1,720,981 research outputs found
Local and regional abundance of exotic plant species on Mediterranean islands: are species traits important? RID F-7454-2011
No full textAim We assess the importance of three relevant and readily obtainable life-history traits (dispersal syndrome, stem height and growth form) and biogeographical origin (European vs. non-European) on the local and regional abundance of over 400 exotic plant species across eight Mediterranean islands. Location The Mediterranean islands of Lesbos, Rhodes, Crete, Malta, Corsica, Sardinia, Majorca and Minorca. Methods We adopt two abundance criteria for each exotic species: the proportion of islands in which the species occurs (regional abundance), and a qualitative estimate of species abundance within each of five islands (local abundance). Subsequently, we assess the relationship between local and regional abundance, as well as the role of key life-history traits on both regional and local abundance. These analyses were undertaken separately for the European exotics and the non-European exotics. Results Only 10.9% of the species occur on more than four islands, and only four species are present on all eight islands. Both local and regional abundances were higher for the non-European than the European species. Local and regional abundances were positively correlated, particularly for exotics with non-European origins. Wind-dispersed species tended to have higher regional abundance than species dispersed by other means but this trend only occurred for local abundance on two islands - Corsica and Majorca. Neither a species' growth form nor its stem height explained trends in regional or local abundance. Conclusions Although wind-dispersed exotics are more widespread in the Mediterranean, plant life-history traits appear to play a lesser role in invasion success than area of biogeographical origin. In general, exotic species of non-European origin were more abundant at both local and regional scales. Invasion patterns should be interpreted at both local and regional scales, but the stochastic nature of biological invasions may limit deterministic interpretations of invasion patterns, especially if islands are studied in isolation
Plantes vasculaires nouvelles ou rares pour la Tunisie presentes sur les iles (Galite, Zembra, Kuriat, Monastir, Kerkennah, Kneiss, Djerba)
Full text linkVascular plants new or rare for Tunisia occurring on the islands (Galite, Zembra, Kuriat, Monastir, Kerkennah, Kneiss, Djerba). - This study concerns the indigenous vascular plants newly reported for Tunisia and discovered on the islands during some field trips performed since 2014. Five native taxa are new to Tunisia: Bellis perennis, Carthamus creticus, Moraea mediterranea, Asplenium balearicum and Galium minutulum, the latter two also being new to North Africa. Information on 24 rare or poorly known taxa, most often of great biogeographical interest, is given, too. Most of these were discovered on the islands of the eastern coast (Kuriat, Monastir, Kerkennah, Kneiss, Djerba), but also on the northern islands of Zembra and La Galite. The new chorological data underline the first-rate conservation importance of these islands and islets for the preservation of the overall coastal biodiversity of Tunisia
Ecological and historical factors affecting distribution pattern and richness of endemic plant species: the case of the Maritime and Ligurian Alps hotspot
No full textDiversity and Distributions, (Diversity Distrib.) (2008) 14, 47–58
Ecological and historical factors affecting distribution pattern and richness of endemic plant species: the case of the Maritime and Ligurian Alps hotspot
Gabriele Casazza1, Elena Zappa2, Mauro G. Mariotti1, Frédéric Médail3 and Luigi Minuto1*
1DIP.TE.RIS. – Università di Genova, Corso Dogali 1M, 16136 Genova, Italy,
2Centro di Servizi di Ateneo Giardini Botanici Hanbury – Università di Genova, Corso Montecarlo 43, La Mortola, I-18039 Ventimiglia, Italy,
3Institut Méditerranéen d’Ecologie et de Paléoécologie (IMEP, CNRS UMR 6116) – Université Paul Cézanne (Aix-Marseille III), Europole
Méditerranéen de l’Arbois, Bâtiment Villemin, BP 80, F –13545 Aix-en-Provence cedex 04, France
The aim of this study was to test a method to locate all the foci, centres, and areas of endemism in a biodiversity hotspot in order to understand the influence of ecological and historical factors on the distribution pattern and to identify priority areas for future conservation projects. The study area was the Maritime and Ligurian Alps hotspot. Analyses were performed on the presence/absence matrix of 36 vascular plant taxa endemic to the study area. For each operational geographical unit, the number of endemic taxa present was counted. Additionally, the weighted endemism value was calculated. Areas of endemism were distinguished using cluster analysis and parsimony analysis of endemicity. The influence of ecological characteristics and historical factors was evaluated using Multi-Response Permutation Procedure and the Nonparametric Multiplicative Regression. The Indicator Species Analysis (INDVAL) method was used to identify the species characterizing the areas of endemism. Our results show the importance and location of four main areas of endemism within the Maritime and Ligurian Alps and explain the distribution pattern of endemic plants. These areas are easily interpreted by historical and ecological factors, and INDVAL indicates which taxa took part in the history of each endemism area.
Keywords
Cluster analysis, geological substrate, glacial refugia, historical factors, Ligurian Alps, Maritime Alps, parsimony analysis of endemism, species richness, vascular plants
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
Biogéographie, écologie et valeur patrimoniale des forêts de pin sylvestre (Pinus sylvestris L.) en région méditerranéenne.
Full text linkLe présent travail a pour objectif de synthétiser une partie des informations disponibles concernant :
- l'origine et l'histoire du pin sylvestre en région méditerranéenne,
- la variabilité et l'originalité des peuplements actuels,
- la situation écologique des pineraies méditerranéennes et leur dynamique en examinant les phases critiques du cycle de vie du pin sylvestre,
- la valeur patrimoniale de ces forêts,
- les opérations de gestion à favoriser, en considérant les tendances dynamiques et les changements climatiques globaux actuels
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
Species attributes and invasion success by alien plants on Mediterranean islands RID F-7454-2011
No full text1 Species attributes have been used to explain invasion patterns assuming the prevalence of biological mechanisms, although this approach often suffers several methodological and conceptual limitations, such as local idiosyncrasies, differences among habitats, phylogenetic constraints and insufficient sample size. 2 The relative importance of 15 species traits for explaining the abundance over 350 naturalized alien plant species was assessed across five Mediterranean islands (Corsica, Crete, Majorca, Malta and Sardinia). A comparative analysis accounting for phylogeny was used to examine variation in semi-quantitative estimates of species abundance in comparable habitats across the five island floras. 3 Species were divided into those with affinity for semi-natural, agricultural and ruderal habitats. Both vegetative and reproductive attributes were evaluated for individual islands and averaged across all islands. 4 Vegetative propagation, large leaf size, summer flowering, long flowering period and dispersal by wind or vertebrates were positively associated with average alien abundance across all five islands. Fewer significant trends were found in island-specific patterns. 5 The relative importance of a few reproductive traits is reflected in over-representation of Caryophyllales, Asterales and Poales (late flowering, large seed size and anemochory). Although significant covariation in traits was found there was no evidence for well-defined invasive syndromes. 6 Succulence was important in ruderal habitats, long flowering period in agricultural habitats and vertebrate seed dispersal in semi-natural habitats, suggesting that empty niches, avoidance of competitors and exploitation of mutualists, respectively, are important. 7 The study highlights the importance of estimating invasion success across a wide region, but analyses of specific invasion stages are also needed. Reproductive traits, which may be more relevant for long-distance colonization, and vegetative traits, which determine local dominance and persistence, were, nevertheless, both related to abundance within islands
Species attributes and invasion success by alien plants on Mediterranean islands. Journal of Ecology
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