• Group size effects on grazing behaviour and efficiency in sheep

      Sevi, A.; Casamassima, D.; Muscio, A. (Society for Range Management, 1999-07-01)
      Two grazing trials were conducted during early winter (January 1996) and spring (April 1996) to evaluate the effect of group size on grazing efficiency and behaviour of sheep. Three treatments were tested, large (LG), medium (MG) and small group size (SG), with 2 replicates for each treatment of 12, 9, and 6 ewes, respectively. Groups were homogeneous for age and weight. Paddock size furnished 10 m(2) per sheep per day. Group size did not affect grazing efficiency and herbage intake in the winter, but in the spring, when herbage mass was more plentiful, the ewes in the small groups grazed shorter, had a lower herbage intake and a less efficient use of forage. Consequently, the sheep in the small groups gained less weight than those in the large groups in spring. Neither group size nor seasonal changes in forage quantity or quality influenced sheep selectivity. These results suggest that the choice of a proper flock size at pasture can play a major role in optimizing grazing efficiency in sheep, especially when feeding is largely based on grazing, as generally occurs in countries of the Mediterranean basin in spring. Under the conditions of this study, our results indicate that a flock size of more than 6 sheep should be used for studies on sheep grazing behaviour.
    • Livestock-guarding dogs in Norway Part II: Different working regimes

      Hansen, I.; Smith, M. E. (Society for Range Management, 1999-07-01)
      Livestock-guarding dogs are an effective way of protecting rangeland sheep from predators. However, open mountain/forest range and widely ranging sheep are factors that may make adaptation to Norwegian conditions difficult. This paper focuses on the dogs' working patterns and effectiveness under different working regimes. A 3,500 ha. unfenced forest/mountain range pasture in bear habitat comprised the research area in which 624 sheep from 2 herds grazed. The field trial lasted 3 months, and a total of 10 Great Pyrenees participated for various time intervals. Three different working regimes were evaluated. 1) loose dogs without the command of a dog handler (Method A); 2) loose dogs under the command of a dog handler (Method B); and 3) loose dogs guarding sheep inside a fenced, 1 km(2) forest pasture (Method C). Nocturnal behavioural activity patterns and data on predation were recorded. Method A proved too uncontrolled for Norwegian conditions, because sheep dispersed too widely and dogs ranged too far, causing conflicts in nearby settlements with wildlife, and with livestock. Pasture dogs (C) were > 3 times less active and were engaged in guarding activities < 50% as often as patrol dogs (B). However, they barked > 15 times more frequently, and no sheep carcasses were found inside the fence. Therefore, Method C probably had the best preventive effect.
    • Pericarp removal has little effect on sagebrush seeds

      Bai, Y.; Hardegree, S. P.; Booth, D. T.; Roos, E. E. (Society for Range Management, 1999-07-01)
      Sagebrush (Artemisia) is commonly recommended for reclamation and restoration of shrublands of the Western United States and seeds are usually obtained from commercial sources. One result of commercial seed processing is the removal of the pericarp. We tested 2 seedlots of Wyoming big sagebrush (A. tridentata Nutt. ssp. wyomingensis Beetle &Young) to determine if pericarp removal affected properties of seed hydration or seed germ inability under different levels of water stress. In general, pericarp removal had a relatively minor effect on these processes and properties.
    • Reclaiming Russian knapweed infested rangeland

      Benz, L. J.; Beck, K. G.; Whitson, T. D.; Koch, D. W. (Society for Range Management, 1999-07-01)
      Russian knapweed [Acroptilon repens (L.) DC.] is a creeping, perennial, unpalatable, noxious weed that infests thousands of rangeland and pasture hectares in the western U.S. often forming monocultures. Chemical or mechanical control of Russian knapweed usually is temporary allowing re-invasion or the weed over time. Our objective was to determine whether combining chemical or mechanical methods with seeding of perennial grasses would reclaim Russian knapweed infested areas more effectively than any of the treatments applied alone. Five suppression treatments combined with 5 seeded perennial grasses were evaluated to reclaim Russian knapweed infested site. Two years after suppression treatments were done, clopyralid + 2,4-D + seeded grasses controlled 66 to 93% or Russian knapweed whereas clopyralid + 2,4-D applied alone controlled only 7% of Russian knapweed. Glyphosate + 'Critana' thickspike wheatgrass [Elymus lanceolatus (Scribn. & Sm.) Gould] controlled 36% of Russian knapweed 2 years after treatment (YAT) while glyphosate + 'Hycrest' crested wheatgrass [Agropyron cristatum (L.) Gaertn.], 'Bozoisky' Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], or 'Sodar' streambank wheatgrass [Elymus lanceolatus (Scribn. &Sm.)] increased Russian knapweed growth 1.5, 2, and 1.6-fold, respectively. Glyphosate applied alone tripled Russian knapweed growth. Metsulfuron + streambank wheatgrass controlled 61% of Russian knapweed 2 years after treatments were applied while metsulfuron applied alone controlled 40% of Russian knapweed. Mowing was ineffective and mowing + crested wheatgrass increased Russian knapweed growth about 2-fold. Clopyralid + 2,4-D + streambank wheatgrass yielded 6, 48, and 18 times more seeded grass than metsulfuron treated, mowed, or non-treated control plots seeded with streambank wheatgrass. Clopyralid + 2,4-D + stream-bank wheatgrass, while expensive (262 ha(-1)), was the best treatment combination because it controlled Russian knapweed effectively while the sod-forming grass established well and helped to prevent re-invasion by the weed.
    • Response of white-tailed deer foods to discing in a semiarid habitat

      Fulbright, T. E. (Society for Range Management, 1999-07-01)
      Discing strips of rangeland to increase wildlife foods is a common management practice. I tested the hypotheses (1) annual discing results in greater canopy cover of annual forbs preferred by white-tailed deer (Odocoileus virginianus Raf.) than discing at less frequent intervals of time, (2) frequent discing reduces the abundance of preferred perennial forbs, and (3) discing only once results in greater total canopy cover of annual and perennial forbs preferred by deer. The experimental design was a split-plot with soil series (Ramadero loam or Delfina fine sandy loam) as main plots and discing treatment in October as subplots. Discing treatments were (1) no treatment (control); (2) discing once in 1990; (3) discing once in 1994; (4) discing in 1990 and 1994; (5) discing in 1990, 1992, and 1994; and (6) discing annually from 1990-1994. Discing increased canopy cover of annuals preferred by white-tailed deer and increased canopy cover of unpalatable forbs, but decreased preferred perennials. Canopy cover of forbs eaten, but not preferred by deer, increased following discing. Based on these results, soil disturbance by discing is not recommended as a habitat improvement practice in the semiarid western Rio Grande Plains of Texas if the objective of management is to increase canopy cover of forb preferred by white-tailed deer.
    • Responses of winterfat seeds and seedlings to desiccation

      Hou, J. Q.; Romo, J. T.; Bai, Y.; Booth, D. T. (Society for Range Management, 1999-07-01)
      Winterfat [Krascheninnikovia lanata (Gueldenstaedt) syn. Ceratoides lanata (Pursh) J.T. Howell, syn. Eurotia lanata (Pursh) Moq.] is a native shrub of mixed prairie of North America. A large portion of hydrated seeds and seedlings can be killed when exposed to seedbed desiccation. Winterfat seeds and young seedlings subjected to varying levels of desiccation were studied to measure the influence of this stress. Germination was unaffected (P > 0.05) when seeds were exposed for 0 to 10 hydration-desiccation cycles (2 hours hydration and 22 hours desiccation cycle(-1) at 20 to 30% relative humidity and 20 degrees C). Linear increases in germination rate (0.6% day(-1) hydration-desiccation cycle(-1)), seedling length (0.1 mm hydration-desiccation cycle(-1)), and seed decay (1.5% hydration-desiccation cycle(-1) occurred with an increasing number of hydration-desiccation cycles. Seedling survival following desiccation decreased 10.4% mm(-1) as seedling length increased from < 2 mm to 10-15 mm. Seedling survival was positively correlated with relative humidity and negatively correlated with duration of desiccation. The difference (P < or = 0.05) in survival between 0 and 90% relative humidity was 62% for seedlings 4-6-mm in length and 70% for seedlings 9-11-mm in length. Seedlings from seeds that germinated rapidly were more tolerant of desiccation than those from seeds germinating slowly. After desiccation in 30% relative humidity, survival of seedlings from seeds germinating on the first day of incubation was 40% greater than those from seeds germinating on the third day of incubation. Electrolyte leakage indicated that desiccation damaged cells. Establishment of winterfat seedlings will be favored by seedbed conditions that protect seedlings from severe and prolonged desiccation and allow fast entry of the radicle into soil.
    • Sagebrush response to ungulate browsing in Yellowstone

      Wambolt, C. L.; Sherwood, H. W. (Society for Range Management, 1999-07-01)
      Big sagebrush (Artemisia tridentata Nutt.) declined from ungulate browsing during the first half of the twentieth century on the Northern Yellowstone Winter Range. It was our objective to compare shrub parameters of Northern Yellowstone Winter Range sagebrush habitat types continually browsed or protected for 32 to 37 years. Measurements were taken in and out of exclosures for 19 environmentally paired, protected, and browsed sites. We found significant differences in development between protected and browsed shrubs. Big sagebrush canopy cover at the 19 sites averaged 19.7% with protection and 6.5% where browsed (P less than or equal to 0.0027), and plants were twice as numerous (P less than or equal to 0.0027) under protection. Winter forage production of individual big sagebrush plants was also greater under protection at 16 of the 19 paired sites (P less than or equal to 0.0027). Subdominant sprouting shrubs generally responded the same as big sagebrush. This ungulate induced decline of shrubs has implications for many Northern Yellowstone Winter Range values. Ultimately many organisms are sacrificed with the loss of quality big sagebrush habitat.
    • Viewpoint: Benefits and impacts of wildlife water developments

      Rosenstock, S. S.; Ballard, W. B.; DeVos, J. C. (Society for Range Management, 1999-07-01)
      Resource managers in the western United States have long assumed that water was a key limiting factor on wildlife populations in arid habitats. Beginning in the 1940s-1950s, state and federal resource management agencies initiated water development programs intended to benefit game species and other wildlife. At least 5,859 such developments have been built in 11 western states. Most state wildlife management agencies in the western United States have ongoing wildlife water development programs that vary greatly in extent. Ranchers and range managers also have developed water sources for livestock, many of which also are used by wildlife. Recently, critics have suggested that wildlife water developments have not yielded expected benefits, and may negatively impact wildlife by increasing predation, competition, and disease transmission. Based upon a comprehensive review of scientific literature, we conclude that wildlife water developments have likely benefitted many game and non-game species, but not all water development projects have yielded expected increases in animal distribution and abundance. Hypothesized negative impacts of water developments on wildlife are not supported by data and remain largely speculative. However, our understanding of both positive and negative effects of wildlife water developments is incomplete, because of design limitations of previous research. Long-term, experimental studies are needed to address unanswered questions concerning the efficacy and ecological effects of water developments. We also recommend that resource managers apply more rigorous planning criteria to new developments, and expand monitoring efforts associated with water development programs.