1,720,959 research outputs found
EFFECTS OF ROBINIA PSEUDOACACIA COVERAGE ON DIVERSITY AND ENVIRONMENTAL CONDITIONS OF CENTRAL-NORTHERN ITALIAN QUERCUS PUBESCENS SUB-MEDITERRANEAN FORESTS (HABITAT CODE 91AA*): A THRESHOLD ASSESSMENT
No full textAbstract
The invasive alien species Robinia pseudoacacia may lead to species homogenization in high invaded forest ecosystems. Its invasive behaviour is poorly known in dry forest habitats and low cover-abundance conditions. We have investigated central-northern Italian Quercus pubescens forest habitats (code 91AA* - EU Habitat Directive) without and with the presence of R. pseudoacacia and in respect of R. pseudoacacia dominant communities that are present in the same forest potential areas. Using levels of R. pseudoacacia cover-abundance values (Braun-Blanquet scale) we classified the vegetation releves in five groups: from 0 (total absence) to 4 (dominant conditions). Through the calculation of some indices, we highlighted the relations between groups of releves and the variation in term of ecological features. A threshold has been identified at low coverage values of R. pseudoacacia. We detected a significant difference in the lower invaded sites in term of presence of nitrophilous and alien species, Shannon diversity index and changes in nutrient, moisture, light and reaction Ellenberg indicator values. These results inform about the early alarm level to set in monitoring Q. pubescens forest habitats in sub-Mediterranean areas
First syntaxonomical contribution to the invasive Ailanthus altissima (Mill.) Swingle forest communities at its southern limit in Europe
No full textAilanthus altissima (tree of heaven), an invasive alien tree native to China, has become invasive all over the world and in Italy is present in all the administrative regions where it can form dense forest communities. Although there are several ecological studies on this species there is a lack of floristic-vegetational data for southern-Europe. The study presents the results of a floristic vegetational study on A. altissima forest communities of central Italy that aims to highlight the possible floristic-vegetational autonomy of these coenoses. The results have allowed the characterization of A. altissima coenoses at the ecological, biogeographic, syntaxonomic and landscape levels. These represent first A. altissima syntaxa described for the Italian peninsula and for southern-Europe. We propose two new sub-Mediterranean and Mediterranean associations comprised in the recently described alliance Lauro nobilis-Robinion pseudoaciae, in the Chelidonio-Robinietalia order and the Robinietea class: Asparago acutifolii-Ailanthetum altissimae: Forest community with stratified structure and high canopy density on the warmer slopes of the hills in dry soil conditions and low anthropic disturbance and Aro italici-Ailanthetum altissimae: Paucispecific forest communities with a monolayered structure typically found in agricultural, and peri-urban areas on pelitic, alluvial silty-sandy substrates, in conditions of edaphic humidity and high anthropogenic disturbance. The comparison with literature data highlights the autonomy of these associations of the sub-Mediterranean and Mediterranean alliance Lauro nobilis-Robinion pseudoacaciae alliance from the Balloto nigrae-Ailanthetum altissimae association of the Central and SE-European Balloto nigrae-Robinion pseudoacaciae allianc
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
Vegetation dynamics in Pinus nigra Arnold subsp. nigra 100 years after reforestation: two case studies in the central Apennines
No full textWe present here an integrated structural and floristic-vegetational study performed in two representative Pinus nigra subsp. nigra reforestation areas
located within Natura 2000 protected areas in the central Apennines, as a mesotemperate thermotype. The aim was to determine the restoration state
a century from the reforestation, in terms of a vegetation dynamics study. A diachronic analysis was also performed using data from the literature
from a previous phytosociological study in 1973 in the same areas, and considering the adjacent native woods as the control. Although these two
reforestation areas had similar ecology and vegetation, this comparison revealed modest structural and flora differences that are mainly related to
geographical and topographical factors. This diachronic analysis highlights the structural and flora changes in the reforestation areas considered, and
thus the structural and floristic-vegetation stages of the succession that was represented by the plant communities towards Ostrya carpinifolia forests
(association, Scutellario-Ostryetum carpinifoliae) in 1973 and 2012. The minor coverage of conifers that was recorded for the two investigated sites
corresponds to an increase in the nemoral species of the class Querco-Fagetea and to a widespread decline in ecotone and grassland species. Although
the same trend is seen for the structural and floristic-vegetation dynamics, the differences that emerged from the comparison between these two
reforestation areas are confirmed by the diachronic analysis. The status of the restoration is a function of the native woods, and thus is a function of
the reference site. In this sense, we can consider that for the two sites the restoration status was similar, but not the same, because only within each
site can the coenoses in 1973 and 2012 be considered as the developmental stages of the same dynamic process. However, if we consider the situation
before reforestation, as derived from the historical documents, it can be seen that the natural vegetation dynamics was favoured, or at least accelerated,
in the topographic positions that guaranteed greater edaphic humidity conditions. On the basis of the data obtained, we can say that 100 years
after reforestation these two areas produced ecological conditions that guaranteed ingression of the nemoral species that were present in the surrounding
woods, with their more than adequate regeneration. As well as representing an essential knowledge base for planning of future silvicultural
actions, the knowledge acquired can provide useful indications of auto-ecological features of the species involved in dynamic restoration processe
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
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