Now showing items 1-20 of 107

    • Understory dynamics in cut and uncut western juniper woodlands

      Bates, J. D.; Miller, R. F.; Svejcar, T. J. (Society for Range Management, 2000-01-01)
      Expansion of western juniper (Juniperus occidentalis spp. occidentalis Hook.) woodlands in the sagebrush steppe has the potential to change composition, structure, and productivity of understory vegetation. Cutting of western juniper woodland can potentially restore understory productivity and diversity. Understory responses were assessed after cutting a juniper woodland in southeastern Oregon in 1991. The experimental design was a randomized complete block with eight, 0.8 ha sized blocks and 2 treatments, cut and uncut woodland. Understory cover, density, diversity, biomass, and nitrogen (N) status were compared between treatments after cutting Plants were separated into S functional groups: bluegrass (Poa spp.), perennial bunchgrass, perennial forte, annual forte, and annual grass. Cutting of juniper reduced below ground interference for soil water and N. Leaf water potentials were less negative (p < 0.01) and understory N concentration and biomass N were greater (p < 0.05) in the cut versus woodland treatment. Cutting of juniper trees was effective in increasing total understory biomass, cover, and diversity. In the second year post-cutting total understory biomass and N uptake were nearly 9 times greater in cut versus woodland treatments. Perennial plant basal cover was 3 times greater and plant diversity was 1.6 times greater in the cut versus woodland treatments. In the cut, perennial bunchgrass density increased by 1 plant m-2 in both duff and interspace zones and bluegrass increased by 3 plants m-2 in interspaces. Plant succession was dominated by pants present on the site prior to juniper cutting suggesting that pre-treatment floristics may be useful in predicting early successional understory response. Early plant dynamics on this site supports the multiple entrance point model of succession as perennial grasses and bluegrass made up the majority of total herbaceous biomass and cover.
    • Seedbank diversity in grazing lands of the Northeast United States

      Tracy, B. F.; Sanderson, M. A. (Society for Range Management, 2000-01-01)
      We evaluated the species composition of soil seed banks from 9 farms (36 pastures total) located in the northeast United States. Our objective was to quantify the soil seed bank composition of pastures managed for intensive grazing and hay production. Seeds from pasture soils were allowed to germinate in a greenhouse under natural light conditions. Seedlings were identified as they germinated, and the experiment was concluded after 4 months. Germinable seed was dominated by annual (40%) and perennial (23%) forbes most of which contributed little useful forage for cattle. Perennial grasses (11%), except for bluegrass (Poa pratensis L.), were largely absent from the terminable seed bank, while legumes (19%) were more abundant. Seed bank species composition showed little similarity (44%) to the existing vegetation. Exceptions were bluegrass, white clover (Trifolium repens L.), and common dandelion (Taraxacum officinale Weber ex Wiggers). These species were abundant in both the germinable seed bank and existing vegetation on most pastures. Overall, our study suggests that seed banks in these northeast pastures support abundant white clover and bluegrass seed, both of which are important forages for cattle. Soil seed banks, however, will not supply a diverse assemblage of useful forages. If a manager seeks to establish diverse, mixed-species pasture, then re-seeding pastures with desired mixes may be the best option.
    • Sagebrush ingestion by lambs: Effects of experience and macronutrients

      Burritt, E. A.; Banner, R. E.; Provenza, F. D. (Society for Range Management, 2000-01-01)
      We investigated how experience early in life and macronutrient content of the diet influenced intake of mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana (Rydb.) Beetle) by sheep. In the first part of our study, 2-month-old lambs were exposed as a group for 2 mo to a 70% barley-30% soybean meal ration (300 g/hd/day) that contained increasing amounts sagebrush (1 to 20%). Control lambs received grain without sagebrush. All lambs had access to alfalfa hay and pellets ad libitum. When lambs were tested at 6 months of age, prior exposure had no effect on sagebrush consumption after the first 4 days of the trial. When sagebrush comprised 20% of an alfalfa/barley ration, lambs ate the sagebrush ration readily even when a nutritious alternative was offered indicating the flavor of sagebrush did not prevent lambs from feeding. Increasing the amount of sagebrush in the ration from 50% to 75% resulted in lambs eating less of the barley/sagebrush ration, but daily intake of sagebrush remained constant throughout the 4 day trial, presumably because toxins (terpenes) limited intake of sagebrush. In the second part of our study, lambs experienced with sagebrush were fed 250 g/hd/day of barley, and nutritional status was varied by offering alfalfa pellets at 33% or 80% of ad libitum (1.2 and 2.7 times maintenance, respectively) to determine if dietary energy levels affected intake of sagebrush. Each day lambs received a 50/50 sagebrush/barley supplement ad libitum for 1 hour. Lambs fed at 33% of ad libitum consumed more of the sagebrush/barley supplement than lambs fed at 80% of ad libitum. Thus, additional energy did not enable lambs to consume more sagebrush. In the last trial, lambs in both treatments were fed a basal ration of alfalfa pellets at 50% of ad libitum. Each morning for 1 hour, lambs were offered macronutrient supplements containing either 50% barley/50% sagebrush (high energy) or 25% barley/25% soybean meal/50% sagebrush (high energy and protein). Lambs consumed the same amount of sagebrush regardless of supplement. Thus, supplemental protein did not improve sagebrush consumption. We conclude lambs readily ingested a high-energy ration containing sagebrush, regardless of exposure early in life, suggesting toxins, not flavor, control intake of sagebrush. Further, supplementing lambs with energy or protein failed to improve intake of sagebrush, which suggests these macronutrients did not enhance detoxification of sagebrush.
    • Response of 2 semiarid grasslands to cool-season prescribed fire

      White, C. S.; Loftin, S. R. (Society for Range Management, 2000-01-01)
      Woody perennials have invaded semiarid grasslands throughout the Southwestern United States. This invasion was coupled with decreased grass cover and increased runoff and soil erosion. Fire, which was a natural force that shaped and maintained the grasslands, is a management tool that may aid in restoring and maintaining grass cover. However, fire also poses the risk of increasing erosion and further soil degradation because protection afforded by vegetation is reduced immediately after the fire. Using a randomized block study design, this study measured vegetation cover, soil potentially mineralizable N, and erosion associated with the first application of prescribed fire on 2 semiarid grasslands. The potential for adverse effects from these fires was great because the fires occurred at the beginning of a drought period. However, the effects of the burn were minor relative to the effects of the drought, which caused the greatest change. Grass cover on the burn plots was nearly equal to grass cover on the controls 1 year after the fire. After 2 growing seasons, grass cover was equal on the control and burn plots. Potentially mineralizable soil N and sediment transport were similar on the control and burned plots during the 2 years following the fire. Thus, prescribed fire for reducing the cover of woody perennials may not increase the risk of site degradation over that caused by drought and weather fluctuations.
    • Reassessment of revegetation strategies for Kaho'olawe Island, Hawai'i

      Ziegler, A. D.; Warren, S. D.; Perry, J. L.; Giambelluca, T. W. (Society for Range Management, 2000-01-01)
      This work investigates 2 US Army Construction Engineering Research Laboratory revegetation experiment sites (Phase I and II) on Kaho'olawe Island, Hawai'i (USA) to determine the long-term success of several revegetation strategies and to identify species that are best suited for future restoration activities in the highly eroded central plateau region of the island. Only the Phase I treatments receiving the highest rates of phosphorus and nitrogen fertilizer and the Phase II strategy (moderately high fertilization and landscaping) produced enough cover to begin providing protection from erosion processes. Buffelgrass (Cenchrus ciliaris L.), glycine (Neonotonia wightii (Wight Arnott) Verdc.), Natal redtop (Rhynchelytrum repens (Willd.) Hubb.), and siratro (Macroptilium atropurpureum (DC) Urb.) appear to be resilient to the harsh island conditions, which include strong winds, low annual rainfall, acute erosion, and a nutrient-depleted soil profile. Although all 4 species offer some protection against erosional processes, none are particularly desirable for long-term restoration of the island. Glycine and siratro, both of which volunteer readily in planting sites, are considered invasive in that they may smother other more desirable species, particularly less competitive natives. Finally, native woody species are shown to have difficulty in surviving on the island without special attention to planting and maintenance.
    • Range research in the far western United States: the first generation

      Young, J. A. (Society for Range Management, 2000-01-01)
      The scientific study of rangelands in the western United States, started with the first collection of natural history specimens in the 18th century. Gradually over the 19th century, a basic catalog of the plants, animals, and geography of the far west was assembled. After the U. S. Department of Agriculture (USDA) was organized, scientists were sent to the western ranges on fact-finding missions designed to assess the existing range livestock industry and its potential. At the turn of the 19th to the 20th century a few visionary scientist began to conduct actual experiments in rangeland environments. The Forest Service, USDA, was established in 1905, and what had been Forest Reserves from the U. S. Department of Interior (USDI) were transferred to the new agency. It was responsible for sustainable timber product and watershed management on millions of acres of wild lands. The Forest Service soon discovered that livestock grazed on four-fifths of the National Forest land and it was estimated that 85% of these rangelands were over-grazed and subject to accelerated erosion. The Forest Service started preliminary research on rangelands in 1907 and formally started an Office of Grazing Studies in 1910. Beginning with the Great Basin Experiment Station in 1912, a series of stations were developed by the Forest Service. As agricultural experiment stations developed at Land Grant colleges in the western states, state sponsored research on rangelands increased in importance.
    • Predictive models for grazing distribution: A GIS approach

      Brock, B. L.; Owensby, C. E. (Society for Range Management, 2000-01-01)
      Grazing distribution and forage use patterns are important influences on rangeland ecosystems. Spatial patterns of grazing by domestic cattle (Bos taurus) were observed over 2 consecutive years under 2 grazing systems, intensive-early stocking and season-long stocking. The purposes were to determine factors influencing observed patterns and develop predictive models for grazing distribution and forage removal. Field-collected data on grazing distribution were linked with associated geophysical properties of pastures utilizing a GIS. Separate models were developed to predict grazing distribution and forage utilization using a backward stepwise regression procedure. The forage utilization model was linked with grazing distribution by utilizing Tobit analysis. Nineteen independent variables were used to interpret the observed variation in grazing distribution. Comparison of predicted probability of grazing values from the model with the observed grazing distribution in a hold-out data set yielded a close fit (R=.99). Eighteen independent variables were included in the forage removal model. Comparison of predicted forage removal with observed values in a hold-out data set yielded a poor fit (R=.28). Lack of forage quality variables probably accounts for the poor performance of the forage removal model. Differences in the success of the 2 models support the hypothesis that grazing distribution and forage utilization operate at different spatial scales and parameters. The use of GIS holds promise as a technique for developing useful predictive models for range management.
    • Policy prospects for brush control to increase off-site water yield

      Thurow, T. L.; Thurow, A. P.; Garriga, M. D. (Society for Range Management, 2000-01-01)
      Water yield from rangeland on the Edwards Plateau, Texas is significantly greater if a site is dominated by grass instead of brush. Brush control programs are being considered by policy-makers as a way to relieve water shortages in the region. This research analyzed ranchers' willingness to participate in a publicly-funded brush control cost-sharing program that would be ranch-revenue neutral. A survey instrument was mailed to 226 ranchers, 119 were completed and returned (53%). The cost sharing program required that brush on enrolled land be cleared and maintained at 3% cover for a 10-year period. Respondents estimated that current brush cover on their land averaged 41%, which contrasted with their preference that brush cover average 27%. This expression of preferred brush cover was similar to an independent estimate by a panel of experts in the region which indicated ranch livestock and deer-hunting lease value would be maximized at 30% brush cover. These estimates indicate that a program designed to increase water yield by reducing brush cover to 3% would likely require a financial incentive to offset the cost of brush control that exceeded the preference of the owner. Sixty-six percent of respondents indicated a willingness to enroll some portion of their land in the cost-sharing program described in the survey instrument. Ranch size, the percentage of ranch income earned from deer-hunting leases and livestock, and whether or not ranchers indicated that expense limited past brush control efforts were the variables measured by the survey instrument which best explained the probability of participation and the amount of land the owner was willing to enroll.
    • Nutrient distribution among metabolic fractions in 2 Atriplex spp

      Islam, M.; Adams, M. A. (Society for Range Management, 2000-01-01)
      The seasonal variations in nitrogen and phosphorus fractions and cations in 2 species of Atriplex common to Western Australia (Atriplex amnicola P.G. Wilson and Atriplex nummularia Lindl.) were investigated. Both species contain high concentrations of nitrogen (N) in winter as compared with summer when both species contain high concentrations of sodium. The sum of soluble protein-N, amino acid-N, nucleic acid-N and nitrate-N is about half of the total nitrogen. The remainder includes non-soluble protein-N and other N associated with cell membranes and walls. Phosphorus was more uniformly distributed among pools of inorganic-P, phytate-P, nucleic acid-P and other (residual) fractions. We suggest that interpretation of animal nutrition studies based on similar trichloroacetic acid (TCA) fractionations might be improved by independent estimation of soluble proteins. Fractionation using TCA provides valuable information about the subcellular distribution of both N and P in foliage tissues for study of plant physiology and animal nutrition. Concentrations of major nutrients in foliage of both species were significantly and negatively correlated with monthly maximum temperature and significantly and positively correlated with monthly rainfall. In summer and early autumn the apparent nutritive value of both species is well below the basic requirement of sheep or other grazing ruminants such as goats.
    • Livestock grazing effects on forage quality of elk winter range

      Clark, P. E.; Krueger, W. C.; Bryant, L. D.; Thomas, D. R. (Society for Range Management, 2000-01-01)
      Carefully-managed livestock grazing has been offered as a tool to improve the forage quality of graminoids on big game winter range. Formal testing of this theory has thus far been done using hand clippers rather than livestock grazing. We report winter standing reproductive culm, crude protein, in vitro dry matter digestibility, and standing crop responses of bluebunch wheatgrass (Agropyron spicatum [Pursh] Scribn. Smith), Idaho fescue (Festuca idahoensis Elmer), and elk sedge (Carex geyeri Boott) to late-spring domestic sheep grazing. The study was conducted in 1993 and 1994 on a big game winter range in the Blue Mountains of northeastern Oregon. Sheep grazing and exclusion treatments were applied to 20-ha plots at 3 sites on the study area Targeted utilization for grazed plots was 50% graminoid standing crop removal during the boot stage of bluebunch wheatgrass. Grazing did not influence the number of standing reproductive culms per plant in bluebunch wheatgrass. Crude protein and in vitro dry matter digestibility of bluebunch wheatgrass in grazed plots increased by 1.0 and 4.3 percentage points, respectively over ungrazed plots. Grazing reduced the standing crop of bluebunch wheatgrass by 116.9 kg ha-1 DM. Standing Idaho fescue reproductive culms decreased by 0.7 culms plant-1 under grazing. Crude protein of Idaho fescue in grazed plots was 1.3 percentage points greater than in unglazed plots. Crude protein and in vitro dry matter digestibility responses of elk sedge were inconsistent between years and may be related to utilization or growth differences between years. The levels of forage quality improvement in bluebunch wheatgrass and Idaho fescue obtained in this study could benefit the nutritional status of wintering Rocky Mountain elk (Cervus elaphus nelsoni Bailey). More research is needed regarding the effects of grazing on the winter forage quality of elk sedge.
    • Leafy spurge (Euphorbia esula) control with glyphosate plus 2,4-D

      Lym, R. G. (Society for Range Management, 2000-01-01)
      Leafy spurge control with glyphosate [N-(phosphonomethyl)glycine] plus 2,4-D [2,4-dichlorophenoxy)acetic acid] applied annually for 3 years alone or rotated with auxin herbicides was evaluated at 3 locations in North Dakota. Glyphosate applied with 2,4-D averaged 67% leafy spurge control 3 months after treatment which was a 10-fold increase compared to glyphosate alone. Glyphosate plus 2,4-D applied annually for 3 years or rotated with dicamba (3,6-dichloro-2-methexybenzoic acid) or picloram (4-amino-3,5,6-trichloro-2-pyridine carboxylic acid) plus 2,4-D provided 80 to 90% leafy spurge control, which was similar to the standard annual picloram plus 2,4-D treatment but at 30 to 65% less cost. Herbage production was similar regardless of treatment. The absorption and translocation of 14C-2,4-D increased 2- to 3-fold when applied wit glyphosate compared to 14C-2,4-D applied alone. However, both absorption and translocation of 14C-glyphosate was severely reduced when applied with 2,4-D compared to 14C-glyphosate applied alone. The increase in control when glyphosate is applied with 2,4-D may be because sublethal concentrations of glyphosate break root bud dormancy in leafy spurge, thereby increasing the amount of 2,4-D in the root. Glyphosate plus 2,4-D provided good leafy spurge control at less cost than current widely used treatments and should provide a new tool for leafy spurge management.
    • Influence of pasture management on soil biological quality

      Banerjee, M. R.; Burton, D. L.; McCaughey, W. P.; Grant, C. A. (Society for Range Management, 2000-01-01)
      The long-term sustainability of pasture management systems, whether related to structural stability or nutrient dynamics, is dependent upon maintaining soil biological properties. This study investigates the extent to which the microbiological and biochemical properties of soil can change with season and pasture management system, including their likely value as indicators of soil quality. The experiment was conducted on a 30-ha pasture near Brandon, Manitoba. Seasonal fluctuations were observed in the soil microbial and biochemical properties. In general, these fluctuations were mainly independent of the small variations in soil organic matter content but were more closely related to soil water content. The data also suggests an impact of stocking rate and grazing system on soil microbial biomass C and on N mineralization potential. However, because duration of the investigation, limited number of replications and the high soil variability encountered, it is not yet possible to recommend any particular grazing system and/or stocking rate favorable for the maintenance of soil biological quality. The trends suggest that light, continuous grazing systems had the largest microbial biomass and nutrient mineralizing activity.
    • Impact of locoweed poisoning on grazing steer weight gains

      Ralphs, M. H.; Graham, D.; Duff, G.; Stegelmeier, B. L.; James, L. F. (Society for Range Management, 2000-01-01)
      Emaciation is one of the clinical signs of locoweed poisoning but few studies have documented impacts of locoweed poisoning on weight gains. Stocker steers (British X Continental cross, 200-210 kg) were grazed on locoweed-infested, short-grass prairie in 1996 and 1997 in northeast New Mexico. Each year, half the steers were averted to locoweed to allow them to graze locoweed-infested pastures without eating locoweed. They did not graze locoweed and steadily gained weight (0.50 kg/day in 1996 and 0.71 kg/day in 1997). The other group of steers were allowed to graze locoweed under natural grazing conditions and became intoxicated. Weight gains were not affected for the first 3 weeks, but thereafter the steers lost weight in both years. In 1996, non-averted steers consumed locoweed for a season average of 20% of bites. They were severely intoxicated and did not begin gaining weight for 50 days after they stopped eating locoweed. Steers in the 1997 trial consumed less locoweed (11% of bites) than those in 1996 and they recovered more rapidly. Seasonal weight gains were 21 to 30 kg less for locoed steers than control steers in 1996 and 1997, respectively. Locoweed poisoning will cause weight loss, and severely intoxicated cattle require a lengthy recover period after they cease grazing locoweed before weight gains resume. Stocker cattle should not be placed on locoweed-infested rangelands until green grass is abundant and locoweed begins to mature.
    • Disk chain effects on seeded grass establishment

      Wiedemann, H. T.; Cross, B. T. (Society for Range Management, 2000-01-01)
      Preparing a seedbed and seeding rangeland littered with brush debris normally requires extensive land cleanup before conventional equipment can be used. Our 3-year study compared grass densities on seedbeds prepared with an anchor chain, a disk-chain implement, and the disk chain followed by an anchor chain on land rootplowed for mesquite (Prosopis glandulosa Torr. var. glandulosa) control. Seedbeds were aerially seeded with 1 or 2 kg/ha pure live seed of kleingrass (Panicum coloratum L.). Treatments were applied to a clay loam and sandy loam site each year. Evaluations were based on established grass densities at the end of the first growing season. A heavy-duty, offset disk was included in the seedbed preparation methods during the third year. The chain, disk-chain, and disk-chain+chain implements traversed the log-littered sites without difficulty. Seedbeds prepared by disk-chaining+chaining significantly (p < 0.05) increased plant densities by 100% in clay loam soil and 42% in sandy loam soil compared with seedbeds prepared by chaining. However, in the year when rainfall was 43% below normal at the clay loam site, disk-chaining+chaining increased plant densities by 218% compared with chaining. Plant densities on disk-chained seedbeds were lower than those on disk-chained+chained seedbeds in clay loam soil while densities on disk-chained seedbeds were significantly (p < 0.05) lower than densities on disk-chained+chained seedbeds in the sandy loam soil, but densities following disk chaining were significantly (p < 0.05) higher than densities following chaining in both soil types. There was no difference in plant densities between disked and disk-chained+chained seedbeds; consequently, there would be little need to rake up the brush so a disk could be used. The 2 kg/ha seeding rate compared with the 1 kg/ha seeding rate significantly (p < 0.05) increased plant densities by 75% in the clay loam and 98% in the sandy loam soil. The results from this study indicate the value of using the disk-chain+chain implement, and the higher seeding rate to enhance the establishment of a seeded grass, especially when rainfall is in short supply or not timely.