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The effect of grazing, mowing and herbicide application of johnsongrass (Sorghum halepense (L.) Pers.) in the Nature Conservancy Patagonia-Sonoita Creek Preserve
No full textJohnsongrass (Sorshum halepense (L.) Pers.) occurred in nearly pure stands on the Patagonia-Sonoita Creek Preserve, Santa Cruz County, Arizona prior to grazing. This study investigated the use of grazing, mowing and herbicides to decrease the abundance of johnsongrass, and increase the diversity of other plant species. The grazed only treatment allowed remaining overstory and limited grazing access. Mowing lowered the overstory and provided accessibility to grazing attracting animal utilization of the areas. The herbicided and grazed treatment reduced total johnsongrass productivity, tiller numbers and impacted tiller growth form. Lower percent botanical composition and tiller emergence of johnsongrass plants occurred in 1995 than in 1994. The number of other plant species increased between study years
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Recovery rate of Lehmann lovegrass (Eragrostis lehmanniana Nees.) in a simulated short duration grazing system
No full textA nearly monospecific stand of Lehmann lovegrass (Eragrostis lehmanniana Nees.) was grazed by cattle during two summer growing seasons to simulate short duration grazing. Grazing treatments were timed to coincide with preboot, boot to early inflorescence and hard seed phenological stages. During each treatment, grazing intensity on individual plants included heavy, moderate or light intensities. In 1990 maximum regrowth occurred when plants were grazed during boot to early inflorescence and at a light grazing intensity. In 1991, plants grazed during preboot or boot to early inflorescence and at a light or moderate intensity produced higher regrowth amounts than the other treatments. Plants grazed during boot to early inflorescence recovered significantly faster than plants grazed during preboot in 1990 and 1991. In 1990 lightly grazed plants recovered biomass faster than plants grazed at heavier intensities. In 1991 plants grazed at light and moderate grazing intensities recovered significantly faster than heavily grazed plants. Heavily grazed plants never produced enough regrowth to resemble moderately or lightly grazed plants within one growing season
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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Monitoring Diet Quality and Projecting Body Condition Score in Cattle Using Fecal Near Infrared Spectroscopy and NUTBAL on a Southern Arizona Rangeland
No full textRange cattle grazing in semi-arid regions are commonly limited by lack of nutrients from low-quality forage. Due to this, ranchers are faced with the challenge of monitoring diet quality in order to address nutrient limitations. Near infrared spectroscopy (NIRS) of fecal samples is a method used to determine diet quality values like crude protein (CP) and digestible organic matter (DOM) in grazing animals. When combined with a nutritional balance analyzer such as the NUTBAL system, fecal NIRS can be used to monitor diet quality and project animal performance. Our research aimed to test the ability of NUTBAL to project animal performance as represented by body condition score (BCS) in cattle (n=82 Animal Units) grazing on the Santa Rita Experimental Range (SRER) in southern Arizona. Previous work conducted on other Arizona rangelands led to the hypothesis that fecal NIRS coupled with NUTBAL can be used to monitor diet quality and project BCS in a southern Arizona commercial grazing operation. Data collection occurred between June 2016 and June 2017. Standing biomass and botanical composition were measured before each grazing period, and relative utilization was measured following each grazing period. During the midpoint of grazing in each pasture, 30 body condition scores and a fecal composite of 15 samples were collected. Fecal derived diet quality varied between a maximum of 10.75% CP and 61.25% DOM in early August 2016, to a minimum value of 4.00 % CP and 58.40 % DOM in March 2017. This study confirmed the ability of fecal NIRS paired with NUTBAL to project future BCS within 0.5 a score point more than 80% of the time in cattle grazing on the SRER. With this information, cattle managers in southern Arizona can better address animal performance needs and nutrient deficiencies
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Adaptive Grazing Management on the Santa Rita Experimental Range: Determining the Extent of Multiple Defoliation Events on Individual Grasses
No full textAbstract In 2007, an adaptive grazing management process began on the Santa Rita Experimental Range (SRER) in southern Arizona with a primary management objective to reduce repeated defoliation of perennial bunchgrass plants during the summer growing season. In order to follow defoliation events, 1400 individual plants were identified in 6 pastures scheduled for summer grazing from June 15 to October 2, 2013. Plant height and diameter categories were measured before cattle entered each pasture and were re-measured daily or alternate days throughout the grazing period. The differences between heights and diameters were used to calculate any regrowth that occurred. Of the 1400 plants marked, 738 (52.7%) were not defoliated, 453 (32.3%) plants were defoliated once, 199 (14.2%) plants were defoliated twice, and 10 (0.7%) plants were defoliated three-times for a total of 881 defoliation events recorded. The majority of first defoliation events and first incidences of second defoliation occurred on day 3. Cattle began switching their grazing strategy from undefoliated plants to new growth of previously defoliated plants by day 9 with 48 of a total 161 previously defoliated plants being defoliated. The highest number of second defoliations were measured on day 11 when 115 plants were observed as having been defoliated for a second time and 5 plants were defoliated for a third time. Arizona cottontop (Digitaria californica) had a higher percentage of both single and multiple defoliation events when compared to the other perennial grass species. Distance from a permanent water source was not found to have a significant impact on the number of defoliations that an individual plant received. Plants defoliated the first time were taller and had a larger circumference (21.0±5.6 cm and 40.8±9.0 cm) than plants that were re-defoliated (15.5±5.6 cm and 31.4±9.0 cm). This study found that the planned 10 day SRER grazing rotation, when followed, would minimize multiple defoliations by cattle on perennial bunchgrasses
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In vitro dry matter digestibility of Lehmann lovegrass (Eragrostis lehmanniana Nees) with grazed patches and lightly grazed areas.
No full textCattle selectively graze grasses for green, leafy material, often restricting their foraging to localized patches surrounded by large, lightly grazed areas. A two year study was conducted on the Santa Rita Experimental Range in Southern Arizona to compare the effects of heavy grazing on Lehmann lovegrass (Eragrostis lehmanniana Nees.) digestibility. Lehmann lovegrass was clipped from within heavily grazed patches and adjacent ungrazed areas. Green and dry plant materials were separated and analyzed for percentage in-vitro dry matter digestibility (IVDMD). Results indicated a significant difference existed in the IVDMD of the total standing crops (p 0.005). When analyzed separately, the IVDMD for both the green and dry plant materials from the grazed patches was significantly higher (p .05) than that from the ungrazed areas. Seasonal trends indicated a greater difference in digestibility during periods of active plant growth. Patch maintenance apparently maintains plants with higher forage values for grazing animals than surrounding ungrazed areas
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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