1,720,984 research outputs found
Maintaining habitat diversity at small scales benefits wild bees and pollination services in mountain apple orchards
No full text1. Landscape context influences wild bee abundance and diversity, alongside pollination- related services. Growing evidence supports the positive effects of landscape heterogeneity on bee diversity and fruit production for pollination- dependent crops in flatlands. However, little remains known about these rela-tionships in mountainous environments where the landscape matrix surrounding crops is often more complex than in lowlands.2. We conducted our study in apple orchards in South Tyrol, an Alpine region in Italy, using pan-traps, direct observations of visitation frequency and a pollinator exclusion experiment. We investigated the scale-dependent effects of landscape heterogeneity and other parameters on wild bee assemblages and the related pollination service they provide at five spatial scales (radius 100–2000 m).3. We found that landscape heterogeneity positively affected the abundance and richness of wild bees, with the strongest effect at 500 m. We calculated a multi-diversity index, reflecting the land-use intensity based on the species richness of vascular plants, grasshoppers, butterflies, birds and bats. We identified a positive relationship between this multidiversity index and wild bee richness. Additionally, we found that visitation rate of wild bees was negatively affected by crop cover and that abundance of honeybees did not influence wild bee visitation rate or re-productive success. Finally, reproductive success was positively related to semi-natural habitat cover.4. Landscape heterogeneity should be maintained in apple orchards to continue to reap the benefits of vital pollination- related services. Diversification strategies should be implemented to promote habitat diversity at small scales, even in re-gions with more than 80% of (semi-)natural habitats
New distribution records of wild bees (Hymenoptera, Apoidea) in South Tyrol (Italy): expanding the wild bee database
Full text linkThroughout South Tyrol, in northern Italy, there is a data deficiency relating to wild bee species pool. Here, we present significant findings from the collection of 3,313 wild bees gathered over two separate studies conducted in consecutive years. Our research focused on the impact of landscape heterogeneity, temperature and land-use change on wild bee communities and their pollination services in an agricultural and mountainous landscape. This article provides a detailed account of the 150 identified wild bee species collected using coloured pan traps. We report habitat type, occurrence data, threat status, sociality, nesting strategy and diet breadth. In Italian regions where information on wild bee distribution is lacking or outdated, sharing data is crucial for developing conservation policies.The compiled species list strengthens regional and national wild bee database by providing new distribution data for extinction-threatened species, such as Dufourea dentiventris (Nylander, 1848), Dufourea inermis (Nylander, 1848), Lasioglossum brevicorne (Schenck, 1870), Lasioglossum laevigatum (Kirby, 1802), Lasioglossum monstrificum (Morawitz, 1891), Nomada mutica Morawitz, 1872 and Nomada villosa Thomson, 1870. Additionally, we present recent findings of species that are valuable for understanding range expansions, recording species previously unreported in South Tyrol and updating historical data for the region
Regeneration of Nothofagus dombeyi (Mirb.) Ørst. in little to moderately disturbed southern beech forests in the Andes of Patagonia (Argentina)
Full text linkNatural forests and stands subjected to little to moderate human impact are continuously declining worldwide and with these, their biodiversity and ecosystem services. Many Nothofagus forests in the south of the South American continent are in a pristine state or only moderately impacted by humans. Forest grazing by livestock, in the past and still today often practiced in a non-sustainable way is, however, increasingly under discussion to meet current environmental and socio-economic challenges. Accordingly, we investigate the regeneration of Nothofagus dombeyi, a keystone species of the Patagonian Andes, in secondary forests in Argentinian northern Patagonia, particularly addressing the role of disturbance through grazing by livestock at various intensities. We test the hypothesis that the regeneration of this tree species is favored by grazing impact and, thus, disturbance of the herb layer and soil surface. In support of our hypothesis, Nothofagus dombeyi regeneration was significantly higher in terms of individuals and height classes in moderately grazed forests. Multivariate analysis shows significant positive effects of moderate grazing pressure, herb layer cover, and the occurrence of bare soil on the regeneration of Nothofagus dombeyi. Our results show that an integration of livestock grazing and forest regeneration is possible and that agroforestry systems can be an adequate management option for stakeholders in the region. A grazing management can also be part of a forest fire prevention strategy. However, the regeneration success and grazing pressure should be continuously monitored.Fil: Zerbe, Stefan. Free University of Bozen-Bolzano; ItaliaFil: Storz, Stefanie T.. Universidad de Innsbruck; AustriaFil: Leitinger, Georg. No especifíca;Fil: Joelson, Natalia Zoe. Universidad de Innsbruck; AustriaFil: Bava, José. Centro de Investigación y Extensión Forestal Andino Patagónico; ArgentinaFil: Heinrichs, Steffi. No especifíca;Fil: Leuschner, Christoph. Centro de Investigación y Extensión Forestal Andino Patagónico; ArgentinaFil: Loguercio, Gabriel Angel. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Simon, Alois. No especifíca;Fil: Urretavizcaya, María Florencia. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Walentowski, Helge. No especifíca
Disentangling biodiversity and temperature effects on bees and pollination services in mountain agroecosystems
Full text linkPollinating insects are declining globally due to habitat loss, agricultural intensification, and climate change. Wild bee loss threatens the delivery of pollination services essential for agriculture and ecosystem stability. Our study examined how multidiversity, reflecting the richness of four functional groups and indirectly indicating land-use intensity, together with temperature as a climatic proxy, shapes wild bee diversity and pollination services in mountainous agroecosystems. We selected 24 farmland sites in South Tyrol (NE Italy) spanning independent gradients of multidiversity and temperature. We used pan traps to quantify wild bee species richness and abundance of wild and managed bees. Additionally, we performed a phytometer experiment using radish and strawberry model plants to assess wild bee visitation and the resulting seed and fruit production. Our results showed that wild bee diversity and visitation rates increased with multidiversity, reflecting the strong influence of land-use intensity. In contrast, temperature had limited direct effect on wild bee diversity, partly because floral resources were not a limiting factor. Visitation rates varied with multidiversity: honeybee visitation rates dominated in low-diversity landscapes, while wild bee visitations peaked in more diversified landscapes. The pollinator exclusion experiment on strawberries revealed that higher temperatures reduced fruit weight more in the absence of insect pollination, suggesting an interaction between climate and pollination provision. Overall, our results findings highlight the complex interplay betweenbiotic and abiotic factors shaping wild bee communities and pollination. They also suggest that preserving biodiversity in agricultural landscapes could help buffer climate change impacts and support more resilient agroecosystems
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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