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Struttura di comunità ornitiche in ambiente mediterraneo percorso da incendio (Castelfusano, Roma – Italia centrale): studio su un ciclo annuale
No full textBreeding bird communities in burnt and unburnt residual pinewoods were studied over 3 years by line-transect method, following a catastrophic fire event in Castelfusano (Rome, Central Italy, July 2000). We applied bootstrap procedures to evaluate whether the observed data were true or just produced by chance, and then examined the emerging patterns of three levels: community, guild and species levels. At community level, fire altered the total abundance pattern: species abundance decreased in burnt pinewood compared to unburnt, but other parameters were not significantly affected by fire. The destruction and structural simplification of camopy and shrubby components, as well as the increase of edge habitat and patchiness at landscape scale, induced a higher turnover of species in burnt pinewoods. At guild and species level, forest species decreased strongly in terms of richness and abundance in burnt pinewoods; on the contrary the species usually occurring in edge and open habitat increased
Effetti del passaggio del fuoco e del successivo taglio di bonifica su comunità ornitiche di foreste mediterranee (Castelfusano, Roma - Italia centrale
No full textDiversity/dominance diagrams show that fire disrupts the evenness in Mediterranean pinewood forest bird assemblages
No full textBreeding bird communities were studied by line-transect in burnt pinewood and unburnt pinewoods, during three
years subsequently to a fire event, in a coastal woodland of Mediterranean central Italy. We analyzed data following a diversity/
dominance approach that ranks the species in order of their abundance, to obtain rank/abundance diagrams (‘Whittaker
plots’). Although it is generally accepted that fire may induce structural changes in forest communities of breeding birds, we
observed more evident effects when considering the assemblage of forest-specialist species. When considering the whole
community of birds, ordinate intercepts of the regression between rank and relative abundance of species were not significantly
different between unburnt and burnt plots in any of the three years of study. However, when considering only the forest-related
species, there was a significant difference between unburnt and burnt plots in all the years of study. Evenness showed lower
values that were explicited by the diversity/dominance diagrams (lower collocation of the curves of burnt pinewoods if compared
to unburnt ones). Overall, the patterns observed in this study suggest that the effects of fire disturbance were more evident
at the ecological level than at the taxonomic-level assemblages. The gradual decline of the more sensitive species due to fires
and the proportional increase of edge/generalist species may induce a species turnover in burnt woods with cascade and relaxation
effects which could be evidenced by diversity/dominance diagrams. Consequently, it is useful to separate the effects of
fires at community-level and at assemblage-level when studying bird communities in areas subjected to fire
The effects of fire on communities, guilds and species of breeding birds in burnt and control pinewoods in central Italy
No full textBreeding bird communities in burnt and unburnt residual pinewoods were studied over 3 years by line-transect method, following a catastrophic fire event in Castelfusano (Rome, Central Italy; July 2000). We applied bootstrap procedures to evaluate whether the observed data were true or just produced by chance, and then examined the emerging patterns at three levels: community, guild and species levels. At the community level, fire acted on breeding bird communities by altering especially the total abundance patterns: the species abundance decreased in the burnt pinewood compared to the residual one, but other parameters were not significantly affected by fire. As a consequence of fire, the destruction and structural simplification of the canopy and shrubby component, as well as the increase of edge habitat and patchiness at landscape scale, induced a turnover in species between pinewoods. Species turnover was higher at the burnt than at the residual pinewoods, during all the 3 years of study. At the guild level, the forest species decreased strongly in terms of richness and abundance in the burnt pinewoods, contrary to the edge and open habitat species which increased in terms of richness, abundance and evenness. Edge species showed the highest turnover in burnt pinewood during the whole period of study. At species level, after an a priori subdivision (based on bibliographic search) of the various species in two ecological guilds (forest versus edge species), it was found that an a posteriori statistical analysis confirmed the expected trend, i.e. that the species which decreased significantly in burnt pinewood were essentially the forest species, whereas the species which increased were essentially the edge/open habitat ones. Overall, in order to investigate the effects of fire catastrophes on birds, the guild approach seems more exhaustive than the taxonomic community approach, where intrinsic confounding trends are presen
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
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