• Designing Perpetual Conservation Agreements for Land Management

      Rissman, Adena R. (Society for Range Management, 2010-03-01)
      Conservation initiatives on working ranches balance flexibility for land management with restrictions to ensure protection over time. Conservation easements are a common tool for range conservation, but the perpetual nature of their individually negotiated rights and restrictions may present a challenge for adaptive land management. The evolution of conservation easement approaches to land management was addressed in a review of 52 grazing easements created by The Nature Conservancy (TNC) in California rangelands between 1973 and 2006 as well as through interviews with TNC staff. Easement terms related to land management increased in complexity over time, particularly for purchased easements on private land. Easements commonly contained restrictions on riparian or wetland management (58%), residual dry matter (50%), and type of animal permitted (46%) but rarely restricted number of cattle or animal unit months (4%). Flexibility was provided by easement terms such as exceptions for drought years and reference to best management practices, the easement holder’s administrative discretion, and easement amendment. Interviews with TNC staff revealed an iterative process in which conservation easements remain relatively fixed once they are established, whereas subsequent easements incorporate lessons learned from easement monitoring, enforcement, management, and applicable science. Conservation easements with an adaptive approach would link compliance terms with conservation goals, require monitoring of those terms, and have a mechanism for altering land management based on monitoring results. All three of these realms present challenges for the conservation easement structure. Improvements could be made in easement terms, ecological monitoring, and stewardship to improve the effectiveness and adaptability of this tool for maintaining ecological function on working ranches. 
    • Avian Community Response to Grazing Intensity on Monoculture and Mixed Florida Pastures

      Wilcox, Emma V.; Tanner, George W.; Giuliano, William M.; McSorley, Robert (Society for Range Management, 2010-03-01)
      Monoculture and mixed pastures in Florida provide habitat for a variety of resident and migratory bird species. The objectives of this study were to investigate the effects of grazing on vegetation structure and bird species richness and abundance in grazed monoculture and mixed pastures. Study pasture units were subject to four cattle grazing intensities: 0 = nongrazed (control), 15 = low, 20 = medium, or 35 = high animal units (AU) per pasture unit (no cattle, 1.3, 1.0, and 0.6 ha AU-1, on monoculture pastures and no cattle, 2.1, 1.6, and 0.9 ha AU-1, on mixed pastures). Monoculture pastures displayed a greater decrease in spatial heterogeneity of the vegetative community in the presence of grazing than mixed pastures. An increase in grazing intensity led to declines in total avian species richness and abundance and species richness within short-distance migrant, neotropical migrant, and permanent resident guilds on monoculture pastures. Declines in total species richness and abundance and neotropical migrant guild species richness and abundance were observed on mixed pastures subject to increasing grazing intensity. However, species richness within short-distance migrant and urban guilds and abundance within the grassland guild increased on this pasture type in the presence of grazing. Loss of spatial heterogeneity typically results in a lack of suitable habitat for birds that occupy the extremes of the vegetation structure gradient. This can lead to a loss of species richness and abundance. For the majority of avian guilds, a low grazing intensity of 1.3 ha AU-1 and 2.1 ha AU-1 on monoculture and mixed pasture, respectively, is recommended to maintain abundance. However, these grazing intensities may result in declines in species richness. Ultimately, if a range of avian species are to be supported on monoculture and mixed pastures, spatial heterogeneity of plant structure and composition must be maintained. 
    • Effect of Previous Experience on Grazing Patterns and Diet Selection of Brangus Cows in the Chihuahuan Desert

      Bailey, Derek W.; Thomas, Milton G.; Walker, John W.; Witmore, Barbara K.; Tolleson, Doug (Society for Range Management, 2010-03-01)
      The ability to adapt to different environments is critical when livestock are moved because of drought or other management considerations. The impact of previous experience on grazing patterns and diet selection of Brangus cows in desert conditions was evaluated. Cows originating from a humid-subtropical environment (Leona, Texas) were brought to the Chihuahuan Desert (native) and evaluated against cows that spent their life in the Chihuahuan Desert (native) and cows that were born and raised in the Chihuahuan Desert but were moved to Leona, Texas during the preceding 3 yr (tourist). In addition, native cows with recent experience in desert conditions were compared with native cows and tourist cows that had not been in the Chihuahuan Desert for at least 3 yr. All cows were mature and had similar pedigrees (n = 21). Cows from the three groups were tracked in three extensive pastures (> 1 000 ha) for three 8-10-d periods during winter, early summer, and later summer. Cows never grazed in the experimental pastures before the study, but native and tourist cows had grazed adjacent pastures. Fecal near-infrared spectroscopy was used to estimate diet quality. Native cows used 335 ha +/- 83 standard error (SE) less area (P = 0.06) and were 479 m +/- 105 SE closer to water (P=0.03) than cows born and raised in the Chihuahuan Desert (native and tourist cows pooled) when first evaluated in winter. After pooling all data, native cows were farther (P = 0.06) from water (730 m +/- 283 SE) and spent less time at water (10.53% +/- 3.93 SE) than cows that did not spend their entire life in the desert (native and tourist pooled). During winter and early summer (drought conditions), native cows selected diets with lower (P < 0.05) crude protein (CP) than cows born in the desert, but during late summer after abundant precipitation native cows selected a diet with higher (P = 0.07) CP. Although Brangus cows are highly adaptable, animals raised in nearby pastures appear to have advantages over native animals when grazing Chihuahuan Desert rangeland. 
    • Aboveground and Belowground Carbon Pools After Fire in Mountain Big Sagebrush Steppe

      Cleary, Meagan B.; Pendall, Elise; Ewers, Brent E. (Society for Range Management, 2010-03-01)
      Postfire succession in mountain big sagebrush (Artemisia tridentata Nutt. subsp. vaseyana [Rydb.] Beetle) ecosystems results in a gradual shift from herbaceous dominance to dominance by shrubs. Determining the quality, quantity, and distribution of carbon (C) in rangelands at all stages of succession provides critical baseline data for improving predictions about how C cycling will change at all stages of succession under altered climate conditions. This study quantified the mass and distribution of above- and belowground (to 1.8-m depth) biomass at four successional stages (2, 6, 20, and 39 yr since fire) in Wyoming to estimate rates of C pool accumulation and to quantify changes in ecosystem carbon to nitrogen (C:N) ratios of the pools during recovery after fire. We hypothesized that biomass C pools would increase over time after fire and that C:N ratios would vary more between pools than during succession. Aboveground and live coarse roots (CR) biomass increased to 310 and 17 g C m-2, but live fine roots (FR) mass was static at about 225 g C m-2. Fine litter (< 1-cm diameter) accounted for about 70% of ecosystem C accumulation rate, suggesting that sagebrush leaves decompose slowly and contribute to a substantial soil organic carbon (SOC) pool that did not change during the 40 yr studied. Total ecosystem C (not including SOC) increased 16 g m-2 yr-1 over 39 yr to a maximum of 1 100 g m-2; the fastest accumulation occurred during the first 20 yr. C:N ratios ranged from 11 for forb leaves to 110 for large sagebrush wood and from 85 for live CR to 12 for bulk soil and were constant across growth stages. These systems may be resilient to grazing after fire because of vigorous regrowth of persistent bunchgrasses and stable pools of live FR and SOC. 
    • Influence of Prescribed Fire on Ecosystem Biomass, Carbon, and Nitrogen in a Pinyon Juniper Woodland

      Rau, Benjamin M.; Tausch, Robin; Reiner, Alicia; Johnson, Dale W.; Chambers, Jeanne C.; Blank, Robert R.; Lucchesi, Annmarrie (Society for Range Management, 2010-03-01)
      Increases in pinyon and juniper woodland cover associated with land-use history are suggested to provide offsets for carbon emissions in arid regions. However, the largest pools of carbon in arid landscapes are typically found in soils, and aboveground biomass cannot be considered long-term storage in fire-prone ecosystems. Also, the objectives of carbon storage may conflict with management for other ecosystem services and fuels reduction. Before appropriate decisions can be made it is necessary to understand the interactions between woodland expansion, management treatments, and carbon retention. We quantified effects of prescribed fire as a fuels reduction and ecosystem maintenance treatment on fuel loads, ecosystem carbon, and nitrogen in a pinyon-juniper woodland in the central Great Basin. We found that plots containing 30% tree cover averaged nearly 40000 kg ha-1 in total aboveground biomass, 80000 kg ha-1 in ecosystem carbon (C), and 5000 kg ha-1 in ecosystem nitrogen (N). Only 25% of ecosystem C and 5% of ecosystem N resided in aboveground biomass pools. Prescribed burning resulted in a 65% reduction in aboveground biomass, a 68% reduction in aboveground C, and a 78% reduction in aboveground N. No statistically significant change in soil or total ecosystem C or N occurred. Prescribed fire was effective at reducing fuels on the landscape and resulted in losses of C and N from aboveground biomass. However, the immediate and long-term effects of burning on soil and total ecosystem C and N is still unclear. 
    • Comparison of Seed Bank Estimation Techniques Using Six Weed Species in Two Soil Types

      Espeland, Erin K.; Perkins, Lora B.; Leger, Elizabeth A. (Society for Range Management, 2010-03-01)
      Evaluation of the viable seeds in a soil, otherwise known as the seed pool or seed bank, is a crucial component of many weed dynamic and plant ecology studies. Seed bank estimation is used to predict the possibility of future weed infestations in rangelands as well as the nascent native plant diversity within them. However, there is no standardized method of reporting seed bank evaluation techniques, limiting the ability to compare across studies. After sowing known quantities of cheatgrass, Bromus tectorum (L.); brome fescue, Vulpia bromoides (L., S.F. Gray); pigweed, Amaranthus retroflexus (L.); kochia, Kochia scoparia (L. Schrad.); lambsquarters, Chenopodium album (L.); and field pepperweed, Lepidium campestre (L. R. Br.) into sterile soil, we compared two different watering regimes in two soil types to Petri plate germination of these seeds. Seed bank estimations from the emergence method were lower compared to estimations from the Petri plate germination. Top-and-bottom watering increased absolute abundance, and the rank order of abundance among species changed with watering method. Emergence levels were the same between the two soil types. The higher water availability of the top-and-bottom watering method resulted in greater seedling emergence (26.3% +/- 10% SD vs. 9.1% +/- 7.5% SD). Lower emergence compared to germination (62.3% +/- 24.4%) may indicate that emergence is an important postgermination barrier to seedling establishment. While emergence techniques may not accurately portray the volume of seeds in the soil, they may more accurately predict which plants can become established in field conditions. Our different species abundances between watering methods show that multiple emergence methods may need to be employed to forecast a range of future rangeland conditions from the soil seed bank. 
    • Long-Term Production and Profitability From Grazing Cattle in the Northern Mixed Grass Prairie

      Dunn, Barry H.; Smart, Alexander J.; Gates, Roger N.; Johnson, Patricia S.; Beutler, Martin K.; Dierson, Matthew A.; Janssen, Larry L. (Society for Range Management, 2010-03-01)
      Conventional wisdom among rangeland professionals has been that for long-term sustainability of grazing livestock operations, rangeland should be kept in high good to low excellent range condition. Our objective was to analyze production parameters, costs, returns, and profit using data generated over a 34-yr period (1969-2002) from grazing a Clayey range site in the mixed-grass prairie of western South Dakota with variable stocking rates to maintain pastures in low-fair, good, and excellent range condition classes. Cattle weights were measured at turnout and at the end of the grazing season. Gross income ha-1 was the product of gain ha-1 and price. Prices were based on historical National Agricultural Statistics Services feeder cattle prices. Annual variable costs were estimated using a yearling cattle budget developed by South Dakota State University agricultural economists. All economic values were adjusted to a constant dollar using the Bureau of Labor Statistics’ Consumer Price Index. Stocking rate, average daily gain, total gain, net profit, gross revenue, and annual costs ha-1 varied among range condition classes. Net income for low-fair range condition (27.61 ha-1) and good range condition (29.43 ha-1) were not different, but both were greater than excellent range condition (23.01 ha-1). Over the life of the study, real profit (adjusted for inflation) steadily increased for the low-fair and good treatments, whereas it remained level for the excellent treatment. Neither drought nor wet springs impacted profit differently for the three treatments. These results support generally observed rancher behavior regarding range condition: to maintain their rangeland in lower range condition than would be recommended by rangeland professionals. Ecosystem goods and services of increasing interest to society and associated with high range condition, such as floristic diversity, hydrologic function, and some species of wildlife, come at an opportunity cost to the rancher. 
    • Altered Herbivore Distribution Associated With Focal Disturbance

      Limb, Ryan F.; Engle, David M.; Fuhlendorf, Samuel D.; Althoff, Donald P.; Gipson, Philip S. (Society for Range Management, 2010-03-01)
      Natural disturbances historically created structurally diverse patterns across the landscape, and large herbivores concentrated herbivory in areas where disturbance decreased standing senesced biomass that acted as a grazing deterrent through decreased palatability and overall forage quality. However, following European settlement, many natural large-scale disturbance regimes that influence vegetation and herbivore grazing selection were altered or removed and replaced with fine-scale anthropogenic disturbances. It is unclear how fine-scale focal disturbance and alteration of vegetation structure influences livestock distribution and grazing. Therefore we used a tracked vehicle as a disturbance agent in a mesic mixed-grass prairie to assess the influence of focal anthropogenic disturbance on livestock distribution and grazing. Track vehicle disturbance decreased the height of vegetation (P<0.05) but did not alter plant species composition (P>0.05). Cattle fecal pat density was greater (P < 0.05) in locations with track vehicle disturbance. Little bluestem tiller height was shorter (P < 0.05) in tracked locations than nontracked locations in grazed treatments, but was not different in nongrazed locations the first growing season following disturbance. Fecal pat density and tiller height were not different (P>0.05) between tracked and nontracked locations following the second growing season. Therefore, we concluded that fine-scale focal anthropogenic disturbance alters herbivore distribution and defoliation and can maintain structural heterogeneity, but the effect is ephemeral and does not create long-lasting grazing lawns. 
    • Consumption of Low Larkspur (Delphinium nuttallianum) by Grazing Sheep

      Pfister, J. A.; Gardner, D. R.; Panter, K. E. (Society for Range Management, 2010-03-01)
      Low larkspur (Delphinium nuttallianum Pritz.) poisoning causes serious economic loss to livestock producers that graze cattle on foothill and mountain ranges in western North America. In general, all Delphinium spp. are five times less toxic to sheep than to cattle. Because low larkspurs are less toxic to sheep than cattle, grazing sheep before cattle on rangelands with dense populations of low larkspur can reduce larkspur density and risk of poisoning to grazing cattle. All previous published work on sheep and larkspur interactions has involved tall larkspurs. This series of studies was conducted to determine if sheep would consume sufficient low larkspur to reduce subsequent risk to cattle. Four summer trials were conducted in Collbran, Colorado, and Soda Springs, Idaho on pastures with dense (> 9 plants m-2) low larkspur populations. In all trials, sheep ate very little low larkspur (< 0.5% of bites). During one final trial using high sheep density (two sheep 0.015 ha-1 for 9 d), sheep consumed little low larkspur, but animals appeared to trample much of the low larkspur. Toxic alkaloid concentrations in low larkspur ranged from 1.1 mg g-1 to 1.6 mg g-1 in all trials. The use of sheep to graze low larkspurs to reduce subsequent consumption by grazing cattle does not appear to be a viable option. 
    • Shrub Microsite Influences Post-Fire Perennial Grass Establishment

      Boyd, Chad S.; Davies, Kirk W. (Society for Range Management, 2010-03-01)
      Woody plants can cause localized increases in resources (i.e., resource islands) that can persist after fire and create a heterogeneous environment for restoration. Others have found that subcanopies have increased soil organic matter, nitrogen, and carbon and elevated post-fire soil temperature. We tested the hypothesis that burned sagebrush subcanopies would have increased seedling establishment and performance of post-fire seeded perennial bunchgrasses compared to burned interspaces. We used a randomized complete block design with five study sites located in southeast Oregon. The area was burned in a wildfire (2007) and reseeded in the same year with a seed mix that included non-native and native perennial bunchgrasses. Seedling density, height, and reproductive status were measured in October 2008 in burned subcanopy and interspace microsites. Non-native perennial grasses had greater densities than native species (P < 0.001) and were six times more abundant in burned subcanopies compared to burned interspaces (P<0.001). Density of natives in burned subcanopies was 24-fold higher than burned interspaces (P=0.043). Seedlings were taller in burned subcanopies compared to burned interspaces (P = 0.001). Subcanopy microsites had more reproductive seedlings than interspace microsites (P < 0.001). Our results suggest that under the fire conditions examined in this study, pre-burn shrub cover may be important to post-fire restoration of perennial grasses. Determining the mechanisms responsible for increased seeding success in subcanopy microsites may suggest tactics that could be used to improve existing restoration technologies. 
    • Precipitation Regulates the Response of Net Ecosystem CO2 Exchange to Environmental Variation on United States Rangelands

      Polley, H. Wayne; Emmerich, William; Bradford, James A.; Sims, Phillip L.; Johnson, Douglas, A.; Saliendra, Nicanor Z.; Svejcar, Tony; Angell, Raymond; Frank, Albert B.; Phillips, Rebecca L.; et al. (Society for Range Management, 2010-03-01)
      Rangelands occupy 50% of Earth’s land surface and thus are important in the terrestrial carbon (C) cycle. For rangelands and other terrestrial ecosystems, the balance between photosynthetic uptake of carbon dioxide (CO2) and CO2 loss to respiration varies among years in response to interannual variation in the environment. Variability in CO2 exchange results from interannual differences in 1) environmental variables at a given point in the annual cycle (direct effects of the environment) and in 2) the response of fluxes to a given change in the environment because of interannual changes in biological factors that regulate photosynthesis and respiration (functional change). Functional change is calculated as the contribution of among-year differences in slopes of flux-environment relationships to the total variance in fluxes explained by the environment. Functional change complicates environmental-based predictions of CO2 exchange, yet its causes and contribution to flux variability remain poorly defined. We determine contributions of functional change and direct effects of the environment to interannual variation in net ecosystem exchange of CO2 (NEE) of eight rangeland ecosystems in the western United States (58 site-years of data). We predicted that 1) functional change is correlated with interannual change in precipitation on each rangeland and 2) the contribution of functional change to variance in NEE increases among rangelands as mean precipitation increases. Functional change explained 10-40% of the variance in NEE and accounted for more than twice the variance in fluxes of direct effects of environmental variability for six of the eight ecosystems. Functional change was associated with interannual variation in precipitation on most rangelands but, contrary to prediction, contributed proportionally more to variance in NEE on arid than more mesic ecosystems. Results indicate that we must account for the influence of precipitation on flux-environment relationships if we are to distinguish environmental from management effects on rangeland C balance. 
    • Sheep Ingestion of Water Containing Quebracho or Black Wattle Tannin

      Kronberg, Scott L. (Society for Range Management, 2010-03-01)
      Ingestion of small amounts of condensed tannin (CT) by ruminants can produce valuable outcomes such as improved nitrogen use and reduced bloating, methane output, and gastrointestinal parasitism. However, many grasses and forbs contain little if any CT. The specific types of CT vary in plants and can have somewhat different effects on ruminants. Individual ruminants can respond differently to CT intake. Not all livestock will consistently consume supplements while grazing, but they all usually drink water daily. Therefore, in order to determine how sheep would respond to CT in their drinking water, eight lambs with the same initial weight of 43 kg were individually penned, fed alfalfa pellets twice daily, and had ad libitum access to two waters. Water intake was measured daily. After an adjustment period to pens, feeding, watering conditions, and water containing CT, three sequential week-long trials were conducted. In Trial 1, lambs chose between tap water and a quebracho tannin (QT)-water mixture (0.19% QT w/w; ca. 1% dry matter intake of QT). In Trial 2, lambs chose between tap water and a QT-water mixture of lower concentration (0.14% QT w/w). In Trial 3, lambs chose between a QT-water mixture and a wattle tannin-water mixture, both with the same concentration (0.14% CT w/w). In Trials 1 and 2, lambs had inconsistent intakes of tannin water and tap water from day to day (P<0.02) and neither preferred nor avoided tannin solutions. They also had inconsistent daily intakes of the two different tannin solutions offered simultaneously (P = 0.01), and showed no preference for either tannin solution (P>0.15). Results support other observations that sheep will voluntarily consume water with small amounts of CT in it, and provide no evidence that sheep prefer consuming small amounts of QT vs. black wattle tannin in water.