1,721,251 research outputs found
Short Rotation Coppice (SRC) Plantations Provide Additional Habitats for Vascular Plant Species in Agricultural Mosaic Landscapes
Get PDFIncreasing loss of biodiversity in agricultural landscapes is often debated in the bioenergy context, especially with respect to non-traditional crops that can be grown for energy production in the future. As promising renewable energy source and additional landscape element, the potential role of short rotation coppice (SRC) plantations to biodiversity is of great interest. We studied plant species richness in eight landscapes (225 km(2)) containing willow and poplar SRC plantations (1,600 m(2)) in Sweden and Germany, and the related SRC alpha-diversity to species richness in the landscapes (gamma-diversity). Using matrix variables, spatial analyses of SRC plantations and landscapes were performed to explain the contribution of SRC alpha-diversity to gamma-diversity. In accordance with the mosaic concept, multiple regression analyses revealed number of habitat types as a significant predictor for species richness: the higher the habitat type number, the higher the gamma-diversity and the lower the proportion of SRC plantation alpha-diversity to gamma-diversity. SRC plantation alpha-diversity was 6.9 % (+/- 1.7 % SD) of species richness on the landscape scale. The contribution of SRC plantations increased with decreasing gamma-diversity. SRC plantations were dominated more by species adapted to frequent disturbances and anthropo-zoogenic impacts than surrounding landscapes. We conclude that by providing habitats for plants with different requirements, SRC alpha-diversity has a significant share on gamma-diversity in rural areas and can promote diversity in landscapes with low habitat heterogeneity and low species pools. However, plant diversity enrichment is mainly due to additional species typically present in disturbed and anthropogenic environments
Stand age characteristics and soil properties affect species composition of vascular plants in short rotation coppice plantations
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Effects of short rotation coppice with willows and poplar on soil ecology
No full textFast growing willow and poplar clones (Salix and Populus spp) grown as short rotation coppice (SRC) on former arable soils lead to a long-term non-tillage management with increased litter amounts Additionally, the litter composition is changed (e.g increased C/N ratios and lignin contents) and thereby the litter decomposition can be retarded An increased C sequestration in the topsoil of former ploughed arable soils can resu t from these effects The leaf litter recycles a high portion of nutrients In contrast to other crops, willows and poplar can be colonised by ectomycorrhizal fungi This leads to the introduction of ectomycorrhizal fungi into arable soils and to changes in the soil microbial colonization and activity The non-tillage management and the high litter supply can change the abundance and diversity of the soil fauna, e g increase the abundance of earthworms (Lumbricidae) and in spite of an increased diversity decrease the abundance of carabids (Carabidae) Willow and poplar clones are highly suitable for phytoremediation of contaminated soils (e g extraction of Cd, Zn and degradation of organic pollution) caused by their high biomass production in combination with high fine root density Several soil ecological advantages of short rotation coppice compared to former arable soils with annual crops can be statec, however, more research-based knowledge is needed especially on the fundamentals of long-term effects and on the sustainability of effects after return to their former commercial arable us
Effects of short rotation coppice with willows and poplar on soil ecology
No full textFast growing willow and poplar clones (Salix and Populus spp) grown as short rotation coppice (SRC) on former arable soils lead to a long-term non-tillage management with increased litter amounts Additionally, the litter composition is changed (e.g increased C/N ratios and lignin contents) and thereby the litter decomposition can be retarded An increased C sequestration in the topsoil of former ploughed arable soils can resu t from these effects The leaf litter recycles a high portion of nutrients In contrast to other crops, willows and poplar can be colonised by ectomycorrhizal fungi This leads to the introduction of ectomycorrhizal fungi into arable soils and to changes in the soil microbial colonization and activity The non-tillage management and the high litter supply can change the abundance and diversity of the soil fauna, e g increase the abundance of earthworms (Lumbricidae) and in spite of an increased diversity decrease the abundance of carabids (Carabidae) Willow and poplar clones are highly suitable for phytoremediation of contaminated soils (e g extraction of Cd, Zn and degradation of organic pollution) caused by their high biomass production in combination with high fine root density Several soil ecological advantages of short rotation coppice compared to former arable soils with annual crops can be statec, however, more research-based knowledge is needed especially on the fundamentals of long-term effects and on the sustainability of effects after return to their former commercial arable us
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
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