• Yield and Digestibility of Old World Bluestem Grasses as Affected by Cultivar, Plant Part, and Maturity

      Dabo, S. M.; Taliaferro, C. M.; Coleman, S. W.; Horn, F. P.; Claypool, P. L. (Society for Range Management, 1987-01-01)
      Old World bluestems (Bothriochloa spp.) have been used in the U.S. for over 60 years but few data are available on effects of management or cultivar differences for forage yield and quality. Field experiments were conducted on a Kirkland silt loam (Uderic Paleustoll) soil for 2 years (1982-83), in order to assess the yield and quality of 4 such cultivars as affected by maturation and plant part. The experimental design was a split-split plot, in a randomized complete block, with 4 replications, 4 cultivars ('Caucasian', 'Ganada', 'Plains', 'WW Spar'), 10 harvest dates, and 3 plant parts (whole plant, stem, and leaf). Cultivars were main plots; harvest dates and plant parts were sub and sub-sub plots, respectively. Response variables were dry matter yield (DMY), in vitro dry matter disappearance (IVDMD), leaf to stem ratio (L/S), and in vitro digestible dry matter yield (IVDDMY). Ganada consistently had the lowest leaf, stem, and whole plant DMY and IVDDMY. Caucasian had higher leaf, stem, and whole plant DMY and IVDDMY than Plains and WW-Spar in 1983, but the DMY and IVDDMY of these cultivars were similar in 1982. Quadratic and linear equations were satisfactorily fit to the DMY and IVDDMY data in 1982 and 1983, respectively. The IVDMD in whole plant samples decreased at average rates of 4.2 and $5.5 g kg ha-1 daily in 1982 and 1983, respectively, during harvest week one. Among cultivars, Caucasian had the highest rate of decline and Ganada the lowest. The decline was quadratic in nature and faster in stem fractions. Cultivar IVDMD differences were consistent over plant parts. Ganada and Caucasian had the highest and lowest IVDMD concentrations, respectively. Plains and WW-Spar had IVDMD values of similar magnitude and intermediate to those of Ganada and Caucasian. Cultivar leaf to stem ratios were similar in 1982 but different in 1983 with Plains and Caucasian having higher L/S ratios than Ganada and WW-Spar. For these cultivars leafiness was a poor indicator of digestibility.
    • Wet-Dry Cycle Effects on Warm-Season Grass Seedling Establishment

      Frasier, G. W.; Cox, J. R.; Woolhiser, D. A. (Society for Range Management, 1987-01-01)
      A series of 14-day field experiments were conducted to evaluate seedling establishment characteristics of Bouteloua, Erogrostis, and Panicum grass species with controlled wet-dry watering combinations. The objective of the study was to validate previously published greenhouse data of Frasier et al. (1985) on the effects of the first wet-dry watering sequence following planting on seedling emergence and survival. Seedling survival numbers were different between the field and greenhouse experiments but the same general responses to watering sequences were measured. With short wet periods (2 days), seeds generally did not germinate but survived the subsequent dry period as viable seeds. Most seeds germinated with 5 wet days and produced seedlings that were able to survive drought periods of 5 to 7 days. Fewer seedlings survived with 3 days wet than with either 2 or 5 days wet. High rates of soil moisture evaporation in a spring field experiment made it difficult to maintain adequate soil moisture for seed germination, and seeds which germinated failed to produce seedlings. Seedlings were successfully established in 2 experiments conducted later in the summer following the onset of summer rains, which increased the relative humidity and reduced the rate of soil moisture evaporation. This effect was verified in a greenhouse study. In both the greenhouse and field experiments, seedlings were established when the relative humidity exceeded 50% for over one-half of the time during the initial wet-dry period.
    • The Woody Vegetation of Eastern Senegal

      Dickie, A.; Pieper, R. D.; Dickey, J. R. (Society for Range Management, 1987-01-01)
      The woody component of the vegetation of eastern Senegal was sampled using the point-centered quarter method. Data were evaluated using cluster, principal component, and multiple discriminant analysis (MDA) techniques. Sites were grouped into 8 ecologically significant groups. Six of these groups were considered woodland lateritic sites, and 2 drainage sediment sites. Species of the genus Combretum dominated all sites. The effect of livestock grazing on the botanical composition was inferred through the use of 4 environmental variables as discriminant factors in MDA. A floristic record of species composition and guidelines for management are embodied in the results of the analyses.
    • Succession of Pinyon-Juniper Communities After Mechanical Disturbance in Southcentral New Mexico

      Schott, M. R.; Pieper, R. D. (Society for Range Management, 1987-01-01)
      Principal component analysis (PCA) was used to interpret secondary succession of pinyon-juniper stands after cabling or bulldozing. Soil types were used to separate 93 sample units into 3 groupings. A PCA was run on 2 of the groupings. Groups of sample units were defined as community types for each ordination. Stepwise discriminant analysis using environmental variables was used to assist in delineation of community types. Species that contributed the most to the first 3 principal components were compared among community types for each ordination using an analysis of variance and a comparison of the least squares means. Grasses on the deeper soils usually increased after cabling, but after 25 years they had declined to near pretreatment levels. Wavyleaf oak (Quercus undulata Torr.) increased after cabling, and on the older cablings it had reached higher cover values than on the other community types. Pinyon and juniper response appeared to be dependent on density and size of trees before cabling. If the stand was near climax before cabling, pinyons rapidly became dominant on the site. If it was seral, there would be more junipers, but their slow growth and the time they require for maturation required more time before they dominated the site. The successional pattern following cabling on relatively deep soils is similar to what was found after fire, but it occurs faster. Cover of grasses and shrubs increased more on rock-free soils compared to sites treated similarly but with rock. The ordinations indicated that succession in pinyon-juniper communities is directional and leads towards climax with a decrease in variability among sites.
    • Shrub Litter Production in a Sagebrush-Steppe Ecosystem: Rodent Population Cycles as a Regulating Factor

      Parmenter, R. R.; Mesch, M. R.; MacMahon, MacMahon. J. A. (Society for Range Management, 1987-01-01)
      This study examines the impact of long-tailed vole (Microtus longicaudus) and deer mouse (Peromyscus maniculatus) population changes and their feeding behavior on shrub populations and the resulting litter production in a shrub-steppe ecosystem in southwestern Wyoming. Rodent populations were monitored on 3 replicate plots over a 3-yr period. Populations peaked in autumn 1983 and declined to lower levels in 1984-86. Damage to shrubs (in the form of bark-stripping and girdling) was observed after the winter of 1983-84, but not after the winters of 1984-85 and 1985-86. We assessed damage to shrubs on 4 sites. Extent of damage, mortality, and biomass-to-litter transformations were quantified. We found that: (1) 21% of all shrubs and 28% of the big sagebrush (Artemisia tridentata) sustained rodent damage; (2) 1% of all shrubs were killed as a result of girdling; (3) mean biomass lost from shrubs that suffered damage was 36%; (4) total aboveground biomass loss occurring on big sagebrush was 231 kg/ha or 4% of the standing crop. These results indicate that rodents feeding on big sagebrush can periodically increase annual rates of litter production by as much as 69% above "normal." Rodents in the sagebrush-steppe ultimately influence ecosystem-level nutrient cycles by accelerating shrub litter production, and may affect plant species composition via feeding-induced shrub mortality.
    • Seasonal Diets of Camels, Cattle, Sheep, and Goats in a Common Range in Eastern Africa

      Migongo-Bake, W.; Hansen, R. M. (Society for Range Management, 1987-01-01)
      Although there have been several reports on the food habits of domestic herbivores in various semiarid regions of the world, there has been no previous report on the partitioning of forage resources by camels (Camelus dromedarius) and sheep (Ovis aries), goats (Capra hircus) and cattle (Bos indicus) using a common range. In the semiarid region of northern Kenya, the seasonal exploitation by these herbivores resulting from herding by the nomadic Rendille pastoralists makes the system for management of these rangelands very complex. Information on the food habits of animals utilizing a common range is important in offering a basis for assessing the usefulness of the range components to the animals. Consequently, food habits information becomes an important tool in making management decisions. Camels were predominantly browsers while cattle were predominantly grazers. Sheep and goats were intermediate feeders. Cattle browsed most during the 'green' season when the browse shoots were most abundant and easiest for their large mouth parts to harvest. Camels grazed most during the very dry season when most trees and shrubs had shed their leaves. The observed variations in food habits among the 4 herbivores suggest that they may require different management to obtain optimum production.
    • Relationship of Saltbush Species To Soil Chemical Properties

      Hodgkinson, H. S. (Society for Range Management, 1987-01-01)
      The relationship of pure stands of 6 saltbush species to sodium adsorption ratio, electrical conductivity, and alkalinity are documented. The data gathered were obtained while correlating soils to range sites for National Cooperative Soil Surveys. Soil scientists gathered detailed soil information and obtained lab data. Range conservationists correlated the saltbush species to specific soils and by using lab data made a direct relationship to pure saltbush stands. Species ranked from highest to lowest adaptability to SAR, EC, and pH are: mat saltbush (Atriplex corrugata S. Wats.), mound saltbush (A. obovata Moq.), Castle Valley clover (A. cuneata A. Nels.), sickle saltbush (A. falcata (M.E. Jones) Standl.), shadscale (A. confertifolia (Torr. & Frem.) S. Wats.) and fourwing saltbush (A. canescens (Pursh) Nutt.). By knowing the SAR, EC, and pH tolerances of these 6 species, interpretations for inventorying, rating plant community potentials, and applying range improvements will be achieved with greater success.
    • Recovery of Compacted Soil on Pastures Used for Winter Cattle Feeding

      Stephenson, G. R.; Veigel, A. (Society for Range Management, 1987-01-01)
      Soil bulk density measurements were taken from pastures used for winter feeding to determine the effects of different stocking rates on soil compaction and recovery. Samples were taken from paired ungrazed (control) pastures, normally grazed pastures (10 head per ha), and pastures grazed 4 times normal. Results show that significant differences occur in soil bulk density with increased stocking rates, and that 2 growing seasons with protection from grazing and trampling are insufficient time for complete recovery.
    • Plant Water Potential for Shrubs in Argentina

      Pelaez, D. V.; Bóo, R. M. (Society for Range Management, 1987-01-01)
      Water relations of Prosopis flexuosa, P. caldenia, Condalia microphylla, Larrea divaricata, and Chuquiraga erinacea, 5 shrub species of a temperate semiarid region of Argentina were analyzed by periodic measurement of soil water potential, plant water potential, and air humidity. Water potential in all species showed recovery during the night, the values obtained early in the morning being higher (less negative) than those recorded in the afternoon. Plant water potential showed higher correlation with soil water potential than with the other environmental variables considered. Results indicate that these species have the capacity to adjust to summer drought conditions.
    • Livestock and Wildlife Population Distributions in Relation to Aridity and Human Population in Kenya

      Peden, D. G. (Society for Range Management, 1987-01-01)
      In response to the demand for inventories of livestock and wildlife populations in Kenya, animal censuses were completed during the period 1977 to 1983 using low level, systematic reconnaissance flights. Total stocking levels, ratios of livestock to wildlife, and ratios of cattle to sheep and goats were estimated in terms of tropial animal units for each administrative district. The total stocking level, the ratio of cattle to sheep and goats, and human population density were negatively correlated to aridity. In the driest districts, livestock were low in absolute density but their per capita importance to the human population was high.
    • Influence of Clipping Frequency on Herbage Yield and Nutrient Content of Tall Wheatgrass

      Undersander, D. J.; Naylor, C. H. (Society for Range Management, 1987-01-01)
      Grazing or cutting frequency has been shown to affect yield and quality of many grasses, but similar data are lacking for tall wheatgrass [Agropyron elongatum (Host) Beauv. 'Jose']. The objective of the research was to determine the effect of frequency of clipping on tall wheatgrass. The study was conducted at the Texas Agricultural Experiment Station at Bushland, Texas, in 1979, 1980, 1981, and 1984 on a Pullman clay loam soil. Plots were irrigated as needed from February to the end of the growing season and fertilized with 112kg N/ha every 2 months for maximum yield and clipped either every week, 2 weeks, of 4 weeks at a 5-cm stubble height. Herbage yield was highest from spring harvests and declined over summer as is typical of cool-season grasses. The plots that were clipped every 4 weeks produced greater herbage yields than plots that were clipped 1 or 2 weeks, suggesting that rotational grazing would increase productivity. The nutrient content of the herbage was highest during summer when herbage yield was lowest. Plants clipped less frequently had the highest concentrations of phosphorus and potassium and the lowest concentrations of calcium and magnesium. The greatest differences in nutrient content occurred among years, which emphasizes the importance of continual herbage analysis to optimize mineral supplementation of grazing cattle.
    • Grazing System Influences on Cattle Performance on Mountain Range

      Holechek, J. L.; Berry, T. J.; Vavra, M. (Society for Range Management, 1987-01-01)
      A 5-year study was conducted to evaluate the influences of rest-rotation, deferred-rotation, and season-long grazing systems on cattle diet botanical composition and quality and weight gains on mountain rangeland in northeastern Oregon. The grazing season in each year lasted from 20 June to 10 October. Esophageally fistulated animals were used to evaluate diet quality and botanical composition. All study pastures included forest, grassland, and meadow vegetation types. Each pasture had a north and southfacing slope divided by a riparian zone and creek. The grazing pressure for each system was similar. Grazing intensity was the same as National Forest Allotments in the area. There were no differences (P>.05) in weight gains among the 3 systems when data were pooled across years. Crude protein, in vitro organic matter digestibility, and acid detergent fiber percentages in fistula samples did not differ (P>.05) among systems for any year of study or for data pooled across years. Mid-season movements of cattle under the rest-rotation system had little influence on their diet and performance compared with cattle under the season-long system. Key forages in cattle diets were Idaho fescue (Festuca idahoensis), bluebunch wheatgrass (Agropyron spicatum), and common snowberry (Symphoricarpos albus). Cattle diet botanical composition under the 3 grazing systems did not differ (P>.05).
    • Grazing Effects on Water Relations of Caucasian Bluestem

      Svejcar, T.; Christiansen, S. (Society for Range Management, 1987-01-01)
      Caucasian bluestem [Bothriochloa caucasica (Trin.) C.E. Hubb.] is a warm-season grass introduced from Eurasia that is currently used for reseeding rangelands in the southern Great Plains. Although this species is thought to be grazing tolerant, no specific information is available concerning its response to grazing. This study was conducted to evaluate the effect of 2 levels of grazing on xylem water potential and total leaf conductance (gT) of Caucasian bluestem. During the grazing period (mid May to mid September) diurnal xylem water potential and gT measurements were made on 3 days in 1983 and 1984, and afternoon measurements were taken at weekly intervals in 1984. Soil moisture at 15, 45, and 75 cm depths was monitored in 1984. Heavily grazed plants exhibited consistently higher (less negative) xylem water potential, and generally higher gT than lightly grazed plants. Averaged over the season, heavy grazing increased mean afternoon xylem water potential and gT by 28 and 76%, respectively, compared to light grazing. Soil moisture was conserved with heavy grazing; treatment differences were greatest during July, which is generally the driest summer month in central Oklahoma. Thus, for Caucasian bluestem, leaves from heavily grazed swards were under less water stress than leaves from lightly grazed swards.
    • Foraging Ecology of Bison in Aspen Boreal Habitats

      Hudson, R. J.; Frank, S. (Society for Range Management, 1987-01-01)
      Studies on several wild and domestic ungulates suggest that large grazers attain higher maximum forage intake rates but require relatively higher forage biomass to do so. In this study, forage intake rates and feeding times of North America's largest wild grazer, the bison (Bison bison), were related to forage biomass during summer and autumn in aspen boreal forest habitats. Irrespective of season, maximum feeding rates of 68 g/min declined by 50% as forage biomass was reduced to 780 kg/ha. This reduction was due primarily to smaller bite sizes. However, bison compensated by increasing cropping bite rates to more than 60 bites/min on heavily grazed swards. Grazing times increased from 9 h/day in summer to 11 h/day in autumn, offsetting slight decreases in average foraging efficiency. During summer, a greater proportion of grazing occurred at night. Upland meadows were preferred habitats for grazing despite relatively low pasture biomass and potential dry matter intake rates.
    • Elk, Mule Deer, and Cattle Habitats in Central Arizona

      Wallace, M. C.; Krausman, P. R. (Society for Range Management, 1987-01-01)
      Elk (Cervus elaphus) and mule deer (Odocoileus hemionus) distribution and use of habitats shared with cattle (Bos spp.) on a ponderosa pine (Pinus ponderosa)-bunchgrass range in central Arizona was examined. Cattle were removed from the range in 1961 and reintroduced in 1980. A 48-km survey route was driven through pastures containing cattle and through pastures without cattle to document the effects cattle had on native ungulates during the summers of 1981 and 1982. Location and number of elk, mule deer, and cattle observed along the route were recorded. Locations where animals were seen were used as sample sites to measure habitat variables: forest overstory, plant species composition, elevation, slope, exposure, and distance to water, fencing, meadow, cover, and draws. Distribution of elk and mule deer and habitats used by elk changed when cattle were introduced to the range. Significantly (P<0.05) fewer elk and mule deer were seen on pastures grazed by cattle than on pastures not grazed by cattle. Use of habitats by elk shifted from open mesic and silviculturally disturbed areas to more closed forest after cattle introduced. Use of habitats by deer was not altered when cattle were introduced to the range.
    • Dietary Relationships Among Feral Horses, Cattle, and Pronghorn in Southeastern Oregon

      McInnis, M. L.; Vavra, M. (Society for Range Management, 1987-01-01)
      Management of sympatric ungulates on multiple use lands requires knowledge of how species exploit resources available to them. We examined seasonal food habits, dietary overlap, and dietary quality of sympatric feral horses (Equus caballus), cattle (Bos taurus),, and pronghorn (Antilocapra americana) in south-eastern Oregon from May 1979 through March 1981. Seasonal diets of each ungulate species were determined by microhistological analysis of feces. At least 88% of the mean annual diets of horses and cattle consisted of grasses. Principal species consumed by these ungulates were bottlebrush squirreltail (Sitanion hystrix (Nutt.) J.G.Smith), bearded bluebunch wheatgrass (Agropyron spicatum (Pursh) Scribn. & Smith), and Thurber needlegrass (Stipa thurberiana Piper). Because dietary overlap between horses and cattle was high each season (62-78%), we concluded a strong potential existed for exploitative competition under conditions of limited forage availability. Pronghorn diets consisted largely of woody sagebrush (Artemisia) species in fall and winter, and a mixture of forbs in spring and summer. Dietary overlap between horses and pronghorn varied from 7% (summer) to 26% (winter). Overlap between cattle and pronghorn varied from 8% (winter) to 25% (spring). These lower levels of overlap indicate a wider buffer between noncompetitive coexistence and exploitative competition. Pronghorn generally selected diets containing higher levels of crude protein (CP) and lower levels of acid-detergent fiber (ADF) than horses or cattle. We observed few differences in seasonal dietary quality between horses and cattle.
    • Crude Terpenoid Influence on Mule Deer Preference for Sagebrush

      Personius, T. L.; Wambolt, C. L.; Stephens, J. R.; Kelsey, R. G. (Society for Range Management, 1987-01-01)
      Samples of current year's growth of leaves and stems were collected in February 1983 from basin big sagebrush (Artemisia tridentata Nutt. tridentata), Wyoming big sagebrush (A.t. wyomingensis Beetle and Young), mountain big sagebrush (A.t. vaseyana [Rydb.] Beetle), and black sagebrush (A. nova Nels.) on a mule deer (Odocoileus hemionus hemionus) winter range near Gardiner, Montana. Samples were from both lightly and heavily used plants (form classes) within each taxon. Crude terpenoids were separated into 3 groups: headspace vapors, volatile, and nonvolatile crude terpenoids. Compounds in each group are thought to stimulate the sensory organs of mule deer. Individual compounds were identified and quantified for comparison with preference ranks among taxa and between utilization form classes. Seven compounds were selected by discriminant analysis as indicators among the 4 taxa, with methacrolein + ethanol, ρ-cymene, and the sesquiterpene lactones the most probable preference determinants. Seven other compounds were found useful for separating plants within taxa into form classes. Chemical differences between the 2 form classes, however, were less distinguishable than were those among the 4 taxa.
    • C3/C4 Production Shift on Seasonal Burns: Northern Mixed Prairie

      Steuter, A. A. (Society for Range Management, 1987-01-01)
      This study investigates the potential of fire to manipulate the balance of C3 (cool-season) and C4 (warm-season) herbage in 2 northern Mixed Prairie communities. The xeric high prairie community and mesic low prairie community were chosen to represent regional moisture extremes. Treatments included dormant spring burn, mid-summer burn, dormant fall burn, and untreated. The high prairie community appears to be a C3-dominant type. All 3 burn treatments increased the C3 herbage fraction relative to untreated sites. Total production, however, was unaffected by treatment. The C3/ C4 ratio of high prairie communities appears to be the result of long-term adaptation rather than short-term adjustments to fire or weather effects. Spring burning shifted low prairie communities towards C4 herbage relative to other treatments. This was due to an increase in C4 herbage (and total) rather than to a decrease in C3 herbage. The C3/C4 ratio of low prairie communities did appear to respond to short-term adjustments in moisture, temperature, and light caused by the spring burn. The response of low prairie C3/C4 ratios to mid-summer and dormant fall burns appeared to be related to phenological and indirect weather effects rather than to changes in site microclimate caused by the fires.
    • An Evaluation of Range Condition on One Range Site in the Andes of Central Peru

      Wilcox, B. P.; Bryant, F. C.; Fraga, V. B. (Society for Range Management, 1987-01-01)
      Little published information is available on the vegetation or its response to grazing in the high elevation (3,900-4,800m) grasslands of the Andes, known as the puna. The objective of this study was to evaluate grazing-induced vegetation changes on a major range site in the puna. Basal cover and diversity were compared on (1) rangelands managed by a cooperative of land holders (moderate grazing); (2) communal grazing land (heavy grazing); and (3) sacrifice or holding pastures (very heavy grazing). Basal cover was determined using point transects. With increased grazing pressure standing height of the vegetation was greatly reduced as was vegetation basal cover. Total cover of grasses was reduced while forb cover increased. Ability of a species to grow close to the soil surface probably enabled it to tolerate very heavy grazing. Species diversity as determined by Simpson's D, Shannon-Weaver's H', and species richness was highest on the community lands.