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  Journal of Range Management, Volume 45, Number 5 (September 1992)

  Society for Range Management, 1992-09-01
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  Journal of Range Management, Volume 45, Number 4 (July 1992)

  Society for Range Management, 1992-07-01
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  Journal of Range Management, Volume 45, Number 6 (November 1992)

  Society for Range Management, 1992-11-01
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  Journal of Range Management, Volume 45, Number 1 (January 1992)

  Society for Range Management, 1992-01-01
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  Journal of Range Management, Volume 45, Number 3 (May 1992)

  Society for Range Management, 1992-05-01
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  Journal of Range Management, Volume 45, Number 2 (March 1992)

  Society for Range Management, 1992-03-01
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  Water-extractable organic matter from plant litter and soil of rough fescue grassland

  Dormaar, J. F.; Willms, W. D. (Society for Range Management, 1992-03-01)

  Little is known about the chemical composition of throughfall, or the water that falls through, and drips from, the grass canopy of Rough Fescue Grassland during the grazing season. Water-extractable C, N, organic acids, and monosoccharides from litter and from soil in the upper 2 cm of the Ah horizon collected at monthly intervals in 1988 were at Stavely, Alberta. Rough fescue (Festuca campestris Rydb.) were stocked at tither light (1.2 AUM/ha) or very heavy (4.8 AUM/ha) fixed rates for 39 years or were ungrazed in exclosures located within each field for an equal period of time. At the high grazing intensity, the soil and litter N was less water-extractable. The C/N ratios of the water-extractable organic matter from litter and soil averaged 11.2 and 2.3, respectively. Soil monosaccharides were essentially not water-extractable. The quality of the litter as reflected by the water-extractable constituents often differed over the season between fields. Observations at regular time intervals are essential. The effect of the quality of leachates of litter on soil was not predictable. The 3 major long-chain fatty acids identified, palmitic, stearic, and arachidic acids, from soil in grasslands that are in good condition because of the low grazing pressure, could well contribute to the resistance of those grasslands to the encroachment of invading species.
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  Viewpoint: Replication, randomization, and statistics in range research

  Wester, D. B. (Society for Range Management, 1992-05-01)

  Appropriate application of significance tests in statistical analyses requires an explicit statement of hypothesis; a clear definition of the population(s) about which inferences are to be made; and a model, a sampling strategy, an analysis, and an interpretation that are consistent with these considerations. In particular, experimental design and analyses must recognize appropriate replication and random selection of experimental units from target population(s). This paper discusses some aspects of these issues in range science research. Textbook examples and examples from range science applications are discussed in parallel in an attempt to clarify issues of randomization and replication in statistical applications.
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  Vegetation responses to 2 brush management practices in south Texas

  Bozzo, J. A.; Beasom, S. L.; Fulbright, T. E. (Society for Range Management, 1992-03-01)

  Brush management for improving wildlife habitat in South Texas is important because of the economic value of wildlife. We determined vegetation responses to (1) roller chopping of guajillo (Acacia berlandieri Benth.)-blackbrush acacia (A. rigidula Benth.)-dominated rangeland and (2) heavy discing of whitebrush (Aloysia lycioides Cham.)-dominated rangeland to improve white-tailed deer (Odocoileus virginianus Raf.) habitat. Canopy cover of vegetation was estimated seasonally during August 1988 to April 1990. Both treatments reduced brush canopy cover, but herbaceous response depended on rainfall. Mean herbaceous cover was 65 and 136% higher on roller chopped sites than on untreated sites when averaged across all sampling dates. Heavy discing reduced relative canopy cover of whitebrush but increased cover of spiny hackberry (Celtis pallida Torr.), an important browse species. Forb species richness was higher on roller chopped and disced sites than on untreated sites, but species diversity was similar. Because herbaceous response to brush removal may depend on rainfall, other factors such n effects on browse availability and nutritional quality may need to be considered when planning brush management strategies to improve white-tailed deer habitat.
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  Training lambs to be weed eaters: Studies with leafy spurge

  Walker, J. W.; Hemenway, K. G.; Hatfield, P. G.; Glimp, H. A. (Society for Range Management, 1992-05-01)

  The objective of the study was to determine if exposure of young lambs to leafy spurge (Euphorbia esula L.) would increase the consumption of this plant. Orphan lambs were exposed to leafy spurge from birth to 11 weeks of age as a water soluble extract mixed with milk replacer and as freshly harvested plants. Ewe-reared lambs were exposed to leafy spurge by grazing them on a leafy spurge-infested pasture. Study 1 investigated the consumption of vegetative and flowering leafy spurge paired with arrowleaf balsam root (Balsamorhiza sagittata (Pursh) Nutt.) by orphan lambs during a 30-min feeding period. Experienced lambs consumed a higher percentage leafy spurge than naive lambs (P<0.03). The interaction of leafy spurge phenophase and previous experience (P<0.02) showed that experienced lambs preferred leafy spurge regardless of phenophase (70% of intake) and naive lambs only preferred leafy spurge when it was vegetative. Study 2 investigated the preference for leafy spurge on pastures with high or low leafy spurge biomass. Experienced compared to naive lambs had a higher percentage of bites (P<0.001) and preferred leafy spurge in the high spurge biomass pasture, but not in low biomass pastures. Naive lambs avoided leafy spurge in both pastures. Study 3 was a pasture trial that investigated spurge consumption by orphan and ewe-reared lambs. Percent bites and time spent grazing leafy spurge were not affected (P>0.23) by previous exposure, but daily herbage removal was greater (P<0.09) in pastures grazed by experienced compared to naive lambs (876 vs. 685 g/lamb, respectively). Experienced ewe-reared lambs had a higher rate of biting on leafy spurge (P<0.06) than naive or orphan Lambs. These studies indicate that previous experience will be an important factor affecting the use of sheep as a biological control agent for leafy spurge.
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  Toxification and detoxification of plant compounds by ruminants: An overview

  Smith, G. S. (Society for Range Management, 1992-01-01)

  Improved usage of rangelands for livestock production requires better ways to reduce losses caused by poisonous plants, such as management practices to minimize ingestion and treatments to improve animal tolerance of ingested poisonous plants. In ruminants, gastrointestinal microbes can detoxify plant compounds, and this capacity has been enhanced in a few cases by deliberate modification of rumen microbial populations. Some plants are poisonous because ingested plant material is made toxic by microbial fermentation in the rumen, and better understanding of such toxifications will provide opportunities to diminish poisonings of that type. Absorption of toxic substances from the gastrointestinal tract into blood and lymph may be modified by feeding binding agents such as clay, resins, and indigestible fibers, or by pharmaceuticals that interfere with absorption of toxicants. Agents that induce or inhibit biotransformational enzymes in tissues of the host animal might modify animal tolerance of some plant toxicants. Provision of substances that serve as co-substrates of detoxification can enhance animal tolerance of other types of plant toxicants. Some reports that illustrate these approaches have been reviewed, and questions have been raised to stimulate further research.
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  The effect of polyacrylamide on grass emergence in southcentral New Mexico

  Rubio, H. O.; Wood, M. K.; Cardenas, M.; Buchanan, B. A. (Society for Range Management, 1992-05-01)

  Seeding rangeland is a challenge for rangeland scientists, especially on those soils with tendency to crusting. Although some information is available on how soil conditioners affect emergence of certain comestible crops, little is known about the effect of synthetic organic matter on grass emergence. We examined the effect of polyacrylamide, a soil conditioner, on seedling emergence of blue panicgrass (Panicum antidotale Retz.), King Ranch bluestem (Bothriochloa ischaemum [L.] Keng), sideoats grama (Bouteloua curtipendula [Michx.] Torr.), plains bristlegrass (Setaria macrostachya H.B.K.), and 'salado' alkali sacaton (Sporobolus airoides [Torr.] Torr.) under field conditions. Emergence of blue panicgrass and sideoats grama was increased with polyacrylamide applications, even at the lowest concentration (10 kg ha-1) during summer 1987. No emergence response to polyacrylamide applications was found for King Ranch bluestem, and plains bristlegrass did not emerge in any experimental plots during summer 1987. During summer 1988, blue panicgrass and sideoats grama emergence was again increased with polyacrylamide applications. Emergence of 'salado' alkali sacaton and King Ranch bluestem was unaffected by polyacrylamide applications. Soil conditioners may be a feasible alternative for seeding some rangeland in areas where crusting is a problem.
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  Technical Note: Automatic sorting of free-ranging cattle

  Anderson, D. M.; Rouda, R. R.; Murray, L. W.; Pieper, R. D. (Society for Range Management, 1992-05-01)

  An automated system to weigh and sort free-ranging cattle was adapted to administer cottonseed pellets (41% crude protein) to free-ranging cattle. The frequency with which animals drank water determined the interval between supplemental feedings. The automatic spacing of individual animals was the weakest link in the chain of events leading to the sorting of cattle into groups to administer treatments. Periodically during the study, free-standing water was available due to above-average precipitation. This resulted in an inconsistent supplementation schedule because animals did not have to return through the maze to drink water. Single herd management eliminated potential pasture-treatment confounding but accentuated individual animal behavior, which resulted in a range of supplement intakes and drinking water patterns.
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  Tannin chemistry in relation to digestion

  Hagerman, A. E.; Robbins, C. T.; Weerasuriya, Y.; Wilson, T. C.; McArthur, C. (Society for Range Management, 1992-01-01)

  Tannins are a diverse group of compounds which precipitate protein. The impact of tannins on herbivory has been difficult to assess because of diversity in tannin chemistry and in animal physiology. We have evaluated the effects of tannin on large ruminants (deer, sheep) using artificial diets containing well-defined tannins, and have compared the results to those obtained with natural forages. The different effects of condensed tannins and gallotannins on herbivores are related to the chemical stability of the tannins. Commercial tannic acid does not have the same effects on herbivores as gallotannins in natural forages. Molecular weight apparently determines the metabolic fate of gallotannins from various sources.
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  Stand density index as a predictor of forage production in northern Arizona pine forests

  Moore, M. M.; Deiter, D. A. (Society for Range Management, 1992-05-01)

  Ponderosa pine (Pinus ponderosa Laws.) overstory-forage understory relationships were studied on the Kaibab Plateau of northern Arizona to evaluate how well forage (graminoid, forb, and current year shrub) production could be predicted by stand density index (SDI). Linear and nonlinear equations were used. Stand density index, a relative measure of stand density, was a useful predictor of understory production for a variety of stand structures and ages. The linear and nonlinear equations produced coefficient of determinations of 0.76 and 0.72, and standard error of the estimates of 5.08 kg ha-1 and 5.51 kg ha-1, respectively.
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  Seedbed ecology of winterfat: Imbibition temperature affects post-germination growth

  Booth, D. T. (Society for Range Management, 1992-03-01)

  Seed imbibition is a critical first step in the awakening of an embryo plant. To determine if imbibitional conditions influenced post-germination growth, seeds of 3 winterfat (Eurotia lanata) ecotypes were imbibed at 5 temperatures from 0 to 20 degrees C, and at 5 oxygen concentrations from 0 to 40%. After a 4-day imbibition period the seeds were either dried and weighed or they were cultured in the dark at 20 degrees C. Seedling axial length was measured 5 times between 5 and 14 days post-germination to assure that maximum growth was measured. The study was repeated 3 times for each ecotype. Oxygen concentration had little effect except at 0%. As imbibition temperature increased both post-imbibition dried seed weight and seedling axil length decreased. This indicates the probability for successful termination, establishment, and survival of winterfat decreases when seeds are imbibed at 15-20 degrees C as compared to 5 degrees C. Therefore winterfat should be sown during those parts of the year when diaspores will imbibe at cool temperatures. Winterfat should be imbibed and held at 5 degrees C for 4 days, then germinated at 15 degrees C when testing germination.
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  Response of Central Plains tallgrass prairies to fire, fertilizer, and atrazine

  Masters, R. A.; Vogel, K. P.; Mitchell, R. B. (Society for Range Management, 1992-05-01)

  Tallgrass prairies are an important forage resource in the eastern Central Great Plains. The effect of spring burning, fertilization, and atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine] on standing crop of selected herbaceous species and categories of vegetation was determined in 6 tallgrass prairie environments located near Lincoln and Virginia, Neb., from 1987 through 1989 and 1 site near Bloomfield, Neb., in 1987. The grasslands were in good to excellent condition at the time these studies were conducted. Portions of each site were burned in mid-to late spring, atrazine was applied at a rate of 2.2 kg a.iha-1 in late April to early May, and fertilizer was applied in mid-May. Despite below-normal precipitation at 6 of the 7 sites, burning combined with fertilization improved warm-season grass standing crop by 50 to 127% in 5 of the 7 grassland environments studied. This reflected the positive response of the dominant warm-season grasses, big bluestem (Andropogon gerardii Vitman var. gerardii Vitman) and indiangrass [Sorghastrum nutans (L.) Nash], to burning or fertilization. Atrazine increased warm-season grass standing crop at only the site near Bloomfield. Kentucky bluegrass (Poa pratensis L.) and annual bromes (Bromus spp.) were more susceptible to atrazine than smooth brome (Bromus inermis Leyss.). Forb standing crop was significantly reduced by atrazine alone or by burning followed by atrazine application in 4 of the 7 prairie environments. Burning combined with fertilizer application improved warm-season grass standing crop in good to excellent condition grasslands and obviated the need to use atrazine.
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  Reducing livestock losses from poisonous plants through grazing management

  Taylor, C. A.; Ralphs, M. H. (Society for Range Management, 1992-01-01)

  Stocking rate, multi-species grazing, and grazing systems are 3 components of grazing management that can be manipulated to minimize losses in animal production due to consumption of poisonous plants. Our study evaluated 3 case studies where either all or some of the above components of grazing management were the experimental treatments. For study 1 the grazing treatments included 3 rates of stocking; a 4-pasture, 3-herd grazing system; and combinations of different kinds of livestock that were measured for 21 years. For study 2 the grazing treatments included 2 rates of stocking, 4 different grazing systems, and combinations of either all sheep or a ratio of 3:2 cattle to sheep (au equivalents) for 11 years. Study 3 measured cattle poisoned by locoweed prior to and following the implementation of a 3-herd, 4-pasture grazing system over 6 years. Sheep death losses to bitterweed (Hymenoxys odorufa DC.) poisoning occurred in 13 of the 21 years on continuously grazed pastures heavily stocked with sheep and only 8 years under both moderate and light stocking rates. Regardless of the stocking rate, death losses were greatest on pastures stocked with sheep only and least with the combination of livestock species on conjunction with a 4-pasture, 3-herd grazing system. Stocking rate, multi-species grazing, or grazing system seemed to have little effect on goat losses due to oak (Quercus spp.) consumption. Cattle and sheep were not affected by sacahuista (Nolina texauo Wats.) in this study; however, their inclusion in the grazing herd reduced goat death losses from 5% with goats only to 2.5 and 1.5% for combinations of cattle and goats and cattle, sheep, and goats, respectively. In study 2 sheep death losses from bitterweed poisoning under continuous yearlong grazing treatments averaged 5.2% vs 3.7% for grazing treatments with some type of grazing system. Death losses were greatest under yearlong continuous grazing stocked at 10.4 ha/auy with 100% sheep and least under yearlong continuous grazing stocked at 15.2 ha/auy with 4% sheep. In study 3 the number of sick calves declined from 20% to about 3% with the implementation of a new grazing system. The reduction in sickness and loss was attributed to the reduction in grazing pressure and the shorter grazing season. It is concluded that for these case studies tactical management decisions such as proper stocking rate, combinations of animal species to be grazed, and grazing system used played an important role in minimizing livestock death losses to poisonous plants.
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  Pyrrolizidine alkaloid content of houndstongue (Cynoglossum officinale L.)

  Pfister, J. A.; Molyneux, R. J.; Baker, D. C. (Society for Range Management, 1992-05-01)

  Houndstongue (Cynoglossum officinale L.) is a biennial weed infesting pasture, hayfields, and disturbed areas throughout North America. Houndstongue contains pyrrolizidine alkaloids (PAs) that are hepatotoxic. First and second year's growth of houndstongue were harvested from emergence to maturity. Nuclear magnetic resonance was used to determine the levels of total PAs, free base, and N-oxide forms of the alkaloids in leaves, stems, buds, flowers, and pods. PA levels generally were highest (1.5 to 2.0% dry weight) in immature plant tissue, with a gradual decline during maturation. Most plant parts contained greater quantities of the N-oxide form of PAs (60-90%) compared to the free base form. Leaves and pods of mature houndstongue contained sufficient PAs to be potentially toxic if ingested by livestock.
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  Protein supplementation of steers grazing tobosa-grass in spring and summer

  Pitts, J. S.; McCollum, F. T.; Britton, C. M. (Society for Range Management, 1992-05-01)

  A 3-year study evaluated weight gain, blood urea nitrogen (BUN), and fecal nitrogen (FN) of beef steers fed 0.00, 0.34, or 0.68 kg/hd/day of cottonseed meal (41% CP) while grazing mesquite (Prosopis glandulosa var. glandulosa Torr.)/tobosagrass (Hilaria mutica [Buckl.] Benth.) range between April and July. Mixed breed beef steers (avg wt 230 kg) were allocated to three 6-pasture grazing cells and group-fed prorated amounts of supplement 3 days a week. Individual weights were recorded every 21 days. Crude protein in clipped forage samples remained above 7.0% except in July, 1985 (6.5%). Gain response varied among periods within year but the primary effects occurred in the first 40 to 60 days of grazing. In 1985, daily gains over 92 days were 0.38, 0.44, and 0.67 kg/hd/day for the 0.00, 0.34, and 0.68 kg supplement groups, respectively. In 1986 and 1987, daily gains during 85-day trials were 0.65, 0.66, and 0.71 kg/hd/day and 0.98, 1.08, and 1.07 kg/hd/day, respectively. Blood and feces were collected from 10 steers in each treatment group on each weigh date during the first 2 years. The 0.68 kg/hd/day supplement maintained higher (P<0.05) BUN and FN than the control group but response to 0.34 kg supplement was inconsistent. Performance and BUN data suggested that protein concentrate was not the appropriate supplement for steers grazing tobosagrass in the spring and summer.

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