• Characterization of crown node elevation in Panicoid grasses

      Tischler, C. R.; Voigt, P. W. (Society for Range Management, 1993-09-01)
      In Panicoid grasses, elevation of the crown node above the soil surface caused by excessive subcoleoptile internode elongation is detrimental to seedling establishment. We describe a technique to screen grass seedlings for excessive crown node elevation. Seed of 11 perennial grass cultivars were germinated and grown in a plywood box 1.2 X 1.2 X 1.2 m at an irradiance of 1.5 micromole m-2 sec-1 at 30 degrees C. A subset of 8 grasses were grown similarly but at an irradiance of 0.75 micromole m-2 sec-1. Elevation of crown nodes above the growth media and shoot length (from crown node to leaf tip) were measured 7 days after planting. The crown nodes of 4 Eragrostis species were not elevated above the soil surface, while other species had mean crown node elevations of 1 cm or more. Relative ranking of crown node elevation was similar for a species within each light level, but response to change in light intensity was not consistent across species. Sideoats grama (Bouteloua curtipendula (Michx.) Torr.), blue grama (Bouteloua gracilis (H.B.K. Lag. ex Steud.)), and kleingrass (Panicum coloratum L.) exhibited significant crown node elevation in this system. Estimates of genetic variation based on comparison of apomictic and sexual grasses within this group suggest that substantial genetic variation exists for excessive subcoleoptile internode elongation and that progress by selection for lower crown node placement should be possible in most of the grasses studied. This system allows characterization of grasses for extent of crown node elevation and is being used in a recurrent selection protocol to select for lower crown node placement.
    • Dinitrogen fixation and transfer in legume-crested wheatgrass mixtures

      Gebhart, D. L.; Call, C. A.; Weaver, R. W. (Society for Range Management, 1993-09-01)
      Crested wheatgrasses [Agropyron cristatum L. Gaertn. and A. desertorum Fisch. ex (Link) Schult.] have been extensively seeded on semiarid western rangelands, but without supplemental N many of these seedings decline in vigor, ground cover, and productivity as the stand ages. Biological N2 fixation by legumes may represent a viable alternative to fertilizer N for increasing stand productivity. Two growth-room studies were designed to investigate N2 fixation and N transfer in mixtures of alfalfa (Medicago sativa L.) or annual sweetclover (Melilotus alba Medik. var. annua Coe) and crested wheatgrass. Growth media were enriched with 15N-labeled KNO3 at a rate of 24.2 kg N ha-1 and used to grow mixtures and monocultures of alfalfa or sweetclover and crested wheatgrass. Fixed and transferred N were determined at 3 harvest dates from differences in isotopic composition between the legume species in mixture with crested wheatgrass and crested wheatgrass in monoculture. The percentage of legume N derived from fixation was >80% for the final 2 harvests and increased as the proportion of crested wheatgrass in the mixtures increased. Nitrogen transfer from alfalfa to crested wheatgrass accounted for < 5 % of the grass total N. Conversely, nitrogen transfer from sweetclover to crested wheatgrass accounted for about 20% of the grass total N. Nitrogen transfer from alfalfa or sweetclover to crested wheatgrass may be important in maintaining stand productivity on N-limited western rangelands.
    • Effect of N-P-K fertilization on yield and tiller density of creeping bluestem

      Kalmbacher, R. S.; Martin, F. G.; Rechcigl, J. E. (Society for Range Management, 1993-09-01)
      Forage quality and quantity from palatable grasses, like creeping bluestem [Schizachyrium scoparium (Michx.) Nash var. polycladus (Schriber & Ball) Bruner (Syn S. stoloniferum Nash.)], are limited, especially in winter when cows graze Florida range. We anticipated that N fertilizer (0, 40, 60, 120 kg ha-1), P (0, 25 kg ha-1) and K (0, 100 kg ha-1) would increase bluestem yield, tiller density, and forage quality. Within sample dates yield and tiller density increased linearly with N rate. For example 31 days after fertilization, intercepts for equations predicting yield were 319 kg ha-1 and 124 m-2 with coefficients of 1.2 and 0.29, respectively, where the independent variable is N rate. Over sample dates yield responses to N rate were quadratic and tiller densities were cubic. Reproductive tiller density was increased by N fertilization (1989 tiller density, nom-2, = 30 + 0.29N). Neither yield nor tiller density was affected by P fertilizer, but K fertilizer increased reproductive tiller density, hence fall yield. After 3 years of fertilization, N had negative quadratic and negative linear effects on yield and tiller density, respectively. Tissue N concentration in the fall was reduced with N fertilization because of increases in reproductive growth (1988 calendar 145 days postfertilization, g kg-1 = 5.7 - 0.041 N + 0.00031 N2). Fertilization of creeping bluestem is not a recommended practice when bluestem is to be grazed in fall and winter.
    • Factors influencing eastern redcedar seedling survival on rangeland

      Schmidt, T. L.; Stubbendieck, J. (Society for Range Management, 1993-09-01)
      Eastern redcedar (Juniperus virginiana L.) is the most rapidly expanding woody species on rangeland in the Great Plains. Reasons for the expansion and management solutions have not been determined. The objective of this study was to determine the effect of year of establishment, grazing impacts, and aspect on the survival of eastern redcedar seedlings. Subplots of 10 transplanted eastern redcedar seedlings were replicated at 2 sites in west-central Nebraska. Plots were established in 1987 and 1988 under 3 different grazing levels: actively grazed, actively grazed until 1987 and then fenced from grazing, and not grazed for greater than or equal to 50 years. Split-plots within the 3 grazing levels were established on 3 different aspects: north-facing, south-facing, and flat. Seedling survival was evaluated 6,18, and 30 months after establishment period. The year that the seedling was established influenced seedling survival after 18 months. Grazing effects and aspect were significant factors in the survival of eastern redcedar seedlings for all 3 evaluation periods. Highest survival for grazing effects occurred where eastern redcedar seedlings were transplanted into plots that were grazed until 1987 and then fenced (57% +/- 1.5%). Lowest survival rates concerning grazing were for areas that were not grazed for greater than of equal to 50 years (40% +/- 3.0%). North-facing slopes had the highest survival after 30 months (65% +/- 2.4%). South facing slopes had the lowest survival after 30 months (34% +/- 2.9%). Land managers may be able to reduce eastern redcedar seedling establishment on grazed range lands through different grazing practices.
    • Factors influencing pine needle consumption by grazing cattle during winter

      Pfister, J. A.; Adams, D. C. (Society for Range Management, 1993-09-01)
      Ponderosa pine (Pinus ponderosa Lawson) needles cause abortions in pregnant cows. We examined pine needle consumption by cattle in 2 trials in eastern Montana. Trial 1 compared pregnant and open cows (n=4) from January to March 1989; trial 2 compared pregnant cattle (n=4) that received either 9 kg alfalfa hay head-1 day-1 or 1.4 kg alfalfa pellets head-1 day-1 from December 1989 to February 1990. Diets were estimated using both bite counts and fecal analysis. During trial 1, bite counts revealed pregnant and open cows consumed 45 and 42% of their grazing diets as pine needles (P>0.1). Fecal analysis showed that pregnant cows consumed more pine needles than did open cows (36% vs. 27%, respectively) (P<0.05). During trial 2, cattle consumed < 1% of their diets as pine needles. In trial 1 cattle consumed less pine litter and consumed more needles from trees as snow depth increased. Consumption of needles from trees increased as ambient temperature declined; no needles were consumed from trees when the minimum daily temperature exceeded -5” C. During both trials, grazing times decreased as temperatures declined, and increased as snow depth and wind speed decreased. We conclude that weather is a major factor influencing needle consumption; other interrelated factors may be forage availability, snow cover, and grazing time. Plne needle consumption, and the risk of abortion, in pregnant cattle appears to be greatly diminished during mild winter weather.
    • Forage value of native and introduced browse species in Tanzania

      Msangi, R. B. R.; Hardesty, L. H. (Society for Range Management, 1993-09-01)
      The nutritional value of Leucaena leucocephala (Lam.) de Wit was compared with that of 3 browse species native to western Tanzania: Antidesma venosum Mey. & Tul., Margaritaria discoides Baill., and Phyllanthus reticulatus Lodd. Foliage samples were collected monthly throughout the dry season from replicated sites on 3 different soil types and analyzed for crude protein, total ash, and in vitro dry matter digestibility. The crude protein content of L. leucocephata (17.60-29.69%) was higher (P<.05) than that of the native species (8.51-16.33%) throughout the study. Phyllanthus reticulatus had the highest crude protein of the native species. Abscised leaves had only half the crude protein of green leaves of the same species. All species showed a significant increase in crude protein when new leaves appeared. L. leucocephala had as much or more ash (6.96-9.77%) than the native species. Margaritaria discoides was more (P<.05) digestible (56.75- 74.06%) than all other species on ail dates but one. The in vitro dry matter digestibility of green and abscised leaves of the same species did not differ (P<.05) until July when green leaves ofikf. discoides, were more digestible. Soil type affected the in vitro dry matter digestibility of ail species except A. venosum (P<.05), but did not affect crude protein values. Both the native species and L. leucoce- phaIa can contribute significantly to meeting animal nutrient demands in the dry season.
    • Nutritional quality of browse after brush management on cross timbers rangeland

      Soper, R. B.; Lochmiller, R. L.; Leslie, D. M.; Engle, D. M. (Society for Range Management, 1993-09-01)
      We evaluated seasonal changes in browse quality 5-6 years after experimental manipulations to control unwanted woody vegetation using combinations of herbicide and fire on cross timbers rangeland in central Oklahoma. The study area consisted of two 32-ha replications of untreated controls and 4 brush treatments (tebuthiuron and triclopyr used singly or in combination with periodic prescribed burning); herbicides were applied in 1983 and fires initiated in 1985. Nutritional quality of blackberry (Rubus spp.), coralberry, (Symphoricarpos orbiculatus Moench), rough-leaf dogwood (Cornus drummondii Meyer), elm (Ulmus spp.), greenbrier (Smilax spp.), hackberry (Celtis spp.), and smooth sumac (Rhus glabra L.) were assessed by measuring crude protein, in vitro dry matter digestibility, neutral detergent fiber, acid detergent fiber, and moisture content. Crude protein concentrations of browse were 14% higher on herbicide-treated areas compared to untreated controls and 11% higher on triclopyr treatments compared to tebuthiuron treatments. In vitro dry matter digestibility was 9% higher on herbicide-treated areas compared to untreated controls. Fiber constituents and moisture content were not influenced by brush treatments. Prescribed burning combined with herbicide applications did not improve the quality of browse. Our results indicate that browse quality can be improved for white-tailed deer by applications of tebuthiuron or triclopyr and improvements persist for up to 6 years post treatment.
    • Old World bluestem response to fire and nitrogen fertilizers

      Berg, W. A. (Society for Range Management, 1993-09-01)
      Old World bluestem (Bothriochloa ischaemum L.) is being extensively established on marginal farmland in the Southern Plains. This 4-year field study in western Oklahoma developed guidelines for burning and N fertilization of Old World bluestem on calcareous and noncalcareous soils. Plots were on 'lron Master' Old World bluestem on a calcareous soil (Quinlan loam, shallow Typic Ustochrepts) and a noncalcareous soil (Carey loam, Typic Argiustolls). On each soil 4 blocks were split (spring burned, unburned) and N treatments (none, urea, ammonium nitrate) and time of N application (early, late) were randomly assigned within each burn treatment. Burning decreased (P<0.01) herbage yields by 6 to 30% per year. Nitrogen fertilizer broadcast at the rate of 50 kg N ha-1 increased herbage production about threefold. Ammonium nitrate fertilization resulted in 20% more herbage production than urea fertilization 1 year, and in equal production 2 years. The 4th year, application of ammonium nitrate in early April increased production by 20% compared to early April application of urea, urea was as effective as ammonium nitrate when either was applied in late April. Burning or calcareous soil had no adverse influence on the effectiveness of urea as compared to ammonium nitrate. Management implications for western Oklahoma and adjacent areas include: burn Old World bluestem only when necessary to remove substantial amounts of standing dead herbage, and broadcast urea 3 to 4 weeks after grass initiates growth when seasonal rains are more likely to move the urea into the soil, thereby decreasing potential for N loss by volatilization.
    • Research Observation: Chemical repellants to reduce grazing intensity on reclaimed sites

      Osko, T. J.; Hardin, R. T.; Young, B. A. (Society for Range Management, 1993-09-01)
      Revegetation of disturbed rangelands in western Canada is severely impeded by cattle grazing. Fencing to protect emergent vegetation is costly and restricts animal movement. Chemically repelling cattle from emergent vegetation may provide a convenient and economical alternative to fencing. This study determined whether certain repellents could reduce grazing intensity on vegetation to which they were applied compared to untreated vegetation. Canopy measurements were used to compare grazing intensity. Three trials were conducted on reclaimed land within the Aspen Parkland region of central Alberta. Time since reclamation was over 10 years in Trial A, 2 years in Trial B, and 3 weeks in Trial C. Pregnant mares' urine, Hinder® (150 mg ml-1 ammonium soaps), Skoot® (120 mg mi-1 tetramethylthiuram disulfide), and Deer-Away Big Game Repellent® (37% putrescent egg solids) were evaluated. Two concentrations of each repellent were sprayed onto 1 X 3-m treatment plots randomized within blocks replicated 4 to 6 times. Plot canopies were measured either by gently resting a sheet of plastic laminate over the canopy, or by lowering a sliding bar attached perpendicularly to a meter stick until it contacted the uppermost leaves of the canopy, and recording the height of the sheet or bar above the soil surface. Canopies of plots treated with Big Game Repellent® were taller than control plot canopies on each measurement date in all trials, indicating grazing was reduced. Big Game Repellent® plots were also generally taller than plots treated with other repellents. Canopies of plots treated with pregnant mares' urine, Hinder®, and Skoot® generally did not differ from control plots, nor did they differ from each other in any trial. Low repellent concentrations did not reduce grazing in any trial, but high concentrations reduced grazing in all trials. Repellent effectiveness was not permanent since all canopy measurements became shorter with time. Big Game Repellent® was effective in reducing grazing intensity by cattle, but practical use of repellents for grazing management requires further investigation.
    • Returns to grasshopper control on rangelands in southern Alberta

      Shewchuk, B. A.; Kerr, W. A. (Society for Range Management, 1993-09-01)
      Economic injury levels (EILs)—the minimum density of insects that would be required to warrant treatment—were estimated for the 4 most common insecticides sprayed on grasshoppers in Alberta. The results indicate that under the assumed conditions spraying was rarely profitable unless the pests were at very high outbreak levels (>30/M2), the benefits of control lasted more than 1 season or the producers' treatment costs were substantially subsidized by a provincial government rebate program. Estimates vary considerably depending on several parameter values. The most important variables were the cost, life, and efficacy of treatments, the derived price of forage, and assumptions regarding grasshopper population dynamics.
    • Revegetation strategies for Kaho'olawe Island, Hawaii

      Warren, S. D.; Aschmann, S. G. (Society for Range Management, 1993-09-01)
      Over the past 2 centuries, the island of Kaho'olawe has suffered the ravages of war, slash-and-burn agriculture, and overgrazing. Today, much of the island is barren and severely eroded. A research project initiated in 1988 has sought to identify effective, economical techniques to revegetate portions of the island. Treatments included drill seeding plus several rates of fertilization with monoammonium phosphate (11-52-0). Some treatments also include jute netting for soil moisture conservation and erosion control. The effect of windbreak fencing was evaluated across all treatments. Drill seeding plus broadcast application of at least 62 kg ha-1 N plus 291 kg h-1 P205 was the most cost-effective treatment. Jute netting and windbreak fencing significantly enhanced plant production, but the high cost of materials and maintenance limits their use to critical areas. The planted species with greatest promise for the windy, semiarid conditions on Kaho'olawe were buffelgrass (Cenchrus ciliaris L.), bermudagrass [Cynodon dactylon (L.) Pers.] and weeping lovegrass [Eragrostis curvula (Schrad.) Nees]. Although not included in the seed mixture, Australian saltbush (Atriplex semibaccata R. Br.), a naturalized species, responded favorably to fertilization. A subsequent, larger scale revegetation project using a specially modified chisel plow seeder to scarify, plant, and apply in-furrow fertilization in a single-pass operation reduced the cost and improved the results of the revegetation process.
    • Seasonal grazing of locoweeds by cattle in northeastern New Mexico

      Ralphs, M. H.; Graham, D.; Molyneux, R. J.; James, L. F. (Society for Range Management, 1993-09-01)
      Locoweed poisoning generally occurs in early spring. We evaluated cattle grazing of woolly locoweed (Astragalus mollissimus var. mollissimus Torr.) at Gladstone, N.M., and of white locoweed (Oxytropis sericea Nutt. ex T&G) at Capulin, N.M., through the spring and into early summer as the phenological development of warm-season grasses progressed from dormancy to rapid growth. Diets of 8 mature cows were quantified by bite count at each location. Cattle initially rejected woolly locoweed at Gladstone, even though it was the only green forage available in late March and early April. Gladstone cattle were then restricted to a small 7-ha pasture where high grazing pressure and limited feed forced them to graze woolly locoweed (41% of bites). When these cows returned to a larger pasture of unlimited forage availability, they continued eating woolly locoweed (23% of bites). At Capulin, cattle with a history of eating locoweed (loco-eaters) consumed more white locoweed (23% of bites) thin cattle without a history of eating locoweed (6% of bites) during the April grazing period. When warm-season grasses started rapid growth and locoweed matured in June, cattle ceased grazing both locoweed species.
    • Sites, mowing, 2,4-D, and seasons affect bitterbrush values

      Kituku, V. M.; Powell, J.; Olson, R. A. (Society for Range Management, 1993-09-01)
      This study was conducted in a sagebrush-bitterbrush vegetation type in southcentral Wyoming to compare the effects of mowing and 2,4-D application on shrub cover and bitterbrush (Purshia tridentata Pursh) use, preference values, browse values, and residual twig weight after summer/fall browsing by cattle and winter big game use. Areas 3 to 6 ha in size were mowed, sprayed with 2,4-D, or left untreated on 4 different sites. Total shrub cover was reduced from 38% (53% mountain big sagebrush (Artemisia tridentata spp. vaseyana), 37% bitterbrush) to 23% (38% sagebrush, 52% bitterbrush) by mowing, and to 17% (18% sagebrush, 64% bitterbrush) by herbicide application. Twig weight use was greater on mowed areas, on the more productive sites, and during summer cattle browsing when leaves were present than during winter browsing by big game. Frequency of use was inversely related to bitterbrush availability, although the relationship was confounded by different snow depths on different sites. Utilization values based on basal diameter were more sensitive to site and treatment effects than length and weight utilization values, but were influenced by differences in twig morphology and did not reflect differences in twig use, preference values, browse values, or browsing residual weights. Mowing produced the greatest preference values and browsing residual weights for cattle browsing and the greatest browse values for both cattle and big game. Preference values, browse values, and browsing residual weight appear to be useful indicators of site, treatment, and browsing effects.
    • Soil water extraction and photosynthesis in Gutierrezia sarothrae and Sporobolus cryptandrus

      Wan, C.; Sosebee, R. E.; McMichael, B. L. (Society for Range Management, 1993-09-01)
      Broom snakeweed (Gutierrezia sarothrae Shinners), a C3 evergreen half-shrub, is a formidable competitor of grasses in the semiarid southwestern rangelands. Sand dropseed (Sporobolus cryptandrus (Toff.) Gray), perennial C4 bunchgrass, is the most drought resistant species in the short-grass prairie. A comparative study on soil water extraction patterns, photosynthesis, and canopy development in both species during spring-summer growing season of 1991 was conducted in pot- and field-grown plants. Sand dropseed extracts water at depths between 0 and 30 cm more effectively than broom snakeweed. In contrast, broom snakeweed can take up more water from the subsoil (30-60 cm) than sand dropseed. Photosynthesis in sand dropseed was more affected by soil water deficit than was broom snakeweed, which was related to their water extraction patterns. Leaf area accumulation of broom snakeweed was not affected by spring drought, but that of sand dropseed was reduced. Because of greater water extraction from the wetter subsoil by broom snakeweed during drought, it can assimilate more carbon and, therefore, prevail in a competitive relationship with sand dropseed.
    • Technical Note: A containerized technique for studying root systems

      Engel, R. K.; Nichols, J. T.; Brummer, J. E. (Society for Range Management, 1993-09-01)
      Quantifying root responses of naturally growing range plants to treatments is difficult. The objective of this study was to develop a containerized technique to study individual plants growing in the field under near natural environmental conditions. Three containers were evaluated: 15 X 100 cm nylon (2,000 pores/cm2) sacks, 15 X 100 cm polyvinyl chloride (PVC) tubes, and 30 X 100 cm PVC tubes. The 15 X 100 cm PVC tubes were easiest to handle, and plants grown in these containers appeared similar in size and growth form to adjacent, undisturbed plants. Survival rate for 165 sand bluestem (Andropogon hallii Hack.) plants grown for 2 years in the 15 X 100 cm PVC tubes was 98.8%. This survival rate was achieved despite clipping treatments during the second year.
    • Viewpoint: "Invisible colleges" and citation clusters in stocking rate research

      Hart, R. H. (Society for Range Management, 1993-09-01)
      Research on the response of livestock gain to stocking rate tends to cluster into 5 "invisible colleges", represented by 5 citation networks which only occasionally intersect. Each college is built around a paradigm of the stocking rate-gain response as developed in 2 key papers sharing 1 or more authors. Researchers tend to cite the paradigm developed by authors in their field of research or in their geographic area. Therefore conficting pardigms have existed side-by-side for decades, an unusual occurrence in most fields of science. Research is needed to critically evaluate the empirical and conceptual soundness of these paradigms.
    • Viewpoint: Plant community thresholds, multiple steady states, and multiple successional pathways: legacy of the Quaternary?

      Tausch, R. J.; Wigand, P. E.; Burkhardt, J. W. (Society for Range Management, 1993-09-01)
      The climate cycles of the 2 million years of the Quaternary were a major force in the evolution of plant response to change. Quaternary climate has been primarily glacial with interglacials such as the current Holocene a minor component. Plant species responded individually to climate changes and, consequently, species composition has continually changed. The legacy of Quaternary climate change is that plant communities are far less stable than they appear to be from our perspective. They are unique at each location, difficult to define, and communities that are relics from a previous environment can be sensitive to small or transient environmental changes. Plant communities are variable both in space and time. Many ecological principles and concepts, and ecosystem paradigms derived from them, require revision to incorporate this variation. The concepts of habitat type and condition and trend, for example, do not reflect dynamic vegetation response to changes in climate. Our knowledge is presently insufficient to adequately describe interactions between ecosystems changing climate, but the patterns of vegetation response to environmental changes of the past may provide important information on vegetation response to present and future climate change. The concepts of thresholds, multiple steady states, and multiple successional pathways are helpful in understanding the dynamic interrelationships between vegetation and environmental changes.