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Breytingar á samfélögum grasbíta í tíma og rúmi: áhrif á virkni íslenskra túndruvistkerfa
No full textRapid environmental changes in the Arctic tundra are driving shifts in herbivore populations, distribution, and phenology, affecting the structure of herbivore community. These changes will have consequences to ecosystem structure and function through the direct effects of herbivores on vegetation biomass and biogeochemical cycles. Yet, the effects of herbivores on ecosystem functions, particularly within a multispecies context, are still poorly understood. Addressing these knowledge gaps in tundra rangelands, which are grazed by both wild and domestic herbivores, is an urgent task to ensure the development of sustainable management practices.
Using Icelandic rangelands as a case study, I investigated how changes in herbivore communities affect tundra ecosystem functions across various spatial and temporal scales, with a focus on nutrient recycling. Specifically, I aimed to: 1) track changes in herbivore community composition through time, 2) assess the impact of herbivore on vegetation biomass, 3) measure the faecal nutrient contributions of different herbivores species, and 4) evaluate the role of herbivores on nutrient distribution. I analysed long-term data to assess shifts in herbivore populations and their impacts on vegetation at a regional scale. Additionally, through extensive fieldwork in 2022, I examined herbivore effects on vegetation, faecal nutrient deposition, and nutrient transport at landscape and local scales in high-elevation rangelands. Specifically, I measured rates of aboveground biomass consumption, faecal nutrient content and faecal deposition rates of pink-footed goose, sheep and reindeer, and forage quality at 21 sampling sites throughout the growing season. Near-infrared reflectance spectroscopy (NIRS) models were calibrated to estimate faecal nutrient content.
Results from the thesis indicate rapid changes in the Icelandic herbivore community: over the past 40 years, the dominant herbivores shifted from domestic (mainly sheep) to wild herbivores, led by the large increase in pinkfooted goose. Overall, herbivores consumed a small percentage (4%) of total plant biomass, but this reached up to 30% in localised areas in the Eastern Highlands toward the end of the growing season. Although the goose population consumed less biomass than the sheep population, geese contributed significantly more to faecal nutrient deposition, especially early in the growing season when nutrient content in their faeces was highest. There was no clear connection between forage quality and herbivore consumption, but areas with low-quality forage showed more nutrient deposition through faeces. These findings highlight the potential of herbivores to redistribute nutrient across the landscape and provide insights into the role of herbivores in shaping tundra ecosystems through their effects on nutrient cycling, particularly in the context of strong and rapid ongoing herbivore community changes.Hraðar umhverfisbreytingar á norðurslóðum hafa í för með sér breytingar á stofnstærð, útbreiðslu og atferli grasbíta, sem hefur áhrif á samfélagsgerð þeirra. Þær breytingar munu síðan hafa afleiðingar fyrir byggingu og virkni vistkerfa, einkum vegna beinna áhrifa grasbíta á lífmassa gróðurs og hringrásir næringarefna. Þrátt fyrir það eru áhrif grasbíta á virkni vistkerfa enn illa þekkt, sérstaklega þegar um er að ræða samspil margra tegunda grasbíta. Mikilvægt er að bæta þekkingu á þessum áhrifum í túndruvistkerfum sem nýtt eru af mismunandi grasbítum, bæði villtum grasbítum og búfé, til að tryggja þróun sjálfbærrar landnýtingar.
Ég rannsakaði hvernig breytingar á samfélögum grasbíta hafa áhrif á virkni íslenskra túndruvistkerfa á mismunandi kvörðum í tíma og rúmi, með áherslu á hringrásir næringarefna. Markmið rannsóknarinnar voru einkum að: 1) fylgjast með breytingum í samsetningu samfélaga grasbíta yfir tíma, 2) meta áhrif grasbíta á lífmassa gróðurs, 3) mæla næringarefnainnihald í skít mismunandi grasbítategunda og 4) meta hlutverk grasbíta við dreifingu næringarefna. Ég greindi langtímagögn til að meta breytingar á stofnum grasbíta og áhrif þeirra á gróður á stærri svæðum. Að auki kannaði ég staðbundin áhrif og landlagsáhrif grasbíta á gróður, næringarefnainnihald í skít þeirra og flutning næringarefna í hálendisvistkerfum með umfangsmikilli vettvangsvinnu árið 2022. Í því fólst að mæla neyslu á ofanjarðarlífmassa gróðurs, magn og næringarefnainnihald í skít heiðagæsa, kinda og hreindýra, ásamt fóðurgæðum á 21 sýnatökustað yfir vaxtartímabilið. Nær-innrauð endurkastsgreining (NIRS) var notuð til að meta næringarefnainnihald í skít þessara tegunda.
Niðurstöður ritgerðarinnar sýna hraðar breytingar í íslenska grasbítasamfélaginu síðustu 40 árin. Hlutfall búfjár (aðallega kindur) sem var ríkjandi áður hefur dregist saman og hlutfall villtra grasbíta hefur aukist, einkum vegna mikillar fjölgunar heiðagæsa. Grasbítar neyttu að jafnaði lítils hlutfalls (4%) af heildarlífmassa gróðurs, en staðbundin neysla náði allt að 30% sums staðar á Austurhálendinu undir lok vaxtartímabilsins. Þrátt fyrir að gæsastofninn neyti minna lífmassa en kindur, lögðu gæsir verulega meira til af næringarefnum í skít, sérstaklega snemma á vaxtartímabilinu þegar næringarefnainnihald skítsins var hæst. Ekki fannst skýr tenging milli fóðurgæða og neyslu grasbíta, en á svæðum með lág fóðurgæði lagðist hlutfallslega meira til af næringarefnum með skít en á svæðum með hærri fóðurgæði. Þessar niðurstöður varpa ljósi á getu grasbíta til að dreifa næringarefnum um landslag og sýna fram á hlutverk þeirra í mótun túndruvistkerfa í gegnum áhrif þeirra á hringrásir næringarefna, einkum með hliðsjón af þeim hröðum breytingum sem eru að verða á grasbítasamfélaginu.This work was supported by the Icelandic Research Fund (grant number 217754 and 2410773-051); the Nordic Borealization Network (NordBorN, funded by NordForsk grant number 164079); and Landsvirkjun (grant number NÝR-22-2022 and NÝR-26-2023)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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