1,720,974 research outputs found
GLI UCCELLI ALPINI E IL CAMBIAMENTO CLIMATICO
Full text linkAlthough considered globally important areas for birds and biodiversity in general, mountain regions remain poorly studied despite their renowned susceptibility to climatic alterations. Basic knowledge of bird species inhabiting these regions is scarce, and even a univocal definition of mountain regions lacks, as interpretations vary across countries and institutions. These ambiguities may prevent the definition of effective large-scale conservation strategies, and it is urgent to define “mountain birds” and investigate the potential impact of climate change on such species. In this thesis, we reviewed evidence for impacts of climate change on Holarctic mountain bird populations in terms of physiology, phenology, trophic interactions, demography and observed and projected distribution shifts, including effects of other factors that interact with climate change. We introduced for the first time an objective classification of mountain bird specialists and generalists, presented the results of a systematic review and meta-analysis of the effects of climate change on Holarctic mountain and upland birds, quantifying the general responses to climate change including altitudinal shifts, changes in life history traits and assessment of mitigation actions. Using Italy as a case-study, we demonstrated a relationship between climate and changes in bird distribution in the last 30-years, by comparing net range variation in cold-adapted and closely related control species. In addition, using the white-winged snowfinch Montifringilla nivalis (a mountain indicator species sensitive to climate change) as a model species, we aimed at improving the knowledge on biology, ecology and demographic aspects of this species to better elucidate the mechanisms driving declines of mountain birds. Finally, we developed adaptation frameworks for climate change at both large and small scale. For the first case, we established a novel approach for selecting conservation priorities, resistant units and resilient areas in the Italian Alps according to structural connectivity and future distribution for a range of mountain bird species to identify strategies that maximize the chances of species persistence in a changing climate. At a finer scale, we evaluated the role of microhabitats as refugia for climate-threatened species, and developed a theoretical approach based on human-mediated actions (i.e. grazing, mowing) to contain the detrimental effects of climate change on our study species, the white winged-snowfinch.
We identified 2316 bird species breeding in the Holarctic realm, 818 (35.3%) of which were defined as either high-elevation mountain specialists (n = 324 species) or mountain generalists (n = 494 species). We found evidence of biological and ecological responses of mountain birds to climate and environmental change, but little is known about underlying mechanisms or synergistic effects. Meta-analyses did not find a consistent direction in elevation change to track suitable climate but suggested that in the future mountain birds will be significantly more impacted than non-mountain species. In Italy, we found a strong positive correlation between change in range size and species thermal index (STI: average temperature of a species’ European range), confirming that recent climatic warming has favoured species of warmer climates and adversely affected species occupying colder areas. A model including STI and birds’ associated habitats was not so strongly supported but further suggested that forest species performed better than alpine open habitat and agricultural ones. Regarding our indicator/model species, we found that the white-winged snowfinch selected specific and climate sensitive microhabitat during the nestling rearing period: cool sites with short grass cover, melting snow margins adjacent to grassland and snow patches.Le regioni montane, sebbene considerate aree globalmente importanti per gli uccelli e la biodiversità in generale, rimangono scarsamente studiate, nonostante la loro ben nota suscettibilità alle alterazioni climatiche. La conoscenza di base delle specie di uccelli che popolano queste regioni è scarsa, e manca persino una definizione condivisa di “regioni montane”, in quanto le interpretazioni variano in base a paesi e istituzioni. Queste ambiguità possono potenzialmente precludere la delineazione di efficaci strategie di conservazione su larga scala, ed è quindi urgente dare una definizione univoca di “avifauna di montagna” per poter indagare il potenziale impatto dei cambiamenti climatici su queste comunità di specie.
In questa tesi abbiamo esaminato le evidenze degli impatti dei cambiamenti climatici sulle popolazioni di avifauna di montagna su scala olartica, riguardo a fisiologia, fenologia, interazioni trofiche, demografia e spostamenti di distribuzione osservati e previsti, considerando anche gli effetti di ulteriori fattori che interagiscono con i cambiamenti climatici, esacerbandone o attenuandone gli effetti. Per la prima volta abbiamo formulato una classificazione oggettiva dell’avifauna di montagna “specialista” e “generalista” e presentato i risultati di una revisione sistematica e di una meta-analisi riguardanti gli effetti dei cambiamenti climatici sugli uccelli montani, quantificando le conseguenze di tali alterazioni, come gli spostamenti altitudinali o i cambiamenti nei tratti biologici, e la valutazione di potenziali azioni mitigatrici e di compensazione degli impatti dovuti alle variazioni nel clima. Utilizzando l'Italia come caso-studio, abbiamo dimostrato l’esistenza di una relazione tra il clima e i cambiamenti nella distribuzione degli uccelli negli ultimi 30 anni, confrontando gli andamenti di occupazione ed abbandono di aree riproduttive da parte di specie legate ad ambienti freddi e di specie-controllo tassonomicamente vicine ma presenti in climi più miti. Inoltre, abbiamo utilizzato il fringuello alpino Montifringilla nivalis come specie modello (in quanto particolarmente sensibile ai cambiamenti climatici), al fine di migliorare le attuali conoscenze su biologia, ecologia e aspetti demografici delle specie d’alta quota, e chiarire meglio così i meccanismi che determinano il declino dell’avifauna di montagna. Infine, abbiamo sviluppato degli approcci conservazionistici innovativi per far fronte agli impatti del cambiamento climatico, su larga scala e poi su piccola scala. Nel primo caso, per identificare strategie che massimizzino le possibilità di persistenza delle specie in un clima che cambia, abbiamo stabilito nuove metodologie che hanno consentito di identificare nelle Alpi italiane le specie e le aree prioritarie per la conservazione (unità geografiche resistenti e resilienti ai mutamenti climatici), basandoci su connettività strutturale e previsioni di distribuzione futura di varie specie di avifauna di montagna. A scala più piccola invece abbiamo valutato il ruolo dei microhabitat come siti di rifugio per le specie minacciate dal clima, e sviluppato un approccio teorico basato sulla capacità di alcune attività umane (attività di pascolo e sfalcio) di contenere gli effetti dannosi del cambiamento climatico, con particolare riferimento alla nostra specie studio, il fringuello alpino, e alla struttura del suo habitat di foraggiamento
Ecology and conservation of birds in upland and alpine habitats: a report on the BOU's Annual Conference held at the University of Leicester, 1-3 April 2014
No full textNative woodland creation is associated with increase in a Black Grouse Lyrurus tetrix population
No full textRethinking road mitigation priorities through detection-informed interpretation of roadkill data and road crossability
No full textRoads play a critical role in biodiversity loss by reducing species survival and promoting habitat fragmentation. Most roadkill studies focus on single species or localized areas, using roadkill as a direct measure of risk, often overlooking or misinterpreting inherent biases (i.e. carcass-location, persistence and observation biases). In this study, we apply two concepts to better understand the relationship between wildlife-vehicle collisions and habitat connectivity. First, we interpret roadkill locations modelled using species distribution models as indicators of roadkill detection, rather than actual roadkill risk. Additionally, we introduce road crossability, a measure of habitat connectivity along roads, assessed using circuit theory. We adopt a multispecies approach, analyzing roadkill data from 15 forest mammals with different mobility across different landscapes (natural and anthropized) in northeastern Italy, to investigate the relationship between roadkill detection and road crossability. Our results show positive correlations between roadkill detection and road crossability for medium and high mobility species, particularly in anthropized landscape, while low mobility species exhibit a weaker correlation. Combining these metrics, we classified the regional road network into zones with different conservation and mitigation priorities: Priority Areas for Connectivity Improvement (PACoIs), Potential Areas for Roadkill Mitigation (PARoMs), and Potential Areas for Connectivity Preservation (PACoPs). Our study suggests that multi-specie roadkill detection and road crossability assessment hold promise to facilitate more effective conservation strategies and mitigation measures to maintain habitat connectivity and reduce the impact of roads in different landscapes
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
- …
