of live weight in the field.
    • Influence of hunting on movements of female mule deer

      Kufeld, R. C.; Bowden, D. C.; Schrupp, D. L. (Society for Range Management, 1988-01-01)
      Hunting is a fundamentally important tool for wildlife managers. We examined the null hypothesis that hunting does not influence deer movement and their use of habitat types. Seventeen radio-collared, adult, female Rocky Mountain mule deer (Odocoileus hemionus hemionus) were located 1 day before the 1983 first Colorado deer season, and during day 2 of the first and day 3 of the second deer seasons in the foothills west of Fort Collins, Colorado. Distance from the preseason location to each location during hunting seasons were calculated for each deer. There were no differences between mean distance from pre-hunting season location to hunting season location for 10 deer that had all 3 locations in the area closed to hunting, and 4 deer that had 3 locations in the area open to hunting (P = 0.34 and 0.52). All 17 deer had all 3 locations in the interior of their minimum convex polygon home ranges. Those home ranges had a mean size of 226 ha and range of 117 to 323 ha. However, deer in the section open to hunting generally moved to vegetation types with increasingly better escape cover as the hunting seasons progressed. We conclude that hunting pressure did not cause deer movement in terms of distance or cause them to leave their normal home ranges, but did cause deer to move into more adequate cover.
    • Growth of Gutierrezia sarothrae seedlings in the field

      Osman, A.; Pieper, R. D. (Society for Range Management, 1988-01-01)
      Broom snakeweed (Gutierrezia sarothrae [Pursh] Britt. and Rusby) has increased in density and distribution on many southwestern ranges. The objective of this study was to determine root and shoot development of snakeweed seedlings as an aid in understanding the establishment of the species. Broom snakeweed seedlings were excavated from the field from March through September at approximately monthly intervals to determine biomass of roots and shoots. Root and shoot biomass growth was comparable from March to July, but shoot growth exceeded that by roots for the rest of the growing season. Root:shoot ratios were below 0.6 for the entire growing season, suggesting that rapid root development is not the primary mechanism for colonizing disturbed areas.
    • Grazing of crested wheatgrass, with particular reference to effects of pasture size

      Hacker, R. B.; Norton, B. E.; Owens, M. K.; Frye, D. O. (Society for Range Management, 1988-01-01)
      Utilization of a crested wheatgrass pasture was studied at constant stocking rate (3 cattle/ha) in pastures of 1, 2, 4, and 8 ha, with herd sizes ranging from 3-24 head. Pasture utilization on a perplant basis and estimated forage consumption per head were significantly lower in the smallest pastures by the end of the trial. Complementary trends in overall pasture utilization and live-weight gain were not significant. Variation among replicates for a number of pasture utilization attributes tended to be greatest in 1-ha pastures. Marked differences in animal behaviour were evident among the herds and are hypothesized to account for these differences. Animals selected against the smallest plants of crested wheatgrass and in favor of areas of higher forage production but no significant differences in uniformity of utilization among pasture sizes were demonstrated.
    • Germination requirements of flameleaf sumac

      Rasmussen, G. A.; Wright, H. A. (Society for Range Management, 1988-01-01)
      Germination characteristics of flameleaf sumac (Rhus lanceolate) seeds were determined in a controlled environmental growth chamber using a short-day cycle (8 hr light/16 dark). Seeds must be scarified before germination can occur. Heat treatments can scarify flameleaf sumac seeds if temperatures reach 76 degrees C in wet environments or 82 degrees C in dry environments. Once scarified, germination of seeds occurred under a wide range of temperatures (10-25 degrees C) and pH (4-10). However, maximum germination of flameleaf sumac occurred when seeds were subjected to alternating temperatures of 10/20 degrees C with a short-day light cycle. Surrounding medium must have a high osmotic potential (-0.1 megapascal) and a pH of 10 for maximum germination. Fire enhances these conditions thus aiding the establishment of flameleaf sumac following burning. No differences in emergence occurred when seeds were placed 0 to 6 cm in the soil profile.
    • Establishment of winter versus spring aerial seedings of domestic grasses and legumes on logged sites

      Brooke, B. M.; Holl, F. B. (Society for Range Management, 1988-01-01)
      Forage grasses and legumes were sown on clearcut-logged sites near Kamloops, B.C., to increase range productivity in the interval before the forest canopy closed. Seed was broadcast by aeroplane during the winter when these sites were snow-covered. On clearcuts above 1,000 m elevation 5 species were used: orchardgrass (Dactylis glomerata L.), timothy (Phleum pratense L.), smooth brome (Bromus intermis Leyss.), alsike clover (Trifolium hybridum L.), and white clover (T. repens L.). The objective of this study was to determine the effect of seeding date on the establishment and survival of these grasses and legumes. A survey of existing operational winter seedings produced establishment estimates (percent of live seeds sown that resulted in established plants) for orchardgrass of 2.3%; timothy, 1.2%; and brome, 1.3%; in contrast to 0.1% for the clover species. On operational spring seedings grass establishment was 1.3, 0.5, and 1.9% respectively for the first 3 species while clover was 2.6%. In a date-of-seeding trial, hand-seeded on a new clearcut, first and second year clover plant establishment averaged 1.5 and 0.2% respectively for 4 winter seedings (November 11 to March 22) compared to 18.3 and 13.2% for a May seeding. First and second year establishment of orchardgrass in winter seedings was 42.1 and 21.9% compared to 35.6 and 12% for the May seeding. These results indicate that while broadcast seeding on snow-covered high elevation clearcuts resulted in successful establishment of some grasses, it was ineffective for establishment of alsike and white clover.
    • Design of rain shelters for studying water relations of rangeland shrubs

      Jacoby, P. W.; Ansley, R. J.; Lawrence, B. K. (Society for Range Management, 1988-01-01)
      A low-cost, fixed-place, subcanopy rain shelter was constructed to facilitate studying water relations of honey mesquite (Prosopis glandulosa) growing in north Texas rangeland. This shelter, combined with a supplemental irrigation system and a barrier to contain lateral roots, permitted the study of moisture influences on transpiration, xylem pressure potential, and leaf temperature on large woody plants in the field.
    • Defoliation impacts on coppicing browse species in northeast Brazil

      Hardesty, L. H.; Box, T. W. (Society for Range Management, 1988-01-01)
      A study was conducted to determine if manually cutting coppice growth from the stump once or twice in the first growing season, exposing the coppice to 2 periods of intensive goat browsing, or no defoliation of coppice caused mortality or compensatory growth in 4 tree species of the Brazilian caatinga. Sabia' (Mimosa caesalpinia), and catingueira (Caesalpinia pyramidalis) suffered no mortality regardless of treatment, but pau branco (Auxemma oncocalyx), and marmeleiro (Croton hemiargyreus) that were browsed or manually defoliated experienced significant mortality. In the year of treatment undefoliated and browsed trees of all species produced significantly more stem material than manually defoliated plants. Browsed catingueira produced more leaf material than undefoliated or manually defoliated plants. The year after treatment, undefoliated trees produced more leaf and stem than either browsed or manually defoliated trees. Normally pau branco and marmeleio are not browsed and both species suffered significant mortality after manual or browsing defoliation, suggesting they are not adapted to herbivory; whereas intact sabia' and catingueira are palatable and suffered no mortality following browsing or removal of coppice. Undefoliated trees produced more biomass than browsed or manually defoliated trees; thus, removal of coppice growth does not stimulate increased forage production. Browsed trees produced regrowth during the dry season when these species are normally leafless. Manually defoliated trees did not, highlighting the fact that trees respond to browsing differently than to manual defoliation. This study demonstrates that regenerating caatinga stands can be manipulated through browsing or manual defoliation of coppice to achieve specific management objectives.
    • Comparison of water use by Artemisia tridentata spp. wyomingensis and Chrysothamnus viscidiflorus spp. viscidiflorus

      Miller, R. F. (Society for Range Management, 1988-01-01)
      With the reduction of fire frequency in the northern Great Basin, shrubs have increased in abundance at the expense of the herbaceous component. The ability of shrubs to acquire limited soil water resources is probably an important process in determining plant succession and composition. Water use by Wyoming big sagebrush (Artemisia tridentata subsp. wyomingensis) and green rabbitbrush (Chrysothamnus viscidiflorus subsp. viscidiflorus) was measured during the growing season. I tested the hypothesis that Wyoming big sagebrush utilizes soil water at a more rapid rate, early in the growing season than green rabbitbrush. Water use by these 2 shrubs was compared by determining total water potential (ψ), leaf conductance, transpiration per unit leaf area, and transpiration per unit of canopy throughout 2 growing seasons. Soil water depletion around isolated plants was also measured during both growing seasons. Both plants initiated spring growth at approximately the same time; however, Wyoming big sagebrush maintained a larger leaf area index within the canopy throughout the growing season. Leaf conductance and transpiration were significantly (P is lesser than or equal to 0.05) higher in green rabbitbrush, while transpiration per unit of canopy was higher in Wyoming big sagebrush. Soil water depletion was significantly (P is lesser than or equal to 0.05) more rapid at the canopy edge of isolated Wyoming big sagebrush than green rabbitbrush plants. Wyoming big sagebrush has a greater capacity to exploit early spring soil water than green rabbitbrush.