bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of water quality on cattle performance
Authors: Willms W. D. , Kenzie O. R. , McAllister T. A. ,   Society for Range Management
Published: March 2016

Water is an important nutrient for livestock production and is often provided on rangelands directly from ponds or dugouts. Cattle may defecate and urinate into the water thereby adding nutrients and reducing palatability. A study was conducted to examine the effects of water source on cattle production and behavior, to determine the relationship of selected chemical and biological constituents on the observed response and to test the effect of fecal contamination on water consumption. Four dugouts or ponds were selected at 4 sites: 2 in the Fescue Prairie near Stavely in southwestern Alberta, 1 in the Mixed Prairie at Onefour in southeastern Alberta, and 1 in the Palouse Prairie near Kamloops, British Columbia. Yearling Herefords were tested at 3 sites and Hereford cow-calf pairs at 1 Stavely site. At each site, three paddocks radiated from the pond that were stocked with 10 yearlings or cow-calf pairs randomly assigned to either clean water (water delivered to a trough from a well, river, or pond), pond water pumped to a trough (pond(trough)), or direct access into the pond (pond(direct)). The trials were repeated at each site for 3 to 6 years. Observations were made on cattle weight gains, cow backfat thickness, and activity budgets. Fecal samples were analyzed for selected parasites and pathogens. Other experiments were conducted to determine the effects of manure-contaminated water on feed and water consumption and water selection. Calves, with cows drinking clean water, gained 9% more (P < 0.10) weight than those with cows on pond(direct) but cow weight and backfat thickness were not affected. Yearling heifers having access to clean water gained 23% (P = 0.045) and 20% (P = 0.076) more weight than those on pond(direct) and pond(trough), respectively. Cattle avoided water that was contaminated with 0.005% fresh manure by weight when given a choice of clean water. Cattle that had access to clean water spent more time grazing and less time resting than those that were offered pond(trough) or pond(direct). Cattle management must consider water quality together with forage conditions in order to achieve optimal production from rangeland.
Vegetation of prairie dog colonies and non-colonized shortgrass prairie
Authors: Winter S. L. , Cully J. F. , Pontius J. S. ,   Society for Range Management
Published: March 2016

Black-tailed prairie dogs have declined by 98% in the past century. Due to continued declines, the U. S. Fish and Wildlife Service designated the species as a candidate for listing in 2000. Prairie dogs foster both plant and animal diversity, and their continued presence is a concern in the Great Plains. We compared vegetation structure and composition of black-tailed prairie dog (Cynomys ludovicianus Ord) colonies in southwest Kansas and southeast Colorado to non-colonized grassland in 1996, and 1997. Dominant species on prairie dog colonies were Bouteloua gracilis (H. B. K.) Lag. ex Griffiths (14% cover in 1996, 15% in 1997), Buchloe dactyloides (Nutt.) Engelm. (7% cover in 1996, 17% in 1997) and Aristida purpurea Nutt. (9% cover in 1996, 16% in 1997). Dominant vegetation at randomly selected non-colonized sites were Bouteloua curtipendula (Michx.) Torr. (16% cover in 1996, 18% in 1997), Bouteloua gracilis (13% cover in 1996, 17% in 1997) and Buchloe dactyloides (5% cover in 1996, 5% in 1997). Non-colonized shortgrass sites were dominated by Bouteloua gracilis (23% cover in 1996, 41% in 1997) and Buchloe dactyloides (8% cover in 1996, 12% in 1997). Cover of grass was higher (P < 0.01) on random sites (44%) than on prairie dog colonies (31%) or shortgrass sites (33%) in 1996, whereas cover of forbs was higher (P < 0.01) on prairie dog colonies (18%) than on random sites (7%) or shortgrass sites (8%) that year. Vegetation height was greater (Q = 3.66) and visual obstruction was greater (Q = 3.39) on random sites (33.6 and 6.4 cm, respectively) than on prairie dog colonies (9.5 and 2.5 cm, respectively) in 1997, the only year these variables were measured. Percent bare ground did not differ (P > 0.05) among treatments either year. While components of the vegetation on prairie dog colonies differed from that found on non-colonized sites, the vegetation of prairie dog colonies was, nonetheless, characteristic of a shortgrass region. Prairie dogs undoubtably alter vegetation structure and composition in shortgrass prairie, and likely have a great influence on landscape heterogeneity, but our results suggest that shortgrass prairie is well adapted to the herbivory and soil disturbing activities of prairie dogs.
Viewpoint: Improving range science through the appropriate use of statistics
Authors: Gould W. R. , Steiner R. L. ,   Society for Range Management
Published: March 2016

We examined a stratified random sample of articles published over 3 decades of the Journal of Range Management to study the applications and changes in statistical methodology employed by range scientists. Our objectives were to characterize the philosophical nature of statistics use in range science and to identify strengths and weaknesses inherent in these approaches. In each article, we examined the research design efficacy and whether the statistical analysis was adeptly used to convey the relevant information. The majority of articles we examined were conducted appropriately. In general, we found more emphasis has been placed on statistical testing than effect size estimation in the last decade. On an average, 82 tests or means comparisons (s.e. = 20) were presented in each article during the 1990's. Articles that reported an effect size via a sample mean frequently did not report an associated standard error. Research designs lacked adequate descriptions in several cases, making it difficult to determine if the appropriate analysis was performed. Improper identification of the experimental or sampling unit and/or the interdependence of observations occurred in all decades. We recommend increased inferential use of confidence intervals and suggest that the practical significance (as opposed to statistical significance) of results be considered more often. Improvements in the 'science' of range science can be made by greater understanding and communication of statistical concepts through consultation with statisticians.
Rangeland health attributes and indicators for qualitative assessment
Authors: Pyke D. A. , Herrick J. E. , Shaver P. ,   Society for Range Management
Published: March 2016

Panels of experts from the Society for Range Management and the National Research Council proposed that status of rangeland ecosystems could be ascertained by evaluating an ecological site's potential to conserve soil resources and by a series of indicators for ecosystem processes and site stability. Using these recommendations as a starting point, we developed a rapid, qualitative method for assessing a moment-in-time status of rangelands. Evaluators rate 17 indicators to assess 3 ecosystem attributes (soil and site stability, hydrologic function, and biotic integrity) for a given location. Indicators include rills, water flow patterns, pedestals and terracettes, bare ground, gullies, wind scour and depositional areas, litter movement, soil resistance to erosion, soil surface loss or degradation, plant composition relative to infiltration, soil compaction, plant functional/structural groups, plant mortality, litter amount, annual production, invasive plants, and reproductive capability. In this paper, we detail the development and evolution of the technique and introduce a modified ecological reference worksheet that documents the expected presence and amount of each indicator on the ecological site. In addition, we review the intended applications for this technique and clarify the differences between assessment and monitoring that lead us to recommend this technique be used for moment-in-time assessments and not be used for temporal monitoring of rangeland status. Lastly, we propose a mechanism for adapting and modifying this technique to reflect improvements in understanding of ecosystem processes. We support the need for quantitative measures for monitoring rangeland health and propose some measures that we believe may address some of the 17 indicators.
Research observation: Desert bighorn sheep diets in northwestern Sonora, Mexico
Authors: Tarango L. A. , Krausman P. R. , Valdez R. ,   Society for Range Management
Published: March 2016

We used microhistological analyses of fresh fecal pellets to determine seasonal diets of desert bighorn sheep (Ovis canadensis mexicana Merriam 1901) in northwestern Sonora, Mexico from April 1997 to December 1998. We identified 41 plant species (22 browse, 10 forbs, 5 grasses, and 4 succulents) in diets of bighorn sheep. We found no differences between diets of males and females, and diet diversity between sexes was similar (P 0.05). Diet included: browse (45.7%), forbs (32.0%), succulents (17.8%), and grasses (4.5%). The consumption of succulents was higher during spring, decreased during summer, increased in autumn, and decreased in winter. Consumption of forbs was higher during winter and summer. Globemallow (Sphaeralceae spp.), desert agaves (Agave spp.), range ratany (Krameria parvifolia Benth.), buck-wheatbrush (Eriogonum spp.), foothill palo verde (Cercidium microphyllum [Torrey] Rose Johnst.), Engelmann prickly pear (Opuntia engelmanii Salm-Dyck), desert ironwood (Olneya tesota A. Gray), and elephant tree (Bursera microphylla A. Gray) were consumed throughout the study. As biologists identify potential release sites for restoration of bighorn sheep in Mexico, studies of diet composition will provide managers with information for successful translocations.
Changes in shrub fecundity in fourwing saltbush browsed by cattle
Authors: Cibils A. F. , Swift D. M. , Hart R. H. ,   Society for Range Management
Published: March 2016

Shrub fecundity is critical to long term persistence of fourwing saltbush (Atriplex canescens (Pursh) Nutt.) populations at our research site on the shortgrass steppe in Colorado. We conducted a 2-year experiment to test hypotheses concerning the impact of cattle-browsing on fecundity-related variables in fourwing saltbush. Protection from cattle browsing was significantly associated with floral phenotype shifts toward femaleness, occurring mostly in monecious shrubs (1% and 13% of grazed and protected shrubs, respectively). Sex shifts observed at the individual shrub level did not translate into detectable alterations of sex ratios at the pasture level. Shrubs exhibiting no flowers were considerably more abundant in browsed pastures (26.5%) than in exclosures (1.5%). Nonflowering occurred as frequently in female (3.6%) as it did in male (1.8%) phenotypes. Percent utricle fill was not related to previous year's cattle browsing regime (39% and 44% in protected and grazed shrubs, respectively) but rather to crown volume of the fruiting female and to the gender of and distance to the nearest neighboring shrub. The influence of cattle-browsing on reproductive output of fourwing saltbush occurred mainly through its inhibition of flowering.
In vivo digestibility of kleingrass from fecal nitrogen excretion
Authors: Ferri C. M. , Stritzler N. P. , Brizuela M. A. ,   Society for Range Management
Published: March 2016

It was proposed that the digestibility of organic matter (OMD) can be estimated from the relationship between total fecal nitrogen (TFN, as a % of organic matter intake (OMI) and fecal nitrogen concentration (FNc) through the equation: OMD = 1 - TFN/FNc. Two assumptions are critical to this equation, total fecal nitrogen (as a % of OMI) is a constant and does not change within a range of diet crude protein and fecal nitrogen concentration is proportional to digestibility of organic matter. The objective of this study was to test if total fecal nitrogen (as a % if OMI) remains constant over 3 feeding levels, and if fecal nitrogen concentration decreases with decreasing organic matter digestibility of maturing forages. Total fecal nitrogen did not change (P = 0.94) with feeding level, but increased (P < 0.05) with evaluation period. The fecal nitrogen concentration correlated (r = 0.60, P < 0.001) to digestibility of organic matter. The results show that digestibility of organic matter cannot be estimated from total fecal nitrogen, unless time of year is considered.
Understory species response to Utah juniper litter
Authors: Horman C. S. , Anderson V. J. ,   Society for Range Management
Published: March 2016

A greenhouse study was conducted to determine the effects of litter leachate and litter depth of Utah juniper [Juniperus osteosperma (Torr.) Little] on seedling emergence and emergence rate of 8 common herbaceous understory species. Species tested were: ‘Secar’ bluebunch wheatgrass [Pseudoroegnaria spicata (Pursh) A. Love], bottlebrush squirreltail [Elymus elymoides (Raf.) Swezey], cheatgrass (Bromus tectorum L.), ‘Paiute’ orchardgrass (Dactylis glomerata L.), ‘Appar’ Lewis flax (Linum lewisii Pursh), ‘Delar’ small burnet (Sanguisorba minor Scop.), antelope bitterbrush [Purhsia tridentata (Pursh) DC.], and mountain big sagebrush [Artemisia tridentata spp. vaseyana (Rydb.) J. Boivin]. Three water treatments (distilled water, 1%, and 10% litter leachates) and 3 litter depths (0, 3, and 5 cm) were tested. Leachates decreased seedling emergence of orchardgrass and small burnet. Emergence rate was unaffected by leachate treatments. Seedling emergence of all species tested decreased significantly with increasing litter depth. Emergence rate was initially slower in pots with litter, but after 2 weeks no differences were found.
A method for determining the onset year of intense browsing
Authors: Keigley R. B. , Frisina M. R. , Fager C. ,   Society for Range Management
Published: March 2016

A survey based on browsing related architectures indicated that browsing level had increased at the Mt. Haggin Wildlife Management Area. We describe a technique for determining the year in which the increase in browsing level occurred. The technique is based on the analysis of stems old enough to have experienced the early period of light browsing; the onset year of intense browsing was determined by using dendrochronology to date the formation of twig clusters produced by intense browsing. Stems from 20 Geyer willow (Salix geyeriana Anderss.) plants were analyzed from each of 6 study sites. Mean onset years at the 6 sites ranged from 1983.1 to 1988.4; the mean onset year for all 6 sites was 1985.4 +/- 0.5 SE (N = 120). The reconstructed history was used to evaluate the relationship between moose (Alces alces) number and browse trend. From 1976 to 2000, the winter trend census of moose increased from 7 to 56. The onset of intense browsing in 1985 occurred when 23 moose were counted.
Creating low-cost high-resolution digital elevation models
Authors: Louhaichi M. , Borman M. M. , Johnson A. L. ,   Society for Range Management
Published: March 2016

Ecologists and agronomists are interested in topography because it affects soil, plant, and hydrologic processes. Digital elevation models (DEMs) accurate to several centimeters of vertical elevation are needed but construction is time consuming and expensive when traditional surveying methods are used. Carrier-phase differential global positioning systems can map vertical changes in topography with root mean square errors (RMSE) of 2 to 9 cm, but equipment is expensive (20,000 to 100,000). Coarse-acquisition code differential global positioning systems (C/A code-DGPS) are much cheaper ( 8,000) and widely available but vertical errors are large with root mean square errors of 100 to 200 cm, which severely limits their usefulness in ecological studies. We combined a coarse-acquisition code differential global positioning system and a laser level (1,000) to map topographic change in fields, wetlands, and research plots. Our technique uses the coarse-acquisition code differential global positioning system for longitudinal and latitudinal (X or easting, Y or northing) position while the laser level provides vertical position (elevation) as measured from a ground control point or monument. Measuring elevation across a field scale area is a 2-step procedure. At each sample location the distance from the laser level to the ground is determined and entered as a comment in the differential global positioning systems data logger. In the office, sample locations are differentially corrected and elevation is calculated by subtracting the laser level-to-ground distance from the elevation of the laser. Data is then imported to geographic information system (GIS) software that interpolates between points. The differential global positioning system yields X, Y locations with a root mean square error of between 0.5 and 1.0 m. Elevations measured with our laser level had anaccuracy of better than 2 cm across its 230 m working radius. Our technique works best for areas up to approximately 40 ha on open, rolling terrain.
Development and use of state-and-transition models for rangelands
Authors: Bestelmeyer Brandon T. , Brown Joel R. , Havstad Kris M. ,   Society for Range Management
Published: March 2016

State-and-transition models have received a great deal of attention since the introduction of the concept to range management in 1989. Nonetheless, only recently have sets of state-and-transition models been produced that can be used by agency personnel and private citizens, and there is little guidance available for developing and interpreting models. Based upon our experiences developing models for the state of New Mexico, we address the following questions: 1) how is information assembled to create site-specific models for entire regions, 2) what ecological issues should be considered in model development and classification, and 3) how should models be used? We review the general structure of state-and-transition models, emphasizing the distinction between changes among communities within states (pathways) that are reversible with changes in climate and “facilitating practices” (e.g. grazing management), and changes among states (transitions) that are reversible only with “accelerating practices” such as seeding, shrub control, or the recovery of soil stability and historical hydrologic function. Both pathways and transitions occur, so these models are complementary. Ecological sites and the climatically-defined regions within which they occur (land resource units) serve as a framework for developing and selecting models. We illustrate the importance of clearly delineating ecological sites to produce models and describe how we have dealt with poorly-delineated sites. Producing specific models requies an understanding of the multiple ecological mechanisms underlying transitions. We show how models can represent and distinguish alternative and complementary hypotheses for transitions. Although there may be several mechanisms underlying transitions, they tend to fall within discrete categories based upon a few, fundamental ecological processes and their relationships can be readily understood. A knowledge of mechanisms is closely related to the use of ecological indicators to anticipate transitions. We conclude that models should include 1) reference values for quantitative indicators, 2) lists of key indicators and descriptions of changes in them that suggests an approach to a transition, and 3) a rigorous documentation of the theory and assumptios (and their alternatives) underlying the structure of each model.
A digital photographic technique for assessing forage utilization
Authors: Hyder P. W. , Fredrickson E. L. , Remmenga M. D. ,   Society for Range Management
Published: March 2016

Changes in forage utilization have been difficult to measure non-destructively without some level of subjectivity. This subjectivity, combined with a lack of reproducibility of visual estimates, has made forage utilization measurement techniques a topic of considerable discussion. The objective of this study was to develop and test the accuracy and repeatability of an objective, computer-based technique for measuring changes in plant biomass. Digital photographs of target plants acquired before and after partial defoliation were analyzed using readily available image analysis software. Resulting data were used to develop a simple linear random coefficient model (RC) for estimation of plant biomass removed based on the area of the plant in the photo. Sample collection took approximately 20 minutes/plant for alfalfa (Medicago sativa L.). Analysis of images took another 60 to 90 minutes. Regression analysis gave an R2 of 0.969 for predicted vs. observed plant weights. Testing this model using 10 alfalfa plants yielded weight estimates of defoliated plants accurate to within +/- 8.5%. The advantage of the RC model is its ability to use easily obtained coefficients from simple linear regression models developed from each plant in a way that accounts for the lack of independence between samples within an individual plant. The technique described here offers an objective and accurate method for measuring changes in plant biomass with possible applications in ecology, botany, and range science. In particular, application of this technique for estimating forage utilization may improve accuracy of estimates and, thereby, improve range management practices.
Prescribed fire effects on dalmatian toadflax
Authors: Jacobs James S. , Sheley Roger L. ,   Society for Range Management
Published: March 2016

Prescribed fires are important for rangeland restoration and affect plant community composition and species interactions. Many rangeland plant communities have been, or are under the threat of noxious weed invasion, however there is little information on how fire effects weeds. Our objective was to determine the effects of prescribed rangeland fire on dalmatian toadflax [Linaria dalmatica (L.) Miller] density, cover, biomass, and seed production. These plant characteristics, as well as density, cover, and biomass of perennial grasses and forbs were measured within burned and adjacent not-burned areas on 3 Artemisia tridentata/Agropyron spicatum habitat types in Montana. Areas were burned in the spring and measured in the fall 1999. Comparisons of plant characteristics between the burned and not-burned sites were made using t-tests and non-parametric Wilcoxon Rank Sum tests. After 1 growing season, fire did not affect density or cover of dalmatian toadflax. Burning increased dalmatian toadflax bio- mass per square meter at 2 sites, and per plant biomass at all 3 sites. Seed production of dalmatian toadflax was increased by fire at all 3 sites. Fire reduced forb cover at 1 site and increased grass biomass at 2 sites. The increases in dalmatian toadflax biomass and seed production suggest that fire used to restore healthy plant communities may increase dalmatian toadflax dominance. We recommend weed management procedures, such as herbicide control and seeding desirable species, be integrated with prescribed fire where dalmatian toadflax is present in the plant community.
An index for description of landscape use by cattle
Authors: Zuo Haitao , Miller-Goodman Mary S. ,   Society for Range Management
Published: March 2016

Understanding the role of landscape diversity in livestock distribution patterns is an important consideration for design of effective grazing systems. The objective of this study was to develop and evaluate a Distribution Evenness Index (DEI) based on the Shannon-Wiener index to characterize cattle distribution patterns for a heterogenous landscape within a given period of time. Observations of diurnal behavior of beef cattle (Bos taurus) were made in grassland, wooded, and riparian habitats within a fenced landscape from March to October 2000 at a farm in north-central Alabama. The DEI was calculated based on observation records at different time intervals (15-, 30-, and 60-min) and different levels of grassland habitat subdivision (18-, 9-, and 6-zones). Comparisons of calculated DEI values were made among different habitat types, observation intervals, landscape subdivision levels, and daytime periods. Annual DEI means indicated low evenness of cattle distribution in riparian (0.517) and wooded habitats (0.606), and consistently high evenness in the grassland habitat (0.860). Although grazing activity in the grassland habitat was uneven between different daytime periods (0.565 to 0.679), when combined for the total daytime period, grazing activity in the grassland habitat had a high evenness value (0.855). Relative stability of the DEI calculated between selected spatial and temporal scales in this study indicated that the index may be useful for comparison of evenness of livestock habitat use and grazing patterns between different studies at similar spatial and temporal scales.
Runoff and soil loss in undisturbed and roller-seeded shrublands of semiarid Argentina
Authors: Aguilera M. O. , Steinaker D. F. , Demaria M. R. ,   Society for Range Management
Published: March 2016

Vegetation influences runoff and soil losses in semiarid environments. In shrublands of Central Argentina, grazing has resulted in a reduction of plant cover, an increase in the proportion of bare soil, and eroded soils. Patterns of runoff and soil losses affected by seeding cultivated grasses were evaluated. We investigated the effects of roller-seeding of Cenchrus ciliaris L and the influence of microsite cover-type on the dynamics of water erosion. Evaluated cover-types were: bare soil, shortgrass cover, and tallgrass cover. Evaluations were performed 2 growing seasons after roller-seeding. The experimental design was a split-plot, replicated 3 times using a portable rainfall simulator. After simulation runs of 45 min at an average rate of 110 mm hour-1, runoff of tallgrass cover was the least, whereas bare soil and shortgrass cover had similar values (ca. 60%). However, both types of grass cover reduced soil splash compared to the bare soil cover-type. An exponential function between runoff and soil loss suggested that increasing runoff beyond 60% produced an abrupt rising of sediment loss. Roller-seeding did not influence runoff or sediment loss at the microsite-scale. Nevertheless, roller-seeding reduced the proportion of area covered by microsites prone to erosion (bare soil and shortgrass cover-types) at the whole plot level. We propose that any management tool that promotes the replacement of bare soil and shortgrasses by tallgrasses should reduce runoff and increase forage productivity via amelioration of hydrologic conditions of the rangeland site. Conversely, overgrazing will result in more bare soil, increasing runoff, and further intensifying the loss of sediments by detachment.
Consumption and dispersion of mesquite seeds by ruminants
Authors: Kneuper C. L. , Scott C. B. , Pinchak W. E. ,   Society for Range Management
Published: March 2016

Consumption of mesquite (Prosopis glandulosa Torr. var glandulosa) fruit by ruminants is an important component of seed dispersal. Two experiments were conducted to estimate the role of livestock and wildlife in the dispersion of mesquite fruit. In Experiment 1, 3 trials were conducted to determine preference for mesquite fruit by different species of livestock, intake relative to fruit maturity, and seed survival of digestion. Cattle, sheep, and goats were offered immature (IM), mature off the tree (MT), or mature off the ground (MG) fruit to quantify intake and seed survival of digestion. Germination of seeds surviving digestion was also assessed. Experiment 2 assessed rate of pod disappearance from pastures with and without livestock grazing and attempted to quantify seed loss to wildlife. In Experiment 1, livestock consumed more (P < 0.05) mature than immature fruit; sheep and goats consumed more fruit than cattle on a body weight basis. Seed survival was greater (P < 0.05) from cattle than from sheep or goats. The number of seeds remaining intact after digestion was greater for mature fruit. Germination of seeds surviving digestion was similar (P > 0.05) to seeds that experienced natural weathering for 6 months. In Experiment 2, the presence or absence of livestock did not affect the disappearance of seeds; seeds disappeared from the ground within 3 weeks in 1999 and 5 weeks in 2000 presumably by wildlife. Deer, raccoons, skunks, bobcats, turkeys, and other birds visited plots with fresh mesquite fruit. Collectively, these results suggest that cattle readily consume and disperse viable mesquite seeds; sheep and goat consumption of mesquite fruit may reduce the number of viable seeds; and mesquite fruit may only remain on the ground for a short period of time even without livestock grazing because of consumption by wildlife.
Technical note: a technique for conducting small-plot burn treatments
Authors: Korfmacher J. L. , Chambers J. C. , Tausch R. J. ,   Society for Range Management
Published: March 2016

An experimental design required burn treatments for 10-m2 circular plots. We constructed a fire enclosure for the plots using sheetmetal, electrical conduit, and other commonly available materials. We field tested the enclosure in sagebrush-grass ecosystems in central Nevada and central Utah, and evaluated peak fire temperatures using small metal tags striped with temperature sensitive paint. We obtained average peak surface temperatures of 310, 307, and 381 degrees C in bare ground, under grass, and under shrub microsites, respectively, for the Nevada sites and 253, 299, and 337 degrees C for the same microsites, respectively, in Utah. Subsurface (2-cm depth) temperatures rarely exceeded 79 degrees C, the lowest temperature detectable by our method. The enclosure contained the fire and did not permit escape of any embers or firebrands. The fire enclosure, burn technique and temperature monitoring method used are inexpensive, easily deployed, and desirable for experiments where larger-scale burns are impractical.
Toxicity and development of tolerance in cattle to timber milkvetch
Authors: Majak W. , Stroesser L. , Lysyk T. ,   Society for Range Management
Published: March 2016

Timber milkvetch (TMV, Astragalus miser Dougl. ex Hook var. serotinus) is widely distributed on rangelands in the southern interior of British Columbia, Canada. It synthesizes large quantities of miserotoxin, a glycoside that is toxic to cattle. Six grazing studies were conducted at Sixtyone Creek on the Cariboo Plateau during 1993 to 2000 to determine which class of livestock was most susceptible to TMV, to record clinical signs of poisoning under range conditions, and to determine the efficacy of protein supplements for the prevention of TMV poisoning. In vitro rates of TMV detoxification in rumen fluid were determined concurrently. Incidents of early, acute and chronic poisoning were documented using a total of 143 cows over the 6 year study. Older cows (more than 3-years old) and yearling heifers were less susceptible to TMV than lactating first-calf heifers, which showed acute signs of poisoning. A chronic syndrome was sometimes seen in second-calf heifers, especially during exertion. Heifers not previously exposed to TMV, such as those that were obtained from the prairie region of Alberta, were also more susceptible than cattle originating in B.C. with a known history of exposure to TMV. Each year, Hereford cows were divided into 2 groups, one of which received free-choice protein supplements in a molasses block, the other did not receive supplement and served as a control group during the 6-week grazing trial. The control group yielded 25 cases of TMV poisoning during the 6-year study, compared with 2 for the supplement group. However, the supplement increased rates of TMV detoxification (> 50%) in only 1 of the 5 years of testing. Native cattle yielded higher rates of TMV detoxification (> 25%) in 2 of the 5 years than introduced cattle. The innate capacity to transfer rumen microbial activity between cattle in close proximity and the natural enrichment of rumen microbial populations could elevate rates of detoxification regardless of supplement or origin.
Contrasting responses of Intermountain West grasses to soil nitrogen
Authors: Monaco T. A. , Johnson D. A. , Norton J. M. ,   Society for Range Management
Published: March 2016

The mechanisms responsible for soil-N-mediated species replacement of native perennial grasses by the invasive annual grasses cheatgrass (Bromus tectorum L.) and medusahead (Taeniatherum caput-medusae [L.] Nevski) on rangelands are not completely understood. In addition, the contributions of distinct forms of inorganic N (i.e., NH4+ and NO3-) to these shifts in species composition are currently unclear. Consequently, we conducted a greenhouse experiment to test 2 hypotheses: 1) that low N availability reduces growth (root and shoot) and N allocation of invasive annual seedlings more than native perennial species, and 2) that seedling growth and N allocation of invasive annual grasses is more responsive than native perennial grasses when supplied with NO3- relative to NH4+. We grew seedlings of 2 annual grasses and the native perennial grasses bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love), and 4 populations of squirreltail (Elymus elymoides [Raf.] Swezey; E. multisetus [J.G. Smith] M.E. Jones) in separate pots and exposed them to treatments differing in N form and availability for 17 weeks. Unexpectedly, root and shoot growth of annual grasses were equal or greater than native perennial grasses under low N availability. Annual grasses took up more NO3- and allocated more growth and N to shoots than the perennial grasses (P 0.05). Perennial grasses had significantly greater root:shoot dry mass ratios than the invasive annual grasses across treatments (P 0.05). Invasive annual and native perennial grasses both had greater (P 0.05) shoot and root mass and allocated more N to these structures when supplied with NO3- relative to NH4+. The ecological implications of these growth and N allocation patterns in response to N availability and form provide important clues regarding the specific traits responsible for differences in competitive ability between invasive annual and native perennial grasses on semiarid rangelands.
Adesmia subterranea Clos germination physiology and pre-sowing treatments
Authors: Parera C. A. , Ruiz M. ,   Society for Range Management
Published: March 2016

The genus Adesmia (Fabaceae, Papilionoideae) is one of the scarce forage resources at high altitude and arid zones of South America. Its germination behavior has not been examined. Seeds of Adesmia subterranea "Cuerno de Cabra" were pretreated with sulfuric acid (1, 3, and 5 minutes soaking) and mechanical scarification to determine their impact upon dormancy and percentage and speed of germination. Treatments were evaluated under a range of constant temperatures (5 to 30 degrees C) and 2 day/night cycles resembling the extreme environmental conditions of this species habitat. Water uptake and leachate conductivity were higher in the seeds scarified mechanically or with 5 minutes chemical scarification. These treatments also had the greatest total germination and rate at all temperatures in a petri dish germination test. However, in a cell tray experiment using a commercial substrate, the highest seedling emergence and rate were observed with chemical scarification (5 and 3 minutes). The high amount of leakage caused by the scarifications affected emergence in a non-sterile media. The results indicate that A. subterranea seeds have an impermeable seed coat which restricts water uptake, and the efficiency of sulfuric acid scarification to overcome seed coat impermeability and improve germination and emergence.
Restoring riparian corridors with fire: effects on soil and vegetation
Authors: Blank R. R. , Chambers J. C. , Zamudio D. ,   Society for Range Management
Published: March 2016

In many riparian corridors of the semi-arid west, stream incision has resulted in lowered water tables, basin big sagebrush (Artemisia tridentata var. tridentata Nutt.) encroachment and the loss of the dominant herbaceous vegetation. To determine the potential for restoring basin big sagebrush-dominated riparian corridors to greater herbaceous cover, a fall prescribed burn on sites with relatively shallow (-153 to -267 cm) and deep (-268 to or = -300 cm) water tables was conducted. We evaluated the separate and interacting effects of water table depth and burning on total soil C and N, soil nutrient availability, and soil enzyme activities by microsite (sagebrush subcanopy, sagebrush interspace), and soil depth (ash/liter, 0-2, 2-5, and 10-20 cm). Three years after the prescribed burn, tissue nutrient content in silvery lupine (Lupinus argenteus Pursh) and Douglas sedge (Carex douglasii Boott), by microsite, growing in burned and unburned areas of 1 shallow water table site was measured. Influence of fire on soil attributes was largely limited to the top 5 cm. As a consequence of prescribed burning, deep water table sites lost relatively more N and C from litter horizons and released more aqueous-soluble Ca+2 from 0-2 cm mineral horizons than did corresponding horizons from shallow water table sites. Overall, compared to unburned controls, burning: (1) increased aqueous-extractable SO4(-2), K+, and KCl-extractable NH4+, (2) decreased activities of the enzymes asparaginase, urease and acid-phosphatase, and (3) decreased KCl-extractable NO3- and aqueous-soluble ortho-P. Out of 16 measured soil attributes reported, 7 were influenced by a microsite main effect and/or interaction. New tissue of silvery lupine on burned plots had greater N, greater Zn and Fe (only on subcanopy microsites) and less Ca than plants on control plots; new tissue of Douglas sedge had greater S and less Na, P, and Zn. The results indicate that burning alone is an appropriate restoration treatment for shallow water table sites because of minimal C and N loss and increased available nutrients for regrowth of understory herbaceous species. Deep water table sites require a burning prescription that minimizes fire severity because of higher potential C and N loss, and reseeding due to a lack of perennial understory herbaceous species and more xeric conditions.
Sustainability of Inner Mongolian grasslands: application of the Savanna model
Authors: Christensen L. , Coughenour M. B. , Ellis J. E. ,   Society for Range Management
Published: March 2016

The sustainability and resilience of an Asian typical steppe grazing ecosystem was assessed by determining thresholds and stable states with an ecosystem simulation model. This analysis used the Savanna model to simulate spatial climate, vegetation, and livestock grazing dynamics, at 14 different stocking rates (5.5-59.8 AUY km-2). Grazing effects on vegetation were assessed, including effects on primary production, vegetation composition, and root biomass. Simulations were run for 100 years: 50 years to examine sustainability and 50 years to examine resilience of the system. Results showed that a grazing intensity (1-g/u; g = biomass in grazed area, u = biomass in ungrazed area) of 0.49 was sustainable for this particular system. This region was resilient to grazing up to the intensity of 0.49, where the system remained dominated by herbaceous production. Grazing intensities higher than 0.49, in combination with low precipitation events, resulted in decreased herbaceous net primary production and root biomass, and increased shrub net primary production and root biomass. Herbaceous vegetation was unable to gain a competitive advantage over shrubs in areas where grazing intensities were above 0.49; consequently, the system shifted to a stable shrub-dominated state that could not return its original composition even without further grazing.
Vegetation indices, CO2 flux, and biomass for Northern Plains grasslands
Authors: Frank A. B. , Karn J. F. ,   Society for Range Management
Published: March 2016

Native grasslands are a sink for atmospheric CO2 sequestration, but ways for extending site-specific CO2 flux measurements to a regional scale are lacking. Objectives of this study were to determine the utility of using canopy radiometric reflectance for estimating CO2 fluxes for semiarid grasslands. The relationship between the normalized difference vegetation index (NDVI) calculated from spectral reflectance data obtained with hand-held radiometers was compared to CO2 flux calculated from Bowen ratio/energy balance measurements. Carbon dioxide flux was measured during the plant growing season over a nongrazed prairie, grazed prairie, and a shrub dominated prairie site near Mandan, N.D. Measurements were also made of evapotranspiration (ET), green biomass, and green leaf area index (LAI). Correlation coefficients of NDVI with vegetation parameters of biomass and LAI for each site and year exceeded 0.84 in 1999, 0.74 in 2000, and 0.91 in 2001; with CO2 flux correlations exceeded 0.63 in 1999, 0.68 in 2000, and 0.69 in 2001; with ET correlations exceeded 0.91 in 1999, 0.92 in 2000, and 0.90 in 2001. Regression analysis over all years and sites produced a nonlinear relation between NDVI and both biomass (R2 = 0.83) and LAI (R2 = 0.77) and a linear relationship between NDVI and both CO2 flux (R2 = 0.51) and ET (R2 = 0.81). The relationships between NDVI and biomass, LAI, CO2 flux, and ET for the 3 grassland sites, which differed in management and vegetation, were generally quite similar suggesting that NDVI has potential for use in predicting canopy CO2 flux rates for semiarid grasslands in the Northern Great Plains.
Impacts of tracked vehicles on sediment from a desert soil
Authors: Fuchs E. H. , Wood M. K. , Jones T. L. ,   Society for Range Management
Published: March 2016

Off-road military vehicle traffic is a major consideration in the management of military lands. The objective of this study was to determine the impacts of military tracked M1A1 heavy combat tank vehicles on sediment loss from runoff, surface plant cover, and surface microtopography in a desert military training environment. A randomized block design was used which had 10 blocks with 4 plots (0.5 m2) in each block. Each block had randomly selected treatments that included an untreated control, 1 pass by a M1A1 tank under wet seasonal conditions, 3 passes by a M1A1 tank under wet seasonal conditions, 1 pass by a M1A1 tank under dry seasonal conditions, and 3 passes by a M1A1 tank under dry seasonal conditions. Data were analyzed using mean separation and stepwise regression techniques. Most sample periods showed that sediment losses from M1A1 tank treatments, single or triple passes under wet or dry seasonal conditions, did not differ statistically from natural sediment losses under nominal rainfall events. However, comparatively intense rainfall events often generated significantly (P 0.05) greater sediment losses from the M1A1 tank triple pass treatments. Triple pass M1A1 tank impacts had detrimental effects that could last many years, particularly when disturbances were imposed under dry seasonal conditions. Seasonal drought for the area, occurring 2 out of 3 years during the study period, may have exacerbated the effects of triple pass M1A1 tank impacts. Analysis showed that grass cover, litter cover, and microtopographic variance were highly and negatively correlated (R = -0.62) with cumulative sediment loss. Depending on precipitation availability, a minimum of 3 years for most triple pass M1A1 tank impacts is suggested for suitable vegetation recovery and soil stability. It is recommended that site repetitious M1A1 tank training maneuvers should be conducted with particular attention to site recovery. Furthermore, the influence of climate, drought in particular, should be among the topics addressed by future military training land use models.
Perennial grass abundance along a grazing gradient in Mendoza, Argentina
Authors: Gonnet J. M. , Guevara J. C. , Estevez O. R. ,   Society for Range Management
Published: March 2016

The study analyzed the basal area and density of perennial grasses along a cattle grazing intensity gradient away from a water development. Several mechanisms explaining combinations of changes in basal area and density with increasing grazing intensity were proposed. There was a curve-linear gradient of decreasing utilization of grasses at greater distances from water, and that gradient declined at greater distances from water. Basal diameter and density of 8 grasses were recorded at 11 distances from water ranged from 0.1 to 4.6 km within 16, 1-m2 plots for each distance. Circular basal area for each species was derived from its mean basal diameter. Plant density was estimated counting each tussock for bunchgrasses and each tiller as an individual for the 1 rhizomatous grass. The abundance of basal area and density to the gradient of distance from water was analyzed for grasses grouped according to their selectivity by cattle (undesirable, preferred, desirable, and secondary preference) and for the major preferred grass, Chloris castilloniana Lillo Parodi and the 2 undesirable grasses, Aristida inversa Haeck. and A. mendocina Phil. Distance from water was regressed separately on basal area and on density for each selectivity group and each individual species. Basal area of total, undesirable, and desirable grasses increased up to intermediate distances from water and decreased at sites farther from water. Basal area of both the preferred grasses combined and the major preferred species increased linearly with distance from water. Basal area of A. inversa showed the same trend as the undesirable grasses while basal area of A. mendocina showed no definite pattern with increasing grazing intensity. Basal area of secondary preference species showed no definite pattern with distance from water. Density of total and desirable grasses increased up to intermediate distances from water and decreased at sites farther from water. Density of preferred species combined and the major preferred grass increased linearly with distance from water. Density of the 2 undesirable grasses and the secondary preference grass showed no definite trend with increasing grazing intensity. The combined patterns of basal area and density across the grazing intensity gradient suggest that the expression of recruitment, mortality, and plant growth (or shrinkage) in relation to grazing intensity varies among species and at different levels of grazing intensity. However, controlled experiments are needed to decipher the relative contributions of grazing intensity, neighboring species composition, or vegetation patterns existing before the establishment of the livestock water in the patterns of abundance.