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Recent Submissions

  • An Introduction and Practical Guide to Use of the Soil-Vegetation Inventory Method (SVIM) Data

    Barker, B.S.; Pilliod, D.S.; Welty, J.L.; Arkle, R.S.; Karl, M.G.,“Sherm”; Toevs, G.R. (Society for Range Management, 2018-11)
    Long-term vegetation dynamics across public rangelands in the western United States are not well understood because of the lack of large-scale, readily available historic datasets. The Bureau of Land Management's Soil-Vegetation Inventory Method (SVIM) program was implemented between 1977 and 1983 across 14 western states, but the data have not been easily accessible. We introduce the SVIM vegetation cover dataset in a georeferenced, digital format; summarize how the data were collected; and discuss potential limitations and biases. We demonstrate how SVIM data can be compared with contemporary monitoring datasets to quantify changes in vegetation associated with wildfire and the abundance of exotic invasive species. Specifically, we compare SVIM vegetation cover data with cover data collected by BLM's Assessment, Inventory, and Monitoring (AIM) program (2011–2016) in a focal area in the northern Great Basin. We address issues associated with analyzing and interpreting data from these distinct programs, including differences in survey methods and potential biases introduced by spatial and temporal variation in sampling. We compared SVIM and AIM survey methods at 44 plots and found that percent cover estimates had high correspondence for all measured functional groups. Comparisons between historic SVIM data and recent AIM data documented significant declines in the occupancy and cover of native shrubs and native perennial forbs, and a significant increase in exotic annual forbs. Wildfire was a driver of change for some functional groups, with greater change occurring in AIM plots that burned between the two time periods compared with those that did not. Our results are consistent with previous studies showing that many native shrub-dominated plant communities in the Great Basin have been replaced by exotic annuals. Our study demonstrates that SVIM data will be an important resource for researchers interested in quantifying vegetation change through time across public rangelands in the western United States.
  • Soil Health as a Transformational Change Agent for US Grazing Lands Management

    Derner, J.D.; Smart, A.J.; Toombs, T.P.; Larsen, D.; McCulley, R.L.; Goodwin, J.; Sims, S.; Roche, L.M. (Society for Range Management, 2018-07)
    There is rapidly growing national interest in grazing lands’ soil health, which has been motivated by the current soil health renaissance in cropland agriculture. In contrast to intensively managed croplands, soil health for grazing lands, especially rangelands, is tempered by limited scientific evidence clearly illustrating positive feedbacks between soil health and grazing land resilience, or sustainability. Opportunities exist for improving soil health on grazing lands with intensively managed plant communities (e.g., pasture systems) and formerly cultivated or degraded lands. Therefore, the goal of this paper is to provide direction and recommendations for incorporating soil health into grazing management considerations on grazing lands. We argue that the current soil health renaissance should not focus on improvement of soil health on grazing lands where potential is limited but rather forward science-based management for improving grazing lands’ resilience to environmental change via 1) refocusing grazing management on fundamental ecological processes (water and nutrient cycling and energy flow) rather than maximum short-term profit or livestock production; 2) emphasizing goal-based management with adaptive decision making informed by specific objectives incorporating maintenance of soil health at a minimum and directly relevant monitoring attributes; 3) advancing holistic and integrated approaches for soil health that highlight social-ecological-economic interdependencies of these systems, with particular emphasis on human dimensions; 4) building cross-institutional partnerships on grazing lands’ soil health to enhance technical capacities of students, land managers, and natural resource professionals; and 5) creating a cross-region, living laboratory network of case studies involving producers using soil health as part of their grazing land management. Collectively, these efforts could foster transformational changes by strengthening the link between natural resources stewardship and sustainable grazing lands management through management-science partnerships in a social-ecological systems framework.
  • Broom snakeweed (Gutierrezia sarothrae) Population Change in Central New Mexico: Implications for Management and Control

    Torell, L.A.; McDaniel, K.C.; Brown, J.R.; Torell, G.L. (Society for Range Management, 2018-03)
    This paper examines changes in broom snakeweed populations (Gutierrezia sarothrae [Pursh] Britt. & Rusby) from 1979 to 2014 at three prairie grassland sites in New Mexico. Data gathered each fall were used to study broom snakeweed population dynamics and to estimate the probability that the relatively short-lived subshrub will die off or invade blue grama (Bouteloua gracilis [H.B.K. Lag]) rangelands. Annual broom snakeweed standing crop data were used to categorize populations as None (< 100 kg ha− 1), Light (< 300), Moderate (< 750), or Heavy (≥ 750). Ordered logit regression was then used to estimate the frequency of transition between these categories over time depending on environmental and site factors. Significant variables found to influence annual variation in broom snakeweed included the broom snakeweed standing crop and density observed the previous period (+ effect for continued broom snakeweed); grass standing crop the previous period (−); rainfall received from April to June (+); and average temperatures during April (+) and June (−). The probability of broom snakeweed invading an area that is currently without the plant ranges from about 1% to > 40% depending on environmental conditions and the amount of grass standing crop present. Transition probability estimates were also used in a Monte Carlo simulation model to evaluate the economics of broom snakeweed control. The economics of chemical broom snakeweed control were most strongly related to the rate of snakeweed reinvasion on treated areas and to the probability of natural die-off if infested areas were not sprayed.
  • Weather-Centric Rangeland Revegetation Planning

    Hardegree, S.P.; Abatzoglou, J.T.; Brunson, M.W.; Germino, M.J.; Hegewisch, K.C.; Moffet, C.A.; Pilliod, D.S.; Roundy, B.A.; Boehm, A.R.; Meredith, G.R. (Society for Range Management, 2018-01)
    Invasive annual weeds negatively impact ecosystem services and pose a major conservation threat on semiarid rangelands throughout the western United States. Rehabilitation of these rangelands is challenging due to interannual climate and subseasonal weather variability that impacts seed germination, seedling survival and establishment, annual weed dynamics, wildfire frequency, and soil stability. Rehabilitation and restoration outcomes could be improved by adopting a weather-centric approach that uses the full spectrum of available site-specific weather information from historical observations, seasonal climate forecasts, and climate-change projections. Climate data can be used retrospectively to interpret success or failure of past seedings by describing seasonal and longer-term patterns of environmental variability subsequent to planting. A more detailed evaluation of weather impacts on site conditions may yield more flexible adaptive-management strategies for rangeland restoration and rehabilitation, as well as provide estimates of transition probabilities between desirable and undesirable vegetation states. Skillful seasonal climate forecasts could greatly improve the cost efficiency of management treatments by limiting revegetation activities to time periods where forecasts suggest higher probabilities of successful seedling establishment. Climate-change projections are key to the application of current environmental models for development of mitigation and adaptation strategies and for management practices that require a multidecadal planning horizon. Adoption of new weather technology will require collaboration between land managers and revegetation specialists and modifications to the way we currently plan and conduct rangeland rehabilitation and restoration in the Intermountain West.
  • Spectrophotometry of Artemisia tridentata to Quantitatively Determine Subspecies

    Richardson, B.A.; Boyd, A.A.; Tobiasson, T.; Germino, M.J. (Society for Range Management, 2018-01)
    Ecological restoration is predicated on our abilities to discern plant taxa. Taxonomic identification is a first step in ensuring that plants are appropriately adapted to the site. An example of the need to identify taxonomic differences comes from big sagebrush (Artemisia tridentata). This species is composed of three predominant subspecies occupying distinct environmental niches, but overlap and hybridization are common in ecotones. Restoration of A. tridentata largely occurs using wildland collected seed, but there is uncertainty in the identification of subspecies or mix of subspecies from seed collections. Laboratory techniques that can determine subspecies composition would be desirable to ensure that subspecies match the restoration site environment. In this study, we use spectrophotometry to quantify chemical differences in the water-soluble compound, coumarin. Ultraviolet (UV) absorbance of A. tridentata subsp. vaseyana showed distinct differences among A.t. tridentata and wyomingensis. No UV absorbance differences were detected between A.t. tridentata and wyomingensis. Analyses of samples from > 600 plants growing in two common gardens showed that UV absorbance was unaffected by environment. Moreover, plant tissues (leaves and seed chaff) explained only a small amount of the variance. UV fluorescence of water-eluted plant tissue has been used for many years to indicate A.t. vaseyana; however, interpretation has been subjective. Use of spectrophotometry to acquire UV absorbance provides empirical results that can be used in seed testing laboratories using the seed chaff present with the seed to certify A. tridentata subspecies composition. On the basis of our methods, UV absorbance values < 2.7 would indicate A.t. vaseyana and values > 3.1 would indicate either A.t. tridentata or wyomingensis. UV absorbance values between 2.7 and 3.1 would indicate a mixture of A.t. vaseyana and the other two subspecies.
  • Seedling Defoliation and Drought Stress: Variation in Intensity and Frequency Affect Performance and Survival

    Denton, E.M.; Smith, B.S.; Hamerlynck, E.P.; Sheley, R.L. (Society for Range Management, 2018-01)
    Our ability to restore rangelands is limited, and it is unknown if seedling herbivory on its own, or in interaction with other stressors, is a major contributor to restoration failure. To address this, we conducted two experiments: a No Defoliation (ND) experiment (n = 48), in which seedlings from three perennial grasses (crested wheatgrass [Agropyron cristatum {(L.} Gaertn.], bluebunch wheatgrass [Psuedoroegnaria spicata {Pursh} Á. Love], Sandberg bluegrass [Poa secunda J Presl]) were subjected to wet and dry water regimes for 4 mo, and a concurrent Defoliation (D) experiment (n = 95), in which seedlings were factorially assigned to two defoliation treatments—frequency (LOW, HIGH) and intensity (30% vegetation removal, 70% vegetation removal). Indicators of seedling performance were aboveground and belowground biomass (AGB and BGB), root:shoot ratio, tillering, and mortality. The effect size statistic, Hedge's g, allowed for comparisons between performance measures. Water stress induced reductions in most performance measures: BGB (g = ND: –1.3; D: –1.6), root:shoot ratio (g = ND: n.s.; D: –0.2), and tillering (g = ND: –1.7; D: –1.2), though not significantly for all species. For ABG, water stress interacted with defoliation, reducing performance less at an intensity of 70% (g = –2.0) as opposed to 30% (g = –3.0), but not always significantly in the former. Water stress also caused less reduction in AGB when no defoliation occurred (ND: –0.8; g = D: –2.5). Intensity and frequency of defoliation interacted; seedlings were generally resistant to reductions in performance except at high frequency, 70% defoliation. Agropyron cristatum and P. spicata displayed similar sensitivity to treatments, mostly in terms of changes in AGB and BGB, while P. secunda also experienced increased mortality and reduced tillering. If these differences in sensitivity result in differential survival, herbivory could impact species postrestoration population demographics.
  • Seasonal Timing of Fire Alters Biomass and Species Composition of Northern Mixed Prairie

    Vermeire, L.T.; Russell, M.L. (Society for Range Management, 2018-11)
    Fire plays a central role in influencing ecosystem patterns and processes. However, documentation of fire seasonality and plant community response is limited in semiarid grasslands. We evaluated aboveground biomass, cover, and frequency response to summer, fall, and spring fires and no fire on silty and clayey sites in semiarid, C3-dominated grassland. The magnitude of change in biomass between years was greater than any differences among fire treatments. Still, differences existed among seasons of fire. Summer fire reduced non-native annual forb frequency (3% vs. 10% ± 2%) and Hesperostipa comata, reduced native annual forbs the first year, increased Poa secunda and bare ground, and increased Vulpia octoflora the second year. Fall fire increased grass biomass (1224 vs. 1058 ± 56 kg ∙ ha− 1), but fall fire effects were generally similar to those of summer fire. Spring fire effects tended to be intermediate between no fire and summer and fall fire with the exception that spring fire was most detrimental to H. comata the first growing season and did not increase bare ground. All seasons of fire reduced litter, forb biomass, and frequency of Bromus japonicus and Artemisia spp., and they reduced H. comata, V. octoflora, and native annual forbs the first year, but increased basal cover of C3 perennial grasses (2.2% vs. 0.6% ± 0.4%). Fire during any season increased dominance of native species compared with no fire (6.6% vs. 2.0% ± 1.0% basal cover) and maintained productivity. Seasonal timing of fire manipulated species composition, but increased C3 perennial grass cover and native species dominance with fire during any season indicated that using fire was more important than the season in which it occurred. In addition, fire effects on the vegetation components tended to be counter to previously observed effects of grazing, suggesting fire and grazing may be complementary.
  • Longer-Term Evaluation of Revegetation of Medusahead-Invaded Sagebrush Steppe

    Davies, K.W.; Boyd, C.S. (Society for Range Management, 2018-05)
    Medusahead (Taeniatherum caput-medusae [L.] Nevski) and other exotic annual grasses have invaded millions of hectares of sagebrush (Artemisia L.) steppe. Revegetation of medusahead-invaded sagebrush steppe with perennial vegetation is critically needed to restore productivity and decrease the risk of frequent wildfires. However, it is unclear if revegetation efforts provide long-term benefits (fewer exotic annuals and more perennials). The limited literature available on the topic questions whether revegetation efforts reduce medusahead abundance beyond 2 or 3 yr. We evaluated revegetation of medusahead-invaded rangelands for 5 yr after seeding introduced perennial bunchgrasses at five locations. We compared areas that were fall-prescribed burned immediately followed by an imazapic herbicide treatment and then seeded with bunchgrasses 1 yr later (imazapic-seed) with untreated controls (control). The imazapic-seed treatment decreased exotic annual grass cover and density. At the end of the study, exotic annual grass cover and density were 2-fold greater in the control compared with the imazapic-seed treatment. The imazapic-seed treatment had greater large perennial bunchgrass cover and density and less annual forb (predominately exotic annuals) cover and density than the untreated control for the duration of the study. At the end of the study, large perennial bunchgrass density average 10 plant ∙ m− 2 in the imazapic-seed treatment, which is comparable with intact sagebrush steppe communities. Plant available soil nitrogen was also greater in the imazapic-seed treatment compared with the untreated control for the duration of the study. The results of this study suggest that revegetation of medusahead-invaded sagebrush steppe can provide lasting benefits, including limiting exotic annual grasses.
  • Insights from Long-Term Ungrazed and Grazed Watersheds in a Salt Desert Colorado Plateau Ecosystem

    Duniway, M.C.; Geiger, E.L.; Minnick, T.J.; Phillips, S.L.; Belnap, J. (Society for Range Management, 2018-07)
    Dryland ecosystems cover over 41% of the earth's land surface, and living within these important ecosystems are approximately 2 billion people, a large proportion of whom are subsistence agropastoralists. Improper grazing in drylands can negatively impact ecosystem productivity, soil conservation, hydrologic processes, downstream water quantity and quality, and ultimately human health and economic well-being. Concerns regarding the degraded state of western US rangelands in the 1950s resulted in an interagency committee to study the effects of land use on runoff and erosion processes. In 1953, a federal research group established four paired watersheds in western Colorado to study the interaction of grazing by domestic livestock, runoff, and sediment yield. Exclusion of livestock from half of the watersheds dramatically reduced runoff and sediment yield after the first 10 yr—primarily due to changes in ground cover but not vegetation. Here, we report results of repeated soils and vegetation assessments of the experimental watersheds after more than 50 yr of grazing exclusion. Results show that many of the differences in soil conditions between grazed and ungrazed watersheds observed in the 1950s and 1960s were still present in 2004, despite reduced numbers of livestock: few differences in vegetation cover but large differences in biological soil crusts, soil stability, soil compaction, and soil biogeochemistry. There were differences among soil types in response to grazing history, especially soil lichen cover and soil organic matter, nitrogen, and sodium. Comparisons of ground cover measured in 2004 with those measured in 1953, 1966, and 1972 suggest much of the differences between grazed and ungrazed watersheds likely were driven by high sheep numbers during droughts in the 1950s. Persistence of these differences, despite large reductions in stocking rates, suggest the combination of overgrazing and drought may have pushed these salt desert ecosystems into a persistent, degraded ecological state.
  • Influence of Land-Use Legacies Following Shrub Reduction and Seeding of Big Sagebrush Sites

    Monaco, T.A.; Jones, A.; Pendergast, M.; Thacker, E.T.; Greenhalgh, L. (Society for Range Management, 2018-11)
    Big sagebrush (Artemisia tridentata Nutt.) plant communities often require management to reduce shrub density and rehabilitate understory vegetation. We studied vegetation responses to a two-way chain harrow treatment and broadcast seeding of 12 herbaceous species at eight Wyoming big sagebrush (A. tridentata Nutt. subsp. wyomingensis Beetle & Young) sites. These sites differed in land-use history; five were cultivated for dryland wheat production during the 1950 − 1980s and then seeded with introduced forage grasses (C-S), while three had not been exposed to this land-use legacy (non C-S). Our objective was to evaluate whether the C-S legacy influences the magnitude of vegetation change following contemporary treatment. Before treatment, C-S sites had lower sagebrush cover, higher dead sagebrush cover, and higher broom snakeweed (Gutierrezia sarothrae [Pursh] Britton & Rusby) cover than adjacent non C-S sites. Plant community change 3 years after treatment, determined with multivariate ordination analysis of species composition, varied between site histories, and response to treatment was most strongly correlated with reductions in sagebrush cover, increases in perennial grasses, and increases in 10 other herbaceous species—including some undesirable species and four that were seeded in 2010. Five years after treatment, mature sagebrush cover remained reduced for both land-use histories, yet density of sagebrush seedlings and broom snakeweed increased in C-S sites during the second and third years after treatment. In addition, perennial forb cover increased for C-S sites, while perennial grass biomass increased for non C-S sites. Our results emphasize that broad variability in plant community responses to sagebrush reduction and seeding is possible within the same ecological site classification and that legacy effects due to the combination of past cultivation and seeding should be considered when planning restoration projects, including the consideration that seeding may not always be necessary on C-S sites.
  • Incorporating Seeds in Activated Carbon Pellets Limits Herbicide Effects to Seeded Bunchgrasses When Controlling Exotic Annuals

    Davies, K.W. (Society for Range Management, 2018-05)
    Revegetation of exotic annual grass − invaded rangeland with preemergent herbicides is challenging because seeding is delayed until herbicide toxicity has diminished, but at this time, exotic annuals can be reinvading. Incorporating seeds into activated carbon pellets may allow seeding to occur at the same time as exotic annuals are controlled with a preemergent herbicide because activated carbon can neutralize the herbicide in the microsite around seeds. I evaluated using activated carbon pellets with six species seeded at the same time imazapic was applied to control exotic annual grasses at two sites. Two of the six species establish enough at one site to evaluate the effects of pellets. These two bunchgrasses had greater density and growth (height, leaf length, number of stems and leaves) when incorporated into activated carbon pellets compared with seeded as bare seed. This demonstrates activated carbon pellets can be used to protect seeded bunchgrasses from imazapic applied to control exotic annuals.
  • Factors Affecting Efficacy of Prescribed Fire for Western Juniper Control

    Clark, P.E.; Williams, C.J.; Pierson, F.B. (Society for Range Management, 2018-05)
    Western juniper (Juniperus occidentalis Hook.) is a tree species occurring on 3.6 million ha in the northern Great Basin. This native species can be quite invasive, encroaching into sagebrush-grassland vegetation, forming woodlands, and dominating extensive landscapes. Control of encroaching juniper is often necessary and important. Efficacy of prescribed fire for western juniper control depends on many factors for which our understanding is still quite incomplete. This knowledge gap makes fire management planning for western juniper control more difficult and imprecise. Natural resource managers require a fire efficacy model that accurately predicts juniper mortality rates and is based entirely on predictors that are measurable prefire. We evaluated efficacy models using data from a fall prescribed fire conducted during 2002 in southwestern Idaho on mountain big sagebrush (Artemisia tridentata Nutt. ssp. vaseyana [Rydb.] Beetle) rangelands with early to midsuccessional juniper encroachment. A logistic regression model, which included vegetation cover type, tree height, fire type, and bare ground as predictors, accurately predicted (area under the receiver operating characteristic [ROC] curve [AUC] = 0.881 ± 0.128 standard deviation [SD]) the mortality rate for a random sample of western juniper trees marked and assessed prefire and 5 yr post fire. Trees occurring in an antelope bitterbrush (Purshia tridentata [Pursh] DC.) type, which had a heavy fuel load, were 8 times more likely to be killed by fire than trees in a mountain big sagebrush type, where loading was typically lighter. Probability of mortality decreased by 28.8% for each 1-meter increase in tree height. Trees exposed to head fire were 3 times as likely to be killed as those exposed to backing fire. Findings from this case study suggest that with just four factors which are readily quantifiable prefire, managers can accurately predict juniper mortality rate and thus make better informed decisions when planning prescribed fire treatments.
  • Establishment and Trends in Persistence of Selected Perennial Cool-Season Grasses in Western United States

    Rigby, C.W.; Jensen, K.B.; Creech, J.E.; Thacker, E.T.; Waldron, B.L.; Derner, J.D. (Society for Range Management, 2018-11)
    Restoring western US rangelands from a site dominated by invasive annuals, such as cheatgrass and medusahead, to a diverse, healthy, perennial plant − dominated ecosystem can be difficult with native grasses. This study describes the establishment and trends in persistence (plant/m2) of native grass cultivars and germplasm compared with typically used crested and Siberian wheatgrasses at four locations in Idaho (one), Wyoming (one), and Utah (two) that range in mean average annual precipitation (MAP) from 290 to 415 mm. Sites were cultivated and fallowed 1 yr before planting using two glyphosate applications to control weeds. We monitored seedling establishment of 10 perennial cool-season grass species and plant persistence over 5 yr. Precipitation during the seeding year varied with the Utah sites locations reviving below MAP (4% and 14%), while the Wyoming and Idaho sites received above MAP at 8% and 26%, respectively. Across these four sites, native grass seedling establishment of bottlebrush squirreltail (29 ± 0.08 [standard error] seedling/m2), bluebunch (28 ± 0.05), slender (30 ± 0.05), and Snake River wheatgrasses (28 ± 0.08) was similar to “Vavilov II” Siberian wheatgrass (36 ± 3.20). By yr 5, western, Snake River, and thickspike wheatgrasses were the only native grasses to have plant densities similar to Vavilov II (37 ± 0.29) Siberian and “Hycrest II” (36 ± 0.29) crested wheatgrasses. On sites receiving between 290 and 415 mm MAP, our data suggest that native grasses are able to establish but in general lack the ability to persist except for western, Snake River, and thickspike wheatgrasses, which had plant densities similar to crested and Siberian wheatgrasses after 5 yr.
  • Evaluating a Seed Technology for Sagebrush Restoration Across an Elevation Gradient: Support for Bet Hedging

    Davies, K.W.; Boyd, C.S.; Madsen, M.D.; Kerby, J.; Hulet, A. (Society for Range Management, 2018-01)
    Big sagebrush (Artemisia tridentata Nutt.) restoration is needed across vast areas, especially after large wildfires, to restore important ecosystem services. Sagebrush restoration success is inconsistent, with a high rate of seeding failures, particularly at lower elevations. Seed enhancement technologies may overcome limitations to restoration success. Seed pillows are one such technology designed to improve seed-soil contact in broadcast seedings by providing a favorable medium for seedling establishment and growth. Seed pillows have shown promising results in greenhouse studies; however, they have not been evaluated in the field. We compared broadcast-seeding seed pillows with broadcast-seeding bare seed in 2 yr across a large, burned elevation gradient. Compared with bare seed, we found no evidence that seed pillows improved sagebrush establishment and growth across the elevation gradient. Though our results suggest that seed pillows do not increase the likelihood of successful sagebrush restoration, they were successful at times when bare seeds were not, and the same was true for bare seeds. At least one of the two treatments was successful at 50% of the elevations over the 2 seeding yr. This suggests that a bet hedging approach, seeding both bare seed and seed pillows, may increase the probability of success. Further supporting the use of bet hedging, if both methods were used and seeding occurred in both years, success would have been 86%. Sagebrush density and cover varied by elevation. In the first-yr seeding, sagebrush density and cover generally increased with increasing elevation. In the second-yr seeding, sagebrush density and cover were greatest at the lowest and highest elevations. We speculate that at the lower elevations an unusually wet spring combined with limited herbaceous vegetation provided an ideal environment for sagebrush establishment and growth. Our results also demonstrate, counter to common assumptions, that lower elevations sagebrush seedings can be successful.
  • Eighty Years of Grazing by Cattle Modifies Sagebrush and Bunchgrass Structure

    Davies, K.W.; Boyd, C.S.; Bates, J.D. (Society for Range Management, 2018-05)
    Grazing by cattle is ubiquitous across the sagebrush steppe; however, little is known about its effects on sagebrush and native bunchgrass structure. Understanding the effects of long-term grazing on sagebrush and bunchgrass structure is important because sagebrush is a keystone species and bunchgrasses are the dominant herbaceous functional group in these communities. To investigate the effects of long-term grazing on sagebrush and bunchgrass structure, we compared nine grazing exclosures with nine adjacent rangelands that were grazed by cattle in southeast Oregon. Grazing was moderate utilization (30 − 45%) with altering season of use and infrequent rest. Long-term grazing by cattle altered some structural aspects of bunchgrasses and sagebrush. Ungrazed bunchgrasses had larger dead centers in their crowns, as well as greater dead fuel depths below and above the crown level compared with grazed bunchgrasses. This accumulation of dry fuel near the meristematic tissue may increase the probability of fire-induced mortality during a wildfire. Bunchgrasses in the ungrazed treatment had more reproductive stems than those in the long-term grazed treatment. This suggests that seed production of bunchgrasses may be greater in ungrazed areas. Sagebrush height and longest canopy diameter were 15% and 20% greater in the ungrazed compared with the grazed treatment, respectively. However, the bottom of the sagebrush canopy was closer to the ground in the grazed compared with the ungrazed treatment, which may provide better hiding cover for ground-nesting avian species. Sagebrush basal stem diameter, number of stems, amount of dead material in the canopy, canopy gap size, and number of canopy gaps did not differ between ungrazed and grazed treatments. Moderate grazing does not appear to alter the competitive relationship between a generally unpalatable shrub and palatable bunchgrasses. Long-term, moderate grazing appears to have minimal effects to the structure of bunchgrasses and sagebrush, other than reducing the risk of bunchgrass mortality during a fire event.
  • Diverse Management Strategies Produce Similar Ecological Outcomes on Ranches in Western Great Plains: Social-Ecological Assessment

    Wilmer, H.; Augustine, D.J.; Derner, J.D.; Fernández-Giménez, M.E.; Briske, D.D.; Roche, L.M.; Tate, K.W.; Miller, K.E. (Society for Range Management, 2018-09)
    Experiments investigating grazing systems have often excluded ranch-scale decision making, which has limited our understanding of the processes and consequences of adaptive management. We conducted interviews and vegetation monitoring on 17 ranches in eastern Colorado and eastern Wyoming to investigate rancher decision-making processes and the associated ecological consequences. Management variables investigated were grazing strategy, grazing intensity, planning style, and operation type. Ecological attributes included the relative abundance of plant functional groups and categories of ground cover. We examined the environmental and management correlates of plant species and functional group composition using nonmetric multidimensional scaling and linear mixed models. After accounting for environmental variation across the study region, species composition did not differ between grazing management strategy and planning style. Operation type was significantly correlated with plant community composition. Integrated cow-calf plus yearling operations had greater annual and less key perennial cool-season grass species cover relative to cow-calf − only operations. Integrated cow-calf plus yearling ranches were able to more rapidly restock following drought compared with cow-calf operations. Differences in types of livestock operations contributed to variability in plant species composition across the landscape that may support diverse native faunal species in these rangeland ecosystems. Three broad themes emerged from the interviews: 1) long-term goals, 2) flexibility, and 3) adaptive learning. Stocking-rate decisions appear to be slow, path-dependent choices that are shaped by broader social, economic, and political dynamics. Ranchers described having greater flexibility in altering grazing strategies than ranch-level, long-term, annual stocking rates. These results reflect the complexity of the social-ecological systems ranchers navigate in their adaptive decision-making processes. Ranch decision-making process diversity within these environments precludes development of a single “best” strategy to manage livestock grazing.
  • Contrasting Effects of Long-Term Fire on Sagebrush Steppe Shrubs Mediated by Topography and Plant Community

    Mata-González, R.; Reed-Dustin, C.M.; Rodhouse, T.J. (Society for Range Management, 2018-05)
    The role of fire in restoration of sagebrush plant communities remains controversial mainly because of paucity of information from long-term studies. Here, we examine 15-year post-fire responses of big sagebrush (Artemisia tridentata ssp wyomingensis) and broom snakeweed (Gutierrezia sarothrae), the two most abundant native shrubs at the John Day Fossil Beds National Monument, a protected area in north-central Oregon, USA. Fire effects were studied along gradients of topography and community type through time post-burn. Community types were distinguished as brush, plots dominated by big sagebrush and woodland, plots with a significant presence of Western juniper (Juniperus occidentalis) trees. Fire reduced big sagebrush cover in brush plots up to 100% and in woodland plots up to 86%. Broom snakeweed cover declined by 92% and 73% in brush plots and woodland plots, respectively. Big sagebrush did not show signs of recovery 15 years after burning regardless of topography and community type while broom snakeweed populations were clearly rebounding and prospering beyond pre-burn levels. Our results showed that an area initially dominated by big sagebrush (cover of big sagebrush 10-20%, cover of broom snakeweed 2-4%) dramatically shifted to an area dominated by broom snakeweed (cover of big sagebrush < 1%, cover of broom snakeweed 5%) in brush-dominated plots. Our results indicated that brush-dominated plots at lower elevation and southern exposures are the least post-fire resilient. We also observed a declining population of big sagebrush on unburned areas, suggesting the lack of post-fire recovery on burned areas was perhaps a result of low seeding potential by extant populations. Although more years of observation are required, these data indicate that recovery time, the encroachment of opportunistic competing shrubs, and the initial condition of vegetation are essential considerations by land managers when prescribing fire in big sagebrush communities.
  • Collaborative Adaptive Rangeland Management Fosters Management-Science Partnerships

    Wilmer, H.; Derner, J.D.; Fernández-Giménez, M.E.; Briske, D.D.; Augustine, D.J.; Porensky, L.M. (Society for Range Management, 2018-09)
    Rangelands of the western Great Plains of North America are complex social-ecological systems where management objectives for livestock production, grassland bird conservation, and vegetation structure and composition converge. The Collaborative Adaptive Rangeland Management (CARM) experiment is a 10-year collaborative adaptive management (CAM) project initiated in 2012 that is aimed at fostering science-management partnerships and data-driven rangeland management through a participatory, multistakeholder approach. This study evaluates the decision-making process that emerged from the first 4 yr of CARM. Our objectives were to 1) document how diverse stakeholder experiences, epistemologies, and resulting knowledge contributed to the CARM project, 2) evaluate how coproduced knowledge informed management decision making through three grazing seasons, and 3) explore the implications of participation in the CARM project for rangeland stakeholders. We evaluated management decision making as representatives from government agencies and conservation nongovernmental organizations, ranchers, and interdisciplinary researchers worked within the CARM experiment to 1) prioritize desired ecosystem services; 2) determine objectives; 3) set stocking rates, criteria for livestock movement among pastures, and vegetation treatments; and 4) select monitoring techniques that would inform decision making. For this paper, we analyzed meeting transcripts, interviews, and focus group data related to stakeholder group decision making. We find two key lessons from the CARM project. First, the CAM process makes visible, but does not reconcile differences between, stakeholder experiences and ways of knowing about complex rangeland systems. Second, social learning in CAM is contingent on the development of trust among stakeholder and researcher groups. We suggest future CAM efforts should 1) make direct efforts to share and acknowledge managers’ different rangeland management experiences, epistemologies, and knowledge and 2) involve long-term research commitment in time and funding to social, as well as experimental, processes that promote trust building among stakeholders and researchers over time.
  • Can Sheep Control Invasive Forbs Without Compromising Efforts to Restore Native Plants?

    Masin, E.; Nelson, C.R.; Valliant, M.T. (Society for Range Management, 2018-03)
    Domestic sheep (Ovis aries) are increasingly being used to control non-native invasive plants in areas where restoration is a management goal. However, the efficacy of sheep grazing depends on both its potential for controlling undesirable plants and its ability to promote natives. To date, few studies have investigated impacts of sheep grazing on native forb recovery in North American grasslands. We assessed the impact of sheep on forbs by measuring the number of stems grazed before and after sheep foraged in western Montana, United States. Sheep grazed a higher percentage of non-native than native forbs (70% vs. 23%, respectively), and number of stems grazed was six times higher for non-natives than natives (48 vs. 5, respectively). Sheep preferentially selected the non-native forbs sulphur cinquefoil and yellow salsify over leafy spurge (fi = 2.075; fi = 0.969; fi = 0.969, respectively), as well as the native forbs white prairie aster (fi = 1.090) and blanketflower (fi = 1.000). Selection of native forbs was positively correlated with their pregrazing abundance and increased over the grazing period. Our findings indicate that when using sheep to control invasive forbs, appropriate timing and monitoring of grazing are critical for reducing nontarget impacts to native vegetation.
  • Appropriate Sample Sizes for Monitoring Burned Pastures in Sagebrush Steppe: How Many Plots are Enough, and Can One Size Fit All?

    Applestein, C.; Germino, M.J.; Pilliod, D.S.; Fisk, M.R.; Arkle, R.S. (Society for Range Management, 2018-11)
    Statistically defensible information on vegetation conditions is needed to guide rangeland management decisions following disturbances such as wildfire, often for heterogeneous pastures. Here we evaluate sampling effort needed to achieve a robust statistical threshold using > 2 000 plots sampled on the 2015 Soda Fire that burned across 75 pastures and 113 000 ha in Idaho and Oregon. We predicted that the number of plots required to generate a threshold of standard error/mean ≤ 0.2 (TSR, threshold sampling requirement) for plant cover within pasture units would vary between sampling methods (rapid ocular versus grid-point intercept) and among plot sizes (1, 6, or 531 m2), as well as relative to topography, elevation, pasture size, spatial complexity of soils, vegetation treatments (herbicide or seeding), and dominance by exotic annual or perennial grasses. Sampling was adequate for determining exotic annual and perennial grass cover in about half of the pastures. A tradeoff in number versus size of plots sampled was apparent, whereby TSR was attainable with less area searched using smaller plot sizes (1 compared with 531 m2) in spite of less variability between larger plots. TSR for both grass types decreased as their dominance increased (0.5–1.5 plots per % cover increment). TSR decreased for perennial grass but increased for exotic annual grass with higher elevations. TSR increased with standard deviation of elevation for perennial grass sampled with grid-point intercept. Sampling effort could be more reliably predicted from landscape variables for the grid-point compared with the ocular sampling method. These findings suggest that adjusting the number and size of sample plots within a pasture or burn area using easily determined landscape variables could increase monitoring efficiency and effectiveness.

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