1,720,967 research outputs found
Causes and consequences of crayfish extinction: Stream connectivity, habitat changes, alien species and ecosystem services
No full textGiven the ongoing decline of many species, it is important to perform multifactorial analyses of conservation status and to assess the effects of species extinction on ecosystem services. In this study, we used long-term surveys to assess the influence of habitat change, landscape alteration and invasive species on extinction risk of the native crayfish Austropotamobius pallipes. We reviewed the existing literature to assess which ecosystem services are threatened by local extinction of A. pallipes and replacement with alien crayfish. We sampled 196 streams and wetlands in northern Italy. Of these, 117 received multiple surveys over a 13-year period (2004–2017), thus allowing accurate measurement of extinction rate. Thirty-four percent of A. pallipes populations underwent extinction between 2004 and 2017. The occurrence of alien crayfish in the catchment basin and urban growth in the landscape surrounding streams were associated with A. pallipes extinction. The probability of persistence was significantly higher in populations close to stream springs and with physical barriers (especially waterfalls) separating them from basins with alien crayfish. Extinction of native crayfish alters community structure and impairs regulating services such as detrital breakdown and pest regulation. Replacement by alien crayfish (Procambarus clarkii and Faxonius limosus) also threatens supporting and regulating services by altering nutrient cycling, food webs, sediments and erosion. The implementation of management practices that control river connectivity using selective barriers is needed to prevent further local extinction of native species. Integrating information on extinction with knowledge of impacts on ecosystem services is essential in developing more effective conservation policies
Informazioni preliminari sulla fauna delle grotte delle province di Pavia e di Alessandria, con cenni sul limite settentrionale del geotritone Speleomantes strinatii (Amphibia, Urodela, Plethodontidae)
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Long term analysis of social structure: evidence of age-based consistent associations in male Alpine ibex
Full text linkDespite its recognized importance for understanding the evolution of animal sociality as well as for conservation, long term analysis of social networks of animal populations is still relatively uncommon. We investigated social network dynamics in males of a gregarious mountain ungulate (Alpine ibex, Capra ibex) over ten years focusing on groups, sub-groups and individuals, exploring the dynamics of sociality over different scales. Despite the social structure changing between seasons, the Alpine ibex population was highly cohesive: fission-fusion dynamics lead almost every male in the population to associate with each other male at least once. Nevertheless, we found that male Alpine ibex showed preferential associations that were maintained across seasons and years. Age seemed to be the most important factor driving preferential associations while other characteristics, such as social status, appeared less crucial. We also found that centrality measures were influenced by age and were also related to individual physical condition. The multi-scale and long-term frame of our study helped us show that ecological constrains, such as resource availability, may play a role in shaping associations in a gregarious species, but they cannot solely explain sociality and preferential association that are likely also to be driven by life-history linked physiological and social needs. Our results highlight the importance of long-term studies based on individually recognizable subjects to help us build on our understanding of the evolution of animal sociality
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
Linee guida volontarie per l’uso sostenibile del suolo per i professionisti dell'area tecnica. Indirizzi per la tutela del suolo dai processi di impermeabilizzazione e dalla perdita di materia organica
No full textThe voluntary guidelines aim to collect and analyses tools, strategies and methods for soil protection and its sustainable management with specific regard on two threats: the increase of Soil sealing and Land take process, and the decline and loss of soil organic matter. The main purpose of the document is to spread awareness on Soil value among professionals respectively to agronomists, architects, geologists, geometers, and engineers sharing knowledge and experiences on best practices and innovative solutions for soil protection.
The Voluntary guidelines are articulated in 8 main strategic actions concerning:
Spread the awareness of the soil value through a participation, communication and training activities;
• Reduce the Land take process in territorial planning adopting an Ecosystem Services-based approach for setting qualitative and quantitative limits and ecological mitigation and compensation measures;
• Increase the ecosystem services provision through the design of green and blue infrastructures;
• Prioritise the regeneration of brownfields and underutilised areas restoring the contaminated soils;
• Monitor and optimise the soil organic matter;
• Increase and restore the soil organic matter for enhancing the ecosystem services provision through the adoption of conservative soil management practices;
• Enhance soil resilience to climate change;
• Promote agro-biodiversity conservation strategies to increase the soil organic matter and the provision of ecosystem services.
The 8 actions are presented through a summary sheet articulated in objectives, stakeholders involved in the action, techniques and methods of action implementation, leading best practices, references and manuals useful for the practical operationalisation of the action. The document includes a glossary section, aiming to set common definitions and terminologies among professionals, a focus on available regional soil database, and a framework on existing regulations on soil protection useful for professional activities
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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