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Editorial: Floristic and vegetation studies in the era of big data: challenges, trends and applications
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Alien plant invasions in Mediterranean habitats. An assessment for Sicily
Full text linkLevels of plant invasions in different habitat types were assessed in several regional studies, but few of them were from the Mediterranean. Here we compare the levels of vascular plant invasion across habitats and plant communities of Sicily. We used a large dataset of plant species presences/absences in vegetation plots to analyze the invasion patterns across habitats considering biogeography, life form and phenology of alien plants. Vegetation plots were classified based on the EUNIS classification of European habitats. The invasiveness of each species was expressed in terms of its absolute and percentage frequency. Representation of different life forms and phenological patterns was compared between alien and native species. The fidelity of alien species to individual habitats was calculated using the phi coefficient. Our analysis shows that annual and woody species are the most represented life forms in the alien flora of Sicily and that alien species tend to have a longer flowering period than the native species. The investigated habitats differed strongly in their level of invasion by alien species, ranging from 0 to 15.6% of aliens of all species recorded. Most of the habitats were colonized by very few alien species or completely lacked them, except for sandy coasts, naturally-disturbed riverbeds, and synanthropic habitats. It must be noted, however, that the number of alien species occurring in a given habitat does not relate to the severity of the impact of invasion in that habitat. Some habitats are invaded by few (or single) species, which attain a high cover, transforming the whole ecosystem. The habitat-based approach proved to be suitable for evaluating the habitat specificity and frequency of alien species at a regional scale, improving the capacity for risk assessment in different ecological contexts
Reciprocal extrapolation of species distribution models between two islands – Specialists perform better than generalists and geological data reduces prediction accuracy
No full textThis study aims to test the extrapolation effects of species distribution models (SDM) using three groups of predictor variables: climate, relief and geology (bedrock type). We highlight potential ecological differences for selected taxa, regarding both generalists and specialists in terms of edaphic conditions. We used distributional data of 12 woody species shared by two large Mediterranean islands (Crete and Sicily) to calibrate Maxent models of their potential distribution. We trained models with data from Crete and extrapolated to Sicily and vice versa. We tested ten proxies for the three variable groups and compared AUC values as a measure of model performance. Extrapolation of SDMs worked fairly well across species and islands for those models including climatic and relief data, while those including geological information performed worse for the tested species. Edaphic generalists performed less well compared to edaphic specialists. The latter performed best with climate data included in models and more poorly with only geological data. This may be due to differences in bedrock type affinities of species between the two islands
Thirty years unmanaged green roofs: Ecological research and design implications
No full textThe variations in species composition and assemblage of unmanaged simple-intensive green roofs in
Hannover, Germany, were investigated over a thirty year period, in order to assess the persistence of
the initial seed mixture and to evaluate floristic changes. The roofs were greened in 1985 with soilbased
turf rolls sown with a mixture of five grasses (Festuca rubra, Festuca ovina, Agrostis capillaris, Lolium
perenne and Poa pratensis). Three sets of 120 phytosociological relevés, sampled in 1987, 1999 and 2014,
have been compared to assess: (1) nestedness vs spatial turnover, (2) functional diversity and (3) the
importance of vegetation dynamics on green roof performance and design. Results demonstrated that
from 1987 to 1999 the species diversity increased and the species turnover prevailed over nestedness,
due to the progressive niche occupation by new species. In contrast, from 1999 to 2014 species diversity
remained steady, suggesting that nestedness prevailed over species turnover. The main driver of the
observed functional changes was a shift towards relatively more thermoxeric conditions. In terms of
plant life strategies, the competitive species sown on the roof gradually gave way to stress-tolerant and
ruderal species, along with a progressive increase in species with shortdistance seed dispersal strategies.
It is concluded that: (a) to create resilient green roofs, spontaneous colonisation should be accepted
and considered as a design factor; and (b) regional plant communities could serve as a model for seed
recruitment and installations
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
Unraveling the Influences of Edaphic and Topographic Factors on High-Mountain Plant Communities: first results from the MO.MO.ME. Project
No full textThe Project ‘Monitoring Network for Studying the Effects of Climate Change on Mediterranean High-Mountain Grasslands
in Natura2000 Sites (MO.MO.ME.)’ aims at analyzing the differences in plant communities, microclimate, and
topography across various study areas. The main goal is to improve understanding of the biotic and abiotic factors
regulating the assembly of high-mountain communities, focusing on the functional and structural dynamics of Mediterranean
grasslands.
We present the first results of our analysis focused on the role of edaphic and topographic gradients on vegetation
patterns above 1900 m a.s.l. on Pizzo Carbonara (Madonie Mountains, Northern Sicily), a carbonate massif shaped by
karst erosion, resulting in a system of sinkholes and windy ridges across the summit plateau. We sampled 42 vegetation
plots, georeferenced using sub-metric GPS. Various topographic variables were derived from Sicily’s regional
technical map (2 m resolution) using QGIS. Additionally, chemical and biochemical soil parameters were analyzed for
each plot.
Plant species were classified into three life-form groups: chamaephytes, hemicryptophytes, and therophytes. Data
were analyzed using three response variables: species richness, vegetation cover, and species composition. For the
first two, we applied a Generalized Linear Model (GLM), while compositional data were processed using distance-based
redundancy analysis (db-RDA) with variation partitioning.
The results indicate that life forms are differentially filtered by edaphic and topographic variables. The topographic
factors influence the relative performance of co-occurring vascular plant species, shaping the structure and composition
of local plant communitie
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
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