1,720,971 research outputs found
Tree species diversity, topsoil conditions and arbuscular mycorrhizal association in the Sidama traditional agroforestry land use, southern Ethiopia
Full text linkSidama farmers cultivate trees to meet their food, wood, fodder and other service needs. Tree cultivation intensity has increased during the past three decades. Significant positive correlation was found between farm size and number of species, and number of stems per farm. The number of tree species per farm averaged 16 and ranged from 4 to 28. Within farms, about ten different field types were identified of which enset fields contain the highest number of species. Wealthy households have more tree species than poor households. In general the largest number of tree species, the largest number of stems and the largest basal area ha⁻¹ were recorded on farms of wealthy households. Based on farmers´knowledge and laboratory studies, nutrient accumulation in the topsoil under Cordia africana, Millettia ferruginea and Eucalyptus camaldulensis managed under three agroforestry practices (AF) on different farms at three sites was evaluated. Significantly higher concentration of P was observed under Millettia and Cordia than under Eucalyptus. pH under Millettia and Cordia were significantly higher than under Eucalyptus at one site. Topsoil under Millettia and Cordia also had significantly higher levels of exchangeable Ca and Mg than Eucalyptus. For scattered AF soil and enset, plants were sampled at laterally increasing distances from the tree trunks and outside the canopy on enset and maize fields. Under canopies of both Cordia and Millettia trees, the diameter of enset was significantly greater than that of enset plants grown in open fields. Topsoil under canopies of scattered Cordia and Millettia trees, compared with open fields, generally had higher pH, CEC, increased total N, organic C and available P, but had no effect on some exchangeable bases. Six tree-crop combinations and two open-maize plots in enset and maize fields were selected to study the level of indigenous arbuscular mycorrhizal (AM), number of spores and levels of root colonization. At field level, tree-crop combinations induced a higher number of spores and level of colonization than in an open-maize field. The proportions of roots were in the following order: tree-enset-coffee > tree-enset > tree-maize for Cordia trees and tree-enset > tree-enset-coffee > tree-maize for Millettia trees. Beneath both Cordia and Millettia trees scattered on maize fields, the proportion of colonized root decreased with increasing distances laterally from the tree trunks. At nursery level, significantly higher levels of root colonization were observed for maize plants grown on soil from beneath tree enset-coffee and enset plots than those grown on soil from tree-maize and open-maize plots. The percentage of AM colonized roots of maize was significantly positively correlated with the number of spore counts for field soils
Comparative Assessment of Soil Organic Carbon Stock Potential under Agroforestry Practices and Other Land Uses in Lowlands of Bale
Full text linkSoil organic carbon is the carbon associated with soil organic matter that is made up of decomposed plant and animal materials. This study was conducted in Dallo Mena district to estimate the amount of soil carbon stock stored in shade grown coffee (SC) and homegarden agroforestry practices (HG), and adjacent natural forest (NF) and annual crop field (CF) and to show the potential of agroforestry practices in soil organic carbon storage capacity. The study site was selected based on spatial analogue approach. From each land uses nine plots were selected by using systematic sampling method following the transect line. Soil organic carbon stock (100cm depth) were the highest for the NF(170.11 ± 14.59 Mg ha-1), followed by SC(127.96 ± 9.43 Mg ha-1), HG(107.62 ± 12.55 Mg ha-1) and CF(97.56 ± 6.85 Mg ha-1). Agroforestry and other land uses of Dallo Mena districts are providing various ecological as well as economical benefits for the community. It is used as income source, conserving different plant species diversity and at the same time storing large amounts of soil organic carbon. Therefore, there is significant difference among natural forest, shade grown coffee agroforestry practice, homegarden agroforestry practice and annual crop field in soil organic carbon storage capacity.International Journal of EnvironmentVolume-6, Issue-3, Jun-Aug 2017, page: 1-14</p
Comparative Assessment of Soil Organic Carbon Stock Potential under Agroforestry Practices and Other Land Uses in Lowlands of Bale
Full text linkSoil organic carbon is the carbon associated with soil organic matter that is made up of decomposed plant and animal materials. This study was conducted in Dallo Mena district to estimate the amount of soil carbon stock stored in shade grown coffee (SC) and homegarden agroforestry practices (HG), and adjacent natural forest (NF) and annual crop field (CF) and to show the potential of agroforestry practices in soil organic carbon storage capacity. The study site was selected based on spatial analogue approach. From each land uses nine plots were selected by using systematic sampling method following the transect line. Soil organic carbon stock (100cm depth) were the highest for the NF(170.11 ± 14.59 Mg ha-1), followed by SC(127.96 ± 9.43 Mg ha-1), HG(107.62 ± 12.55 Mg ha-1) and CF(97.56 ± 6.85 Mg ha-1). Agroforestry and other land uses of Dallo Mena districts are providing various ecological as well as economical benefits for the community. It is used as income source, conserving different plant species diversity and at the same time storing large amounts of soil organic carbon. Therefore, there is significant difference among natural forest, shade grown coffee agroforestry practice, homegarden agroforestry practice and annual crop field in soil organic carbon storage capacity.International Journal of EnvironmentVolume-6, Issue-3, Jun-Aug 2017, page: 1-14</jats:p
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
Woody Species Richness, Use Diversity and Management in Agroforestry Practices: The Case of Assosa District Benishangul Gumuz Region, Ethiopia
No full textDispelling 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
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