1,721,006 research outputs found
More species, less effort: Designing and comparing sampling strategies to draft optimised floristic inventories
No full textFloristic inventories are an essential part of basic and applied research in botany. Despite their long history, floristic research is still carried out following non-objective (preferential) sampling approaches. Accordingly, final outputs (i) are extremely variable in the quality and quantity of collected data and hardly repeatable, (ii) rely on the researcher ability, and (iii) miss the basic assumptions to allow inferential statistical analyses. The aim of this work is to explore the drafting of a floristic inventory by means of geostatistical approaches to locate sampling units (plots) in the study area. We planned, carried out and then compared two different sampling strategies: (i) ‘basic strategy’, a stratified random sampling design based solely on a spatial optimization criterion (no prior information is available), and (ii) ‘advanced strategy’, a sampling design based on the maximisation of the spectral heterogeneity among sampling units, quantified in terms of Normalized Difference Vegetation Index values (NDVI). The strategy that maximises collected floristic information was assessed based on a combination of descriptive and quantitative statistics, such as (i) the completeness of the floristic inventory, (ii) the steepness of the rarefaction curves, (iii) the sampling time effort, and (iv) the plot contribution to the total β diversity. The 'advanced strategy' detects more species than the 'basic strategy' in all the sampling sites. The 'advanced strategy' accumulates species more quickly than the 'basic strategy'. The 'advanced strategy' selects sampling units more homogeneously contributing to total β diversity; in addition, they are better spatially arranged across the study area to capture environmental peculiarities of sampling sites. The 'advanced strategy' needs a little more effort in the design of the sampling strategy, but it is more effective than the 'basic strategy' in drafting a species inventory. We provide here the R routine to perform the 'advanced strategy', which can be profitably and freely used in any other geographic location and vegetation context
Determining plant diversity within interconnected natural habitat remnants (Ecological network) in an agricultural landscape: A matter of sampling design?
Full text linkIn intensively used and human-modified landscapes, biodiversity is often confined to remnants of natural habitats. Thus, identifying ecological networks (ENs) necessary to connect these patches and maintain high levels of biodiversity, not only for conservation but also for the effective management of the landscape, is required. However, ENs are often defined without a clear a-priori evaluation of their biodiversity and are seldom even monitored after their establishment. The objective of this study was to determine the adequate number of replicates to effectively characterize biodiversity content of natural habitats within the nodes of an EN in north-eastern Italy, based on vascular plant diversity. Plant communities within habitat types of the EN’s nodes were sampled through a hierarchical sampling design, evaluating both species richness and compositional dissimi-larity. We developed an integrated method, consisting of multivariate measures of precision (MultSE), rarefaction curves and diversity partitioning approaches, which was applied to estimate the minimum number of replicates needed to characterize plant communities within the EN, evaluating also how the proposed optimization in sampling size affected the estimations of the characteristics of habitat types and nodes of the EN. We observed that reducing the total sampled replicates by 85.5% resulted to sufficiently characterize plant diversity of the whole EN, and by 72.5% to exhaustively distinguish plant communities among habitat types. This integrated method helped to fill the gap regarding the data collection to monitor biodiversity content within existing ENs, considering temporal and economic resources. We therefore suggest the use of this quantitative approach, based on probabilistic sampling, to conduct pilot studies in the context of ENs design and monitoring, and in general for habitat monitoring
ITV-net: leveraging intraspecific trait variability to bridge vegetation science and trait-based research in Italy
No full textVegetation science is a branch of community ecology that relies on species identities and abundance to classify vegetation in coherent units and to explore species coexistence and turnover dynamics. The advent of trait-based ecology has expanded vegetation science, providing a framework that allows for a better understanding of plant strategies and the functional structure of communities. These complementary disciplines have remained largely independent among Italian plant ecologists. Therefore, in 2021, we launched the ITV-net initiative, a national collaborative effort for bringing together vegetation plots and field-measured plant trait data to develop a national platform that can serve both vegetation and trait-based ecologists. In the first data call, we were able to gather trait data on two key leaf traits (i.e., Leaf Area and Specific Leaf Area) for >700 species across 1,043 georeferenced vegetation plots, complemented with species relative abundances, across eight different EUNIS habitat types. Despite this remarkable first milestone, we aim to enlarge the scope of this initiative to include more vegetation plots and functional traits across more habitat types in Italy. Here, we provide an overview of the ITV-net initiative and its underlying methodological details as a ‘manifesto’ to spread the data call to other potential contributors in the Italian community of plant ecologists. Our ultimate objective is to bridge the vegetation science and trait-based ecological research in Italy towards developing a national database of vegetation plots and plant functional traits. We believe this effort will contribute to building a solid network among Italian plant ecologists to cross the artificial boundaries of different, yet complementary, disciplines
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
Metodi quantitativi per la redazione di flore (parte II): strategie di indagine floristica basate su approcci probabilistici
Full text linkLa redazione di una flora richiede enormi sforzi da parte del florista, spesso con risultati incompleti. Le flore sono generalmente redatte conducendo le attività di campo senza alcun protocollo quantitativo standardizzato, ma secondo criteri soggettivi, che scaturiscono da una combinazione di abilità, esperienza e intuito del florista (il cosìddetto “algoritmo del botanico” sensu Palmer et al. 2002). Se da un lato questo approccio aiuta a massimizzare il numero di taxa rilevati sul campo, dall’altro le flore così prodotte possono differire sensibilmente in quantità e qualità dei dati raccolti. Il passaggio verso un tipo di campionamento probabilistico – anziché opportunistico – è dunque auspicabile per poter (i) applicare analisi statistiche rigorose e comparabili, (ii) confrontare flore di regioni e periodi diversi (Chiarucci, Palmer 2006) e (iii) facilitare la riproducibilità e verificabilità di metodi e risultati. Lo scopo di questo lavoro è quindi quello di sperimentare l’introduzione di approcci probabilistici nella ricerca floristica e misurarne l’efficacia
Invasion at the edge: The case of Rosa rugosa (Rosaceae) in Italy
Full text linkThe Japanese Rose (Rosa rugosa) is a perennial shrub belonging to the family Rosaceae. It was introduced in Europe from East Asia as an ornamental plant in the XIX century and is now considered an invasive species, especially in northern Europe, colonising the Atlantic and Baltic coastal dune habitats and threatening local biodiversity. However, little is known about its presence and invasion patterns in the Mediterranean area. In Italy, R. rugosa has been classified as naturalised and just a few observations have been recorded in dune habitats in the North Adriatic coast. Here, we review the published data on R. rugosa in Europe and present preliminary data on the invasive pattern of R. rugosa on the Italian North Adriatic coast. We surveyed the coastline in two locations (i.e., Brussa and Bibione, Italy) where we characterised the dimension and structure (i.e., number of ramets and stem height) of the R. rugosa populations and listed the associated floristic composition. No occurrence of R. rugosa was recorded in Bibione, probably due to the success of the restoration project carried out on that site. In contrast, several stands of R. rugosa were found in Brussa, where many other alien species were also found (accounting for 15.28% of the sampled species). Given the strong invasiveness of R. rugosa, it is important to keep data on its distribution up-to-date and investigate its ecology and physiology to promote appropriate management strategies to control its spread and anticipate its future potential distribution
Climate Change Risk and Vulnerabilities Analysis in Trieste SECAP
Full text linkClimate change is affecting more and more local communities, which are now facing different hazards; in answer to this threat, specific actions at the local level should be taken. The Covenant of Mayors (CoM) is an initiative that tries to involve municipalities and communities in developing SECAPs, i.e., plans for sustainable energy and climate with the aim to develop adaptation and mitigation measures. In order to identify and evaluate hazards, the CoM developed a template relative to the current risk level and expected changes in the future. This paper develops a methodology to fill the template using a data driven approach instead of a heuristic one. The methodology was applied to the city of Trieste in northeast Italy and uses local weather station data and projections obtained from GCM-RCM models. Data were manipulated using different approaches for current risk levels and the Mann–Kendall test is proposed as a method to identify the future evolution of hazard intensity and frequency. The results showed that the developed approach could help municipalities in developing their SECAPs and in identifying the present and future evolution of hazards
Drivers of distance-decay in bryophyte assemblages at multiple spatial scales: Dispersal limitations or environmental control?
Full text linkQuestions: Despite the increasing scientific interest in distance decay of compositional similarity in ecology, the scale dependence of geographical versus environmental control on distance decay of biological communities has not been properly addressed so far. The present work highlights the relative importance of niche-based processes versus dispersal limitations on distance decay patterns of epilithic bryophyte assemblages at different spatial scales. Location: Serra de Sintra, central Portugal. Methods: We adopted a nested sampling design with 32 selected sampling sites in each of which two clusters, each with five rocks, were surveyed. Each cluster was characterized by a set of 15 macroscale variables, which were divided into environmental and anthropogenic. For each rock eight microscale variables were recorded. Partial Mantel tests were used to assess the relative importance of geographical and environmental distance on community dissimilarity for each grain size (site, cluster, rock). Quantile regressions were used to describe the decay patterns of community similarity with respect to geographical and environmental distances. Ordination analyses and variation partitioning techniques were applied to assess the pure and shared effects of measured variables on bryophyte community composition. Results: Environmental distance based upon macroscale predictors was significantly correlated to community similarity, while no significant correlation was found for ecological distance calculated for microscale predictors, except at the largest grain size. The decrease of community similarity with geographical and environmental distance was thus consistently strengthened with increasing sample grain. Compositional variation was best explained by anthropogenic variables. Conclusions: The relative importance of environmental versus geographical distance on compositional similarity in epilithic bryophyte communities varies with the spatial scale of the predictors and with the sample grain. The decrease of similarity with increasing distance is related to changes in habitat features, especially those driven by human disturbance, while it is weakly affected by variations in substrate features
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
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