• Annual medic establishment and the potential for stand persistence in southern Arizona

      Brahim, K.; Smith, S. E. (Society for Range Management, 1993-01-01)
      Few perennial legumes have been successfully introduced into western North American rangelands receiving less than 250 mm annual precipitation. Winter annual legumes in the genus Medicago (medics) are native to add sites in North Africa and the Middle East and have been successfully introduced into arid and semiarid rangelands. The objective of this study was to evaluate the potential of establishing medics in areas of the southwestern U.S. receiving between 100 and 200 mm winter precipitation (November-May). Five medic accessions from 4 species (M. laciniata (L.) Miller, M. littoralis Rhode ex Loix. Delong., M. polymorpha L., M. truncatula Gaertn.) that could avoid drought were identified in a preliminary screening nursery in 1987-89. These accessions established and produced seed in 1989-90 in a field plot at Tucson, Ariz., with 125 mm winter precipitation. Less than 5% of all seed produced by these accessions germinated following summer precipitation. Plant re-establishment in the winter 1990-91 (181 mm precipitation) from pods produced in 1989-90 was observed for only 1 accession (M. truncatula 'Cyprus'). New plant re-establishment and seed production was observed in 1990-91 for an 5 accessions from seed produced in 1989-90 with supplemental irrigation (300 mm) in addition to precipitation. Failure to observe comparable establishment from seed produced without irrigation was attributed to the scarcity of germinable (permeable) seeds in the soil seed bank. Rapid maturing medics that exhibit breakdown of hardseededness by autumn appear to be well adapted to southern Arizona sites receiving as little as 110 mm winter precipitation. If such introductions are to be successful, initial seeding rates in excess of 115 pure live seeds/m2 may be necessary to develop a large soil seed bank.
    • Biodiversity of rangelands

      West, N. E. (Society for Range Management, 1993-01-01)
      Biodiversity is a multifaceted phenomenon involving the variety of organisms present, the genetic differences among them, and the communities, ecosystems, and landscape patterns in which they occur. Society will increasingly value biodiversity and influence the passage of laws and writing of regulations involving biodiversity which rangeland managers will have to abide by over the coming decades. Even private and developing world rangelands will be affected. While taxonomic knowledge of vertebrates and vascular plants and their abundance, rarity, and distribution, in the developed nations is generally adequate, the same cannot be said of the developing world. Furthermore, adequate knowledge of invertebrates, nonvascular plants, and microbes is deficient everywhere. Although the basis of variation at all higher levels, genetic variation within rangeland species, even the major ones, has barely been assessed. Obtaining statistically adequate data on populations of rare species that are small and secretive is well nigh impossible. We have many means of measuring community diversity, but all of them are value laden. That is, choice of variables to measure and how they are indexed betrays what we consider are important. We should be more forthright in stating to the users the biases of these methods. There are many other, more useful ways to describe community-level diversity besides the traditional focus on species. Ungulate grazing is an important process in many ecosystems. Thus, removal of grazing destabilizes some systems. Livestock grazing will actually increase the chances of survival of some species. Moderate livestock grazing can also enhance community and landscape-level diversity in many instances. Attention is now shifting from "charismatic" species to defensively managing larger tracts of land with habitat or ecosystems holding suites of sensitive species. Since some accelerated extinction of isolated populations and species is inevitable, we need to know which species and ecotypes are most valuable. Understanding of modular, guild, and functional group structure would also help us identify keystone or critical link species and better focus our attention on truly important tracts of land where they live. It is probably more important to sustain soils and ecosystem processes than any randomly selected species, especially if functionally redundant species can be identified. Similarly, not all introduced, alien, or exotic species are equal threats; it depends on how they fit into ecosystems. Sustainable development will depend on finding balance between use and protection, from range sites 10 landscapes, and even on a global basis.
    • Biological and physical factors influencing Acacia constricta and Prosopis velutina establishment in the Sonoran Desert

      Cox, J. R.; Alba-Avila, A.; Rice, R. W.; Cox, J. N. (Society for Range Management, 1993-01-01)
      Over the past century woody plants have increased in abundance on sites formerly occupied by grasslands in the Sonoran Desert. Woody plant invasion has been associated with a multitude of biological and physical factors. This study was conducted to determine temperature, soil, fire, rodent, and livestock effects on the germination and establishment of whitethorn acacia (Acacia constricta Benth.) and velvet mesquite (Prosopis velutina (Woot.) Sarg.). Optimum termination temperatures for both shrubs ranged from 26 to 31 degrees C, and seedling emergence was greatest from seed sown at 1 to 2 cm depths in sandy loam soil. Merriams kangaroo rats (Dipodomys merriami) fed seeds in the laboratory removed seed coats and planted embryos at 2 to 4 cm depths in a sandy loam soil. Prescribed fire killed 100% of seed placed on the soil surface but had no measurable effect on the germination of seed planted at 2 cm. After passage by sheep, about 6% of the A. constricta and 13% of the P. velutina seeds germinated while after passage by cattle, only 1% of the A. constricta and 3% of the P. velutina seed terminated. Embryo planting by rodents may improve survival efficiencies for these legunminous shrub seedlings, but seed consumption and passage by sheep and cattle appear to adversely affect seed germination. Dipodomys merriami, rather than domestic livestock, may be responsible for the spread of these shrubs in the Sonoran Desert.
    • Changes in rangeland pricing method during the inflation-deflation price cycle

      Rowan, R. C.; Workman, J. P. (Society for Range Management, 1993-01-01)
      Utah rangeland real estate underwent an inflation-deflation price cycle from 1975 through 1988. A total of 166 Utah land sales were analyzed to determine whether factors affecting rangeland prices changed during the price cycle. Regression analysis was used to test changes in method of pricing rangeland between the inflation phase (1975-81) and deflation phase (1982-87). The effects on sale price of parcel size (acres or hectares) and number of deeded animal unit months (AUMs) differed between the 2 time periods. Size of parcel sold significantly affected land price in the first time period, but not in the second. Conversely, the number of deeded AUMs did not significantly influence land price in the first time period, but did in the second. Thus rangeland tended to be priced per acre (hectare) during the inflation phase of the price cycle and per AUM of carrying capacity during the deflation phase. These results indicate that rangeland owners should try to maintain or improve range condition and carrying capacity to preserve real estate values during deflationary times.
    • Dependence of 3 Nebraska Sandhills warm-season grasses on vesicular-arbuscular mycorrhizae

      Brejda, J. J.; Yocom, D. H.; Moser, L. E.; Waller, S. S. (Society for Range Management, 1993-01-01)
      Vesicular-arbuscular mycorrhizae (VAM) are rare or absent in actively eroding soils of the Sandhills. The objective of this study was to determine if 3 major Sandhills warm-season grasses used in reseeding eroded Sandhills sites are highly mycorrhizal dependent, and evaluate the response of VAM at different phosphorus (P) levels. In 2 greenhouse experiments, sand bluestem [Andropogon gerardii var. paucipilus (Nash) Fern.], switchgrass (Panicum virgatum L.), and prairie sandreed [Calamovilfa longifolia (Hook) Scribn.] were grown in steam-sterilized sand in pots and inoculated with either indigenous Sandhills VAM, Glomus deserticola, or noninoculated. In the second experiment, VAM inoculated and control plants were treated with 5 P levels ranging from 5.4 to 27.0 mg P pot-1. Increasing levels of P fertilizer caused an initial increase, then dramatic decrease, in percentage colonization by Glomus deserticola but bad no effect on percentage colonization by indigenous Sandhills VAM. Mycorrhizal inoculated plants had a greater number of tillers, greater shoot weight, root weight, tissue P concentration and percentage P recovered, and a lower root/shoot ratio and P efficiency than noninoculated plants. Noninoculated sand bluestem had significantly lower shoot P concentration but greater P efficiency over all P levels thin any other grass-VAM treatment combination. Phosphorus fertilizer and VAM effects were often complementary at P levels up to 16.2 to 21.6 mg P pot-1, with no change or a decrease in plant responses at higher P levels. These 3 major Sandhills warm-season grasses were highly mycorrhizal dependent. Successful reestablishment of these on eroded sites in the Sandhills may be greatly improved if soil reinoculation with VAM occurred prior to revegetation.
    • Dynamics of vegetation along and adjacent to an ephemeral channel

      Smith, M. A.; Dodd, J. L.; Skinner, Q. D.; Rodgers, J. D. (Society for Range Management, 1993-01-01)
      Ephemeral channels may be greater contributors to nonpoint sediment loads than perennial channels because of their abundance and lower vegetative cover. This study examines above- and belowground standing crop responses of selected vegetation classes and density of shrubs to grazing use and yearly weather variation along an ephemeral stream in northcentral Wyoming. Aboveground biomass standing crop was determined yearly in channel, floodplain, and upland habitats in ungrazed and grazed pastures during the 4-year study. Belowground biomass and shrub densities were determined yearly in the channel habitat only. Perennial grass standing crop in channels did not respond to grazing but decreased up to 73% with decreases in frequency and amount of precipitation. In floodplains, perennial grasses were not responsive to grazing; annual grasses were twice as abundant in grazed pastures. Vegetation standing crop in uplands was not influenced by grazing. Over the study period in all pastures, standing crop of blue grama (Bouteloua gracilis (H.B.K.) Lag. ex Griffiths) declined 4 fold while cool-season grasses increased 5 fold. Shrub density did not increase as much in grazed as in ungrazed pastures. Root biomass of the channel decreased 23% in years with less precipitation but was greater by 24% on concave than convex bank types. Location on channels influenced root biomass but grazing did not. Lack of general negative grazing influences on vegetation suggest short periods (10 days) of grazing as used in this study represent a sustainable management alternative for grazing in the cold desert.
    • Effect of grazing strategies and pasture species on irrigated pasture beef production

      Nichols, J. T.; Sanson, D. W.; Myran, D. D. (Society for Range Management, 1993-01-01)
      Irrigated cool-season grasses can be used as complementary forages with other forage resources. Improved efficiency of animal production from irrigated pasture could increase their utility as a complementary forage. The factors of species composition, grazing management, irrigation, and fertilization all have the potential to affect efficiency of irrigated pasture production. Specific objectives of this study were: (1) to determine the effect of deferring irrigated pasture and restricting irrigation water and fertilization during mid-summer on pasture and livestock production; and (2) to evaluate different pasture stands for adaptability to different grazing strategies. Eight, adjacent 1.25-ha pastures were established as 2 replications of 2 different pasture stands grazed under 2 grazing management strategies. Pasture stands consisted of intermediate wheatgrass (Agropyron intermedium Host. Beauv.) as a monoculture (IWG) and a 4-species mixture (MIX) of orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), meadow bromegrass (Bromus biebersteinii R. & S.), and Garrison creeping foxtail (Alopercurus arundinaceus Poir.). Grazing treatments with yearling steers consisted of season-long grazing (SLG) and a graze-defer-graze (GDG) strategy. For the GDG pastures, 38% less fertilizer and 34% less irrigation water were applied, but animal days of grazing were reduced only 16% over the 3-year study. Animal weight gains were comparable between pasture types when considered over the entire grazing season but were higher for IWG early in the growing season and for MIX late in the season. Persistence of pasture stand was better for the MIX pastures than IWG pastures which were invaded by annual weeds after the first grazing season. Highest gains ha-1 were from the SLG pastures because of more days of grazing, but animal productivity was not proportionally reduced for the GDG strategy. The MIX pastures were suited for either grazing strategy.
    • Fee hunting in the Texas Trans Pecos area: A descriptive and economic analysis

      Butler, L. D.; Workman, J. P. (Society for Range Management, 1993-01-01)
      Previous studies of fee hunting have focused only on fee-hunting ranches with little consideration given to ranches that choose not to operate fee-hunting enterprises. Our study compares feed-hunting with non-fee-hunting ranches. The most important reasons given for engaging in fee hunting were increased income, trespass control, and prevention of nuisance requests for free hunts. The most important reason offered for choosing not to have fee hunting was to keep the ranch available for hunting by family and friends. The potential exists for a large expansion of private land fee hunting by current non-fee-hunting ranches. Ranchers with fee hunting were more likely to manage the grazing resources, wildlife population, and wildlife habitat than non-fee-hunting ranchers. The typical hunting enterprise in the Texas Trans Pecos ares provided a total annual net revenue of about 7,900. Average annual net grazing returns per livestock animal unit were smaller on fee-hunting ranches but fee-hunting revenue offset the difference. The fee-hunting enterprises also reduced risk by providing a second source of cash returns.
    • Grazing systems, pasture size, and cattle grazing behavior, distribution and gains

      Hart, R. H.; Bissio, J.; Samuel, M. J.; Waggoner, J. W. (Society for Range Management, 1993-01-01)
      Reduced pasture size and distance to water may be responsible for the alleged benefits of intensive time-controlled rotation grazing systems. We compared cattle gains, activity, distance traveled, and forage utilization on a time-controlled rotation system with eight 24-ha pastures, on two 24-ha pastures grazed continuously (season-long), and on a 207-ha pasture grazed continuously, all stocked at the same rate. Utilization on the 207-ha pasture, but not on the 24-ha pastures, declined with distance from water. At distances greater than 3 km from water in the 207-ha pasture, utilization was significantly less than on adjacent 24-ha pastures, at distances of 1.0 to 1.6 km from water. Cows on the 207-ha pasture travelled farther (6.1 km/day) than cows on the 24-ha rotation pastures (4.2 km/day), which traveled farther than cows on the 24-ha continuously grazed pastures (3.2 km/day). Grazing system, range site, slope, and weather had minimal effects on cow activity patterns. Gains of cows and calves were less on the 207-ha pasture (0.24 and 0.77 kg/day, respectively) than on the 24-ha rotation pastures or 24-ha continuously grazed pastures (0.42 and 0.89 kg/da, respectively), with no differences between the latter. Calculated "hoof action" on the rotation pastures was less than that demonstrated to increase seed burial and seedling emergence. Intensive rotation grazing systems are unlikely to benefit animal performance unless they reduce pasture size and distance to water below previous levels, decreasing travel distance and increasing uniformity of grazing.
    • Impacts of big game on private land in south-western Montana: landowner perceptions

      Lacey, J. R.; Jamtgaard, K.; Riggle, L.; Hayes, T. (Society for Range Management, 1993-01-01)
      Increasing populations of big game animals are a problem for private landowners in some parts of western North America. Influence of bit game costs, hunting-related income, noneconomic benefits, size of private land holding, and proportion of total income from agriculture upon landowner management goals as well as perception of damage to forage resources were studied in 1989-1990 using a mail survey of 858 randomly selected southwestern Montana landowners. They reported that elk (Cervus canadensis) populations increased, did not change, or decreased on 71%, 25%, or 4% of their private lands, respectively. Similar trends were reported for mule deer (Odocoileus hemionus), whitetail deer (Odocoileus virginia), and antelope (Antilocapra americana). More than 50% of the respondents thought that bit tame damaged forage and crop yields, while less than 2% of the respondents thought that bit game was beneficial to forage and crop yields. Big Same consumed a mean of 511 AUMs per private landowner, which contributed to the mean big game cost of 6,353 per landowner. Respondents desiring fewer elk, deer, and antelope outnumbered those desiring more by a 4-to-1 margin. As costs of big game increased and as dependency on agricultural income for livelihood increased, respondents desired fewer big game animals and perceived the impact of big game to be more harmful to forage and crop yields. Landowner attitudes toward big game were not significantly affected by economic returns from big game. Although owners with larger land holdings were more likely to allow hunters access to hunt big game, owners of large- and of small-sized ranches generally regarded big game populations similarly. Results from this survey should be useful in forming natural resource policy.
    • Interactions of pinyon and juniper trees with tebuthiuron applications at 2 matched reinvaded sites in Utah

      Van Pelt, N. S.; West, N. E. (Society for Range Management, 1993-01-01)
      Tebuthiuron [N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]N,N'-dimethylurea] controls small trees in regrown pinyon-juniper woodland chainings. Precise applications by hand minimize cost and damage to forage plants. Little information exists on the applicability of local trials to varying Intermountain sites slated for reinvestment. We conducted 2 balanced factorial experiments at well-separated sites in the Great Basin and Colorado Plateau. Four rates (0.12, 0.25, 0.50, and 0.75 gm a.i. per 130 dm3 crown volume) of tebuthiuron boluses were applied to tree stembase, mid-crown, or dripline placements. Four size classes (12-99, 100-299, 300-599, and 600-1099 dm3 crown volume) of Utah juniper [Juniperus osteosperma (Torr.) Little] and single needle (Pinus monophylla Torr. and Frem.), and Rocky Mountain (P. edulis Engelm.) pinyon trees were treated in September 1985. Defoliation and mortality levels were estimated 24 and 36 months following treatments. Both sites received highly similar amounts of herbicide and cumulative precipitation. Analysis of variance showed that the presence and strength of main effects and first order interactions was largely site-specific. Pinyon was more susceptible than juniper at tither site. Medium-sized and large saplings were apparently more readily defoliated than seedlings and small saplings. Dosage effects were generally nonlinear for both species. The highest, most rapid and most uniform defoliation and mortality of trees resulted from application of tebuthiuron at the stem bases. This placement option has strong operational advantages and minimizes damage to forage plants beneath trees.
    • Potential forage species for deer in the southern mixed prairie

      Schweitzer, S. H.; Bryant, F. C.; Wester, D. B. (Society for Range Management, 1993-01-01)
      Improving wildlife habitat through the introduction of nutritious forage species is a management tool that may be used to increase target populations such as deer. By increasing deer numbers the potential of leasing hunting rights on private land is improved. Our objectives were to evaluate and compare establishment and production of 2 browse species and to determine the production and nutritional quality among 6 forb species in range-land conditions. Browse species were littleleaf lead-tree (Leucaena retusa Gray) and four-wing saltbush (Atriplex canescens (Pursh) Nutt.). Forb species were 'Cody' alfalfa (Medicago sativa L.), 'Renumex' sainfoin (Onobrychis viciifolia Scop.), 'Howard' subterranean clover (Trifolium subterraneum L.), 'Nungarin' subterranean (T. subterraneum L.), 'Eldorado' Englemann daisy (Engelmannia pinnatifida Nutt.), 'Sabine' Illinois bundleflower (Desmanthus illinoensis (Michx.) MacM.), and 'Plateau' awnless bush sunflower (Simsia calva (Engelm. & Gray) Gray). Establishment for littleleaf lead-tree was 21%. Successful four-wing saltbush plants produced a greater volume (m3) of plant material than littleleaf lead-tree. Littleleaf lead-tree leaf material contained crude protein (CP) values from 11.6 to 16.9%. Of the cool-season forbs, alfalfa, and sainfoin produced the most above-ground phytomass at 23.6 and 22.6 g/m of planted row, respectively. The subclovers produced intermediate amounts of phytomass while Engelmann daisy produced negligible amounts at phytomass of 4.2 g/m of planted row. Warm-season forages, awnless bush sunflower, and Illinois bundleflower produced an average of 115.1 and 120.2 g/m of planted row, respectively. Seasonal CP means were greatest for alfalfa (16.5%) and awnless bush sunflower (16.1%). Our results suggest that littleleaf lead-tree, awnless bush sunflower, and Illinois bundleflower would supply adequate supplemental forage from summer to fall; subterranean clovers, alfalfa, and sainfoin would provide forage from winter through spring. Four-wing saltbush could provide forage year-round.
    • Private forest landowner's perceptions of forest grazing in Washington state

      Hardesty, L. H.; Lawrence, J. H.; Gill, S. J.; Chapman, R. C. (Society for Range Management, 1993-01-01)
      Nonindustrial private forest landowners (NIPF) control 21.4% of Washington's commercial forestland, much of which produces forage. Resident NIPF owners in 3 regions in the state were surveyed to determine their perceptions of forest grazing. Thirty-nine percent of the respondents grazed livestock on forestland they leased or owned, and grazing was perceived by practitioners to contribute significantly to household income. Nonincome-related motivations for owning and managing land were also significant: passing land on to children, keeping it 'natural', conservation, aesthetics, and as a current or future homesite. In western Washington, some forest grazing occurred year round while in eastern Washington it was all seasonal. Cow/calf pairs were the most commonly grazed livestock. The median size forestland parcel owned by forest grazers was 47 ha versus 24 ha for nongrazers. Leasing additional land increased the likelihood of forest grazing. Significant opportunities exist to improve both the condition and productivity of forested ranges. Achieving this requires a clear understanding of landowner's objectives and beliefs. Data are needed to evaluate landowner's perceptions that forest grazing has both economic and amenity benefits.
    • Technical Notes: Double sampling revisited

      Reich, R. M.; Bonham, C. D.; Remington, K. K. (Society for Range Management, 1993-01-01)
      The decision to use double sampling with a regression or ratio estimator is not a simple task. This study was conducted to determine whether a ratio or regression estimator should be used to estimate aboveground biomass of stands dominated by blue grama (Bouteloua gracilis (H.B.K.) Lag ex Steud.) in eastern Colorado. One hundred 0.25-m-1 circular plots were systematically located in a homogeneous stand of blue grama, and on each plot biomass was estimated visually and then clipped. Three methods (classical, jackknife, and bootstrap) of estimating the variance for double sampling with regression and ratio estimator were compared in a simulation study using sample sizes 10, 20, 30, 40, and 50 clipped plots. The ratio estimator consistently had smaller bias and should be used for estimating average clipped weight of blue grama. For n = 10 clipped plots, the jackknife variance estimator is recommended for constructing confidence intervals. For n greater than or equal to 20 clipped plots, the classical variance estimate should be used to obtain reliable estimates of the population variance and in estimating confidence intervals.
    • Thin layer measurement of soil bulk density

      Frasier, G. W.; Keiser, J. (Society for Range Management, 1993-01-01)
      Measurement of soil bulk densities is difficult if there are gravel, stones, or other materials present in the soil profile. A technique is offered for estimating the soil bulk density in thin layers (1.0 cm) in loose, nonuniform soils with low moisture levels. The technique consists of the removal of the soil in shallow layers. As each layer is removed, the hole is filled with a molten paraffin wax to obtain a casting of the excavated volume. Measured bulk densities values using this procedure compare well to results obtained with other techniques.