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  Journal of Range Management, Volume 41, Number 4 (July 1988)

  Society for Range Management, 1988-07-01
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  Winterfat diaspore morphology

  Booth, D. T. (Society for Range Management, 1988-07-01)

  Diaspores are disseminules specialized for dispersal and for other functions contributing to seedling establishment and seedling vigor. The winterfat (Eurotia lanata) diaspore consists of hairy bracts enveloping a utricle. Testa, embryo, and perisperm make up the enclosed seed. This general diaspore morphology also occurs in Atriplex and Grayia. The potential for seedling establishment is not equal between diaspores and diaspore subunits; therefore, authors should take care to use terminology that refers to the correct entity.
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  Vigor of needleandthread and blue grama after short duration grazing

  Reece, P. E.; Bode, R. P.; Waller, S. S. (Society for Range Management, 1988-07-01)

  Grazing treatments were applied to pastures in western Nebraska from 1980 through 1983 to examine the influence of short duration grazing (SDG) on plant vigor. The 3 treatments were: (1) 4 years of SDG, (2) 3 years of SDG followed by 1 year of rest, and (3) 4 years of rest. Total nonstructural carbohydrate (TNC) concentrations of stem bases, mean tiller weight, and tiller number/plant of etiolated growth, and paired differences in spring growth between covered and uncovered plants were used to evaluate vigor of needleandthread (Stipa comata Trin. & Rupr.) and blue grama [Bouteloua gracilis (HBK) Lag. ex Griffiths]. Two 7-pasture, 1-herd SDG systems were used. Length of use and deferment periods, stocking density, stocking rate, and sequence of pasture use were constant throughout the study. Grazing treatments reduced the vigor of both study species, but the vigor of blue grama was more sensitive to treatments than needleandthread. Levels of TNC in needleandthread were not affected by grazing treatments. Concentrations of TNC in blue grama recovered to levels of ungrazed plants after 1 year of rest in some but not all pastures. Grazing increased the number of tillers/plant, but reduced total organic reserves of both species as measured by etiolated growth. Assimilates produced in early spring growth appeared to be more important for tiller initiation in plants that had been grazed than in ungrazed plants.
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  Vegetation response to the Santa Rita grazing system

  Martin, S. C.; Severson, K. E. (Society for Range Management, 1988-07-01)

  Changes in vegetation under yearlong grazing were compared with those under the Santa Rita grazing system, a rotation system designed for southwestern US rangelands where 90% of the forage is produced in mid- to late-summer. The study was conducted on the Santa Rita Experimental Range near Tucson, Arizona, from 1972 to 1984. In 1984 there were no differences (P<0.05) in grass densities (16 vs. 17 to 18 plants/m2), forb densities (0.6 vs 0.7 to 1.4 plants/m2), shrub densities (2.0 vs 1.9 to 2.4 plants/m2), or shrub cover (20 vs 21 to 26%) on pastures grazed yearlong or in the Santa Rita rotation, respectively. Lack of response to grazing schedules is attributed to initial plant densities near the maximum the sites could support and to moderate grazing during the study period. Average herbage yields of pastures were not related significantly to grazing treatments but correlated strongly (r = 0.909) with long-time summer rainfall means. Results support the observation that rotation grazing may not improve ranges that are in good condition. It is concluded, however, that the Santa Rita Grazing System may accelerate recovery of ranges in poor condition.
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  Technical Notes: The grass spikelet formula: an aid in teaching and identification

  Allred, K. W.; Columbus, J. T. (Society for Range Management, 1988-07-01)

  The structure and arrangement of the grass spikelet may be summarized by use of a spikelet formula. The parts of the formula are stacked vertically to correspond to the parts of the grass spikelet. Nerves and numbers of parts are indicated by super- and subscripts. Spikelet formulae may be a useful teaching tool, as well as a convenient field notation.
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  Small-mammal mycophagy in rangelands of central and southeastern Oregon

  Maser, C.; Maser, Z.; Molina, R. (Society for Range Management, 1988-07-01)

  Most arid and semiarid rangeland plants form a mycorrhizal symbiosis with certain fungi through which the host plants absorb water and nutrients from the soil. Small mammals are known to disperse viable spores of hypogeous, mycorrhizal fungi in forests, but little is known about small mammals as vectors of fungal spores in rangelands. We therefore examined the stomach contents of 575 mammals (16 genera, 26 species) for fungal spores. Spores of hypogeous, mycorrhizal fungi, representing 15 genera, were identified from 21% of the mammals. Although wind and water are thought to be the main means of dispersal for fungal spores in rangelands, a variety of mammals may be locally important in dispersing spores of mycorrhizal fungi.
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  Root growth of Artemisia tridentata

  Welch, B. L.; Jacobson, T. L. C. (Society for Range Management, 1988-07-01)

  We designed a greenhouse study to test the following 2 hypotheses: (1) root growth of Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) exceeds that of basin big sagebrush (A.t. ssp. tridentata) and mountain big sagebrush (A.t. ssp. vaseyana) during the first 10 to 40 days after planting, and (2) root length of basin big sagebrush exceeds that of mountain big sagebrush, and root length of mountain big sagebrush exceeds that of Wyoming big sagebrush, at the end of a 174-day growing period. For the first 10 days, Wyoming big sagebrush root growth significantly (p=0.05) exceeded that of basin and mountain big sagebrush. At 20 and 30 days, Wyoming and basin big sagebrush were not significantly different, but both significantly exceeded mountain big sagebrush. At 40 days, basin big sagebrush root growth significantly exceeded that of Wyoming big sagebrush, which significantly exceeded mountain big sagebrush. Basin and Wyoming big sagebrush root lengths at 174 days were not significantly different, but both significantly exceeded mountain big sagebrush. Significant differences in root lengths at 174 days occurred among accessions. We concluded that Wyoming big sagebrush can survive on xeric sites where basin and mountain big sagebrush cannot because of smaller aboveground parts and rapid and long root growth.
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  Prediction of soil cover and soil rock for rangeland infiltration

  Rawls, W. J.; Brakensiek, D. L.; Simanton, J. R.; Hanson, C. L. (Society for Range Management, 1988-07-01)

  Lane et al. (1987) found that the proportion of bare or covered ground surface under the canopy is important for modeling infiltration in rangeland soils. Using a total of 322 composite plant canopy cover and ground cover measurements collected in Idaho, Arizona, and Nevada, equations were developed for predicting the ground cover under plant canopy from standard resource surveys or remote sensing techniques which primarily measure ground cover outside plant canopy. Equations were developed for predicting (1) percent by weight of soil rock in the top 76 mm of soil from ground cover measurements made outside of plant canopy, and (2) surface rock cover outside plant canopy from soil texture.
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  Physical development of orphaned white-tailed deer fawns in southern Texas

  Demarais, S.; Zaiglin, R. E.; Barnett, D. A. (Society for Range Management, 1988-07-01)

  The effect of doe harvest on the physical development of orphaned fawns is an important unanswered question in white-tailed deer management. Twenty-seven white-tailed deer (Odocoileus virginianus) fawns were captured, fitted with telemetry collars, and released in southern Texas during 15-16 October 1985. Three fawns died from capture-related trauma. Thirteen of the remaining 24 fawns were orphaned during 15 October-8 November 1985. Eleven fawns remained with their dams as controls. Surviving animals were collected 9-10 October 1986. Covariate-adjusted eviscerated carcass weight was lower (P = 0.08) for orphaned females (mean = 28.3 kg) than for control females (mean 32.4 kg). Two of 4 orphaned females bred as fawns compared to 0 of 5 control females. Metabolic demands associated with lactation could account for the lower eviscerated carcass weight and weight gain of orphaned females. Physical development of males was not affected by dam harvest (P>0.10). We conclude that in good quality habitat there are minimal, if any, negative effects of dam removal on physical development of surviving fawns.
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  Patterns of American licorice seed predation by Acanthoscelides aureolus (Horn) (Coleoptera: Bruchidae) in South Dakota

  Boe, A.; McDaniel, B.; Robbins, K. (Society for Range Management, 1988-07-01)

  The bruchid beetle Acanthoscelides aureolus (Horn) is a major seed predator on American licorice (Glycyrrhiza lepidota Pursh) and other legumes in North America. Mature pods of American licorice from eastern South Dakota populations were examined for seed predation by A. aureolus over a 2-year period from 1985-1986. Frequency of seed predation varied significantly between years. Percent seed predation was similar for 2-, 3-, 4-, 5-, and 6-seeded pods, indicating pods were attacked in proportion to number of seeds in the pod. Highest predation frequencies were found for seeds at the rachis end of the pod, regardless of pod size (seeds/pod). The largest seeds in pods with 4 or more seeds were from central positions while the smallest were from proximal and distal positions, suggesting beetle larvae did not select seeds on the basis of large size. When predation levels were low, seed position in the pod was more important than pod or seed size in determining frequency of seed predation by A. aureolus.
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  Justification for grazing intensity experiments: analysing and interpreting grazing data

  Bransby, D. I.; Conrad, B. E.; Dicks, H. M.; Drane, J. W. (Society for Range Management, 1988-07-01)

  Grazing trials in which treatments are compared at only 1 grazing intensity greatly outnumber those in which treatments are compared at several grazing intensities. This suggests that, compared to other treatments and the need for replication in grazing trials, researchers consider grazing intensity lower in priority. In this study, a regression modeling approach for analyzing and interpreting data was developed to enhance the value of grazing intensity trials. As an example, results from 5 irrigated bermudagrasses (Cynodon dactylon (L.) Pers) (Callie, Coastal, Brazos and experimental hybrids S-54 and S-16) which were continuously grazed without field replication by Santa Gertrudis steers at 4 grazing intensities were considered. The relationships between average daily gain (ADG) and stocking rate, ADG and herbage present (Mg/ha), and between stocking rate (animals/ha) and herbage present were well described by linear functions for all cultivars, with correlation coefficients (r) mostly above 0.9. Coefficients of determination (R2) for linear regression models derived for ADG vs stocking rate, ADG vs herbage present, and stocking rate vs herbage present were 0.90**, 0.89**, and 0.87**, respectively. Significant cultivar × grazing intensity (as measured by stocking rate or herbage present) interactions (P≤0.01) were observed. Furthermore, estimated stocking rates which provided maximum gain/ha ranged from 6.6 to 9.4 animals/ha, and the range in herbage present which provided maximum gain/ha was 0.35 to 1.95 Mg/ha. Callie provided an estimated maximum gain/ha of 881 kg/ha/season, while maximum gain/ha for the other cultivars ranged from 613 to 687 kg/ha/season. Comparison between these 5 cultivars at only 1 grazing intensity would have had very narrow application. The procedure described allowed statistical comparison of cultivars without replication, and inferences about the separate effects of forage quality and quantity on animal performance could be made. Herbage present and cultivar were descriptors of the pasture. Since there was a substantial range of values for herbage present and stocking rate, all important assumptions underlying linear regression were met and designs utilized in analysis of variance were not needed.
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  Infiltration and interrill erosion responses to selected livestock grazing strategies, Edwards Plateau, Texas

  Thurow, T. L.; Blackburn, W. H.; Taylor, C. A. (Society for Range Management, 1988-07-01)

  Understanding the temporal response of infiltration rate and interrill erosion to selected livestock grazing strategies is necessary for the continued soil and water conservation of rangeland. Infiltration rate and interrill erosion were sampled bimonthly from 1978-1984 on pastures grazed continuously (MCG) and moderately stocked (8.1 ha AU-1); continuously (HCG) and heavily stocked (4.6 ha AU-1); high-intensity, low-frequency (HILF) and moderately stocked (8-1; 17:119 day, stocked at 8.1 ha AU-1); short duration (SDG) and heavily stocked (14-1; 4:50 day, stocked at 4.6 ha AU-1). The MCG and HILF pastures were able to recover from droughts and maintain initial infiltration rates and interrill erosion. In contrast, infiltration rates decreased and interrill erosion increased on HCG and heavily stocked SDG pastures. The trend of infiltration rate and interrill erosion deterioration in the heavily stocked SDG and HCG pastures was not gradual; rather, it followed a stair-step pattern typified by decreasing condition during drought and an inability to recover to pre-drought level during periods of above-normal precipitation. The heavy stocking rate and climate rather than grazing strategy were the primary factors influencing the hydrologic responses. Infiltration rates were seasonally cyclic in the SDG and HCG pastures, but no significant seasonal trend could be identified in the MCG pasture. This was attributed to greater midgrass cover and litter accumulation in the MCG pasture which provided cover stability compared to less litter accumulation and a greater dominance of seasonal shortgrasses and forbs in the SDG and HCG pastures. Total organic cover was the most important factor determining infiltration rate. The midgrass bunch growth form and litter accumulation were the most important factors influencing interrill erosion. Both factors increased microrelief, and obstructed sediment transport and interrill erosion.
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  Indian ricegrass seed damage and germination responses to mechanical treatments

  Griffith, L. W.; Booth, D. T. (Society for Range Management, 1988-07-01)

  Indian ricegrass [Oryzopsis hymenoides (Roem. and Schult.) Ricker] is a valuable forage species in the western United States; however, low fresh-seed germination has limited its use in rangeland revegetation. Seed damage and germination effects were evaluated on 2 seedlots of 'Nezpar' Indian ricegrass exposed to 3 mechanical treatments. The air-gun scarifier and the Quaker Oats dehuller improved germination whereas the Forsberg dehuller decreased germination. Disruption of the seed coat before storage appears to be a practical method of reducing storage time required for improved germination of freshly harvested seed.
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  Hydrologic impacts of sheep grazing on steep slopes semiarid rangelands

  Wilcox, B. P.; Wood, M. K. (Society for Range Management, 1988-07-01)

  Infiltration, sediment concentration of runoff, and sediment production from lightly grazed and ungrazed semiarid slopes were compared using a hand-portable rainfall simulator. The study slope was located in the Guadalupe Mountains of southeastern New Mexico. Average slope steepness was 50%. The objective of this study was to determine the impacts of light grazing by sheep (10 ha/ AU) on steep slope infiltrability and sediment production. Infiltrability on the grazed slopes was 12-17% lower than on the ungrazed slopes. These results are comparable to what has been reported from moderate slope gradients. Sediment concentration of runoff from the lightly grazed slopes was significantly higher than from the ungrazed slopes only at the end of the dry run (45 min). Sediment production was significantly greater from the grazed slopes for the dry run, but not the wet run. Percentage difference of sediment production between the grazed and ungrazed slopes was well within the range published for moderate slope conditions. These data give no indication that steep slopes (30-70%) in semiarid regions are any more hydrologically sensitive to light grazing than are moderate slopes (<10%).
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  Herbicidal control of pricklypear cactus in western Texas

  Petersen, J. L.; Ueckert, D. N.; Potter, R. L. (Society for Range Management, 1988-07-01)

  The recommended practice for pricklypear (Opuntia spp.) control in western Texas has been aerial spraying with a 1:1 mixture of 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] and picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid) at 0.56 kg/ha in late spring-early summer. This practice did not consistently control pricklypear. Experiments were conducted at 2 locations to determine if efficacy of the herbicide mixture could be improved by increasing the rate or by spraying at night. The herbicide mixture was applied at 0.56 and 1.12 kg/ha to dense pricklypear stands in morning and near midnight in December, June, August, and October. The high rate killed more Lindheimer pricklypear (O. lindheimeri) and Edwards pricklypear (O. edwardsii) growing on clay loam soils compared to the low rate during most seasons. The higher rate did not increase control of hybrid pricklypear growing on clay soils sufficiently to justify the added treatment cost or to satisfy the management objectives of most ranchers. Night treatments killed significantly more pricklypear than daytime treatments only during late spring-early summer. The pricklypear species and hybrids were most susceptible to herbicide applications in late summer and early autumn and least susceptible to those in late spring-early summer. The efficacy of early winter treatments was intermediate.
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  Grazing, stocking, and production efficiencies in grazing research

  Scarnecchia, D. L. (Society for Range Management, 1988-07-01)

  The term harvest efficiency has been used with increasing frequency to describe results of intensive grazing management. A concept of harvest efficiency for grazed systems, i.e., a grazing efficiency concept compatible with the dynamics of herbage growth and disappearance is needed. This paper (1) describes variables and objectives needed in constructing a concept of grazing efficiency, (2) offers a formal definition of the term, (3) defines 2 other efficiencies related to grazing efficiency, and (4) discusses the interpretation and use of grazing efficiency and the other efficiencies in grazing research. More effective application of the efficiency concepts will require improved methods of measuring or modeling herbage growth and disappearance.
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  Effect of drying method on the nutritive composition of esophageal fistula forage samples: influence of maturity

  Burritt, E. A.; Pfister, J. A.; Malechek, J. C. (Society for Range Management, 1988-07-01)

  Researchers continue to oven- and air-dry extrusa samples from esophageally fistulated animals, despite evidence that this practice leads to erroneous nutritional evaluations. Two studies were conducted to determine how method of drying affects the nutritional composition of esophageal extrusa collected from sheep and goats browsing forage at different stages of maturity. In trial 1, extrusa collected from free-ranging sheep and goats in Northeast Brazil from July to April was freeze- or oven-dried (40 degrees C) and analyzed for neutral detergent fiber (NDF) and lignin (L). NDF and L were artificially elevated (31-93%) in oven-dried extrusa collected from January to April when forage was immature. No differences were observed in the fiber content of oven- and freeze-dried extrusa collected during the dry season (July-December). In trial 2, Dactylis glomerata, Medicago sativa, Acer grandidentatum and Purshia tridentata were hand-harvested and fed to esophageally fistulated sheep. Extrusa was either freeze-, air- or oven dried (40 degrees C) and analyzed for hemicellulose, cellulose, L and in vitro organic matter digestibility (IVOMD). Hemicellulose and L concentrations were significantly increased in air- and oven-dried forage for all plant species. Cellulose was least affected by method of drying. IVOMD was depressed most by oven- and air-drying in species containing phenolic compounds. When there were significant treatment by period interactions, method of drying was most critical early in the growing season. Results reemphasize that freeze-drying extrusa is an important preliminary step to obtain accurate nutritional information.
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  Coyote and bobcat responses to integrated ranch management practices in south Texas

  Bradley, L. C.; Fagre, D. B. (Society for Range Management, 1988-07-01)

  Predator use of La Copita Research Area, a 1,093-ha ranch in south Texas, was determined from 2,037 telemetry locations of 11 coyotes and 5 bobcats and numerous sightings of uncollared predators from May 1985 through September 1986. Predator home ranges were small, approximately 3 km2 for both species, and densities were high despite intensive management operations and high levels of human activity. Slight avoidance by predators of cattle and the short duration grazing system was indicated. Roads and fencelines did not defer predator home range establishment and were used as travel lanes and hunting areas. Predators with established home ranges were highly mobile and moved between ranches. Thus, on small ranches in south Texas, management practices conducted on 1 ranch will likely influence predator use of the neighboring ranches as well.
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  Cellulase vs rumen fluid for in vitro digestibility of mixed diets

  Dickerson, R. L.; Dahl, B.; Scott, G. (Society for Range Management, 1988-07-01)

  Nutritional studies frequently require an estimate of animal diet digestibility, but current in vitro techniques require costly fistulated animals, and variation in rumen fluid activity often results in poor precision. Hoping to find a more precise, yet cheaper, alternative, we examined estimates of organic matter digestibility of cattle diets based on a cellulase technique and compared them to those based on in vitro digestions. Diets were determined using microhistological analysis of native range forages, weeping lovegrass, and wheat pasture from May 1985 through May 1986. The 2 techniques offered estimates that were highly correlated (r = 0.91 to 0.94) when diets consisted of cool-season grasses and forbs. Digestibility estimates of diets by the 2 techniques for predominantly warm-season species on native range were less well correlated (r = 0.81 to 0.86). Agreement between the 2 techniques was relatively poor for mixed species diets from weeping lovegrass pastures (r = 0.48). We conclude that in vitro digestion using cellulase offers a promising approach for assessing diet quality, particularly with diets dominated by graminoids.
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  Cattle, vegetation, and economic responses to grazing systems and grazing pressure

  Hart, R. H.; Samuel, M. J.; Test, P. S.; Smith, M. A. (Society for Range Management, 1988-07-01)

  Manipulating stocking rate and duration of grazing is fundamental to range management. It has been claimed that rotation grazing systems will increase stocking capacity of range while maintaining or improving animal gains, range condition, and forage production. To test these claims, we compared continuous, 4-pasture rotationally deferred, and 8-paddock short-duration rotation grazing on mixed-grass range near Cheyenne, Wyo. from 1982 through 1987. Grazing pressures ranged from 19 to 81 steer-days per tonne of forage dry matter produced. Steers were weighed biweekly; forage production, utilization, and botanical composition were estimated by clipping; and basal cover was estimated by inclined point frame. Basal cover of litter and bare ground responded to stocking rate or grazing systems, but basal cover of vegetation was affected only by years. Steer average daily gain decreased as grazing pressure increased (r2=0.66); systems had no significant effect. The most profitable stocking rate at 1986-87 costs and prices was approximately 60 to 80% above SCS recommendations, but the increase in return was small and range conditions and forage production probably could not be maintained at this rate.

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