bluuebunny/crossref_metadata_2025 huggingface dataset:
Low density of prickly acacia under sheep grazing in Queensland
Authors: Tiver F. , Nicholas M. , Kriticos D. ,   Society for Range Management
Published: March 2016

Populations of an introduced woody weed, prickly acacia (Acacia nilotica (L.) Delile ssp. indica (Benth.) Brenan syn. Acacia arabica (Lam.) Willd. ssp. indica Benth.), were surveyed at 4 sites in central Queensland. There is a significantly lower frequency of plants of 3 m in height within populations which have been grazed by sheep, indicating that browsing by sheep reduces regeneration. There were higher losses of seedlings at a sheep-grazed site than at cattle-grazed sites. These results support previous assertions that prickly acacia is regenerating more successfully on cattle properties, because cattle both disperse seeds and are less effective herbivores. In regions of low annual rainfall, prickly acacia is capable of forming dense stands (up to 2,700 shrubs ha(-1)) in lowland landscape types. Stands are less dense in upland landscapes (maximum of 718 shrubs ha(-1)). Of most concern is that in regions of high annual rainfall prickly acacia can form extremely dense thickets across most landscape types (up to 3,400 shrubs ha(-1)). We suggest that prickly acacia is most likely to become a management problem on cattle properties, and an extreme problem in high annual rainfall areas. The inclusion of sheep in livestock rotations may be an effective control measure in the Mitchell Grasslands, but this may not always be possible. A high priority is to prevent prickly acacia from expanding its range into equivalent high rainfall areas within Queensland, and also in the Northern Territory, northern New South Wales, and Western Australia. This could be achieved by quarantining livestock which have come from infested properties until seeds have passed through the digestive tract, after about 6 days. Management strategies at the property level should aim to prevent further spread of prickly acacia by controlling cattle movements between paddocks during periods when cattle are ingesting pods and seeds.
Bitterbrush and cheatgrass quality on 3 southwest Idaho winter ranges
Authors: Bishop C. J. , Garton E. O. , Unsworth J. W. ,   Society for Range Management
Published: March 2016

Nutritional stress is an important mortality factor for wintering mule deer (Odocoileus hemionus hemionus Rafinesque), particularly fawns. The rate at which fawns utilize existing fat stores is at least partially dependent upon the quality of available forage during winter. Although numerous studies have determined the nutritive value of various forage species, more research is needed to determine whether individual forage species vary in quality across the landscape. We determined whether differences existed in the nutritional quality of antelope bitterbrush (Purshia tridentata [Pursh] DC.) and cheatgrass brome (Bromus tectorum L.) among 3 winter ranges and 6 habitats within the winter ranges. In vitro dry matter digestibility (IVDMD) of bitterbrush varied among winter ranges in 1996 and 1997 (P < 0.001). The highest mean IVDMD measured on a winter range was 29.8% (n = 36, SD = 3.87) in 1997 while the lowest was 15.2% (n = 38, SD = 4.42) in 1996. Bitterbrush crude protein (CP) was different among habitats in 1997 (P = 0.005), with mean CP values ranging from 7.0% (n = 19, SD = 0.73) to 8.0% (n = 13, SD = 0.70). The length and diameter of available bitterbrush leaders varied within and among winter ranges because of differential utilization. Bitterbrush IVDMD and CP varied in relation to the mean diameter of leaders obtained from each random sampling site (P 0.001). The quality of bitterbrush decreased as browse intensity increased. Cheatgrass IVDMD was different between winter ranges (P < 0.001) in 1996, with mean values ranging from 65.8% (n = 36, SD = 4.34) to 69.6% (n = 36, SD = 3.83). Site-specific variation should be considered when evaluating the nutritional quality of mule deer habitat, at least during winter when species diversity in deer diets is limited.
Spatial modeling of rangeland potential vegetation environments
Authors: Jensen M. E. , Dibenedetto J. P. , Barber J. A. ,   Society for Range Management
Published: March 2016

Potential vegetation environments (e.g., habitat types, range sites, ecological sites) are important to land managers because they provide a conceptual basis for the description of resource potentials and ecological integrity. Efficient use of potential vegetation classifications in regional or subregional scale assessments of ecosystem health has been limited to date, however, because traditional ecological unit mapping procedures often treat such classifications as ancillary information in the map unit description. Accordingly, it is difficult, if not impossible, to describe the precise location, patch size, and spatial arrangement of potential vegetation environments from most traditional ecological unit maps. Recent advances in remote sensing, geographic information systems (GIS), terrain modeling, and climate interpolation facilitate the direct mapping of potential vegetation through a predictive process based on gradient analysis and ecological niche theory. In this paper, we describe how a predictive vegetation mapping process was used to develop a 30 m raster-based map of 4 grassland, 5 shrubland, and 6 woodland habitat types across the Little Missouri National Grasslands, North Dakota. Discriminant analysis was used in developing this potential vegetation map based on 6 primary geographic information system themes. Geoclimatic subsections and remotely sensed vegetation lifeform maps were used in predictive model stratification. Terrain indices, LANDSAT satellite imagery, and interpolated climate information were used as independent (predictor) variables in model construction. A total of 616 field plots with known habitat type membership were used as dependent variables and assessed by a jackknife discriminant analysis procedure. Accuracy values of our map ranged from 54 to 77% in grasslands, 62 to 100% in shrublands, and 70 to 100% in woodlands dependent on geoclimatic subsection setting. Techniques are also described for generalizing the 30 m pixel resolution habitat type map to appropriate ecological unit maps (e.g., landtype associations) for use in ecosystem health assessments and land use planning.
Suppression of annual bromes impacts rangeland: Vegetation responses
Authors: Haferkamp M. R. , Heitschmidt R. K. , Grings E. E. ,   Society for Range Management
Published: March 2016

Presence of invading annual bromes (Bromus spp.) can alter seasonal patterns of forage production and quality and require management changes for efficient use of infested rangelands in the Northern Great Plains. We studied biological impacts of the presence of brome by comparing brome infested rangeland to similar sites in which brome had been suppressed with autumn applications of atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)- 1,3,5-triazine-2,4-diamine] at 0.56 kg ha(-1) in 1992 and 1993. Each treatment was randomly assigned to three, 12-ha pastures. Vegetation was measured for 5 months (May to September) each year from 1993 to 1995. Each pasture was stocked with 8 cross-bred steers (Bos taurus) from mid-May to mid-September 1993 and 1995 and to mid-August 1994. The forage base varied temporally by date and year, but generally was not less than 800 kg ha(-1). Brome suppression increased (P less than or equal to 0.05) crude protein concentration for western wheatgrass (Pascopyrum smithii Rydb. [Love]) in July (7.1 vs. 9.1%) and August (6.0 vs. 7.1%). With the variation in annual brome stands among years, as influenced by growing conditions, this experiment demonstrated that improvement in forage nutritional quality can be expected from suppression of annual bromes on semiarid rangelands.
Suppression of annual bromes impacts rangeland: Animal responses
Authors: Haferkamp M. R. , Grings E. E. , Heitschmidt R. K. ,   Society for Range Management
Published: March 2016

Presence of annual bromes (Bromus spp.), introduced annual weedy grasses, can alter seasonal patterns of forage production and quality and require management changes for efficient use of infested rangelands. We determined biological impacts of the presence of brome by comparing livestock performance on brome infested rangeland to similar sites on which brome had been suppressed by autumn application of atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)- 1,3,5-triazine-2,4-diamine] at 0.56 kg ha(-1) in 1992 and 1993. Each treatment was randomly assigned to three, 12-ha pastures. Vegetation was measured for 5 months (May to September) each year from 1993 to 1995. Each pasture was stocked with 8 crossbred steers of British breed origin (Bos taurus) from mid-May to mid-September 1993 and 1995 and to mid-August 1994. Initial body weights averaged 329 kg SD = 31 in 1993, 273 kg SD = 14 in 1994, and 272 kg SD = 21 in 1995. Brome suppression and environment influenced plant species in diets, diet quality, and livestock performance. Brome suppression reduced percentage of annual grasses in diets from 14% to 10%. Annual grasses were replaced in the diet by a variety of forb and grass species [western wheatgrass [Pascopyrum smithii Rydb. (Love)], and blue grama [Bouteloua gracilis [H.B.K.] Lag. ex Griffiths]], with specific replacement depending on year and month. Steer gains were increased from 0.92 to 1.04 +/- 0.02 kg head(-1) day(-1) (P < 0.02) and from 69 to 81 +/- 2.8 kg ha(-1) (P < 0.05) with brome suppression. This experiment demonstrated that improvement in livestock performance can be expected with the suppression of annual bromes on semiarid rangelands.
Adoption of Brush Busters: Results of Texas county extension survey
Authors: Kreuter U. P. , Amestoy H. E. , Ueckert D. N. ,   Society for Range Management
Published: March 2016

Changing landowner demographics and the increasing recognition that some quantity of woody plants is valuable for certain rangeland management objectives has led to increasing interest in selective brush management practices. Brush Busters is a collaborative extension/research program developed in response to this growing interest. A survey of Texas County Extension Agents-Agriculture was conducted in 1999 to determine their perceptions about the interest in and adoption of Brush Busters practices. Using 3 threshold photographs, Extension Agents representing almost 50% of the counties in the 9 Extension Districts surveyed estimated that 44, 34, and 49% of the total area of mesquite, juniper and pricklypear, respectively, could be treated using Brush Busters. They also indicated that over 405,000 ha (78% mesquite) were treated with Brush Busters methods between 1995 and 1998, but that this represented less than 7% of the potentially treatable area. In most Extension Districts, more time was spent disseminating information about Brush Busters methods than any other brush management method since 1995. Extension Agents indicated that Brush Busters has become popular because it is perceived to be an inexpensive, convenient, safe, effective and predictable method for controlling brush, and because user-friendly information is widely available. Our findings suggest that increasing the adoption rates of ecologically sound rangeland management technologies requires: (1) greater emphasis on developing and disseminating user-friendly messages to rangeland managers and Extension Agents; and (2) greater emphasis on short-term efficacy rather than the long term advantages of new technologies.
Influence of off-stream supplements on streambanks of riparian pastures
Authors: McInnis M. L. , McIver J. ,   Society for Range Management
Published: March 2016

Accelerated erosion of streambanks in grazed riparian pastures is of concern to land managers. We tested the hypothesis that providing cattle free-choice off-stream water and trace mineralized salt would lessen negative impacts of grazing on cover and stability of streambanks compared to pastures lacking these amenities, and may therefore reduce the potential of accelerated erosion. The study was conducted on Milk Creek at the Hall Ranch Unit of the Eastern Oregon Agricultural Research Center near Union, Ore. Three replications each of 3 grazing treatments were examined: (1) non-grazed control; (2) grazed with supplemental water and trace mineralized salt provided ("supplemented"); and (3) grazed with no supplemental water or salt ("nonsupplemented"). Each grazed pasture (approximately 12 ha) was stocked with cow-calf pairs for a mean stocking rate of 0.8 ha per AUM to achieve moderate grazing intensity of approximately 50% utilization of key forages. Pastures were grazed for 42 consecutive days during each of 2 years (1996-1997) beginning mid-July. Estimates of streambank cover ("covered" or "uncovered") and stability ("stable" or "unstable") were taken before (June) and after (September) grazing by examining 0.5 X 0.3 m plots placed on the greenline. Additionally, frequency of cattle hoof prints (number of plots with hoof prints/total number of plots) was measured as an indication of cattle presence in the greenline. Treatment effects were compared using one-way ANOVA. Streambank effects were consistent with observations of cattle distribution, with 26% of the streambank in supplemented pastures showing cattle presence (hoof prints), versus 31% for non-supplemented pastures. Off-stream water and salt attracted cattle into the uplands enough to significantly (p less than or equal to 0.05) reduce development of uncovered and unstable streambanks from 9% in non-supplemented pastures to 3% in supplemented pastures. An "erosion index" indicated no significant (p < 0.05) difference in potential accelerated streambank erosion between supplemented and non-supplemented pastures.
Frequency grid—a simple tool for measuring grassland establishment
Authors: Vogel K. P. , Masters R. A. ,   Society for Range Management
Published: March 2016

Simple, reliable tools are needed by land managers to quantify establishment success when seeding or re-seeding pastures or rangeland. A frequency grid was designed to measure seedling or plant establishment success for a single species, mixtures of species, or single species of a mixture. The frequency grid is a metal frame containing 25 squares (5 x 5) or cells and can be made from concrete reinforcing sheets that have 15 x 15 cm squares. When used, the frequency grid is either randomly or systematically placed within a seeded area. The number of cells containing 1 or more seeded plants are counted. The grid is then flipped, end-over-end, and the counts are repeated. The process is repeated until a total of 100 cells have been counted per sampling location within a seeded area. Counts can be directly converted into frequency of occurrence or stand percentages by dividing the number of cells that contain a seeded plant by 100. The process can be repeated at several locations within a seeded area to characterize establishment success. Multiplying frequency of occurrence percentages by 0.4 provides a conservative estimate of plant density (plants m(-2)). A single measurement of 100 frequency grid cells can be taken in less than 5 minutes. The frequency grid is inexpensive to make, requires minimal training, permits rapid measurements, and provides a meaningful estimate of plant density. The frequency grid has been used to document herbicide efficacy and seeding rates for use in grassland establishment in the central Great Plains and should be easily adaptable for use in other geographic regions.
Intake and digestive kinetics of leaf and stem fractions
Authors: Lamb J. B. , Adams D. C. , Klopfenstein T. J. ,   Society for Range Management
Published: March 2016

Ruminally fistulated steers were used in a 4 x 4 Latin square to test effects of immature (vegetative) and mature (post reproductive) leaf and stem fractions from subirrigated meadow hay on organic matter intake (OMI), organic matter digestibility (OMD), and digestive kinetics. Hay was harvested 1 June (immature) and 1 October (mature), chopped into 3- to 5-cm lengths, then separated into leaf and stem fractions using a modified Clipper Cleaner Model Super 69D. Steers were provided ad libitum access to fractions and supplemented with urea so that diets were iso-nitrogenous. Particulate passage was determined using Yb labeled large hay particles [greater than or equal to 1.7-mm screen] and Er labeled small particles [< 1.7-mm and greater than or equal to 0.212-mm screen]. Samples were collected from the rumen, omasum, feces, and un-masticated diets for particle size determination. Particle size was determined using wet sieving techniques. Voluntary OMI of immature fractions (15.4 g kg(-1) BW) was greater (P < 0.05) than mature fractions (12.5 g kg(-1) BW). Within maturity OMI and OMD of leaves and stems were similar. Immature fractions had greater (P < 0.05) OMD (63.2%) than mature fractions (55.7%). Large and small particle passage rates were faster (P < 0.05) for immature fractions [3.2% hour(-1) (large) and 4.3% hour(-1) (small)] than mature [(2.3% hour(-1) (large) and 2.9% hour(-1) (small)]. Critical particle size for ruminal escape was less than or equal to 1.18 mm for both leaves and stems regardless of maturity. Differences in OMI and OMD between immature and mature fractions were explained by changes in structural components of the cell wall that made particles more resistant to mechanical and microbial breakdown.
Effects of nitrogen availability on the growth of native grasses exotic weeds
Authors: Lowe P. N. , Lauenroth W. K. , Burke I. C. ,   Society for Range Management
Published: March 2016

Many studies have shown that high nitrogen availability encourages the community dominance of exotic, weedy species. Other researchers have attempted to reduce existing exotic species infestations by reducing soil nitrogen availability. We tested the hypothesis that exotic weeds and native species differ in their response to nitrogen availability, predicting that the exotics would have a much more positive response than the natives at high nitrogen levels but that natives would better tolerate low nitrogen levels. To test this hypothesis, we conducted a greenhouse experiment investigating the aboveground biomass, belowground biomass, height, and aboveground tissue nitrogen concentration response of 2 North American native plant species, blue grama (Bouteloua gracilis H.B.K. Lag.) and western wheatgrass (Pascopyrum smithii (Rybd.) A. Love), and 4 exotic species, cheatgrass (Bromus tectorum L.), leafy spurge (Euphorbia esula L.), Canada thistle (Cirsium arvense L.), and Russian knapweed (Centaurea repens L.), to 5 levels of nitrogen availability, 0 g N/m2, 1 g N/m2, 4 g N/m2, 7g N/m2, and 10 g N/m2. We grew single individuals of each species from seed in 3 liter pots in the greenhouse for 75 days. The exotics and natives did differ in their response to nitrogen availability, but not in the predicted manner. The exotics did not have a more positive response to nitrogen availability than the native species, and the species with the poorest response was an exotic. There were no differences between the exotic and native species at any level of nitrogen availability in root:shoot ratios, total biomass, or percent leaf tissue nitrogen, but the native species as a group gained more height than the exotics at every level of nitrogen availability. Our data do not show a generalizable relationship between exotic or native plant groups and growth response to nitrogen.
Does ruminal retention time affect leafy spurge seed of varying maturity?
Authors: Olson B. E. , Wallander R. T. ,   Society for Range Management
Published: March 2016

Grazers ingest seeds of invasive forbs and may contribute to their spread by depositing viable seeds in uninfested areas. Some mature seed pass through the gastrointestinal (GI) tract of ruminants, but grazers consume flowerheads of invasive species from anthesis to dehiscence. We collected seed from the Eurasian leafy spurge (Euphorbia esula L.) at 3 stages of maturity (soft dough, hard dough, mature). With seed collected from these different stages, our objectives were to determine effects of 1) rate of passage through the GI tract of sheep on leafy spurge seed recovery, germinability and viability, 2) residence time in sheep rumen on seed germinability and viability, and 3) acid pepsin digestion, simulating the lower GI tract, on seed germinability and viability after different residence times in the rumen. More seed from the later stages of maturity were recovered in the manure. The greatest number of seed recovered only represented 3.9% of the number of ingested seed. Few seeds were recovered after day 4. Soft dough seed in manure would not germinate and was not viable, whereas hard dough and mature seed collected from manure during the first 4 day were viable. Pepsin had a slight effect on the number of mature seed recovered, but eliminated viability of recovered seed. Viability of non-pepsin treated seed from the hard dough and mature stages declined with greater residence time in the rumen. Thus, managers should be aware that livestock ingesting hard dough as well as mature seed may be dispersing viable weed seed.
Seasonal grazing affects soil physical properties of a montane riparian community
Authors: Wheeler M. A. , Trlica M. J. , Frasier G. W. ,   Society for Range Management
Published: March 2016

The effects of seasonal grazing treatments (early spring and late summer) on soil physical properties were studied in a montane riparian ecosystem in northern Colorado. Infiltration rates and bulk density were used as primary indicators of responses to a 1-time heavy grazing event on previously protected paddocks. Soil bulk density, porosity, gravimetric water content, organic carbon concentration and texture were measured at 0-5 cm, 5-10 cm, and 10-15 cm depths to determine how these parameters affected infiltration rates. Assessment of initial changes and subsequent recovery of the soil properties in response to the grazing treatments was conducted by measuring these parameters before each grazing event and at 4 time periods following the grazing event. Few differences between spring or late summer grazing periods on soil physical properties were found. A stepwise multiple regression model for infiltration rate based on soil physical properties yielded a low R2 (0.31), which indicated much unexplained variability in infiltration. However, infiltration rates declined significantly and bulk density increased at the 5-10 cm depth and 10-15 cm depth in grazed plots immediately following grazing, but the highly organic surface layer (0-5 cm) had no significant compaction. Infiltration rates and soil bulk densities returned to pre-disturbed values within 1 year after grazing events, suggesting full hydrologic recovery. This recovery may be related to frequent freeze-thaw events and high organic matter in soils.
Northern dry mixed prairie responses to summer wildlife and drought
Authors: Erichsen-Arychuk C. , Bork E. W. , Bailey A. W. ,   Society for Range Management
Published: March 2016

In August 1994, wildfire burned 6,500 ha of native Dry Mixed Prairie in southeastern Alberta. The following year, a study was initiated to monitor the recovery of major plant communities. Burning was followed by 3 successive years of drought, reducing total vegetative cover by 10%. Exposed soil increased to a high of 23%, three years after the fire. Litter and grass production were reduced through 1997, with the greatest decline in 1995 when grass production on burned and unburned areas averaged 890 and 1,468 kg ha(-1), respectively. Of the major forage species, Stipa spp. and Koeleria macrantha (Ledeb. J.A. Schultes f.) were affected for a single year and Agropyron spp. 2 years by burning. Both Agropyron and Stipa abundance displayed interactions with topographic position in response to fire. In 1995, Agropyron increased on uplands with burning from 90 to 143 kg ha(-1), but decreased on lowlands from 383 to 238 kg ha(-1), a pattern repeated in 1996. In contrast, Stipa declined at both positions, but only for a single year. Where livestock grazing occurred after the fire, forage removal was greater on burned areas. Drought conditions, in combination with summer wildfire, reduced Dry Mixed Prairie range productivity and ground cover for several years and intensified livestock grazing, highlighting the need for changes in rangeland management under these conditions.
Bud viability in perennial grasses: water stress and defoliation effects
Authors: Flemmer A. C. , Busso C. A. , Fernández O. A. ,   Society for Range Management
Published: March 2016

Effects of the timing and frequency of defoliation under different levels of soil water availability were evaluated on bud metabolic activity and subsequent outgrowth in the desirable (i.e., palatable) Stipa clarazii Ball. and S. tenuis Phil. in competition with the undesirable (i.e., unpalatable) S. gynerioides Phil. Field studies on these native, perennial tussock grasses were conducted from 1995 to 1997 in temperate, semiarid Argentina. Our working hypotheses were 1) axillary bud activation and subsequent tillering are lower under water stress than under higher soil moisture conditions in S. clarazii, S. tenuis, and S. gynerioides, 2) when compared to undefoliated controls, activation, and subsequent outgrowth of axillary buds reach similar or greater values in S. clarazii and S. tenuis after early (vegetative stage of development), but not late (during internode elongation) defoliations or increased defoliation frequency (vegetative+ during internode elongation) during each growing cycle. Additionally, it was expected that the greatest reduction of axillary bud metabolic activity and outgrowth would ocurr on plants defoliated twice, and 3) axillary bud activation and succeeding tillering are greater in the undefoliated S. gynerioides when the desirable species are defoliated than when they remain undefoliated. With a few exceptions, our results led us to reject all 3 hypotheses. Responses of axillary buds were in general specific to the species and treatments, to sampling time, and to the cumulative effects of previous treatments. This makes predictions of plant responses of these species under natural field conditions difficult, where they are often defoliated under water stress.
Nutritional value and intake of prickly pear by goats
Authors: McMillan Z. , Scott C. B. , Taylor C. A. ,   Society for Range Management
Published: March 2016

Prickly pear (Opuntia sp.) is both a benefit and hindrance to the livestock industry in the southwestern U.S. It competes with herbaceous forage but is sometimes used as emergency feed during drought. Spineless prickly pear (O. fiscus-indica Engelm. and O. rufida Engelm.) has been planted in some regions of the southwest but little is known about its nutritional value. Our objectives were to determine: (1) the nutritional value of both spined (O. macrorhiza Engelm.) and spineless prickly pear (O. rufida Engelm.); (2) if goats can be conditioned to eat prickly pear after prescribed burning; and, (3) if goats would consume prickly pear when alternative forage was available. In Experiment 1, 8 goats were placed in metabolism stalls and fed either spineless or spined prickly pear with singed spines in both summer and winter. Intake, digestibility, and nitrogen balance were measured. In Experiment 2, 18 goats were placed in individual pens, and 9 were fed spineless prickly pear to determine if this increased acceptance of spined prickly pear with singed spines. In the third experiment, we varied the amount of alfalfa pellets fed to goats (below, near, and above maintenance) to determine if level of alfalfa intake affected prickly pear intake. Spineless prickly pear was higher (P < 0.05) in digestibility and crude protein than singed prickly pear, but nitrogen balance was similar for goats consuming the 2 species. Goats ate more spineless prickly pear on an as fed basis, but on a dry basis, intake was similar. Familiarity with spineless prickly pear increased (P < 0.05) subsequent intake of singed prickly pear. Level of alfalfa intake did not affect prickly pear intake. We concluded that both species are moderately nutritious, spineless prickly pear is more digestible than spined prickly pear, and once a preference for prickly pear has developed, goats may continue to eat prickly pear even though other forage is available.
Evaluating the ecological relevance of habitat maps for wild herbivores
Authors: Stalmans M. E. , Witkowski E. T. F. , Balkwill K. ,   Society for Range Management
Published: March 2016

Informed management of large herbivores depends largely on how well habitat availability and suitability are understood. The aims of the study were to quantify and map the distribution of sour and mixed grasslands in the 48,000 ha Songimvelo Game Reserve, Mpumalanga, South Africa. Mixed grassland retains its forage quality and hence its ability to sustain animal production for longer in the year than sour grassland. An unsupervised classification technique was applied to a LANDSAT 5 TM image acquired in 1993. The probability that each resulting cluster represented either sour or mixed grassland was calculated based on the proportional allocation of 428 sample plots. The 2 resulting probability maps were combined into a single image by selecting the class image that contained the maximum posterior probability and assigning that class to the output pixel. The accuracy of the vegetation map was assessed by ground-truthing with an independent set of 85 plots. This yielded a correct classification of 84.8% for the sour and 76.9% for the mixed plots. The mixed grasslands covered only 31.0% of the area but accounted for 66.1% of the game stocking. Water is widely distributed and is not a limiting factor to habitat selection. Based on a GIS analysis, the qualitative difference between mixed and sour grasslands overrides quantitative differences in forage availability, fire history and human disturbance in influencing herbivore distribution. The integration of field data and satellite imagery into a GIS system thus offers a powerful tool for the objective quantification and mapping of available habitat.
Vegetation responses following wildfire on grazed and ungrazed sagebrush semi-desert
Authors: West N. E. , Yorks T. P. ,   Society for Range Management
Published: March 2016

A 20-year set of cover data on sagebrush semi-desert plant communities responding to wildfire and livestock grazing near Mills in central Utah provided an opportunity to compare the assumptions and adaptability of classical and state-and-transition models for describing secondary succession. Cover data were organized and analyzed by plant species, growth forms, and other ground cover classes. Graphical analysis, ordination (employing semi-strong hybrid multi-dimensional scaling), regression, and analysis-of-variance were used to determine whether the patterns observed were best described as community change (tightly linked species) or individualistic change (each species acting independently). Distinct differences in total plant cover, growth form, and species composition were found between burned (both grazed and ungrazed) and the unburned and grazed treatments. Conventional graphical and statistical analyses of burned and ungrazed plots showed greater and earlier expansion of perennial grasses and then relatively less cover-weighted compositional change in recent years compared to the other treatments. Vegetation on none of the treatments appears to have stabilized toward either the pre-burn sagebrush semi-desert, a new state or the potential natural community for the site involved. Pathways of change reflected in the ordinations have been complex in all treatments. The only obvious trends in responses of individual species were to fire and the inverse relationship of cheatgrass to total perennial vegetational cover. All this evidence points to few tight linkages between species or growth form groups and thus favors viewing these patterns individualistically. While the state-and-transition model allows greater flexibility than the classical model in the depiction of plant community/individual species changes consequent to any management action, it doesn't apply readily everywhere, as exemplified by this case study.
Herbicide residues and perennial grass on establishment perennial pepperweed sites
Authors: Young J. A. , Clements C. D. , Blank R. R. ,   Society for Range Management
Published: March 2016

Perennial pepperweed (Lepidium latifolium L.) is a creeping rooted exotic weed that has infested native hay meadows, riparian areas and agronomic fields throughout the western United States. This highly invasive species causes major losses in forage quality and creates numerous management problems. On many sites infested with perennial pepperweed, a near mono-culture exist. Sustainable suppression programs require the establishment of a competitive perennial species. You can not establish seedlings of a perennial competitive species without some initial substantial reduction in perennial pepperweed stands through weed control. Because tillage is not feasible with this creeping rooted species, herbicidal weed control is the primary option. Experience has shown, that the massive and extensive root system of perennial pepperweed can not be completely eliminated with one application of a herbicide. This means that repeated applications of a selective herbicide are required after the perennial seedlings of a competitive species are established. Perennial pepperweed is a broadleaf species that is some what susceptible to applications of 2,4-D. Therefore, the choice revegetation species is limited to a perennial grass that is resistant to 2,4-D applications at low rates as a seedlings and moderate rates once established. The saline/alkaline nature of the soils where perennial pepperweed is often found limit the adapted perennial grasses to tall wheatgrass (Elytriga elongata [Host] Nevski). The herbicide chlorsulfuron has been shown to be more effective in initially controlling perennial pepperweed than 2,4-D. We determined that applications of chlorsulfuron at rates sufficient to control perennial pepperweed resulted in herbicidal residues that severely reduced or eliminated the establishment of tall wheatgrass seedlings. Application of 2,4-D at flower budding for perennial pepperweed (June), followed by seeding tall wheatgrass in the fall (October), and application of low rates of 2,4-D over the wheatgrass seedlings the next spring (May), gave the best grass seedling establishment and suppression of the perennial weed.
Ecological relationships between poisonous plants and rangeland condition: A Review
Authors: Ralphs M. H. ,   Society for Range Management
Published: March 2016

In the past, excessive numbers of livestock on western U.S. rangelands, reoccurring droughts, and lack of management resulted in retrogression of plant communities. Poisonous plants and other less palatable species increased with declining range condition and livestock were forced to eat these poisonous species because of a shortage of desirable forage, resulting in large, catastrophic losses. The level of management on most western rangelands has improved during the last 60 years, resulting in marked improvement in range condition; yet losses to poisonous plants still occur, though not as large and catastrophic as in the past. Some poisonous species are major components of the pristine, pre-European plant communities [tall larkspur (Delphinium barbeyi Huth), Veratrum californicum Durand, water hemlock (Cicuta douglasii (DC.)Coult. Rose), bracken fern (Pteridium aquilinum (L.) Kuhn), chokecherry (Prunus virginiana L.), Ponderosa pine (Pinus ponderosa Lawson), and various oak species (Quercus spp.)]. Although populations of many poisonous seral increaser species have declined with better management, they are still components of plant communities and fluctuate with changing precipitation patterns [locoweed (Astragalus and Oxytropis spp.), lupine (Lupinus spp.), death camas (Zigadenus spp.), snakeweed (Gutierrezia spp.), threadleaf groundsel (Senecio longolobis Benth.), low larkspur (Delphinium nuttallianum Pritz.), timber milkvetch (Astragalus miser Dougl. ex Hook.), redstem peavine (A. emoryanus (Rydb.) Cory), western bitterweed (Hymenoxys odorata D.C.), orange sneezeweed (Helenium hoopesii Gray), twin leaf senna (Cassia roemeriana Schelle), and white snakeroot (Eupatorium rugosum Houtt)]. Many of the alien invader species are poisonous: [Halogeton glomeratus (Bieb.) C.A. Mey, St. Johnswort (Hypericum perforatum L.), poison hemlock (Conium maculatum L.), tansy ragwort (Senecio jacobaea L.), hounds tongue (Cynoglossum officinale L.), leafy spurge (Euphorbia esula L.), yellow star thistle (Centaurea solstitialis L.) and other knapweeds (Centaurea spp.)]. Poisoning occurs when livestock consume these plants because they are either relatively more palatable than the associated forage, or from management mistakes of running short of desirable forage.
Water stress and triclopyr on clopyralid efficacy in honey mesquite
Authors: Roche A. R. , Bovey R. W. , Senseman S. A. ,   Society for Range Management
Published: March 2016

Water stress may affect herbicide efficacy in herbaceous and woody plants. Chamber studies were conducted to evaluate the influence of water stress (-1.3 to -2.8 MPa) and triclopyr on the absorption and translocation of clopyralid in greenhouse-grown honey mesquite (Prosopus glandulosa Torr.). Xylem water potential was determined in honey mesquite at time of herbicide application. Absorption and translocation of clopyralid was determined at low (-1.3 MPa), medium (-2.2 MPa), and high (-2.8 MPa) water stress at 4 h after application for 1.5-mo-old plants, while only translocation was determined at either a low (-1.4 or -1.6 MPa) or a high (-2.4 MPa) water stress treatment at 24 hours after herbicide application for 3-mo-old plants. Water stress did not affect (P < 0.05) absorption or translocation of clopyralid alone in either study. With 1.5-mo-old plants, the addition of triclopyr to clopyralid increased (P < 0.05) clopyralid absorption in leaves at low (63 microgram) and medium (54 microgram) water stress compared to high water stress (33 microgram) but did not affect (P > 0.05) translocation at 4 hours after application. On 3-mo-old plants, triclopyr decreased (P < 0.01) clopyralid translocation 24 hours after treatment at high water stress. The reasons for reduced uptake and 24 hours post-treatment translocation of clopyralid when applied with triclopyr at high water stress are unclear, but have implications for field applications.
Irrigation impact on harvest efficiency in grazed Old World bluestem
Authors: Teague W. R. , Dowhower S. L. ,   Society for Range Management
Published: March 2016

In 1992 and 1993, pastures of WW-Spar Old World bluestem (Bothriochloa ischaemum L.) were maintained at 2 levels of soil water, rainfall and rainfall plus 25 mm/week of supplementary irrigation. At both moisture levels the grass was maintained at 2 levels of standing crop, averaging 1,548 and 2,154 kg ha(-1), using continuous variable stocking. Measurements were made to determine how different levels of soil moisture interacted with grazing intensity to change leaf area index, leaf-stem and live-dead ratios, tiller density, and the proportion of gross leaf production that was grazed (harvest efficiency). The proportions of live to dead, and leaf and stem biomass, remained constant under the different levels of soil water content. Soil water content alone had no effect on leaf area index, tiller density and the proportion of live or dead, leaf and stem. Winter tiller survival was significantly higher in the pastures with higher soil water content. Increasing soil water content and increasing grazing intensity interacted to reduce the proportion of dead leaf, increase production of new tillers, and increase the proportion of leaf grazed by decreasing leaf that died and was not grazed. This study indicates that if continuously grazed Old World bluestem was maintained at a standing crop of 1,500 kg ha(-1), harvest efficiency would be higher in wet years or under irrigation than if standing crop was higher.
Evaluation of a technique for measuring canopy volume of shrubs
Authors: Thorne M. S. , Skinner Q. D. , Smith M. A. ,   Society for Range Management
Published: March 2016

Cover methods quantify vegetative communities in only 2 dimensions. The addition of height measurements to cover data, resulting in canopy volume estimates, provide a more practical level of description for shrub communities. We evaluated a technique to estimate canopy volume of shrubs that used a formula [2/3piH (A/2 x B/2)] derived from the basic ellipsoid volume formula. Objectives of this study were to determine if there were significant differences among means of repeated observations on sample units: (1) among observers; (2) within observers; and (3) between sample periods when using this technique. At 2 locations in Wyoming, 10 planeleaf willow (Salix planifolia var. planifolia Pursh) plants along each of 5 randomly established transects were sampled during 2 consecutive periods by 4 observers. Differences among observers were significant at both sites (P < 0.05). However, within observer variation between sample periods was not significant (P > 0.05) at either site. Mean canopy volume did not vary significantly (P > 0.05) between sample periods when averaged across observers. Estimated sample sizes ranged between 2 and 31 transects depending on the desired sampling precision and confidence level. The average time per transect among all observers decreased from 13 minutes (SD = 3.7) in sample period 1 to 9 minutes (SD = 1.3) in sample period 2. Using this method, managers can better describe and monitor trends in the structural diversity of shrub communities. This canopy volume technique can be applied with minimal training and is precise, efficient, and repeatable.
Response of the mixed prairie to protection from grazing
Authors: Willms W. D. , Dormaar J. F. , Adams B. W. ,   Society for Range Management
Published: March 2016

The Mixed Prairie plant communities developed with the influences of fire and grazing. Available evidence suggests that removal of these disturbances could cause succession toward a more mesic type with the accumulation or litter or loss in productivity as nutrient turnover is delayed. Exclosures constructed in 1927 in a semiarid Mixed Prairie community provided an opportunity to examine the effects that protection had on vegetation and soils. Fifteen exclosures were selected for detailed examination; of these, 11 were located on Chernozemic soil and 4 on Solonetzic soil. We measured plant and soil variables both inside and outside the exclosures in a test of the hypothesis that protection from grazing will lead to a loss of production potential of the semi-arid. Mixed Prairie communities in the Northern Great Plains of southeastern Alberta. We found little evidence that 70 years of protection from large animal disturbance reduced the production potential of the plant communities. Conversely, most evidence suggested a neutral effect or an improvement as reflected in an increased cover of Pascopyrum smithii Rydb. (Löve) (P = 0.049) and increased annual net primary production (P = 0.047). The effect of protection appeared largely driven by the accumulation of litter mass that primarily benefits soil and plant indices of quality on the Chernozemic soil type. Although protection tended to reduce species diversity (P = 0.097) among native plants on the Chernozemic soil type, evenness and richness were not affected (P > 0.10). The potential effect that reduced diversity might have on reducing production stability appears more than compensated for by increased litter mass.
Fingerprint composition of seedling root exudates of selected grasses
Authors: Dormaar J. F. , Tovell B. C. , Willms W. D. ,   Society for Range Management
Published: March 2016

The competitiveness of plants within a community is dictated to some extent by their association with microorganisms in the soil. That association is affected by root exudates and possibly by their quality. The competitiveness of species under various grazing regimes has been defined by their response to grazing as decreaser, increaser, or invader. To test the hypothesis that there are recognisable differences in the chemical fingerprints of the root exudates of decreasers, increasers and invaders, seeds of 8 grasses, representing these 3 designations, were germinated and grown for 2 weeks in a root exudate trapping system in the laboratory. Tentative identification of the suite of compounds recovered from the root exudates by a solvent extraction technique was done with the help of gas chromatography/mass spectrometry and authentic samples. Eleven identified compounds, present in all exudates as major peaks, but absent in the blanks, were selected for semi-quantitatively comparing the 3 grazing response groups. For all 11 compounds, there was always at least 1 of the grazing response groups that had the highest percentages. That is to say, they were qualitatively, based on the 11 compounds selected, but not quantitatively similar.
Sediment movement and filtration in a riparian meadow following cattle use
Authors: Mceldowney R. R. , Flenniken M. , Frasier G. W. ,   Society for Range Management
Published: March 2016

Improper livestock grazing practices in western U.S. riparian areas may reduce the nutrient and pollutant removal function of riparian communities, resulting in degradation of surface water quality. Short duration-high intensity cattle use in 3 x 10 m plots was evaluated in a montane riparian meadow in northern Colorado to quantify livestock effects on sediment movement and filtration under simulated rainfall (approximately equal to 100 mm hour(-1)) plus overland flow (approximately equal to 25 mm hour(-1)) conditions. Four treatments: 1) control, 2) mowed to 10 cm stubble height, 3) trampled by cattle, and 4) cattle grazed plus trampled (grazed) were evaluated. Sixty kg of sediment was introduced to overland flow in each plot. Sediment movement was evaluated using sediment traps positioned in microchannels and on vegetation islands at 5 distances downslope from the upper end of the plots and by sediment front advancement. Most sediment deposition occurred within the first meter downslope from application. About 90% of the applied sediment was filtered from runoff within 10 m in the control and mowed treatments, while approximately 84 and 77% of the applied sediment was trapped in the trampled and grazed treatment plots, respectively. The primary variables that influenced sediment filtration were stem density and surface random roughness. Stem density was the most influential variable that affected sediment filtration. Cattle grazing reduced the stem density by 40%. Monitoring of stem density should aid land managers in regulating cattle use of riparian communities and facilitate the protection of surface water quality from sediment in overland flow.