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      Society for Range Management, 2015-07
    • Stocking Rates and Vegetation Structure, Heterogeneity, and Community in a Northern Mixed-Grass Prairie

      Lwiwski, T. C.; Koper, N.; Henderson, D. C. (Society for Range Management, 2015-07)
      Currently, livestock management in the North American Great Plains aims for even use of forage, which creates a homogenous landscape. Reintroducing heterogeneity, defined here as the variation in vegetation structure and composition, to native North American rangelands is imperative to maintaining grassland biodiversity, and using a variety of cattle stocking rates on the landscape could accomplish this. We assessed effects of stocking rates on northern mixed-grass prairie vegetation structure, structural heterogeneity, and plant species diversity. The study took place in Grasslands National Park in Saskatchewan, Canada, using nine pastures (∼300 ha) that were grazed at a range of stocking rates from very low to very high for this region. Three of these pastures were ungrazed controls. We used generalized linear mixed models to describe effects of stocking rate on vegetation over 4 years, following the reintroduction of livestock grazing to this landscape after 15 years without grazing. We used a Mantel test to determine whether plant communities changed with varying stocking rates and over time. Effects of grazing on many response variables were cumulative and changed over time. Species richness in uplands increased with stocking rate and time, but richness decreased with stocking rate in lowlands. Heterogeneity generally increased with stocking rate and time in upland but not lowland habitats. While natural annual variability influenced many variables, the cumulative effects of grazing were still apparent. A variety of stocking rates could be used to maximize structural heterogeneity and provide a diversity of habitat structure at the landscape scale. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Restoration of Native Plants is Reduced by Rodent-Caused Soil Disturbance and Seed Removal

      Gurney, C. M.; Prugh, L. R.; Brashares, J. S. (Society for Range Management, 2015-07)
      Granivory and soil disturbance are two modes by which burrowing rodents may limit the success of native plant restoration in rangelands. This guild of animals has prolific effects on plant community composition and structure, yet surprisingly little research has quantified the impact of rodents on plant restoration efforts. In this study, we examined the effects of seed removal and soil disturbance by the giant kangaroo rat (Dipodomys ingens) on native plant restoration in a California rangeland. Using experimental exclosures and stratifying restoration plots on and off rodent-disturbed soil, we assessed the individual and combined effects of seed removal and soil disturbance on seedling establishment of four native plant species. Across all species, biotic soil disturbance by kangaroo rats reduced seedling establishment by 19.5% (range = 1-43%), whereas seed removal reduced seedling establishment by only 6.7% (range = 4-12%). Rates of seed removal across species weakly paralleled kangaroo rat dietary preferences. These results indicate the indirect effects of burrowing rodents such as kangaroo rats on native seedling establishment via changes in soil properties may rival or exceed the direct effects of seed removal. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Long-Term Trade-Offs among Herbage Growth, Animal Production, and Supplementary Feeding in Heavily Grazed Mediterranean Grassland

      Henkin, Z.; Ungar, E. D.; Perevolotsky, A.; Gutman, M.; Yehuda, Y.; Dolev, A.; Landau, S. Y.; Sternberg, M.; Seligman, N. G. (Society for Range Management, 2015-07)
      A 17-yr grazing trial was conducted in the eastern Galilee of Israel to quantify trade-offs among the responses of pasture and livestock productivity, duration of grazing, amount of supplementary feed, and profitability to higher stocking density during the growing season of a Mediterranean grassland. Treatments included two stocking densities and two grazing protocols. The stocking densities throughout the grazing period were 0.55 animal unit (AU)·ha-1, which is common in this region, and 1.1 AU·ha-1, which is considered high. The grazing protocols were continuous grazing throughout the grazing season and split-paddock grazing in which the herd grazed one subpaddock from the onset of grazing until the pasture was depleted, after which the herd was moved to the second ungrazed subpaddock. Under both protocols, heavier stocking density reduced standing biomass of the whole paddock at the end of the growing season by 43% and grazing duration during the subsequent dry season by 38% but increased the daily consumption of supplementary feed and the weaned live-weight production per unit area. Under continuous grazing the high stocking density of 1.1 AU·ha-1 was maintained throughout the grazing season for 17 consecutive yr with no detectable effect on productivity of the pasture, typical to the resilience of Mediterranean grasslands that have been grazed for thousands of years. The lower pasture biomass production was compensated by higher weaned calf production. At the current local prices, the heavier stocking density was close to the economically optimal stocking density for the pasture in the region. It is concluded that on Mediterranean grassland intensive use of the pasture with high stocking density during the growing season can be economically feasible in those cases where the feed requirement of the herd can be maintained throughout the growing season. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Litter Reduction by Prescribed Burning Can Extend Downy Brome Control

      Kessler, K. C.; Nissen, S. J.; Meiman, P. J.; Beck, K. G. (Society for Range Management, 2015-07)
      Downy brome (Bromus tectorum L.) is a highly successful invasive species primarily because it fills an open niche in native plant communities. It also produces large amounts of litter over time. We hypothesized that removing accumulated litter with a prescribed burn before applying herbicides would improve herbicide efficacy, extending the duration of control. In January 2012, two downy brome-infested sites were burned. In March 2012, postemergent applications of glyphosate, imazapic, and tebuthiuron were made in a split-plot design. Above-ground biomass was collected at 6, 18, and 27 months after treatment (MAT) to evaluate treatment effects. In nonburned areas, all herbicide treatments were similar to the control 27 MAT; however, burning combined with imazapic or tebuthiuron reduced downy brome biomass 27 MAT by 81% ± 4.6 SE and 84% ± 19.3 SE, respectively. Remnant species responded positively to burning and herbicide treatments. Native cool-season grass biomass increased after burning whereas native warm-season grass biomass increased following tebuthiuron treatments. The impact of litter on imazapic and tebuthiuron availability was also evaluated. Herbicide interception increased in a linear relationship with increasing litter. For every 50 g · m-2 increase in litter there was a 7% increase in the amount of herbicide intercepted, meaning that 75% of the applied herbicide was intercepted by 360 g · m-2 of litter. A simulated rainfall event of 5 mm, 7 days after application, removed a significant amount of herbicide. This indicates that in sites with surface litter, timely precipitation could be critical for herbicide efficacy; however, when burning was used to remove litter and was followed by herbicides with residual soil activity, downy brome control was extended. Due to downy brome's relatively short seed viability in the soil, extending herbicide efficacy to several years could help to reduce the soil seed bank. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Herd Size-Dependent Effects of Restricted Foraging Time Allowance on Cattle Behavior, Nutrition, and Performance

      Odadi, W. O.; Rubenstein, D. I. (Society for Range Management, 2015-07)
      We tested the influence of herd size on the effects of restricted foraging time on cattle (Bos indicus) foraging behavior, nutrition, and performance in a Kenyan savanna rangeland. Using a randomized block design, we compared weight gain, forage intake, diet selection, dietary crude protein (CP) and digestible organic matter (DOM), bite and step rates, distance travelled, and activity time budgets between steers allowed unlimited foraging time (DNG) in predator-free areas with those herded diurnally in predator-accessible areas in large (200 steers; LDG), medium (150 steers; MDG), or small (100 steers; SDG) herds and corralled at night. Daily weight gain was greater (P < 0.01) in DNG (0.61 kg) or SDG (0.56 kg) than in LDG (0.19 kg) or MDG (0.29 kg) but did not differ (P = 0.591 ) between DNG and SDG. Likewise, daily organic matter intake was greater (P < 0.05) in DNG (6.2 kg) or SDG (5.4 kg) than in LDG (3.7 kg) or MDG (3.7 kg) but did not differ (P = 0.288) between DNG and SDG. Grazing time was lower (P < 0.01) in DNG (42.2%) than in LDG (71.3%), MDG (72.2%), or SDG (69.5%), while the reverse was the case for ruminating and/or resting time (47.1%, 12.1%, 11.9%, and 10.3% in DNG, LDG, MDG, and SDG, respectively). Bite rate was lower in DNG (13.1 bites · min-1) than LDG (21.0 bites · min-1; P = 0.068), MDG (27.7 bites · min-1; P = 0.13) or SDG (26.2 bites · min-1; P = 0.007). However, diet selection, CP, DOM, step rate, and distance travelled did not differ among treatments. Our findings demonstrate subdued negative effects of restricted foraging time when cattle are herded diurnally in small-sized herds. Application of this strategy could reduce the need for eliminating wild carnivores to facilitate unrestricted foraging time for cattle. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Habitat Selection by Free-Ranging Bison in a Mixed Grazing System on Public Land

      Ranglack, D. H.; Du, Toit, J. T. (Society for Range Management, 2015-07)
      Domestic livestock have replaced bison (Bison bison) on almost all the remaining rangelands of North America. One of the few places where bison and cattle (Bos taurus) comingle on shared rangelands is in the Henry Mountains (HM) of southern Utah. Ranchers there are concerned, however, that bison are selecting the same grazing areas that are needed by cattle. We used global positioning system telemetry on bison across the entire HM rangeland to determine which habitats are most important for bison throughout the seasonal cycle. Sexual segregation was also measured (using the segregation coefficient, SC) to determine if bison bulls exert localized impacts by congregating in certain habitats separate from cow/calf groups. The HM bison exhibited low levels of sexual segregation for both the breeding (SC = 0.048) and nonbreeding seasons (SC = 0.112). We found bison habitat use to be diverse and dynamic, with bison grazing effects distributed widely across habitats throughout the seasonal cycle. Patches of grassland, whether naturally occurring or created through burning or mechanical treatments, were favored regardless of their distance to water. Our findings should assist ranchers and agency personnel in moving forward with the integrated management of free-ranging bison and cattle on the HM rangeland, with implications for bison conservation on public lands elsewhere in the United States. © 2015 The Authors.
    • Demographic Changes Drive Woody Plant Cover Trends - An Example from the Great Plains

      Berg, M. D.; Sorice, M. G.; Wilcox, B. P.; Angerer, J. P.; Rhodes, E. C.; Fox, W. E. (Society for Range Management, 2015-07)
      Woody plant encroachment - the conversion of grasslands to woodlands - continues to transform rangelands worldwide, yet its causes and consequences remain poorly understood. Despite this being a coupled human-ecological phenomenon, research to date has tended toward ecological aspects of the issue. In this paper, we provide new insight into the long-term relationships between human demographics and woody plant cover at the landscape scale. We used time-series aerial imagery and historical census data to quantify changes in population, land ownership patterns, and woody cover between 1937 and 2012 in three different settings in central Texas, USA. Woody cover closely paralleled population in a semi-urban watershed (R2 = 0.81) and two separate clusters of rural watersheds (R2 = 0.88 and 0.93), despite exhibiting very different directional trends over time in each setting. Woody cover also closely tracked average farm size in each rural watershed cluster (R2 = 0.57 and 0.90). These results highlight a tight coupling between demographic trends and the extent of woody plant cover. Such human factors may explain a great deal of woody plant cover patterns in other global rangeland systems with similar historical contexts and serve as a predictive proxy of landscape trends. Accordingly, policy recommendations should consider these demographic factors, and future woody plant encroachment research should explicitly include human dimensions. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • China's Rangeland Management Policy Debates: What Have We Learned?

      Gongbuzeren; Li, Y.; Li, W. (Society for Range Management, 2015-07)
      In China, three major rangeland management policies have caused dramatic social, economic, and ecological changes for pastoral regions in the past 30 yr: the Rangeland Household Contract Policy (RHCP), Rangeland Ecological Construction Projects (RECPs), and the Nomad Settlement Policy (NSP). The impacts of these policies are greatly debated. In this paper, we conduct a systematic review of academic perspectives on the impacts of the three policies and the causes of ineffective and negative effects. The findings demonstrate that academics increasingly report negative impacts of RHCP on the ecosystem, animal husbandry, pastoralist livelihoods, and pastoral society. An increasing number of scholars, although not the majority, attribute the negative impacts to improper policy itself rather than incomplete implementation. Regarding the RECPs, most academics believe that policies have improved the rangeland ecosystem but with obvious negative impacts on pastoralist livelihoods and pastoral society; they attribute the problems to incomplete policy implementation. For the NSP, most academics report positive impacts on pastoralist livelihoods and animal husbandry, although recent researchers have identified negative impacts on pastoral society and the ecosystem. Although they are not in the mainstream, more and more academics attribute the negative impacts to improper policy. Finally, we apply the concept of coupled social-ecological systems (SES) to further analyze the outcomes of these three policies and propose a more flexible and inclusive land tenure policy that recognizes the diverse local institutional arrangements; an integrated RECP framework that considers coadaptation between social and ecological systems; and facilitating voluntary choice in nomad settlement and developing innovative approaches to provide social services for pastoralists who would like to remain in pastoral areas. As these three policy approaches are applied in rangeland management and pastoral development worldwide, this paper may provide useful implications for future policy development in pastoral regions on a global scale. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Big Game and Cattle Influence on Aspen Community Regeneration Following Prescribed Fire

      Walker, S. C.; Anderson, V. J.; Fugal, R. A. (Society for Range Management, 2015-07)
      Aspen (Populus tremuloides Michx.) is a major component of Intermountain forest ecology and relies on periodic disturbance, such as prescribed fire, to perpetuate. On the Manti-LaSal National Forest in central Utah, both big game and cattle depend on forage growing on forested lands, which has contributed to intense conflict. Understanding the effects of browsers on recently burned aspen stands is critical to managing the regeneration of these communities. This study measured the effects of cattle and big game foraging on regenerating aspen communities. Three study sites were selected from a 142-ha prescribed burn conducted in an aspen-conifer stand on the Ferron District of the Manti-LaSal National Forest in 1989. Each of the three study sites was subdivided into four areas and randomly assigned one of the following treatments: big game and cattle exclusion (No Use), big game exclusion (Cattle Use), cattle exclusion (Big Game Use), and open access (Dual Use). Vegetation was sampled in 1991-1994, 1999, and 2005. Density, biomass, height, nested frequency, and cover of aspen suckers were measured. Nested frequency and cover were measured for all other species encountered. Aspen cover, density, and biomass showed a significant year-by-treatment interaction (P < 0.05). Aspen and understory regeneration responded similarly to No Use, Cattle Use, and Big Game Use. Dual Use resulted in lower (P < 0.05) aspen regeneration and more annual, weedy species in the understory. In 2005, Dual Use aspen cover (4%) was lower (P < 0.05) than the other three treatments: Big Game Use (25%), Cattle Use (31%), and No Use (34%). Controlled burning to regenerate aspen will be most successful under light stocking rates for both big game and cattle to allow suckers to develop beyond the browse line (>2 meters). © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.