• Tidal Suppression Negatively Affects Soil Properties and Productivity of Spartina densiflora Salt Marsh

      Jacobo, E. J.; Rodriguez, A. M.; Fariña, C. M.; Paggi, Y. (Society for Range Management, 2015-05)
      In order to intensify cattle utilization, embankments were constructed to avoid tidal ingressions in Samborombon Bay, Argentina, The objective of this study was to evaluate the effect of tidal suppression and cutting frequency of a salt marsh dominated by Spartina densiflora Brongn. Two paddocks of a commercial cow-calf operation farm, one prevented from tidal flooding and another exposed to overflow from natural tidal pattern (control), were the main plots of the nested design. The experiments were carried out during a dry (2008- 2009) and a wet growing season (2012-2013). Two defoliation frequencies, simulating light and moderate grazing pressure, were performed in the subplots nested within each main plot. Soil organic matter and N content were lower and soil structural instability index was much higher in the embankment than in the control treatment. Soil salinity during the dry growing season was higher in the embankment than in the control treatment. Bare soil was higher under embankment treatment and high defoliation frequency exacerbated this response. Relative contribution of Spartina densiflora was lower under embankment than control treatment and the changes of floristic composition depended on the growing season. Aboveground net primary production (ANPP) in the wet growing season was almost 70% higher than in the dry growing season. Embankment reduced ANPP and high defoliation increased ANPP with respect to low defoliation frequency in the control paddock, to a much higher extent in the wet season. Dry matter digestibility of S. densiflora was not affected by treatments. Crude protein was higher in control paddocks under high frequency. Our results showed that tidal suppression by embankment was not effective to increase productivity and forage value of S. densiflora saltmarsh but caused soil and structural changes that may negatively alter ecosystem processes of this vulnerable grassland of high importance for biodiversity conservation. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Success of Seeding Native Compared with Introduced Perennial Vegetation for Revegetating Medusahead-Invaded Sagebrush Rangeland

      Davies, K. W.; Boyd, C. S.; Johnson, D. D.; Nafus, A. M.; Madsen, M. D. (Society for Range Management, 2015-05)
      Millions of hectares of Wyoming big sagebrush (Artemisia tridentata Nutt. subsp. wyomingensis Beetle & Young) rangeland have been invaded by medusahead (Taeniatherum caput-medusae [L.] Nevski), an exotic annual grass that degrades wildlife habitat, reduces forage production, and decreases biodiversity. Revegetation of medusahead-invaded sagebrush plant communities is necessary to restore ecosystem services. Disagreement, however, exists over whether to seed native or introduced perennial species to revegetate communities after controlling medusahead. Though native species generally do not establish as well as introduced species, interference from co-seeded introduced species has often been attributed to the limited success of natives. The potential for seeding natives to revegetate communities after medusahead control is relatively unknown because they have been largely co-seeded with introduced species. We compared the results of seeding native and introduced perennial species after controlling medusahead with prescribed burning followed with an imazapic herbicide application at five sites. Perennial bunchgrass cover and density were 5- and 10-fold greater in areas seeded with introduced compared with native species 3 years post seeding. Furthermore, exotic annual grass cover and density were less in areas seeded with introduced compared with native species. Seeded introduced and native shrubs largely failed to establish. High perennial bunchgrass density (15 individuals · m-2) in areas seeded with introduced species in the third year post seeding suggests that the succession trajectory of these communities has shifted to becoming perennial dominated. Average perennial bunchgrass density of 1.5 individuals · m-2 with seeding native species will likely not limit medusahead and appears to already be converting back to exotic annual grass-dominated communities. These results suggest that seeding introduced compared with native species after medusahead control will likely be more successful. Our results also imply that if natives are selected to seed after medusahead control, additional resources may be necessary to recontrol medusahead and repeatedly sow native species. © 2015, Elsevier Inc. All rights reserved.
    • On-Ranch Grazing Strategies: Context for the Rotational Grazing Dilemma

      Roche, L. M.; Cutts, B. B.; Derner, J. D.; Lubell, M. N.; Tate, K. W. (Society for Range Management, 2015-05)
      Considerable debate remains over the efficacy of rotational grazing systems to enhance conservation and agricultural production goals on rangelands. We analyzed responses to grazing management questions in the Rangeland Decision Making Surveys of 765 California and Wyoming ranchers in order to characterize on-ranch grazing strategies and identify variables influencing strategy adoption. Two-thirds of respondents practice on-ranch rotational grazing strategies, indicating ranchers do experience benefits from rotation which have not been documented in experimental comparisons of rotational and continuous grazing systems. Limited on-ranch adoption of intensive rotational strategies (5% of respondents) indicates potential agreement between research and management perceptions about the success of this particular strategy for achieving primary livestock production goals. Over 93% of all rotational grazer respondents were characterized as using extensive intragrowing season rotation with moderate (few wk to mo) grazing period durations, moderate (2.4-8 ha·animal unit) livestock densities, and growing season rest periods. Variables associated with ranchers' grazing preferences included a mixture of human dimensions (goal setting, views on experiment and risk tolerance, information networks), ranch characteristics (total number of livestock, land types comprising ranch), and ecoregions. We also found that the majority of grazing systems research has largely been conducted at spatial and temporal scales that are orders of magnitude finer than conditions under which on-ranch adaptive grazing management strategies have been developed. Resolving the discrepancies between the grazing systems research and management knowledge base will require substantive communication and novel approaches to participatory research between scientists and managers. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Managing Medusahead (Taeniatherum caput-medusae) on Rangeland: A Meta-Analysis of Control Effects and Assessment of Stakeholder Needs

      James, J. J.; Gornish, E. S.; DiTomaso, J. M.; Davy, J.; Doran, M. P.; Becchetti, T.; Lile, D.; Brownsey, P.; Laca, E. A. (Society for Range Management, 2015-05)
      Invasive plant response to control efforts is strongly modified by site-specific factors, treatment timing, and environmental conditions following treatment, making management outcomes challenging to predict. Systematic reviews, which involve quantitative synthesis of data, can address this challenge by identifying general patterns of treatment effects across studies and quantifying the degree to which these effects vary. We conducted a systematic review of medusahead (Taeniatherum caput-medusae [L.] Nevski) control treatments that couples a meta-analysis on control data with an assessment of stakeholder needs to identify critical medusahead management knowledge gaps. With the meta-analysis we generated effect size estimates of how combinations of herbicide, burning, seeding, and grazing impacted medusahead on rangeland dominated by either annual or perennial vegetation. All combinations of treatments in both rangeland systems provided significant short-term control of medusahead, although treatment effects were highly transient on perennial rangeland, particularly for seeding treatments. Stakeholders listed grazing as a preferred management tool, and on annual rangeland an almost twofold reduction in medusahead abundance was achieved by timing high stocking rates to match phenological stages when medusahead was most susceptible to defoliation. Insufficient data were available to evaluate effects of grazing on medusahead on perennial rangeland. On the basis of these data and our stakeholder survey, four major information needs emerged, including the need to better understand 1) seedbank response to burning and herbicide treatments, 2) how to optimize grazing animal impacts on medusahead given ranch enterprise constraints, 3) costs and benefits of control and risk of practice failure, and 4) impacts of adaptive management treatments conducted on larger scales and at longer time intervals. Addressing these knowledge gaps should help overcome key ecological and economic barriers inhibiting implementation of medusahead and other invasive plant management programs on rangeland and provide a positive step toward conserving the critical ecosystem services these systems provide. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Long-Term Protection from Heavy Livestock Grazing Affects Ponderosa Pine Understory Composition and Functional Traits

      Strahan, R. T.; Laughlin, D. C.; Bakker, J. D.; Moore, M. M. (Society for Range Management, 2015-05)
      Making accurate predictions of plant community responses to grazing management is a major objective of rangeland ecology. Metrics such as species composition are site specific, whereas others such as functional groups and functional traits can be generalized across different rangeland types. We analyzed long-term (1912-1941) shifts in the understory community at five sites in a ponderosa pine (Pinus ponderosa P. & C. Lawson var. scopulorum Engelm.) forest when protected from heavy livestock grazing. We examined differences in total basal cover, species composition, species richness, functional group composition, and community-weighted mean (CWM) functional traits between heavily grazed and ungrazed areas in four time periods (1912, 1920, 1930, 1940). Total understory basal cover was greater in ungrazed than heavily grazed areas in 1920 but not in later time periods. Understory species composition diverged by 1930 and continued to differ in 1940. Functional group composition differed from 1920 onwards. In 1920 and 1930, C3 graminoids declined more in relative abundance in heavily grazed than ungrazed areas. By 1940, forbs accounted for much more of the cover in heavily grazed than ungrazed areas. During the study period, CWM specific leaf area and foliar Nmass declined by 8% and 11%, respectively, in ungrazed quadrats, while CWM leaf dry matter content increased 8%. Leaf traits, but not maximum height or seed mass, demonstrated consistent and predictable responses to protection from heavy grazing. Herbaceous understory species with leaf traits that allow for slower resource acquisition became more abundant in response to protection from heavy grazing. Our results indicate that managers should expect to observe more rapid changes in functional group composition and leaf functional traits than in species composition and species richness following protection from heavy livestock grazing. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Improving Cattle Nutrition on the Great Plains with Shrubs and Fecal Seeding of Fourwing Saltbush

      Kronberg S. L. (Society for Range Management, 2015-05)
      Two in vitro trials were conducted for estimates of dietary percentage of fourwing saltbush (Atriplex canescens; FS) or winterfat (Krascheninnikovia lanata; WF) for improved dietary digestibility when cattle graze mature cool-season grass. Three in vitro trials were conducted to estimate percentage of FS and WF seeds that could survive passage through the bovine gastro-intestinal tract (GIT) with potential for fecal seeding. Mixtures of FS and mature smooth bromegrass (Bromus inermis; SB) or WF and SB had greater apparent digestibility than SB alone (P < 0.0001). There were positive linear relationships (r2 ≥ 0.93) between the amount of each shrub in digested mixtures and digestibility. Similar relationships were observed with mixtures of FS and mature Altai wildrye (Leymus angustus). Germination of Dakota FS seeds in the first trial, incubated for 24 or 48 h, was 55% and 47%, respectively, with no difference in germination of seeds for the 24- and 48-h incubations (P = 0.26), but more seeds germinated if incubated versus not (P ≤ 0.002). Germination of Utah FS seeds, which were incubated for 24 or 48 h with high-, medium-, or low-quality forage, averaged 9% and 8%, respectively. Length of incubation, forage quality, and their interaction did not influence germination (P ≥ 0.45). Germination of nonincubated Utah FS seeds was 21% and greater than for incubated seeds (P = 0.004). Average germination of WF seeds was 0.6% and 0.1% for 24- and 48-h incubations, respectively, with incubation length, forage quality, and their interaction not significant (P ≥ 0.31). Nonincubated WF seeds had greater germination (42%) than incubated seeds (P < 0.0001). Results from the third trial were confirmatory for Dakota FS seed. FS and WF can improve diet quality of grazing cattle in late summer through winter, and some FS seeds have potential for fecal seeding. © 2015, Elsevier Inc. All rights reserved.
    • Drought Influences Control of Parasitic Flies of Cattle on Pastures Managed with Patch-Burn Grazing

      Scasta, J. D.; Engle, D. M.; Talley, J. L.; Weir, J. R.; Fuhlendorf, S. D.; Debinski, D. M. (Society for Range Management, 2015-05)
      We compared the influence of patch-burn grazing to traditional range management practices on abundance of the most economically injurious fly parasites of cattle. Horn flies (Haematobia irritans), face flies (Musca autumnalis), stable flies (Stomoxys calcitrans), and horse flies (Tabanus spp.) were assessed at study locations in Oklahoma and Iowa, USA, in 2012 and 2013. Experiments at both locations were spatially replicated three times on rangeland grazed by mature Angus cows. Grazing was year-long in Oklahoma and seasonal in Iowa from May to September. One-third of patch-burn pastures were burned annually, and traditionally managed pastures were burned completely in 2012 but not at all in 2013. Because of significant location effects, we analyzed locations separately with a mixed effects model. Horn flies and face flies were below economic thresholds with patch-burn grazing but at or above economic thresholds in unburned pastures in Iowa. Pastures in Iowa that were burned in their entirety had fewer horn flies but did not have fewer face flies when compared with no burning. There was no difference among treatments in horn fly or face fly abundance in Oklahoma pastures. Stable flies on both treatments at both locations never exceeded the economic threshold regardless of treatment. Minimizing hay feeding coupled with regular fire could maintain low stable fly infestations. Horse flies at both locations and face flies in Oklahoma were in such low abundance that treatment differences were difficult to detect or explain. The lack of a treatment effect in Oklahoma and variable year effects are the result of a drought year followed by a wet year, reducing the strength of feedbacks driving grazing behavior on pastures burned with patchy fires. Patch-burning or periodically burning entire pastures in mesic grasslands is a viable cultural method for managing some parasitic flies when drought is not a constraint. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Controls of Carrying Capacity: Degradation, Primary Production, and Forage Quality Effects in a Patagonian Steppe

      Golluscio, R. A.; Bottaro, H. S.; Oesterheld, M. (Society for Range Management, 2015-05)
      Rangeland carrying capacity depends on aboveground net primary production (ANPP) and on the sustainable harvest index (HIsust), the portion of ANPP that livestock can consume without undermining the production capacity of the system. At a regional scale, the observed harvest index (HIreal) increases with ANPP, but at a landscape scale the pattern is less clear, and controls of HIreal and HIsust are unknown. We analyzed the landscape patterns of variation of HIreal and HIsust across gradients of ANPP, pastoral value of vegetation (PV), and degradation. In 15 plots of a 2 753-ha paddock in a western Patagonian grass-shrub steppe, we estimated ANPP, consumption, forage pastoral value, and degradation. To estimate degradation we used PV weighed by forage cover because it was negatively correlated with a combination of ecosystem traits formerly linked to grazing-induced degradation. We calculated HIreal (consumption/ ANPP) and HIsust (consumption removing 40% of aerial biomass of the key species/ANPP). We choose Festuca pallescens as the key species because of its high abundance and moderate preference. As the paddock was grazed with low stocking rate to maximize among-plots selection, HIreal was lower than HIsust. As in regional models, HIsust and HIreal increased with ANPP within the paddock (R2 = 0.33 and 0.30, respectively). Multiple regressions showed that HIreal increased with ANPP and degradation, while HIsust increased with ANPP but decreased with degradation (R2 = 0.64 and 0.77, respectively). This suggests that at stocking rates lower than carrying capacity, sheep choose highly productive stands and, at a given level of ANPP, they prefer degraded stands. In contrast, carrying capacity increases with productivity and decreases with degradation. Management systems based on HIsust may result in severe biomass removal of species more preferred than the key species (Poa ligularis), and it is necessary to include strategies to preserve their individuals and populations. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.
    • Biological Soil Crust Response to Late Season Prescribed Fire in a Great Basin Juniper Woodland

      Warren, S. D.; St. Clair, L. L.; Johansen, J. R.; Kugrens, P.; Baggett, L. S.; Bird, B. J. (Society for Range Management, 2015-05)
      Expansion of juniper on U.S. rangelands is a significant environmental concern. Prescribed fire is often recommended to control juniper. To that end, a prescribed burn was conducted in a Great Basin juniper woodland. Conditions were suboptimal; fire did not encroach into mid- or late-seral stages and was patchy in the early-seral stage. This study evaluated the effects of the burn on biological soil crusts of early-seral juniper. Fire reduced moss cover under sagebrush and in shrub interspaces. Mosses were rare under juniper; their cover was unaffected there. Lichens were uncommon under juniper and sagebrush and therefore not significantly impacted there. Their cover was greater in shrub interspaces, but because the fire was spotty and of low intensity, the effects of burning were minimal. Compared with unburned plots, the biomass of cyanobacteria was diminished under juniper and sagebrush; it was reduced in the interspaces in both burned and unburned plots, presumably in response to generally harsher conditions in the postburn environment. Nitrogen fixation rates declined over time in juniper plots and interspaces but not in sagebrush plots. Although fire negatively affected some biological soil crust organisms in some parts of the early-seral juniper woodland, the overall impact on the crusts was minimal. If the intent of burning is to reduce juniper, burning of early-seral juniper woodland is appropriate, as most affected trees were killed. Control of sagebrush can likewise be accomplished by low-intensity, cool season fires without eliminating the crust component. Intense fire should be avoided due to the potential for greater encroachment into the shrub interspaces, which contain the majority of biological soil crust organisms. Burning early-seral juniper may be preferred for controlling juniper encroachment on rangeland. © 2015, Elsevier Inc. All rights reserved.
    • Anchor Chaining's Influence on Soil Hydrology and Seeding Success in Burned Piñon-Juniper Woodlands

      Madsen, M. D.; Zvirzdin, D. L.; Petersen, S. L.; Hopkins, B. G.; Roundy, B. A. (Society for Range Management, 2015-05)
      Broadcast seeding is one of the most commonly applied rehabilitation treatments for the restoration of burned piñon and juniper woodlands, but the success rate of this treatment is notoriously low. In piñon-juniper woodlands, postfire soil-water repellency can impair seeding success by reducing soil-water content and increasing soil erosion. Implementing anchor chaining immediately after seeding can improve establishment of seeded species by enhancing seed-to-soil contact and may improve restoration success by decreasing soil-water repellency through soil tillage. The objectives of this research were to 1) determine if anchor chaining in postfire pinyon-juniper woodlands diminishes soil-water repellency, and 2) determine meaningful relationships between soil-water repellency, unsaturated hydraulic conductivity [K(h)], and the establishment of seeded and invasive species. Research was conducted on two study sites, each located on a burned piñon-juniper woodland that had severe water repellency and that was aerially seeded. At each location, plots were randomly located in similar ecological sites of chained and unchained areas. At one location, anchor chaining considerably improved soil hydrologic properties, reducing the severity and thickness of the water-repellent layer, and increasing soil K(h) 2- to 4-fold in the first 2 yr following treatment. At this same location, anchor chaining increased perennial grass cover 16-fold and inhibited annual grass and annual forb cover by 5- and 7-fold, respectively. Results from the second site only showed improvements in soil K(h); other hydrologic and vegetative treatment responses were not significantly improved. Overall, this research suggests that anchor chaining has the potential to improve restoration outcomes, though additional research is warranted for understanding the direct impact of anchor chaining on soil-water repellency without the interaction of a seeding treatment. © 2015, Elsevier Inc. All rights reserved.
    • Alternative Rangeland Management Strategies and the Nesting Ecology of Greater Prairie-Chickens

      McNew, L. B.; Winder, V. L.; Pitman, J. C.; Sandercock, B. K. (Society for Range Management, 2015-05)
      Population declines of grassland birds over the past 30 yr have followed the widespread implementation of intensive rangeland management practices that create homogenous grassland habitats. Patch-burn grazing (PBG) was tested as an alternative management technique that is ecologically similar to historically heterogeneous fire and grazing regimes and holds promise as a rangeland management tool that may benefit grassland wildlife. We conducted a 3-year study to compare nest-site selection and nest survival of greater prairie-chickens, an umbrella species for tallgrass prairie conservation, on private lands managed with PBG or intensive fire and grazing in the Flint Hills of Kansas. The goal of our field study was to evaluate the relationships among rangeland management practices, habitat conditions, and nesting ecology of greater prairie-chickens. Nest-site selection and nest survival of prairie-chickens were both directly related to vertical nesting cover, which was determined by the fire return interval of a pasture. Nesting habitat was affected little by stocking rate in PBG management regimes because preferred nest sites were unburned patches that were not grazed by cattle. Overall, the quantity and quality of nesting sites was improved under PBG management when compared with more intensive rangeland management regimes. Our results join a growing body of evidence that rangeland management strategies that mimic historical heterogeneous fire and grazing regimes benefit native species of prairie wildlife. © 2015 Society for Range Management. Published by Elsevier Inc. All rights reserved.