1,720,997 research outputs found
Small-scale heterogeneity in urban ecosystems shapes plant community biodiversity: a case study in Southern Italy
No full textUrban ecosystems exhibit a high degree of spatial heterogeneity because of the complex interactions among the different elements of the urban landscape. For instance, impervious surfaces and various kinds of construction, together with the activities they serve, tend to cause landscape fragmentation and edge effects even at small spatial scales, with potential implications for biodiversity. This is especially concerning in urban green areas, where the
combined effects of landscape configuration and management can crucially affect ecological dynamics and the functioning of the urban ecosystem. The present research aims at filling this gap by focusing on the small-scale landscape configuration and the management of green areas as drivers for the structural and functional biodiversity of the herbaceous plant communities. Briefly, the study was conducted in two areas in Southern Italy, subjected to
similar Mediterranean climate but different management strategies in terms of mowing, fertilization and irrigation. The structural and functional biodiversity of plant communities in both the areas was investigated through three transects of phytosociological relevées, performed at different distances from the sidewalk surrounding the areas to evaluate the edge effect. The structural biodiversity was investigated by identifying taxa at the species level and estimating their abundance using the cover as a proxy, measured through the Braun-Blanquet scale, whereas the functional diversity was investigated by means of the Raunkiaer biological forms, chorology and the family to which species belong. Results show that the distance from the sidewalk plays a major role in shaping vegetation biodiversity. Where vegetation is subjected to occasional mowing and absence of anthropogenic fertilization/irrigation, patches
close to the sidewalk are mainly characterized by opportunist species, in contrast to the species with longer life cycles colonizing the inner parts of the area. Conversely, where vegetation is subjected to frequent mowing such variations in functional traits are not clearly observable, and opportunist species, especially alien and cosmopolitan chorotypes, tend to dominate irrespective of the distance from the sidewalk. Findings shed light on the role of small-scale spatial heterogeneity in shaping vegetation communities in complex urban ecosystems, with potential implications in terms of management, species conservation and preservation of ecosystem functioning
Small-scale land use effects on plant communities in Mediterranean urban ecosystems
No full textThe spatial configuration of urban landscapes, characterized by complex mosaics of fragmented patches subjected to different land uses, shapes biodiversity and, therefore, affects ecosystem stability and functioning. The present study focuses on evaluating the small scale variations of vegetation structural and functional biodiversity in Mediterranean urban ecosystems, in relation to land use and fragmentation. For the structural biodiversity, taxa were identified at the species level, estimating their abundance through several measures (number, dry mass, Braun-Blanquet cover), whereas functional traits (biological form, chorological type, Ellenberg indices) were adopted in evaluating vegetation functional diversity. Data analysis relied on the derivation of synthetic structural and functional diversity indices, employed together with community composition and species abundances in ascertaining how land use (pathways, lawns, tree rows) and margin effect (distance from interfaces) drive the diversity of plant communities. Overall, results indicate a remarkable heterogeneity of plant communities, even at scales in the order of few meters, with land use and margin effect differentially affecting their structural and functional biodiversity. The main drivers of biodiversity appear to be a combination of anthropogenic pressures (e.g. trampling/soil sealing) and the presence/absence of canopy shading, determining higher abundances of therophytes (especially Asteraceae and Poaceae) in open and trampled spaces and a proportional increase in hemichryptophytes under canopies. Findings suggest a large leeway in enhancing biodiversity and environmental heterogeneity in urban ecosystems through sustainable land planning, focusing on the type and spatial arrangement of green areas
From species ecology to ecosystem restoration – a modelling approach to successfully restore Posidonia oceanica meadows
No full textPosidonia oceanica (L.) Delile is a widespread slow-growing endemic seagrass of the Mediterranean Sea, colonizing the coastal environments from the surface down to 40-50 meters in depth. The meadows formed by P. oceanica constitute one of the most important Mediterranean marine ecosystems in terms of productivity and biodiversity, with associated communities representing climax assemblages on soft and shallow substrata (González-Correa et al., 2007). The meadows act as nurseries and refugia for several species, sustain diverse trophic webs, host endangered species, and are able to alter water circulation and sedimentation rate, preventing coastal erosion and shaping the seascape (Ruiz et al., 2001).
Unfortunately, this habitat is dramatically shrinking across large sections of the Mediterranean coasts, due to anthropogenic pressures such as the mechanical damage by anchoring and trawling, as well as the coastal development (Boudouresque et al., 2009). The slow growth of P. oceanica means that countering meadow regression implies not only the local protection of this habitat, but also the restoration, whenever possible, of the already lost meadows. The latter is crucial in recovering the functioning and ecological integrity of coastal ecosystems, and the practice is gaining momentum with the development of increasingly efficient approaches. However, in spite of the widespread engagement in restoration programs, the success and outcomes of these actions, in terms of meadow evolution over time, are still hard to predict.
In this context, ecological modeling can provide crucial support in evaluating the potential evolution of the meadows, especially through approaches focusing on describing the growth and the interactions with the environment of the planted propagules. The accuracy of these models, however, critically depends on the understanding of the biology and ecology of P. oceanica. To this end, the present research focuses on summarizing through an extensive meta-analysis the wealth of data and findings published on P. oceanica during the last 5 decades, using the derived information to parameterize individual based models of meadow evolution in time and space.
Specifically, a spatial energy dynamic budget model (sDEB) was developed, including resource gathering and allocation processes, competitive interactions among shoots for light and space, as well as the effects of environmental factors such as light, nutrients, temperature and substrate type on species physiology.
On the one hand, the model allows evaluating the potential evolution of planted meadows in time and space, on the other hand, meta-analysis results, provided in the form of a georeferenced database, highlight the current knowledge gaps toward which future researches should be oriented to improve our understanding of the ecology of this species and, thus, optimize the management of the unique ecosystem it forms
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
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
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