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Nutrient dynamics in miombo woodlands in Zimbabwe
Get PDFMiombo woodlands are tropical savanna formations dominated by genera Brachystegia,
Julbernardia and Isoberlinia and are widespread in central and southern Africa. These
woodlands are an important resource providing among other things, grazing and browse
for livestock and wildlife, medicines for local people, food like mushroom and honey
and timber for building and fuel. Understanding the structural and functional
characteristics of miombo ecosystems and the factors affecting and controlling
production is therefore important, both for their significance in understanding the
environment and also for their value to local communities. In addition to soil moisture,
herbivory and fire, soil nutrients are known to be an important determinant of savanna
ecosystems.Nutrient dynamics have been studied at two Zimbabwean sites providing a range of
representative miombo environments - the Henderson Research Station near Mazowe
and the Mukuvisi Woodlands in Harare. The aim of the research has been to assess the
major inputs and outputs of macronutrient nutrients (principally N, P, K, Ca and Mg) in
miombo woodlands and to determine the effects of fire on nutrient cycling.The quantities of nutrients added in rainfall and throughfall were measured during the
1999/2000 and 2000/2001 rainy seasons. Additions of mineral N in rainfall were 14.7
and 7.4 kg/ha/yr at the Mukuvisi Woodlands experimental sites for the 1999/2000 and
2000/2001 rainy seasons respectively. Mineral N added at the Henderson Research
Station experimental sites was 12.3 and 5.7 kg/ha/yr for the 1999/2000 and 2000/2001
rainy seasons respectively. Cation input in rainfall was very low at Henderson
compared to Mukuvisi, a result which can be explained by the high level of pollution in
and around Harare. The amount of cations added during the 2000/2001 ranged from 0.8
to 7.8 kg/ha/yr and 0.2 to 1.2 kg/ha/yr for Mukuvisi Woodlands and Henderson
Research Station experimental sites respectively, with K being the highest added in
rainfall at both study areas. Nutrients were altered significantly by the canopy. Most of
the N was absorbed and/or adsorbed whereas cations were significantly increased. Stem
flow was measured only at Henderson Research Station sites and nutrient additions
were very low (<0.3 kg/ha/yr) compared to throughfall.Dominant miombo tree species were found to conserve nutrients by re-absorbing them
from senescing leaves. Phosphorus had the largest percentage withdrawn for all the
dominant tree species and this ranged from 48 to 75 % of the total P in mature leaves (in
November 1999). Total N, K and Mg withdrawn ranged from 22 to 33, 22 to 31 and 12
to 21 % respectively. Litterfall at the study sites ranged from 2.20 to 4.44 t/ha/yr.
Litterfall (<2 cm) is the largest nutrient cycling pathway in miombo woodlands,
transferring between 36.6 to 65.2 kg N/ha/yr; 5.5 to 10.2 kg P/ha/yr; 15.3 to 26.7 kg
K/ha/yr; 28.7 to 53.8 kg Ca/ha/yr; 4.9 to 8.6 kg Mg/ha/yr and 1.2 to 2.1 kg Na/ha/yr to
the woodland floor. Litter decomposition was faster at the Henderson sites where there
is evidence of high termite activity. K and Na were released fastest from decomposing
litter compared to other nutrients.Nutrients leached from miombo soils were in the order K (1.24-2.52 kg/ha/yr) > N03_-N
(1.11-2.30 kg/ha/yr) > Ca (0.82-1.49 kg/ha/yr) > NH4+-N (0.39-0.83 kg/ha/yr) > Na
(0.28-0.54 kg/ha/yr) « Mg (0.32-0.52 kg/ha/yr). Potassium was the most easily leached
nutrient from litter and it was also found to be the highest cation in leachate collected
from 100 cm depth. Losses of N in the form of N2O were also measured and were found
to range from 0.29 to 0.60 kg/ha/yr and 0.27 to 0.62 kg/ha/yr at Mukuvisi Woodlands
and Henderson Research Station experimental areas respectively. Compared to nutrient
additions, losses through this pathway are low. Early burning resulted in loss of
nutrients N, P, Ca, Mg, K and Na from herbaceous vegetation and, from litter, only N
was lost in significant amounts.From the study it can be concluded that rainfall is an important nutrient input.
Throughfall also contributes substantially to nutrients added to soils in miombo
woodlands especially bases. The results from this study seem to indicate that miombo
woodlands cycle nutrients efficiently with minimum losses. The internal nutrient
cycling comprising mainly litterfall is able to re-circulate the largest proportion of
nutrients. Losses through gaseous N20 emissions and leaching losses relative to the sum
of throughfall and stem flow were found to be low. Fire resulted in some nutrient losses
confirming the hypothesis that burning miombo woodlands results in significant loss of
nutrients
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
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
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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