1,720,962 research outputs found
Comparability of river quality assessment using macrophytes: A multi-step procedure to overcome biogeographical differences
No full textThis paper exposes a new methodological approach to solve the problem of intercalibrating river quality national methods when a common metric is lacking and most of the countries share the same Water Framework Directive (WFD) assessment method. We provide recommendations for similar works in future concerning the assessment of ecological accuracy and highlight the importance of a good common ground to make feasible the scientific work beyond the intercalibration.The approach herein presented was applied to highly seasonal rivers of the Mediterranean Geographical Intercalibration Group for the Biological Quality Element Macrophytes. The Mediterranean Group of river macrophytes involved seven countries and two assessment methods with similar acquisition data and assessment concept: the Macrophyte Biological Index for Rivers (IBMR) for Cyprus, France, Greece, Italy, Portugal and Spain, and the River Macrophyte Index (RMI) for Slovenia. Database included 318 sites of which 78 were considered as benchmarks. The boundary harmonization was performed for common WFD-assessment methods (all countries except Slovenia) using the median of the Good/Moderate and High/Good boundaries of all countries. Then, whenever possible, the Slovenian method, RMI was computed for the entire database. The IBMR was also computed for the Slovenian sites and was regressed against RMI in order to check the relatedness of methods (R2=0.45; p<0.00001) and to convert RMI boundaries into the IBMR scale. The boundary bias of RMI was computed using direct comparison of classification and the median boundary values following boundary harmonization. The average absolute class differences after harmonization is 26% and the percentage of classifications differing by half of a quality class is also small (16.4%). This multi-step approach to the intercalibration was endorsed by the WFD Regulatory Committee. © 2013 Elsevier B.V
Response of macrophyte communities to flow regulation in mountain streams
No full textRiver macrophytes are widely used in freshwater ecosystem assessment because of their sensitivity to anthropogenic pressures, even if there are only a few studies that investigated how macrophytes respond to water regime alterations. In this study, we analyzed the effects of dams on river macrophyte communities through a comparison between upstream and downstream sides from 18 dams located in Alps and Apennines. A co-inertia analysis and a Mantel test were applied to assess if the analysis of environmental parameters could be effective in predicting macrophyte community structure. We analyzed morphological and physicochemical inter-site differences and tested the influence of dams on various aspects of community structure (composition, richness, diversity, dominance, coverage) using multivariate randomized block permutation procedure. Plant similarity between sites was evaluated at the level of phylum, and indicator species analysis was performed to identify the taxa most sensitive or tolerant to water regulation. We found that the overall environmental setting overwhelms the dam impact and that the influence of hydrological alteration became apparent when comparing upstream and downstream assemblages at the same dam. In particular, we found that most of taxa had a higher affinity with the downstream side and that in general, stream regulation increases plant richness and coverage, but reduces community evenness. Analyses based on higher taxonomic groups (phyla) demonstrated that this community can be effectively used in bioassessment even at phylum level analysis. In particular, we found that bryophytes, strictly linked with changes in substrate stability, show particular sensitivity to water regulation in mountain streams. © 2016, Springer International Publishing Switzerland
Black flies (Diptera, Simuliidae) as ecological indicators of stream ecosystem health in an urbanizing area (Rome, Italy)
No full textIntroduction. The effectiveness of Simuliidae (Diptera. Nematocera) as indicators of stream health was tested in the urbanizing area of Rome, Central Italy. Methods. 108 sampling sites were investigated in the spring to acquire data on environmental variables and black fly species. Results and discussion. The comparison of sampling and literature data highlighted the disappearance of some species (Simulium reptans, S. vernum, S. liriense), possibly due to water pollution and land use changes. Correspondence analysis confirms altitude as the main factor influencing black fly species' distribution. However, water quality becomes predominant when considering exclusively plain sites: "ornatum" and "equinum" species groups show the greatest tolerance to chemical pollution. The high course of the Aniene river and its tributaries were sampled bimonthly, confirming the spatial- Temporal black fly successions previously observed in central Apennines. The results also indicate that S. omatum may supplant all other species in areas where the rural use is substituted by urban landscape. Conclusion. In conclusion, black flies can be considered good environmental indicators to assess ecological health of both watercourses and surrounding landscapes
Water quality and relationship between superficial and ground water in Rome (Aniene River basin, central Italy)
No full textChemical, physical and biological features of streams and groundwater of the North-Eastern area of Rome are jointly analyzed in order to assess the status of water resources. Groundwater was investigated with classical survey methods (pH, temperature, and electric conductivity). Microbiological pollution, faunal composition, and stream surrounding area conditions of surface waters were studied, inorder to quantify the residual value of these ecosystems from both a human and an environmental point of view. Results show a general impairment of the system and the comparison between superfical waters and shallow groundwaters makes it possible to detect the presence of a connection between the two levels. This relationship occurs as an exchange from superfical waters (streams and rivers) to the shallow aquifers. Where superfcial waters are contaminated, as in the Tor Sapienza stream, pollutants move to the shallow aquifers too, due to the decreased pressure of the overexploited aquifer. Moreover, uncontrolled drilling activity, diffused in urban areas, makes it possible the connection between shallow and deep groundwater. Notwithstanding this, the mixing between superficia and deep groundwater system in Rome is not very widespread and, apparently, limited to restricted areas
Modalità tecniche per l'analisi e il miglioramento della reticolarità ecologica del territorio. Applicazione al territorio della città metropolitana di Torino
Full text linkLa progressive perdita di connettività tra gli elementi naturali che caratterizza il territorio del nostro Paese impone di attuare politiche finalizzate non solo alla tutela ma anche al miglioramento della reticolarità ecologica. Vi è necessità di metodologie che possano indirizzare in modo efficace ed oggettivo la pianificazione e la progettazione anche attraverso l’individuazione di priorità di intervento. La ricerca condotta ha consentito di evidenziare come, a partire da cartografie di Uso del Suolo di adeguato dettaglio anche in termini di Legenda, sia possibile definire un processo che parte dalla caratterizzazionedella reticolarità ecologica esistente e giunge sino alla definizione di modalità per laprogettazione della suo miglioramento. A partire del territorio campione dell’Anfiteatro Morenico di Ivrea (TO), si è giunti alla definizione della funzionalità reticolare dell’intero territorio della Provincia di Torino attraverso l’attribuzione di valori ecologici, in termini di Naturalità, Rilevanza per la Conservazione, Fragilità, Estroversione ed Irreversibilità a ciascuna delle tipologie di uso del suolo presenti. La ricerca applicata, svolta per (ed in collaborazione con) la Città Metropolitana di Torino ha condotto ad una proposta metodologica che rappresenta uno dei documenti di riferimento che sono entrati afar parte delle Linee guida del Sistema del Verde e della Rete Ecologica Provinciale previste all’art. 4 e 35 delle Norme di Attuazione del Piano Territoriale di Coordinamento Provinciale.The progressive loss of connectivity between the natural elements that characterizes the territory of our Country requires the implementation of policies aimed not only to protect but also improve ecological networking. Tools that can effectively and objectively guide planning and design are necessary, including identification of intervention priorities. The research carried out made it possible to highlight how, starting from maps of Land Use with a detailed Legend, it is possible to outline a process starting from the analysis of the existing ecological reticularity, up to to the definition of procedures for the planning and design of its implementation and improvement. From the sample area of the MorainianAmphitheater of Ivrea (TO), the reticular functionality of the entire territory of the Province of Turin has been defined through the attribution of ecological values, in terms of Naturalness, Relevance for Conservation, Fragility, Extroversion and Irreversibility to each of the types of land use existing in study area. Applied research, carried out for and in collaboration with the Metropolitan City of Turin, led to a methodological proposal that represents one of the reference documents that became part of the Guidelines of the Green System and of the Provincial Ecological Network provided for art. 4 and 35 of the Implementation Rules of the Provincial Coordination Territorial Plan
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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