1,720,983 research outputs found
Vers un bocage forestier : les haies de feuillus, une solution fondée sur la nature pour améliorer la résistance des paysages de forêts de plantations
No full textIn the context of global change, forest ecosystems are increasingly exposed to disturbances, particularly insect pest outbreaks. Monospecific plantation forests are particularly vulnerable and also support lower biodiversity compared to semi-natural forests. Forest diversification, whether implemented at the stand or landscape scale, is a promising approach to enhancing their resistance, but this raises management and governance challenges that often slow down or hinder its implementation. In this thesis, we applied the concept of Nature-Based Solutions to explore the potential benefits of establishing a network of broadleaved hedgerows within a pine plantation landscape, referred to as a “forest bocage”. Inspired by the traditional “bocage” (i.e., agricultural landscape with hedgerows), this forest landscape diversification strategy is based on two main hypotheses: (1) hedgerows can host natural enemies that help control pests (i.e., conservation biological control), and (2) they promote biodiversity conservation. These hypotheses were tested in the Landes de Gascogne Forest in southwestern France, a large forested area of over one million hectares, dominated by monospecific stands of maritime pine (Pinus pinaster). Using existing broadleaved hedgerows and remnants (considered as source habitats for forest biodiversity), we assessed their effects on infestation by the pine processionary moth (Thaumetopoea pityocampa) and on the activity of its avian and bat predators. In parallel, we compared multi-taxonomic biodiversity (i.e., understorey vegetation, butterflies, carabids, spiders, birds and reptiles) between broadleaved hedgerows and pine stand borders, and characterized hedgerow structure using an innovative airborne LiDAR approach. Our results show that broadleaved hedgerows reduce pine processionary moth infestations through a barrier effect that limits host tree detection by adult moths. The great tit (Parus major), particularly active in hedgerows during spring, contributes to the winter regulation of processionary caterpillars. Moreover, multi-taxonomic biodiversity was significantly higher in hedgerows than in pine edges, with hedgerows harbouring more forest specialist and rare species. LiDAR data analyses also revealed that hedgerows with dense canopy harbour more forest specialist species, while high structural heterogeneity in canopy and understory promotes a greater multi-taxonomic biodiversity. By demonstrating that broadleaved hedgerows can simultaneously mitigate pest damage and restore biodiversity, this thesis highlights that the “forest bocage” represents a relevant Nature-Based Solution to enhance the resistance of pine plantation landscapes against pest insects. Further research is nonetheless needed to assess their potential role in mitigating abiotic disturbances, particularly storms and wildfires.Dans le contexte des changements globaux, les écosystèmes forestiers sont de plus en plus exposés à des perturbations, notamment les pullulations d’insectes ravageurs. Les forêts de plantation monospécifiques se révèlent particulièrement vulnérables, en plus d’abriter une biodiversité moins importante que les forêts semi-naturelles. La diversification forestière, qu’elle soit appliquée à l’échelle du peuplement ou du paysage, constitue une piste prometteuse pour accroître leur résistance, mais elle soulève des enjeux de gestion et de gouvernance qui ralentissent ou empêchent sa mise en œuvre. Dans cette thèse, nous avons mobilisé le concept de Solution fondée sur la Nature pour explorer les bénéfices d’un réseau de haies de feuillus implanté au sein d’un paysage de plantation de conifères, et appelé « bocage forestier ». Inspirée du bocage agricole, cette stratégie de diversification du paysage forestier repose sur deux hypothèses : (1) les haies peuvent héberger des ennemis naturels contribuant à la régulation des ravageurs (i.e., lutte biologique par conservation), et (2) elles favorisent la conservation de la biodiversité. Nous avons testé ces hypothèses dans la Forêt des Landes de Gascogne, massif forestier de plus d’un million d’hectares majoritairement composé de peuplements monospécifiques de pin maritime (Pinus pinaster). En nous appuyant sur des haies existantes et des ilots de feuillus (considérés comme habitats sources pour la biodiversité), nous avons évalué leurs effets sur les infestations par la processionnaire du pin (Thaumetopoea pityocampa) et sur l’activité de ses prédateurs oiseaux et chauves-souris. Parallèlement, nous avons comparé la biodiversité multi-taxonomique (i.e., plantes du sous-bois, papillons de jour, carabes, araignées, oiseaux et reptiles) entre haies de feuillus et bordures de plantations de pins, et caractérisé la structure des haies grâce à une approche innovante par LiDAR aéroporté. Nos résultats montrent que les haies de feuillus réduisent les infestations de processionnaires via un effet barrière limitant la détection de l’arbre hôte par les papillons. La mésange charbonnière (Parus major), particulièrement active dans les haies au printemps, contribue à la régulation hivernale des populations de processionnaires. Par ailleurs, la biodiversité multi-taxonomique est significativement plus élevée dans les haies que dans les bordures de pins, avec davantage d’espèces spécialistes forestières et d’espèces rares. Enfin, l’analyse LiDAR révèle que les haies à canopée dense hébergent plus d’espèces spécialistes forestières, tandis qu’une forte hétérogénéité structurelle de leur canopée et sous-bois favorise l’accueil d’une plus grande biodiversité multi-taxonomique. En montrant que les haies de feuillus peuvent simultanément limiter les dégâts liés aux insectes ravageurs et restaurer la biodiversité, ces travaux de thèse montrent que le bocage forestier constitue une Solution fondée sur la Nature pertinente pour accroître la résistance des paysages de plantations de pins aux attaques de ravageurs. Des recherches complémentaires sont néanmoins nécessaires pour évaluer leur rôle vis-à-vis des perturbations abiotiques, en particulier les tempêtes et les incendies
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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