1,720,966 research outputs found
Monitoring of alien aquatic plants in the inland waters of Sicily (Italy)
Full text linkUpdated and reliable data on the presence and distribution of alien aquatic
plant species in Sicily are lacking, and there is a need to fill this gap for a proper and
efficient management of freshwater ecosystems and biodiversity. This paper reviews
the available knowledge about alien aquatic vascular plants in the inland waters of
Sicily (Italy). The aim is to provide an updated checklist, as a first step in the study of
the impact of those plants on the native species and ecosystems of this Mediterranean
island. The paper focuses on the strictly aquatic species (hydrophytes), excluding emergent
macrophytes. Four species were listed, all of them free-floating and with American
origin. Most of them occur within protected areas, and their introduction in the island
appears to be anthropogenic. A set of functional traits of the alien species, such as relative
growth rate, leaf mass per area, nitrogen and carbon content, were screened. These
traits are useful for assessing the species invasive potential compared to native ones
Investigating the ecology of Chara cf. baltica (Characeae) in the Lago Preola ecosystem (Sicily, Italy)
No full textLago Preola is a small lake, located in SW Sicily, in a karstic depression within the Nature Reserve “Lago Preola e Gorghi Tondi”. With about 33 ha (maximum depth: 2 m), it is the widest of the 5 natural lakes occurring in the Reserve. The presence of species of conservation concern (e.g., Emys trinacris, the Sicilian Pond Turtle, and several migratory birds), but also of invasive alien species (e.g., Procambarus clarckii, the Red Swamp Crayfish), has been reported for the area. The flora of terrestrial habitats surrounding the basins has been studied extensively, while the aquatic flora and vegetation have not been studied in detail. The coastal aquifer supplying groundwater to the study area lakes has shown fluctuations in the last decades: Curry et al. (2016) reported that in 2000/2001 Lago Preola dried out completely during the summer drought. Irrigation well pumpage was reduced in 2004, and ceased in 2008, which in combination with abundant precipitation has since resulted in high, stable lake levels (Curry et al. 2016). The finding of a Chara, provisionally identified as C. baltica Bruzelius (troia et al. 2018), has led us to study the distribution and ecology of the species in this area. C. baltica forms a thick monospecific meadow along the shore at the sampling site. In Summer 2018 the water was slightly brackish (conductivity ca. 4 mS/cm) and slightly alkaline (pH ca. 9). At an analogous sampling site in the nearby lago Murana (conductivity ca. 3 mS/cm, pH ca. 8.6), macrophyte vegetation was instead characterized by a monospecific meadow of the angiosperm Najas marina L. s.l., not reported up to now for the Reserve. In the framework of providing an isotopic baseline for future studies on the ecophysiology of these two macrophytes and on trophic relations within the water basins (rodrigo et al. 2016), we have started analysing carbon and nitrogen stable isotope composition. Macrophytes for these analyses were sampled at ca. 2 m from the shore, at a depth of approximately 0.5 m. Samples were dried to constant weight, powdered, and analysed with an isotope ratio mass spectrometer and an elemental analyser
The ancient irrigation system of the Palermo Plain (Sicily, Italy) as a substitute ecosystem: preliminary investigations on its aquatic flora
No full textMany cities around the world are expanding, including in their perimeters green and blues spaces that could be crucial for the maintaining of biodiversity. Urban waterbodies are generally created to provide other services, but correctly managed they can provide also relevant ecosystem services. The Palermo Plain was characterized, in the past centuries, by several wetlands that were progressively destroyed (or “reclaimed”). The ancient irrigation system, probably set during the Arab domination (IX-XI century A.D.), became a substitute ecosystem able to host a significant biodiversity. Our research focused on the remains of this system, scattered in the relictual green areas of the Plain, and especially on typical open cisterns, named (with a term of Arabic origin) “gebbie”; we checked the presence of strictly aquatic flora (vascular plants and charophytes), taking also into account some water parameters (conductivity, pH and hydroperiod) and the type of management of these water bodies. The floristic richness of these urban reservoirs appears to be generally low; however, they sometimes support rare species, or species otherwise disappeared from the Plain. If well managed, they have the potential to support a much greater biodiversity than they currently do; on the contary, abandoned “gebbie” are the poorest ones
Is in vitro micrografting a possible valid alternative to traditional micropropagation in Cactaceae? Pelecyphora aselliformis as a case study
Full text linkSeveral taxa of Cactaceae are endangered by overcollection for commercial purposes, and most of the family is included in the Convention on International Trade in Endangered Species of Fauna and Flora (CITES). Micropropagation may play a key role to keep the pressure off wild populations and contribute to ex situ conservation of endangered taxa. One of the limits of micropropagation is the species-specific requirement of plant regulators for each taxon and sometimes even for different genotypes. With the micrografting technique the rootstock directly provides the scion with the necessary hormonal requirements. In this paper we present data on in vitro grafting of Pelecyphora aselliformis Ehrenberg, an Appendix I CITES listed species critically endangered and sought after by the horticultural trade, on micropropagated Opuntia ficus-indica Miller. Apical and sub-apical scions of P. aselliformis were used to perform micrografting with a successful rate of 97 and 81 % respectively. Survival rate after ex vivo transfer was 85 %. We hypothesize that this method could be applied to other endangered, slow growing taxa of Cactaceae thus contributing to the conservation of this endangered family.Several taxa of Cactaceae are endangered by overcollection for commercial purposes, and most of the family is included in the Convention on International Trade in Endangered Species of Fauna and Flora (CITES). Micropropagation may play a key role to keep the pressure off wild populations and contribute to ex situ conservation of endangered taxa. One of the limits of micropropagation is the species-specific requirement of plant regulators for each taxon and sometimes even for different genotypes. With the micrografting technique the rootstock directly provides the scion with the necessary hormonal requirements. In this paper we present data on in vitro grafting of Pelecyphora aselliformis Ehrenberg, an Appendix I CITES listed species critically endangered and sought after by the horticultural trade, on micropropagated Opuntia ficus-indica Miller. Apical and sub-apical scions of P. aselliformis were used to perform micrografting with a successful rate of 97 and 81 % respectively. Survival rate after ex vivo transfer was 85 %. We hypothesize that this method could be applied to other endangered, slow growing taxa of Cactaceae thus contributing to the conservation of this endangered family
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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