• Switchgrass recruitment from broadcast seed vs. seed fed to cattle

      Ocumpaugh, W. R.; Archer, S.; Stuth, J. W. (Society for Range Management, 1996-07-01)
      Fecal seeding by livestock may be an effective, low-cost means of rangeland restoration. We compared recruitment of switchgrass (Panicum virgatum L.) from seed fed to cattle and deposited in dung to that of broadcast-seeded plots receiving a comparable number of unfed seed. Although germinability of seed passed through livestock (52 to 62%) was reduced relative to that of broadcast seed (85 to 91%), recruitment of switchgrass from seed in cattle feces was equal to or superior to that of broadcast seed in terms of establishment (frequency of occurrence and density), plant growth and final plant size. The frequency of plot with emerging switchgrass plants ranged from 62 to 100% when seeds were delivered in feces, but only 2 to 40% when seeds were broadcast. After 1 year, the frequency of occurrence of switchgrass plant in fecal vs. broadcast-seeded plot was comparable for autumn trials. However, evaluations 1 year after the spring trials continue to result in higher frequency of plot with switchgrass plant from seed delivered in feces than of broadcast seedings (56 vs. 4% for May 1990, P < 0.05; and 90 vs. 51% for May 1991, P less than or equal to 0.01). Enhanced plant recruitment on fecal-seeded plots occurred even though broadcast-seeded plots received 1.5 to 1.7 times more pure live seed (PLS). Plants on fecal-seeded plots had a greater plant size score (based on visual ratings of height, culm density, and biomass) than plants on broadcast-seeded plots (P < 0.05 for May seedings; P < 0.05 for October 1990; P < 0.10 for October 1991). Results suggest significant advantages of fecal seeding over conventional broadcast seeding in terms of seedling emergence, establishment and growth.
    • Partial and full dehydration impact on germination of 4 warm-season grasses

      Emmerich, W. E.; Hardegree, S. P. (Society for Range Management, 1996-07-01)
      Precipitation patterns in the arid southwest U.S. can be highly variable during the summer monsoon season. The ability of germinating seeds to withstand temporary periods of dehydration may determine their potential for successful regeneration under present and future climatic regimes. Germination with short-term hydration and dehydration sequences was compared to constant water potential germination for sideoats grama [Bouteloua curtipendula (Michaux) Torrey], buffelgrass [Cenchrus ciliaris L.], Lehmann lovegrass [Eragrostis lehmanniana Nees], and kleingrass [Panicum coloratum L.]. Seeds were imbibed at -0. MPa for 1 to 4 days, then either air dried or partially dehydrated d -3.0 MPa for 1 to 4 days before being returned to the initial imbibition solution for a total 14-day incubation-dehydration period. One day of imbibition at -0.2 MPa advanced germination to a stage that resulted in significant reductions (P < 0.05) in total germination from subsequent dehydration. The significant reductions still allowed > 48% of the viable seeds to germinate after dehydration. Longer imbibition times also exhibited significant reductions in germination for buffelgrass and kleingrass. For kleingrass air-dried dehydration compared to -3.0 MPa produced significant reductions (P < 0.05) in germination with 2-3 days imbibition. The length of the dehydration periods produced significant differences (P < 0.05) in total germination for Lehmann lovegrass and kleingrass. Partial dehydration significantly increased germination rate for sideoats grama, buffelgrass, and kleingrass, while air-dried dehydration significantly reduced buffelgrass germination rate. Any dehydration during germination was detrimental and > 1-day imbibition followed by dehydration seemed the critical time upon which a dramatic reduction in germination occurs.
    • Observations of shoots and roots from interspecific grafted rosaceous shrubs

      Kyle, N. E.; Righetti, T. L. (Society for Range Management, 1996-07-01)
      Plants with various shoot and root combinations of Cowania mexicana var. stansburiana (Torr.) Jeps. (cliffrose), Purshia glandulosa Curran (desert bitterbrush), and Purchia tridentata (Pursh) DC. (antelope bitterbrush) were relatively easy to produce by grafting. The foreign roots or shoots in multi-shoot or multi-root systems were not as vigorous as the original scion or rootstock. With time the original scion or rootstock became dominant and the foreign portions usually senesced. If growth of the original scion or rootstock was restricted by pruning or removal, satisfactory growth for both shoot or root types occurred. Manipulating grafted systems where Fallugia paradoxa, (D. Don) Endl., Apache plume, (a non-nodulating genus) is combined with any of the above 3 nodulating species was much more difficult. Graft incompatibility occurred in most intergeneric Fallugia systems, but some combinations survived for several years. A large quantity of nodules was produced on 1 very sparsely rooted P. tridentata scion attached to a Fallugia rootstock. Apparently, the plant derived much of its nitrogen from Purshia nodules, and the majority of its other nutrients and water from the Fallugia roots.
    • Nitrogen fertilization of dryland grasses in the Northern Great Plains

      Jacobsen, J. S.; Lorbeer, S. H.; Houlton, H. A. R.; Carlson, G. R. (Society for Range Management, 1996-07-01)
      Dryland grass production is an important agricultural commodity in the Northern Great Plains. Nitrogen (N) fertilizer can increase dry matter production and forage quality, yet there are relatively few rangeland and improved pasture managers who utilize fertilization practices to optimize production. Two trials (1972-1975 and 1978-1981) with 10 common grass species used a single application of 0, 56, or 112 kg N ha-1 and 0, 112, or 224 kg N ha-1 to evaluate long-term grass performance to N fertilization. Dry matter production in each trial was measured annually for 4 years. Yields increased on average 1,340 kg ha-1 with the application of 56 kg N ha-1, and 1,662 kg ha-1 with 112 kg N ha-1 in Trial 1. In Trial 2, yields increased 3,499 and 5,140 kg ha-1 with applications of 112 and 224 kg N ha-1, respectively. Responses to applied N were evident 4 years after application for some species, most likely due to the combination of improved grass vigor and recycling of fertilizer N immobilized in organic forms. Single applications of N were effective in improving dry matter production of some common grasses for multiple years, when water was suitable. The magnitude of response and potential economic return from fertilization were species dependent.
    • Native forage quality, quantity, and profitability as affected by fertilization in northern Mexico

      Rubio, H. O.; Wood, M. K.; Gomez, A.; Reyes, G. (Society for Range Management, 1996-07-01)
      Fourteen treatments of nitrogen (N) and phosphorus (P) fertilizers were applied in an overgrazed eight rangeland in northern Mexico, during 1990 and 1991. Eight treatments were applied using ammonium nitrate as a source of N (60-0-0, 60-30-0, 60-60-0, 80-40-0, 120-30-0, 120-60-0, 120-90-0 and 180-60-0 kg ha-1), 2 treatments with ammonium sulfate (60-30-0 and 120-60-0 kg ha-1), 2 with urea (60-30-0 and 120-60-0 kg ha-1), only P (0-30-0 kg ha-1), and the control (0-0-0 kg ha-1). Triple superphosphate was applied as a source for P. The 80-40-0 treatment was included because it was the commonly recommended rate for the area. Fertilizers were applied at the beginning of the rainfall season (July) and forage was harvested in late October (1990) and mid-November (1991). Dry matter production, crude protein (CP) content, and in situ digestibility were determined. An economic analysis was used to obtain the best economic treatment for forage production. In 1990 with a precipitation of 377 mm, dry matter production was significantly affected for both source and rate of N. The maximum amount of dry matter was obtained with a rate of 120-90-0 kg ha-1 using ammonium nitrate. However, the best treatment in terms of economic return was 120-30-0 kg ha-1 as ammonium nitrate. Urea did not produce as well as other N source treatments. Crude protein was highest in treatments with the higher N, but no significant trend was evident. In situ digestibility was not affected by rate or source of N fertilizer. During 1991, precipitation was higher than in 1990. Significant differences were determined among N rates but not in N source. In fact, urea produced greater in dry matter production than other N sources at the same rate. The maximum amount of dry matter was obtained with the 180-60-0 treatment using ammonium nitrate with 4,190 kg ha-1, but the best economic treatments were the 120-30-0 and 60-0-0 with a marginal return rate of 377% and 355%, respectively. Results of CP and in situ digestibility were similar to those of 1990.
    • Leafy spurge and grass response to picloram and intensive grazing

      Lacey, J. R.; Sheley, R. L. (Society for Range Management, 1996-07-01)
      More information about the effects of combining intensive livestock grazing of noxious weeds and associated desirable plants with other control measures is needed to develop effective rangeland weed management strategies. We studied the response of leafy spurge (Euphorbia esula L.) and Kentucky bluegrass (Poa pratensis L.) to intensive short-duration grazing by either sheep or cattle, in combination with picloram (4-amino-3,5,6-trichloropicolinic acid) for 5 years. In the first year, 2 pastures (16 and 24-ha) were split into 3 blocks and picloram was applied to one-half of each block at a rate of 0.9 kg ha-1. Exclosures were established to include both treated and untreated portions in each block. The smaller and larger pastures were grazed by sheep and cattle, respectively. There were 1 or 2 grazing periods per year, varying from 1- to 2-days in length. Leafy spurge stem densities were counted annually, and grass cover and plant biomass were also examined. Data from each pasture (cattle or sheep) were analyzed separately using analyses of variance. Leafy spurge was selectively grazed by sheep, and stem densities were reduced by sheep grazing (P < 0.01). Cattle did not utilize leafy spurge and stem densities were not affected. Picloram reduced leafy spurge stem densities throughout the study in both the sheep (P < 0.001) and cattle (P < 0.001) pastures. Picloram also reduced leafy spurge biomass in the sheep pasture (P < 0.05), which allowed an increase in Kentucky bluegrass biomass. Grazing X picloram interactions affecting either leafy spurge stem densities or leafy spurge biomass were not detected. An integrated leafy spurge management system may require a longer time frame, additional control measures, and (or) more intensive grazing management.
    • Impact of clipping on root systems of 3 grasses species in Tunisia

      Chaieb, M.; Henchi, B.; Boukhris, M. (Society for Range Management, 1996-07-01)
      The study concerns the impact of herbivory on the root systems of 3 perennial grasses, buffelgrass (Cenchrus ciliaris), digitgrass (Digitaria commutata) and needlegrass (Stipa lagascae), growing in the arid zones of Tunisia. The study simulated animals feeding of the grasses by affecting cuttings at various times throughout the spring growing period. The following effects on the root systems of the grasses were observed. When there is continual overgazing (simulated by cutting all sprouts down the ground level along the spring), more than 65% of the roots off all 3 species are found in the salty upper 15 cm of soil. In case of medium average grazing (simulated by 2 to 3 cuttings), the root system again remains superficial for buffelgrass (C. ciliaris), with 58 to 67% of the roots located in the upper 15 cm of soil. Digitgrass (Digitaria commutata) and needlegrass (Stipa lagascae), however, develop deeper roots with 68 to 86% in the upper 30 cm of soil. When grazing is light (just one cutting), all 3 species perform all most exactly as if there had been no grazing compared to (a control plot) with 85% of the root system located in the upper 50 cm and about 15% at 50 to 75 cm of ground depth. On the basis of this experiments, it is suggested that grazing on these grasses should be allowed just once each spring, thereby allowing: 1- To take advantage of the aboveground contained in these grasses in spring. 2- Preservation of a deep root system which will thereby have a much better chance of getting through the water stress summer season.
    • Germination response of Russian wildrye to variations in seed mass at fluctuating temperatures

      Limbach, W. E.; Call, C. A. (Society for Range Management, 1996-07-01)
      The effects of seed mass and fluctuating temperatures on the germination and heterotrophic seedling development of 3 seed sources of Russian wildrye, Psathyrostachys juncea (Fisch) Nevski, were studied. Seeds that weighed 2.4, 3.0, 3.6, and 4.2 +/- 0.1 mg of each seed source were germinated in an unlighted incubation chamber at 5-10 degrees C, 5-15 degrees C, 10-l5 degrees C, and 10-20 degrees C. Germination and heterotrophic seedlings development were assessed using: 1) mean time to germinate (T/1), 2) the mean proportion of seeds to germinate (G) and 3) mean maximum radicle and coleoptile extension. Data were analyzed using a 4 X 4 X 3 factorial analysis of variance (n = 144) comprised of main effects, temperature (T), seed mass (M), and seed source (S). Time to germination was significantly affected by T (F = 647.44, P < 0.0001), S (F = 28.29, P < 0.0001) and the T X S (F = 4.71, P < 0.0003) and S X M (F = 2.21, P < 0.0489) interact. The mean maximum proportion of seeds to germinate was significantly affected by T (F = 13.63, P < 0.0001), S (F = 10.53, P < 0.0001), M (F = 8.11, P < 0.0001) and the T X M interaction (F = 2.21, P < 0.0276). Radicle extension was significantly affected by T (F = 21.94, P < 0.0001), S (F = 14.29, P < 0.0001), M (F = 12.70, P < 0.0001), and the T X S (F = 13.69, P < 0.0001) interaction. Coleoptile extension was significantly affected by T (F = 810.24, P < 0.0001), S (F = 68.83, P < 0.0001), M (F = 56.00, P < 0.0001), and the T X M (F = 3.84, P < 0.0003) interaction. Apparently, Syn-A seeds germinate more vigorously and have longer coleoptiles than Vinall but apparent differences remain confounded between seed sources since the effects of seed age and maternal environment cannot be eliminated from the study.
    • Effects of restricted suckling on forage intake of range calves

      Sowell, B. F.; Wallace, J. D.; Branine, M. E.; Hubbert, M. E.; Fredrickson, E. L.; Bowman, J. G. P. (Society for Range Management, 1996-07-01)
      Twenty two-year-old primiparous Angus X Hereford cows and their heifer calves were used to study effects of milk consumption on calf performance, suckling behavior, and forage intake. Ten cow-calf pairs were allotted to each of 2 treatments on blue grama (Bouteloua gracilis [H.B.K.] Lag.) rangeland. Calves from 5 cows were prevented from suckling the rear udder quarters for 4 weeks to reduce milk intake by 32% when calves averaged 71 +/- 4 days of age. The other 5 calves were allowed to suckle normally. Four 12-day sampling periods were conducted from June through September. Calves from the control treatment weighed more (P < 0.05) than restricted calves in each period and at weaning. Calves from the restricted treatment did not (P > 0.10) suckle longer or more frequently than control calves during any sampling period. Forage organic matter intake was not (P > 0.10) different between cows or calves from either group at any date. Milk production was not different (P > 0.10) between groups 1 month after restriction periods were terminated. Calves on 4 week milk restriction did not increase forage organic matter intake and had decreased weaning weights compared to control animals.
    • Effects of reducing sheep grazing in the Scottish Highlands

      Hope, D.; Picozzi, N.; Catt, D. C.; Moss, R. (Society for Range Management, 1996-07-01)
      The effects of reducing sheep grazing on upland vegetation and wild herbivores was studied at 11 sites in the Scottish Highlands. Areas where sheep had been removed for periods of up to 25 years were compared with areas where stocking rates had remained unchanged. At 5 sites, removal of sheep was associated with taller vegetation and more signs of vole activity. While the removal of sheep appeared to have resulted in relatively few changes in floristic composition at these sites, patches of dwarf shrub-dominated vegetation tended to be larger and patches of grassland to be smaller where sheep had been removed. One previously open site was being invaded by birch woodland after sheep removal. At the remaining 6 sites removal of sheep appeared to have had little or no effect on vegetation or on wild herbivore activity. This was probably due to an increase in grazing by red deer, along with continued heather burning, at these sites. It is concluded that sheep removal is only likely to cause significant changes in vegetation composition and structure in the Scottish Highlands where red deer numbers are low and heather burning infrequent. When this occurs, vole numbers are likely to increase.
    • Effects of Flourensia cernua ingestion on nitrogen balance of sheep consuming tobosa

      King, D. W.; Frederickson, E. L.; Estell, R. E.; Havstad, K. M.; Wallace, J. D.; Murray, L. W. (Society for Range Management, 1996-07-01)
      Flourensia cernua DC. (tarbush) is a deciduous shrub with potential as a high-protein forage source for livestock. Twenty-four Polypay X Rambouillet wethers housed in metabolism crabs were used to evaluate tarbush as a N source for sheep fed a low quality grass diet. Treatments were 100% ground tobosa grass (Pleuraphis mutica BuckL) or tobosa substituted with 10, 20, or 30% whole pre-bloom tarbush leaves (n = 5) or 26% ground alfalfa (n = 4, Medicago sativa L.) on a dry matter basis (dmb). Sheep were fed ad libitum for 11 days, after which feed was restricted to 1% (dmb) of body weight for 11 days to reduce sorting and maintain uniform intake. Apparent dry matter digestibility was not improved (P = 0.2646) with tarbush or alfalfa. Fecal N was similar (P = 0.1626), but urinary N varied (P = 0.0008) among treatments. Apparent N digestibility differed (P = 0.0042) among treatments (43, 46, 50, 56, and 63% for sheep consuming 0,10, 20, or 30% tarbush or alfalfa, respectively). All treatments resulted in similar (P = 0.1569) but negative N retentions (-2.4, -2.2, -2.8, -2.0, and -1.5 g day-1 for sheep consuming 0, 10, 20, or 30% tarbush or alfalfa, respectively). Serum clinical profiles (day 22) confirmed all sheep were nutritionally stressed, but did not indicate toxicosis. Although neither tarbush nor alfalfa N compensated for the low quality basal diet, N from 30% tarbush was utilized with similar efficiency to alfalfa N. The major impediment for using tarbush as a N source appeared to be low palatability.
    • Effects of Flourensia cernua ingestion on intake, digesta kinetics, and ruminal fermentation of sheep consuming tobosa

      King, D. W.; Estell, R. E.; Fredrickson, E. L.; Havstad, K. M.; Wallace, J. D.; Murray, L. W. (Society for Range Management, 1996-07-01)
      Tarbush (Flourensia cernua DC.) contributes substantially to the Chihuahuan Desert shrub biomass, but is browsed sparingly by livestock. This study was designed to assess nutritional benefits and/or toxicosis of ingestion of pre-bloom tarbush leaves by sheep fed a low quality native grass diet. Sixteen ruminally cannulated sheep (46 kg) housed in individual pens were randomly assigned to 1 of 4 treatments for 28 days. Treatments were ground tobosa grass (Pleuraphis mutica Buckl.) substituted with 0, 10, 20, or 30% (dry matter basis) whole tarbush leaves (19% CP). At 20 and 30% of the diet, tarbush increased (P = 0.0049) dry matter intake during week 3, and sheep consuming 30% tarbush tended to increase dry matter intake during week 2 (P = 0.0559). Dietary tarbush did not affect any variable associated with ruminal fluid kinetics, particulate digesta kinetics, or in situ degradation rates of tobosa dry matter or neutral detergent fiber (P > 0.05). Molar butyrate proportions (P = 0.0032) and total volatile fatty acid concentrations (P = 0.0064) were greater for the 30% tarbush treatments. Ruminal ammonia was greater (P < 0.0029) at 6, 8, and 12 hours postfeeding for the 30% tarbrush treatment. Sheep lost body weight regardless of treatment; however, sheep not fed tarbush boded (P = 0.0945) to lose more weight. &rum clinical profiles (day 0, 7, 15, and 21) confirmed nutritional stress but did not suggest toxicosis.
    • Economic feasibility of grazing sheep on leafy spurge-infested rangeland in Montana

      Williams, K. E.; Lacey, J. R.; Olson, B. E. (Society for Range Management, 1996-07-01)
      Leafy spurge (Euphorbia esula L.) is a noxious weed on rangelands throughout the Northern Great Plains. Most of these ranges are grazed by cattle which do not use leafy spurge as forage. Although sheep graze leafy spurge, most land managers are reluctant to use sheep to control this noxious weed, which may be related to economic uncertainties regarding their profitability. The purpose of this study was to evaluate the economic feasibility of implementing a sheep enterprise to control leafy spurge on cattle ranches. The physical characteristics of a typical Northern Great Plains ranch, recommended stocking rates for cattle and sheep on native and leafy spurge-infested rangelands, and a sheep enterprise budget were developed using information from the literature. A LOTUS® spreadsheet was developed to calculate returns over total costs of implementing various sheep enterprises. Annual returns from implementing sheep grazing on 520 ha of leafy spurge on a 4,905 ha ranch exceeded total costs by 4,675. Given the ownership costs and returns of our ranch, the breakeven lamb price would be 1.16 kg-1. Returns per head and per unit of land will vary with the distribution and size of a leafy spurge infestation, and sheep production costs and returns. Returns from sheep grazing were higher when leafy spurge was concentrated in fewer rather than in many pastures. Returns were positive when as little as 4% of the ranch was infested with leafy spurge. The availability and utility of our model will allow land managers to assess the feasibility of developing sheep enterprises to control leafy spurge.
    • Economic damage to forage crops by native ungulates as perceived by farmers and ranchers in Montana

      Irby, L. R.; Zidack, W. E.; Johnson, J. B.; Saltiel, J. (Society for Range Management, 1996-07-01)
      The perceived economic damage to forage crops in Montana attributed to native ungulates during 1992 was estimated using a mail survey of 2,200 randomly selected farms and ranches. The 1,120 respondents indicated that wild ungulates were present on 97% of the agricultural operations in Montana. White-tailed deer (Odocoileus virginianus [Zimmermann]) were the most widespread wild ungulate species and were most frequently cited as responsible for damage to forage crops by those respondents who reported damage. Damage to forage crops was most frequently reported in southwestern Montana and from agricultural operations with gross annual sales > 200,000. The aggregate perceived economic damage to forage crops by wild ungulates in Montana during 1992 was 12.2 million.
    • Changes of surface oil nutrients and sustainability of pastoralism on grazed hilly and steep land, South Island, New Zealand

      Mcintosh, P. D.; Ogle, G. I.; Patterson, R. G.; Aubrey, B.; Morriss, J.; Giddens, K. (Society for Range Management, 1996-07-01)
      Soil nutrients in topsoils (0-7.5 cm) on grazed hilly and steep land on 2 high country sheep farms with contrasting climate in the upper Waitaki district, South Island, New Zealand, were compared before and after a 14-15 year period. In addition, effects on soils of 2 farm management systems were compared by sampling similar soils on adjacent farms. On a farm with mean annual rainfall of 700-1,000 mm (study area A) that had been fertilised and oversown, and grazed with about 1.6 ewe equivalents per hectare for 14 years, levels of exchangeable cations (Ca, K, Mg) increased in topsoils on sunny slopes, but there was little change on shady slopes. The Ca increase on sunny slopes was the increase to be expected from the amount of Ca contained in the superphosphate applied but increases of exchangeable K and Mg could not be explained by fertiliser additions. There was an overall 29% increase of CEC, 7.5% decline of base saturation, and decline of soil pH by 0.4 units over the 14 year period. On a farm with mean annual rainfall of 500-600 mm (study area B) that had been grazed for 15 years with about 0.6 ewe equivalents per hectare but not fertilised or oversown, levels of exchangeable cations in topsoils declined. Base saturation values declined from 98% to 73% and pH declined by 0.4 units. Losses of Ca and Mg were greater than could be explained by direct effects of sheep grazing and we conclude that processes such as erosion or removal of vegetation and nutrients by rabbits are important loss pathways. In the spatial comparison on land with mean annual rainfall of approximately 1,000 mm, oversown and fertilised soils (grazed with about 1.6 ewe equivalents per hectare) had higher levels of exchangeable cations, organic C and total N than soils that had neither been oversown or fertilised (grazed with about 0.6 ewe equivalents per hectare). Questions of ecological and economic sustainability arise both on the moister and drier high country. On moister land like area A, if lime can be applied economically, and fertiliser can continue to be applied with positive financial returns, oversowing and fertilising may be sustainable on sunny slopes. The sustainability of pastoralism on shady slopes is more problematical. If on drier land losses of topsoil nutrients such as those measured on area B are widespread, they are considered to be unsustainable. Although the nutrients lost could be readily replenished using modest amounts of fertiliser and lime, the changes have occurred concurrently with declines of organic C and total N. Restoration of organic matter levels is likely to require either reduced grazing, or oversowing and application of fertiliser. Because oversowing and fertilising the drier high country is not financially viable except during periods of high commodity prices, both these options would require major changes in farm management and/or financial assistance with soil conservation measures.
    • Cattle trampling of simulated ground nests in rotationally grazed pastures

      Paine, L.; Undersander, D. J.; Sample, D. W.; Bartelt, G. A.; Schatteman, T. A. (Society for Range Management, 1996-07-01)
      For many grassland songbird species, pastures represent some of the best available breeding habitat in the Upper Midwest. Increasing interest in intensive rotational grazing (IRG) among midwestern livestock farmers may result in an expansion of pasture hectares in the region. We evaluated the effects of several cattle stocking densities on ground nest survival in rotationally grazed cool-season pastures in southwestern Wisconsin. Ground nests were simulated with clutches of 3 unwashed pheasant eggs. We tested 3 rotational grazing systems: a 1-day dairy rotation stocked at 60 head ha-1; a 4-day beef rotation at 15 head ha-1; and a traditional, non-intensive 7-day rotation at 8 head ha-1. Paddock size (1.2 ha) and nest density (15 nests paddock(-1)) were held constant. The simulated nests were observed 4 times day(-1) to document trampling patterns during the herds' diurnal grazing and rumination cycles. Trampling damaged a mean of 75% (+/- 3.1%) of the nests for all 3 treatments during 8 consecutive replications. While the 7-day treatment exhibited a pattern of greater nest trampling during cattle grazing periods than during rumination periods, this pattern was less evident in the 4-day treatment and absent in the 1-day treatment. Increasing vegetation height-density and percent vegetation cover were associated with reduced nest trampling rates, but pasture forage production and removal were not associated with nest damage.
    • Availability of foods of sage grouse chicks following prescribed fire in sagebrush-bitterbrush

      Pyle, W. H.; Crawford, J. A. (Society for Range Management, 1996-07-01)
      A study was conducted to determine the influence of prescribed fire on the availability of primary foods of sage grouse (Centrocercus urophasianus Bonaparte) chicks at Hart Mountain National Antelope Refuge, Lake County, Ore. from 1987 to 1989. Responses of certain primary foods and general food categories to fire were evaluated in sagebrush (Artemisia tridentata ssp. vaseyana Beetle)-bitterbrush (Purshia tridentata Pursh.) communities with a randomized block design established in stands where shrub cover exceeded 35%. Within blocks, habitat response was evaluated for 2 growing seasons on 4 pots used as controls, 3 plots burned in November 1987, and 4 plots burned in March 1988. Fall burning increased (P < 0.05) frequency of taxa in the dandelion tribe (Cichorieae). Other primary foods, including microsteris (Microsteris gracilis Hook.), desert-parsley (Lomatium spp. Raf.), and ground-dwelling beetles (Scarabaeidae, Tenebrionidae) were not influenced by burning. Spring and fall burning increased (P < 0.05) total forte cover and diversity, but decreased (P < 0.05) sagebrush cover. Prescribed fire may increase the supply of forbs available to sage grouse in montane sagebrush habitats used for brood-rearing where shrubs dominate stands at the expense of the herbaceous component.