bluuebunny/crossref_metadata_2025 huggingface dataset:
Research observation: Effects of rangeland ecological condition on scaled quail sightings
Authors: Joseph J. , Holechek J. L. , Valdez R. ,   Society for Range Management
Published: March 2016

Scaled quail (Callipepla squamata) numbers were evaluated during and after a 2-year drought period using strip census techniques on 2 pastures in late seral rangeland ecological condition and 2 pastures in mid-seral rangeland ecological condtion. This study was conducted on the Chihuahuan Desert Rangeland Research Center (CDRRC) in south-central New Mexico on 4 adjoining pastures that were similar in size and terrain. During part of the study (August 1994 to April 1997) all 4 pastures were destocked due to depletion of perennial grass cover and biomass from a combination of drought and heavy cattle grazing. Scaled quail sightings pooled across sampling periods (9) were different (P = 0.08) on high and low rangeland ecological condition treatments. They averaged 10.72 birds per pasture on late-seral and 4.22 birds per pasture on mid-seral rangeland ecological condition treatments. Autumn perennial grass cover and standing biomass levels was higher (P < 0.10) on late seral than on mid-seral rangeland ecological condition pastures during both years of study. Availability of scaled quail foods such as leatherweed croton and broom snakeweed did not differ (P > 0.10) between treatments. Our study indicates that during extended dry periods livestock grazing at moderate intensities may adversely affect scaled quail populations in the Chihuahuan Desert by depleting perennial grass cover. However, in years of above average precipitation there is evidence scaled quail prefer mid-seral pastures over late-seral pastures. Maintaining a mosaic of conservatively (late-seral) and moderately (mid-seral) grazed pastures should best meet the habitat needs of scaled quail in the Chihuahuan Desert.
Cattle distribution patterns and vegetation use in mountain riparian areas
Authors: Parsons C. T. , Momont P. A. , DelCurto T. ,   Society for Range Management
Published: March 2016

To quantify the effects of season of use on beef cattle distribution relative to the riparian area, 52 cow/calf pairs were used to evaluate 1) early summer grazing (mid-June to mid-July), and 2) late summer grazing (mid-August to mid-September) during the summers of 1998 and 1999. Within a block, cow/calf pairs used during early summer were also used during late summer grazing periods. Pastures were stocked to achieve 50% utilization of herbaceous vegetation after a 28-day grazing trial. Livestock location and ambient air temperature were recorded hourly during two, 4-day periods in each season of use. Locations were transcribed to a geographical information system for the study area. Ocular vegetation utilization estimates, forage quality, and fecal deposits within 1-m of the stream were recorded post-grazing. During early summer, cattle were further from the stream (P < 0.01) than late summer, averaging 161 and 99-m, respectively. Cows were observed closer (P < 0.01) to the stream when ambient air temperatures were higher. Fecal deposits within 1-m of the stream were similar (P = 0.13) following early and late summer grazing. Forage quality varied (P < 0.01) between seasons, with early summer forages having lower dry matter, greater crude protein, lower fiber, and greater in situ dry matter disappearance compared with late summer forages. Utilization of riparian vegetation was lower and use of upland vegetation greater during early summer than late summer (P < 0.05). In summary, season of use affected cattle distribution relative to the riparian area, with late summer pastures having more concentrated use of riparian vegetation.
Defoliation effects on reproductive biomass: importance of scale and timing
Authors: Anderson M. T. , Frank D. A. ,   Society for Range Management
Published: March 2016

Community-level (per unit area) and individual tiller reproductive biomass inside and outside of long-term exclosures on the northern winter range of Yellowstone National Park, USA were compared. Grazed areas had twice the number of reproductive tillers m-2 (186 compared to 88 tillers m-2), and greater total reproductive biomass m-2 than ungrazed plots (13 compared to 7 g m-2). In contrast, seed number tiller-1 was greater for grasses in exclosures. Because of these offsetting responses, seed production (nom-2) was unaffected by herbivores. On an area basis, grazed grasses allocated proportionally more biomass to reproduction (reproductive biomass/aboveground biomass) than ungrazed grasses. We propose that altered plant demography and morphology following defoliation explain how grazers might increase the allocation of biomass to reproduction in Yellowstone grasslands. To understand these results in light of ecological and agronomic studies, we reviewed literature from 118 sources that reported the effects of defoliation on the production of reproductive biomass. The review suggested that the results of herbivory or defoliation on plant reproductive biomass depended on the scale of measurement (community vs. plant). In addition, timing of grazing or defoliation emerged as a key factor that determined whether sexual reproduction was inhibited. Like the early season grazing that is typical of Yellowstone's northern winter range, studies often showed that early season defoliation stimulated production of community-level reproductive biomass. Our results rectify disagreements in the literature that ultimately derive from differences in either timing of defoliation or measurement scale.
Non-selective grazing impacts on soil-properties of the Nama Karoo
Authors: Beukes P. C. , Cowling R. M. ,   Society for Range Management
Published: March 2016

Non-selective grazing (NSG) is a relatively novel way of farming livestock in the Nama Karoo of South Africa. Our key question was how heavy grazing under this high-intensity, low-frequency grazing system would impact on certain soil properties. The study was designed to compare the impacts of NSG (treatment) with no grazing (control) in terms of: (1) amount of soil organic carbon (OC); (2) soil microbial respiration rates; (3) soil stability and infiltration properties. The treatment significantly lowered the amount of OC in the topsoil. Microbial respiration rates corresponded with the fertile patch matrix in both treatment and control with significantly higher respiration rates measured under plants compared to open, unvegetated areas. Respiration rates in treatment open areas were significantly higher than in control open areas. There was a trend (P < 0.1) for higher aggregate stability, final infiltration rate and cumulative infiltration for treatment open soils compared to controls during an initial rain event of 44 mm hour-1 in a rainfall simulator. During a second rain event on sealed soils only aggregate stability was significantly higher for treatment compared to control soils. We conclude that the short-duration, low-frequency, intensive herbivory by livestock under the non-selective grazing system resulted in a more active microbial community, which turned over organic matter more rapidly and led to higher soil stability and infiltration capacity of open, unvegetated soils. We present this as an example of conditions where herding by high densities of large herbivores can have positive impacts on soil quality.
Clubmoss effects on plant water status and standing crop
Authors: Colberg T. J. , Romo J. T. ,   Society for Range Management
Published: March 2016

Clubmoss (Selaginella densa Rydb.), a low growing, vascular cryptogam forms carpet-like mats that cover up to 80% of the ground in the Northern Mixed Prairie. Many range managers believe clubmoss competes with grasses for water or intercepts precipitation and negatively affects plant water relations and productivity. The objective of these studies was to test the hypothesis that precipitation has greater effects on leaf xylem water potentials (Leafxwp) and plant productivity than clubmoss. Studies examined the effects of clubmoss on Leafxwp of Junegrass (Koeleria cristata Pers.) and blue grama (Bouteloua gracilis [HBK.] Lag.), and productivity of forbs and graminoids by: 1) irrigating or reducing precipitation relative to natural precipitation; 2) removing clubmoss relative to clubmoss present, and; 3) irrigating with 0.0 to 25 mm of water when clubmoss was present or removed. Leafxwp of Junegrass and blue grama were unaffected by clubmoss through the growing season (P = 0.33), but Leafxwp were lowest (P or = 0.05) when precipitation was reduced relative to the control and when irrigating. Standing crop of forbs was similar in the control and clubmoss removal treatment (P = 0.22) and among precipitation treatments (P = 0.13), averaging 28 g m-2 (SE = 2.2). Graminoid standing crop was unaffected by clubmoss (P = 0.35) and was greatest (P = 0.02) when irrigated (74 g m-2), intermediate in the control (53 g m-2), and least (36 g m-2) with reduced precipitation (SE = 8.7). Clubmoss did not affect (P = 0.70) total standing crop; total standing crop declined from 102 g m-2 when irrigated to 76 g m-2 in the control, and 69 g m-2 (SE = 9.0) with reduced precipitation. Clubmoss had no influence (P = 0.06) on Leafxwp when irrigated with 0 to 25 mm of water. The decline in Leafxwp from 1 to 7 days after irrigation was the product of the interacting effects of the amount of water applied and days after irrigation (P = 0.03). More than 10 mm of irrigation water were required to impart a significant increase (P < 0.05) in Leafxwp. The hypothesis that clubmoss reduces productivity of associated plants in the Northern Mixed Prairie by increasing water stress is rejected. Similarly clubmoss does not reduce plant water stress or increase production. Precipitation amounts overshadow any effects clubmoss has on Leafxwp and plant production. Range managers in the Northern Mixed Prairie may want to consider maximizing the effectiveness of precipitation in this water-limited environment instead of focusing on reducing or attempting to eliminate clubmoss.
Nitrogen and row spacing on Digitaria eriantha production and digestibility
Authors: Gargano A. O. , Adúriz M. A. , Busso C. A. ,   Society for Range Management
Published: March 2016

Research on the effects of the rate and method of fertilizer application or row spacing on dry matter yield and digestibility of perennial forage crops either is scarce or has produced contradictory results. The objective of this study was to determine the effects of various rates of N fertilization, method of fertilizer application and row spacing on dry matter yields and in vitro dry matter digestibility (IVDMD) in the cultivated, perennial forage grass Digitaria eriantha Steud. subsp. eriantha cv. Irene. Field studies were conducted on a petrocalcic Ustipsament, sandy loam soil. The total annual N fertilizer (0, 50 or 100 kg ha-1) was applied once (in early spring) or split (half in early spring, half in early summer) on rows 0.3 or 0.5 m apart. Plants were clipped, leaving 50 mm of stubble, whenever they reached 260-280 mm height during the 1998-1999 and 1999-2000 growing seasons. All fertilized treatments produced higher (P < 0.05) dry matter yields than unfertilized controls. Averaged across both seasons, annual dry matter yields were 3.5, 5.2, and 6.0 Mg ha-1 for 0, 50, and 100 kg ha-1 N treatments, respectively. Dry matter yields during summer were greater (P < 0.05) under split than single application. Row spacing did not affect dry matter yield. Although small, increases in IVDMD due to fertilization were significant (P > 0.05). Mean IVDMD was 602, 633, and 656 g kg-1 for N fertilization rates of 0, 50, and 100 kg ha-1. It is suggested that N application should be between 50 and 100 kg ha-1 for D. eriantha, and that this application should be split rather than applied at one time in early spring.
Mechanism by which ammonium fertilizers kill tall larkspur
Authors: Ralphs M. H. , Woolsey L. , Bowns J. E. ,   Society for Range Management
Published: March 2016

Environmental concerns of using pesticides on public lands have greatly reduced the use of herbicides to control tall larkspur (Delphinium barbeyi Huth). An alternative method of control used ammonium sulfate placed at the base of individual plants. The objective of this study was to determine the mechanism by which fertilizers kill tall larkspur. We hypothesize the salt from the fertilizers kill the plant. We applied ammonium sulfate, ammonium nitrate and sodium chloride at equivalent salt concentrations and evaluated their effect on tall larkspur plants. There was no difference among treatments in larkspur mortality (P > 0.10). The high rate of all treatments (ammonium sulfate 400 g plant-1, ammonium nitrate 264 g, and sodium chloride 180 g, at equivalent salt concentrations) killed greater than 70% of larkspur plants. We conclude the salt in fertilizers kills tall larkspur, not the nitrogen. It is necessary to place the fertilizer or salt at the base of the plant to concentrate it in the root zone, rather than broadcast it. At the end of the study, bare areas left around the dead tall larkspur plants were only 13% of the original size of the tall larkspur plants at Yampa Colo. and Cedar Ut., and 46% at Emery Ut., indicating the surrounding vegetation was quickly filling in the vacated space. The relative cost of materials per plant for both ammonium sulfate and nitrate was 12.9 cents, and 2.6 cents for salt.
Seed germination of willow species from a desert riparian ecosystem
Authors: Young J. A. , Clements C. D. ,   Society for Range Management
Published: March 2016

The restoration of riverine riparian areas following mechanical, herbicidal, or biological control of the invasive species tamarisk (Tamarix ramosissima Ledeb.) is a major issue in the western United States. Recruitment of seedlings of native woody species is necessary in these restoration efforts. Species of willow (Salix) are often considered essential in these efforts. We studied the germination of seeds of tree willow (Salix lutea Nutt.) and coyote willow (S. exigua Nutt.) at a wide range of constant or alternating incubation temperatures. Seeds were collected from native stands in the delta of the Walker River in western Nevada over a 3 year period. Seed germination was very similar for both species. On 2 of the 3 years of testing the seeds had 100% germination at some incubation temperatures and some germination over almost all of the 55 temperature regimes used in the experiments. A late frost in May of 2000 markedly reduced total germination of both species, but did not greatly restrict the temperature regimes where some germination occurred. Optimum germination, defined as that not lower than the maximum observed minus one half the confidence interval at the 0.01 level of probability, occurred over a very wide range of temperatures, but for tree willow only the temperature regimes 15/25 (15 degrees C for 12 hours and 25 degrees C for 8 hours in each 24 hour period) and 15/30 degrees C always supported optimum germination. No temperature regime always supported optimum germination of coyote willow seeds, but the most frequent optima tended to be at lower temperatures than for tree willow. Because of the similarity in germination responses and overlapping phenology, seeds of these 2 species probably compete for germination safesites.
Recreationist responses to livestock grazing in a new national monument
Authors: Brunson Mark W. , Gilbert Lael ,   Society for Range Management
Published: March 2016

Several U.S. rangeland areas recently have been designated as national monuments to protect scientifically or culturally important resources. Typically recreation and livestock uses have been retained in these areas. Because some people believe protection and use are incompatible, and because monument designation can increase public scrutiny of management while attracting new visitors to the area, we surveyed hunters and hikers in the Grand Staircase-Escalante National Monument, Utah, about their perceptions of livestock grazing in the monument. We examined associations between visitors' personal characteristics and their reports of how livestock grazing and multiple-use management affect recreation experiences. Recreation activity type was a significant predictor of experience effects, but we found no evidence that the act of designating a national monument itself affected experiences. Locations of current and childhood residence also were significantly associated with experience effects. Because designation tends to attract certain types of visitors more than others, creating rangeland national monuments may foster increased conflict between recreation and livestock grazing uses in those areas.
Responses of bahiagrass to nitrogen and defoliation
Authors: Hirata M. , Pakiding W. ,   Society for Range Management
Published: March 2016

Pensacola bahiagrass (Paspalum notatum Flgge) swards pretreated with fertilizer nitrogen rates of 0 and 66-99 kg N ha-1 year-1 were exposed to repeated, severe defoliation (i.e., removal of all laminae) of every day (D1), every 2 days (D2), and every 4 days (D4). Responses of the grass were monitored in terms of tiller survival, lamina production and changes in the mass of the stubble-stolon-root system, in an effort to investigate the effects of nitrogen rate and defoliation frequency on defoliation tolerance, to examine differences in survival ability of tillers among tiller age cohorts, and to evaluate contribution of the stubble-stolon-root system to defoliation tolerance. With the progress of defoliation treatments over 12 weeks, the swards degraded with decreasing tiller density, lamina production, and mass of stubble and stolons. Defoliation tolerance in terms of tiller survival was influenced only by defoliation frequency (D1 = D2 < D4), with no significant effect of nitrogen fertilizer rate. There were no differences in survival ability of tillers among age cohorts formed before the defoliation treatments, suggesting that all tillers in bahiagrass were able to share energy and nutrients in connecting stolons under severe defoliation. It was confirmed that stolons play a key role in defoliation tolerance in bahiagrass as the main storage organ supporting aboveground parts, whereas the contribution of roots seems nil.
Defoliation, waterlogging and dung influences allocation patterns of Deschampsia caespitosa
Authors: Merrill E. H. , Colberg P. J. S. ,   Society for Range Management
Published: March 2016

Wet meadows are some of the most productive communities in the northern Rocky Mountains, USA but are also among the most sensitive to grazing by native ungulates and domestic livestock. These meadows typically are inundated with floodwater in spring and early summer but are relatively dry in summer. To determine the interactive effects of clipping and flooding on plant recovery after clipping, we subjected plants of tufted hairgrass (Deschampsia caespitosa (L.) Beauv) to 6-week and 10-week waterlogging treatments in combination with 1 and 2 clipping events, with and without dung amendment in a greenhouse experiment. The experiment was designed to mimic early and late growing-season patterns of herbivory by native and domestic herbivores on a dominant species of wet meadows of this region. Waterlogged plants produced a higher percentage of roots at the surface, elongated stems to the first axial leaf, increased the proportion of tillers that flowered, but increased aboveground yield and tiller height only with the addition of dung. Root biomass declined with waterlogging when dung was not added, and a second defoliation exacerbated the negative effects of waterlogging on roots. Defoliation with short-duration waterlogging increased shoot nitrogen (N) concentration and N yield/root biomass, while continuous waterlogging reduced shoot N concentration of aboveground biomass. Dung amendment did not reverse this effect. Although extended flooding in combination with moderate rates of defoliation did not reduce aboveground biomass of Deschampsia caespitosa, it aggravated total root loss, caused shifts to a shallower root distribution, and altered N concentration of aboveground biomass for herbivores.
Big sacaton and endophyte-infected Arizona fescue germination under water stress
Authors: Neil K. L. , Tiller R. L. , Faeth S. H. ,   Society for Range Management
Published: March 2016

Water availability in the germination stage of plants is crucial for seed germination and as a resource for developing seedlings. The effect of osmotic potential on percent germination and time to germination for big sacaton (Sporobolus wrightii Munro) and Arizona fescue (Festuca arizonica Vasey) was investigated. We predicted that seeds native to semi-arid environments would germinate at osmotic potentials less negative than about -1.5 MPa, the permanent wilting point (PWP) of many agronomic grasses. In addition, the systemic, asexual endophyte Neotyphodium is transmitted through the seed in Arizona fescue and is thought to increase germination of its host. Therefore, we also tested for an effect of the endophyte on germination and time to germination of Arizona fescue under varying osmotic potentials. To test for minimum osmotic potential supporting germination, big sacaton and Arizona fescue seeds were placed on acetate membranes in contact with PEG solutions of varying osmotic potentials for 2 weeks. Both grasses germinated at 50% of maximum germination (at soil saturation) at and below the standard PWP (-1.5 Mpa). Big sacaton and Arizona fescue germinated at 64% and 60% at -1.5 MPa, respectively, and Arizona fescue germinated at 35% at -1.8 MPa (70% was the maximum at saturation). The presence of the Neotyphodium endophyte did not affect percent or time to germination of Arizona fescue at any of the osmotic potentials tested.
Soil carbon, nitrogen and phosphorus in modified rangeland communities
Authors: Whalen J. K. , Willms W. D. , Dormaar J. F. ,   Society for Range Management
Published: March 2016

Rangelands contain between 10 and 30% of global soil organic C reserves and may be an important sink for atmospheric CO2, but less C tends to be stored in rangelands cultivated for agricultural use than undisturbed rangelands. Establishing perennial plant communities on formerly cultivated rangelands is expected to stabilize soil properties and increase the amount of C stored in rangeland soils, but there is little information on what plant communities are most effective at building soil C reserves. The purpose of this study was to compare soil C, N, and P pools in ungrazed native rangelands with ungrazed, unfertilized rangelands that were cultivated and then 1) abandoned, 2) seeded with non-native perennial grasses or legumes, or 3) cropped annually for 5 to 6 years. Three study sites in southern Alberta, Canada with native Stipa-Bouteloua, Stipa-Bouteloua-Agropyron and Festuca campestris plant communities represented the major ecotypes of the Northern Great Plains. The total C, N, and P content of rangeland soils were greatest at the Festuca campestris site, followed by the Stipa-Bouteloua-Agropyron and Stipa-Bouteloua sites, probably due to climatic conditions (precipitation and temperature). Generally, soils under modified plant communities contained less total C and N than soils under native rangeland, but the total P content was related more to site preparation than experimental treatments. Soils under alfalfa, orchardgrass and bromegrass tended to have more total C and N than soils cultivated annually in continuous wheat or wheat-fallow systems. The accumulation of C and N in soils under permanent cover was not related to net primary productivity and may be influenced more by the chemical composition and rate of decomposition of plant residues.
Research observation: Daily movement patterns of hill climbing and bottom dwelling cowsfull access
Authors: Bailey Derek W. , Keil Martina R. , Rittenhouse Larry R. ,   Society for Range Management
Published: March 2016

Individual animal selection has been proposed as a tool for increasing uniformity of grazing on rugged rangeland. Daily grazing patterns of cows previously identified as preferring steeper slopes and higher elevations (hill climbers) were compared to cows preferring gentler slopes and lower elevations (bottom dwellers). Cows were ranked for slope use and vertical distance traveled to water during late summer in 1997 using horseback observers. In 1998, 9 extreme cows based on 1997 rankings (4 hill climbers and 5 bottom dwellers) were tracked using Global Positioning System (GPS) collars for 3 weeks during late summer on foothill rangeland. Hill climbers (1027 hours) arrived at water about 1 hour later (P = 0.04) than bottom dwellers (0928 hours). Hill climbers and bottom dwellers left water at the same time (1801 hours, P = 0.3). During this interval, 90% and 98% of the observations were within 100 and 200 m of water, respectively. While cattle were away from water (1901 to 0846 hours), 56%, 77%, and 87% of the observations were within 200, 300, and 400 m, respectively, from the cow's location at 0700 hours. Hill climbers spent 14% of their time on steeper slopes (20 to 30 degrees) while bottom dwellers spent 7% (P = 0.01), and hill climbers (41%) tended (P = 0.07) to spend less time on gentler slopes (0 to 10 degrees) than bottom dwellers (47%). Hill climbers (1323 m) were observed at higher elevations (P = 0.01) than bottom dwellers (1277 m). Horizontal distance traveled to water (633 m) was similar (P > 0.1) for hill climbers and bottom dwellers. Cow location during the early morning (0700 hours) was a good predictor of terrain used during the morning and previous evening grazing bouts. Cows tracked in this study did not appear to regularly associate with each other. They usually grazed in different areas of the pasture and regularly used different water sources. Individual cows within a herd can use different terrain even though many aspects of the grazing patterns are similar. Location of cows during the early morning and perhaps the time that cows travel to water can be used to identify differences in terrain use among individual animals.
Book Review: Modeling in Natural Resource Management: Development, Interpretation, and Application, Tanya M. Shenk, Alan B. Franklin (Eds.)
Authors: Batabyal Amitrajeet A. ,   Society for Range Management
Published: March 2016

Book Review: Modeling in Natural Resource Management: Development, Interpretation, and Application, Tanya M. Shenk, Alan B. Franklin (Eds.). Island Press, Washington, DC (2001).
Revegetating weed-infested rangeland with niche-differentiated desirable species
Authors: Carpinelli M. F. , Sheley R. L. , Maxwell B. D. ,   Society for Range Management
Published: March 2016

The goal of this study was to determine the potential to revegetate weed-infested rangeland by maximizing niche occupation and resource capture by desirable species. We hypothesized that as desirable species richness increases, weed establishment and growth decrease, provided that the desirable species differ in niche. Three desirable species with differing spatial and temporal growth patterns, [Agropyron cristatum (L.) Gaertn., var. Hycrest (crested wheatgrass), Elytrigia intermedia (Host) Nevski, var. Rush (intermediate wheatgrass), and Medicago sativa L., var. Arrow (alfalfa)], and 1 weed [Centaurea maculosa Lam. (spotted knapweed)], were grown in a multiple replacement series. All species were sown simultaneously in spring 1996, simulating revegetation of a site containing spotted knapweed seeds in the seed bank because of prior infestation. Desirable species richness varied among plots, while the total number of desirable seeds sown per plot was held constant. Although the desirable species were shown to differ in niche, desirable species richness or mixture did not affect soil water depletion or spotted knapweed recruitment in 1996 or 1997. These results suggest that revegetation of weed-infested rangeland must also include active control of weeds emerging from the soil seed bank. Only then can other strategies, such as maximizing niche occupation by desirable species, be expected to provide long-term success.
Research observation: Nitrogen effects on Arizona cottontop and Lehmann lovegrass seedlings
Authors: Fernandez-Giménez Maria E. , Smith Steven E. ,   Society for Range Management
Published: March 2016

We compared the responses of seedlings of introduced Lehmann lovegrass (Eragrostis Lehmanniana Nees) and a native perennial grass, Arizona cottontop (Digitaria californica (Benth.) Henr.) to 7 nitrogen and 2 water treatments to determine if Lehmann lovegrass displayed greater growth or nitrogen use efficiency than Arizona cottontop. After 8 weeks, the lovegrass seedlings had greater shoot N concentrations (2.07 vs. 1.20%), and lower C:N ratios (27.7 vs. 49.6) than Arizona cottontop seedlings. Arizona cottontop seedlings produced more biomass per plant (1.09 vs. 0.31g), exhibited greater nitrogen use efficiency (63 vs. 39%), and tolerated high N levels better. Arizona cottontop may be a superior N competitor under both N-limited and high N conditions, while Lehmann lovegrass may outcompete Arizona cottontop at moderate N levels.
Grazing management effects on plant species diversity in tallgrass prairie
Authors: Hickman Karen R. , Hartnett David C. , Cochran Robert C. ,   Society for Range Management
Published: March 2016

A 6-year study was conducted in tallgrass prairie to assess the effects of grazing management (cattle stocking densities and grazing systems) on plant community composition and diversity. Treatments included sites grazed season-long (May to October) at 3 stocking densities (3.8, 2.8, and 1.8 hectares per animal unit), ungrazed control sites, and sites under a late-season rest rotation grazing system at this same range of stocking densities. Plant communities were sampled twice each season using a nearest-point procedure. Native plant species diversity, species richness, and growth form diversity were significantly higher in grazed compared to ungrazed prairie, and diversity was greatest at the highest stocking density. This enhancement of plant species diversity under grazing was not a result of increased frequency of weedy/exotic species. There were no significant effects of grazing system on plant diversity, nor any significant stocking density × grazing system interactions, indicating that animal density is a key management variable influencing plant species diversity and composition in tallgrass prairie and that effects of animal density override effects of grazing systems. Increasing cattle stocking densities decreased the abundance of the dominant perennial tall grasses, and increased abundance of the C4 perennial mid-grasses. The frequency of perennial forbs was relatively stable across grazing treatments. Abundance of annual forbs varied among years and grazing treatments. In half of the years sampled, annual forbs showed the highest frequency under intermediate stocking density. Patterns of responses among plant groups suggest that some species may respond principally to direct effects of grazers and others may respond to indirect effects of grazers on competitive relationships or on the spatial patterns of fuel loads and fires. Thus, this study suggests that large grazer densities, fire, and annual climatic variability interact to influence patterns of plant community composition and diversity in tallgrass prairie. Effects of varying management such as stocking densities and grazing systems on plant species diversity and the relative abundances of different plant growth forms or functional groups may have important consequences for grassland community stability and ecosystem function.
Accuracy assessment for detection of leafy spurge with hyperspectral imagery
Authors: Parker Williams Amy E. , Hunt E. Jr. Raymond ,   Society for Range Management
Published: March 2016

When flowering, leafy spurge (Euphorbia esula L.) has conspicuous yellow-green bracts that are spectrally distinct from other vegetation and may be distinguished with hyperspectral remote sensing. In July 1999, Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data were acquired in northeastern Wyoming, near Devils Tower National Monument. Using the reflectance spectrum of flowering leafy spurge, leafy spurge occurrence was determined using a new method of spectral mixture analysis, Mixture Tuned Matched Filtering (MTMF). Ground reference data (146 sites) were obtained 2 weeks before and after AVIRIS overflight to test the classification accuracy of leafy spurge. For 3 land cover types: mixed prairie, riparian, and coniferous woodlands, the presence or absence leafy spurge was detected with an overall accuracy of 95% using a 0.10 threshold for detection. Differences in classification thresholds resulted in a trade-off between false positives, pixels that were mapped as leafy spurge but did not contain leafy spurge on the ground, and false negatives, areas that had leafy spurge on the ground but were not mapped as leafy spurge. Detection of leafy spurge occurrence was best for mixed prairie and riparian cover types, and somewhat less successful for conifer woodlands because of interference from tree crowns and their shadows. The advantage of the MTMF technique is it allows automated processing of hyperspectral imagery to generate accurate maps of leafy spurge occurrence.
Vegetation response of a mesquite-mixed brush community to aeration
Authors: Ruthven Donald C. , Krakauer Keith L. ,   Society for Range Management
Published: March 2016

Responses of plant communities to mechanical treatments such as aeration on semiarid rangelands are not clearly understood. Our objective was to compare woody and herbaceous plant cover, density, and diversity on aerated and nontreated rangelands. Five rangeland sites that were aerated with a double/tandem drum aerator during summer 1998 and 5 sites of nontreated rangeland were selected for study on the Chaparral Wildlife Management Area, La Salle County, Tex. Woody plant cover was estimated using the line-intercept method, and stem density was estimated in 30 × 1.5 m plots in 1999 and 2000. Forb and grass cover and density were estimated in 20 × 50 cm quadrats during spring and fall 1999. Woody and herbaceous plant diversity did not differ between treatments. On aerated sites percent woody plant cover was 4-fold less 1-year after aeration and increased 89% from the first to the second growing-season post treatment. Canopy cover of honey mesquite (Prosopis glandulosa Torr.), twisted acacia (Acacia schaffneri S. Wats.), and Texas pricklypear (Opuntia lindheimeri Engelm.) was greater on non-treated sites. By the second growing season after aeration, density of honey mesquite was greater on aerated sites, whereas Texas pricklypear had declined on aerated sites. Density of spiny hackberry (Celtis pallida Torr.) and Texas persimmon (Diospyros texana Scheele) was greater on aerated sites during the first growing-season post treatment. Cover and stem density of hog-plum (Colubrina texana T. G.), coma (Bumelia celastrina Kunth), and whitebrush [Aloysia gratissima (Gill. Hook.) Tron.] did not differ among aerated and nontreated sites by the first growing season after aeration. Forb cover was greater on aerated sites in spring 1999. Fringed signalgrass [Brachiaria ciliatissima (Buckl.) Chase], fall witchgrass [Digitaria cognata (Schult.) Pilger], and bristlegrass (Setaria spp. Beauv.) cover was greater on aerated sites in spring and fall 1999, whereas purple threeawn (Aristida purpurea Nutt.) was greater on nontreated sites. It is unclear to what degree environmental factors such as pre- and post-treatment climatic conditions and herbivory may have influenced vegetation response to aeration. The rapid regrowth of many woody plants following aeration may require the application of maintenance treatments within a relatively short time period to maintain treatment benefits. Aeration reduced total woody plant cover, increased the density of desirable woody plants, maintained woody plant diversity, increased grass cover, and may be a useful tool in managing South Texas rangelands for white-tailed deer (Odocoileus virginianus Boddaert) and cattle.
Seedling recruitment of perennial grasses in degraded areas of the Patagonian Monte
Authors: Bisigato Alejandro Jorge , Bertiller Monica Beatriz ,   Society for Range Management
Published: March 2016

The recruitment of perennial grass seedlings in degraded areas of the Patagonian Monte was analyzed. Recolonization of large bare-soil areas by dwarf shrubs or perennial grasses was hypothesized to create favorable microsites for grass seedling recruitment. Under natural field conditions, soil moisture (0-20 cm), root biomass (0-20 cm), the soil seed bank of perennial grasses, and density of perennial grass seedlings in the center of large bare soil areas and in microsites neighboring isolated plants of perennial grasses and dwarf shrubs were assessed. A manipulative experiment was conducted to evaluate seedling recruitment at the 3 microsites with identical density of seed addition of perennial grasses, under situations of root exclusion, and water addition. Under natural field conditions, root biomass did not differ among microsites. Soil moisture, seed density, and seedling density of perennial grasses were higher near perennial grasses than in bare soil or next to dwarf shrubs. Recruitment of perennial grass seedlings did not differ among microsites when the density of seeds did not vary among them or roots of the established plants were excluded. Water increased perennial grass seedling recruitment at all microsites. In degraded areas of the Patagonian Monte the spatial distribution of the soil seed bank followed by water availability are the main limiting factors of seedling recruitment of perennial grasses. Managerial practices oriented to maintain and increase the soil seed bank of perennial grasses, such as grazing exclusion during the grass reproductive period, might contribute to promote the re-establishment of perennial grasses.
Increasing native diversity of cheatgrass-dominated rangeland through assisted succession
Authors: Cox Robert D. , Anderson Val Jo ,   Society for Range Management
Published: March 2016

Increasing attention, resources and efforts are being focused on the conversion of weedy dominated rangelands back to perennial plant communities that resemble predisturbance communities in form, function and composition. A study was conducted in 1998 and replicated again in 1999 to determine whether native plants could be established through “assisted succession” - manipulating a cheatgrass-dominated area to perennial plant domination, then to native or near-native diversity. Cheatgrass dominated rangeland that had been successfully revegetated with crested wheatgrass (Agropyron cristatum [L.] Gaertner) was seeded with native species. Another area dominated by cheatgrass, but without crested wheatgrass, was also seeded. Four seedbed preparation methods were investigated: tilling, harrowing, application of a herbicide, and no treatment. Four different seeding methods were used in the 2 areas and 4 seedbed preparation techniques: drilling, broadcasting, a broadcast-cover method, and no seed. Seeding was done in February, and data were collected in mid-summer each year. Native grasses and shrubs emerged in greater numbers on treatments established on the crested wheatgrass matrix than on those established on the cheatgrass matrix. Perhaps in general, but especially in years with normal or below average precipitation, the assisted succession approach proved successful for restoration of native sagebrush-grassland steppe from cheatgrass range.
Geologic grazing refuges and grassland diversity: A shortgrass steppe study
Authors: Milchunas Daniel G. , Noy-Meir Imanuel ,   Society for Range Management
Published: March 2016

Geologically isolated, natural grazing refuges that have never been grazed by domestic livestock can be foci of diversity for rare species. This study compared refuges protected from grazing by ravines to adjacent grazed sites in an uncommon grassland type in eastern Colorado. We also tested whether differences between refuge and grazed sites were due to protection from grazing versus abiotic conditions, based on temporary caging of little bluestem plants (Schizachyrium scoparium [Michaux] Nash). Regionally rare species were not exclusive to refuges, but occurred also on adjacent grazed sites. However, refuges showed greater species richness, as well as greater abundance of several tall stature species that are uncommon in the surrounding shortgrass steppe. Temporary protection of little bluestem plants in grazed sites resulted in significant changes in growth and reproductive output, in the direction of refuge plants. Though this geological refuge did not manifest an exclusive set of rare species as reported from other systems, it does preserve strong source populations of uncommon species that are sensitive to grazing and thereby contributes to regional grassland diversity.
Leafy spurge effects on patterns of plant species richness
Authors: Butler Jack L. , Cogan Daniel R. ,   Society for Range Management
Published: March 2016

The objective of this study was to simultaneously evaluate the impact of leafy spurge (Euphorbia esula L.) on plant species richness within and among a wide variety of vegetation types typical of the region. The study was conducted in Theodore Roosevelt National Park in southwestern North Dakota where 11 plant associations were identified as being particularly susceptible to invasion by leafy spurge. Representative infested and non-infested stands of the 11 associations were sampled using the protocol described by the National Vegetation Classification System. To evaluate the effects of leafy spurge infestation across a variety of vegetation types, the 11 associations were grouped into 1 of 4 general physiographic/vegetative units (floodplain, grassland, woodland, and shrubland). Species richness per sampled infested stand was reduced by an average of 51% (P ≤ 0.05) in 7 of the 11 sampled associations. Total species richness in infested stands averaged 61% less than species richness within their non-infested counterparts for 10 of the 11 associations. Thirty species common to the majority of the associations were completely absent from infested stands and classified as sensitive, whereas 25 were minimally impacted and classified as persistent species. The overall effects of leafy spurge on species richness is complex and probably involves patterns of soil moisture, nutrient conditions, and disturbance that influence the abundance and distribution of all alien plants in Theodore Roosevelt National Park. However, because of the considerable redundancy in species distribution among a wide variety of plant associations and an aggressive control program, overall species richness does not appear to be threatened by infestations of leafy spurge at this time.
Effects of distance from cattle water developments on grassland birds
Authors: Fontaine Andrea L. , Kennedy Patricia L. , Johnson Douglas H. ,   Society for Range Management
Published: March 2016

Many North American grassland bird populations appear to be declining, which may be due to changes in grazing regimes on their breeding areas. Establishment of water developments and confining cattle (Bos taurus L.) to small pastures often minimizes spatial heterogeneity of cattle forage consumption, which may lead to uniformity in vegetative structure. This increased uniformity may provide suitable habitat for some bird species but not others. We assessed how cattle use, vegetative structure, and bird population densities varied with increasing distance from water developments (0-800 m) on the Little Missouri National Grassland (LMNG) in North Dakota. Lark buntings (Calamospiza melancorys Stejneger), which are typically associated with low vegetative cover, decreased with increasing distance from water developments. Horned larks (Eremophila alpestris L.), also a low-cover associate, followed a similar but weaker trend. Densities of another low-cover associate as well as moderate- and high-cover associates were not related to distance from water. Vegetative height-density and litter depth increased by 50 and 112%, respectively, while cowpie cover and structural variability decreased by 51 and 24%, respectively, with distance from water. Confidence interval overlap was common among all measures, showing substantial variability among study sites. Our results indicate cattle use is higher closer to water developments, and this pattern may positively affect the densities of lark buntings and horned larks. The absence of density gradients in the other bird species may be due to the paucity of locations 800 m from water on the LMNG.
Long-term grazing effects on genetic variation in Idaho fescue
Authors: Matlaga David , Karoly Keith ,   Society for Range Management
Published: March 2016

The effect of cattle grazing on the genetic structure of native grass populations has received little attention. We investigated the effect of cattle grazing on genetic variation in Idaho fescue (Festuca idahoensis Elmer) using ISSR (inter-simple sequence repeat) DNA markers. The ISSR markers are hypervariable and are generally interpreted as being selectively neutral. Idaho fescue tillers were sampled from inside (N = 31) and outside (N = 34) a 64-year-old cattle exclosure in southeastern Oregon. We extracted DNA and used 2 ISSR primers to determine the genotypes for grazed and ungrazed plants at 60 variable loci. No statistically significant differences were observed between grazed and ungrazed samples for percent polymorphic loci (grazed = 85%; ungrazed = 80%), mean expected heterozygosity (grazed = 0.1393; ungrazed = 0.1365), or for a measure of loci dissimilarity (grazed = 0.506; ungrazed = 0.536). We also found that the ungrazed individuals sampled inside the exclosure were not significantly genetically differentiated from the grazed individuals sampled outside the exclosure (Gst = 0.0008 averaged across all loci). Our results differ from past studies that found demographic and physiological differences between Idaho fescue inside and outside of grazing exclosures at the same site. Our results mirror those of other researchers who have also failed to detect genetic differences at marker loci in response to grazing. We propose that either the mechanisms that must be present to cause changes in neutral genetic variation are not affected by cattle grazing for Idaho fescue at this site, or that any effects of grazing on neutral genetic variation were overwhelmed by gene flow between the grazed and ungrazed samples.