1,721,154 research outputs found
Patterns of native and exotic species richness in the urban flora of Brussels: rejecting the 'rich get richer' model
No full textIn this study we analyzed patterns of native and exotic species richness in the urban flora of Brussels (Belgium) using a coarse-scale systematic sampling grid of 1 km(2). The observed correlation between native and exotic richness within the grid cells sampled was then compared to the results of an adequate null model assuming no species interactions. In addition, ordinary least-squares and quantile regressions were used to analyze the relationship between the ratio of exotics to natives and the proportion of densely built up areas in each cell. Though the results obtained conform to the Eltonian expectation that exotic species preferably invade areas of low native species diversity, traditional niche-filling mechanisms seems inadequate to explain the observed pattern. Rather, aliens simply tend to have different environmental requirements than natives
Are landscapes as crisp as we may think?
No full textGeographic information is traditionally represented by a one-entity–one-class method, assuming that each geographical entity in the map can be unambiguously assigned to a single thematic class. Also, thematic map classes are assumed to be exhaustive and mutually exclusive. By contrast, fuzzy classifications overcome the traditional limitations on the mutually exclusive nature of map classes assigning varying levels of class membership for individual map entities. The aim of this paper is to show that the substitution of fuzzy set theory for classical set theory is an essential improvement for representing geographic information using hierarchical classification schemes
Valutazione delle foreste europee attraverso il Li-BioDiv database all’interno della rete ICP Forest
No full textIl Li-BioDiv database (ICP Forests) che deriva dal progetto BioSoil-Biodiversity, rappresenta un database
multidimensionale riguardo alle foreste con dati provenienti da 19 paesi europei, investigati tra il 2005 e il
2008. Tale database contiene informazioni riguardo agli alberi vivi, legno morto e dati riguardo allo strato
erbaceo. Il progetto BioSoil-Biodiversity rappresenta l’unica iniziativa di monitoraggio standardizzato
multidimesionale della diversità forestale a livello europeo, tuttavia, il Li-BioDiv database risulta essere
sottoutilizzato dal mondo scientifico a causa di passate restrizioni di tipo amministrativo-politico e fino ad
oggi non sono state effettuate analisi esplorative profonde.
Pianificazioni ambientali e forestali efficienti richiedono una valutazione e una gestione attenta della
struttura e dell’incertezza legata a grandi moli di dati. Basandoci sui dati grezzi:
(i) abbiamo confrontato informazioni derivate dagli alberi vivi e dal legno morto, con i rispettivi dati
derivanti dagli inventari nazionali. Inoltre;
(ii) abbiamo cercato di caratterizzare l’incertezza relativa ai dati dello strato erbaceo;
(iii) abbiamo calcolato indici classici di diversità forestale e analizzato le loro relazioni e i loro trend spaziali
nei diversi tipi forestali e in diverse condizioni ambientali.
I risultati saranno utili per comprendere con maggiore accuratezza le stime della biodiversità forestale
europea, per interpretarle correttamente e per facilitare l’uso dei dati.Forest ecosystems are the most biodiverse and complex habitats. For this reason, it is very important to
monitor them specifically. The importance of forest monitoring is recognized from several years, and the
most extensive and complete data on the European forest status are given by National Forest Inventories
(NFIs). This information concerns trees but usually it marginally considers other ecosystem components such
as ground vegetation.
The LI-BioDiv (ICP Forests) database, derived from the BioSoil-Biodiversity project, is a multi-dimensional forest
database that contains records collected in 19 European countries in the period 2005-2008. The database includes
information on living trees, deadwood and a ground vegetation survey. The BioSoil-Biodiversity project represents
an unique pan-European effort for a standardized multi-dimensional forest diversity monitoring survey, however
the LI-BioDiv database is still under-utilized by scientists due to policy restrictions and no depth exploratory
analysis of the dataset was carried out until now.
Efficient environmental and forest planning require careful assessment and management of big data
structure and uncertainty. On the basis of row data:
(i) we compared information of standing living trees and deadwood with results of NFIs. Furthermore;
(ii) we characterized uncertainty related on ground vegetation data;
(iii) we calculated several forest biodiversity indicators analyzing therefore their inter-relationship and
their trend over the space and over different forest types and environmental conditions.
The results will be useful for achieving satisfactory accuracy of European forest biodiversity estimates, for
correctly interpretating the estimates, and for facilitating comparable use of the data
Invasiveness of alien plants in Brussels is related to their phylogenetic similarity to native species
No full textAim Understanding the processes that drive invasion success of alien species has received considerable attention in current ecological research. From an evolutionary point of view, many studies have shown that the phylogenetic similarity between the invader species and the members of the native community may be an important aspect of invasiveness. In this study, using a coarse-scale systematic sampling grid of 1 km2, we explore whether the occupancy frequency of two groups of alien species, archaeophytes and neophytes, in the urban angiosperm flora of Brussels is influenced by their phylogenetic relatedness to native species. Location The city of Brussels (Belgium). Methods We used ordinary least-squares regressions and quantile regressions for analysing the relationship between the occupancy frequency of alien species in the sampled grid and their phylogenetic distance to the native species pool. Results Alien species with high occupancy frequency in the sampled grid are, on average, more phylogenetically related to native species than are less frequent aliens, although this relationship is significant only for archaeophytes. In addition, as shown by the quantile regressions, the relationship between phylogenetic relatedness to the native flora and occupancy frequency is much stronger for the most frequent aliens than for rare aliens. Main conclusions Our data suggest that it is unlikely that species with very low phylogenetic relatedness to natives will become successful invaders with very high distribution in the area studied. To the contrary, under future climate warming scenarios, present-day urban aliens of high occupancy frequency are likely to become successful invaders even outside urban areas
Spatially-based accuracy assessment of forestation prediction in a complex Mediterranean landscape
No full textChanges in land use and land cover can lead to irreversible changes in forests that result in overall reductions in biodiversity and loss of elements of high ecological and cultural value. Land use and cover change models can be an important resource for scientists to develop a sustainable land management program. This paper presents a method to assess the accuracy of a forestation predictive model built through GEOMOD. This model was applied to simulate the pattern of land-use change forward in time from 1933 to 2000, in a Mediterranean area, using topographic parameters as predictive variables. In Mediterranean areas, modeling landscape transformation by stressing the relationship between environmental variables and historical anthropogenic transformation, is crucial for many conservation and management practices. In order to analyze the goodness-of-fit of simulation, a cross-classification map was realized by overlaying the map produced by the simulation model and a reference map (CLC 2000). Then, a statistical validation procedure was carried out based on the kappa index of agreement. Results showed that: i) the study area has undergone great changes in the last decades with a marked increase in forest surface, and ii) GEOMOD represents a powerful model tool for land-use change prediction, but it is necessary to properly calibrate and validate the model in order to avoid misleading results
Landscape complexity and spatial scale influence the relationship between remotely sensed spectral diversity and survey-based plant species richness
No full textQuestions: Species rarefaction curves have long been used for estimating the expected number of species as a function of sampling effort. Nonetheless, sampling species based on standard plant inventories represents an effort-intensive approach. Hence, rarefaction based on remotely sensed information can provide a rapid tool for identifying regions with exceptional richness and turnover. The aim of this paper is to examine (i) if the rates of spectral and species accumulation are positively correlated with one another at different spatial scales, and (ii) if the strength of this correlation differs between regions of varying landscape complexity. Location: Switzerland, Europe. Methods: The plant species data were derived from the Swiss "Biodiversity Monitoring" programme. Seven Landsat ETM+ images covering the whole study area were acquired. We applied species and spectral rarefaction for five biogeographical areas ranging from flat to mountainous zones. The relative increments (rates) of the species and spectral rarefaction curves were compared using Pearson correlation together with locally weighted scatterplot smoothing (LOWESS). Results: The biogeographic regions differed from one another in both their spectral and species diversity. The relationship between spectrally- and species-derived rates of accumulation was non-significant in simple landscapes, but we observed a significant positive correlation in complex landscapes over fine-to-intermediate spatial scales. Conclusions: Spectral rarefaction represents a powerful tool for measuring landscape diversity and potentially predicting species diversity at regional to global spatial scales. Based on remotely sensed information, more efficient diversity-based monitoring programmes can be developed
Plant spectral diversity from high-resolution multispectral imagery detects functional diversity patterns in coastal dune communities
No full textThe .zip file contains all datasets necessary to replicate the analyses found in the paper titled "Plant spectral diversity from high-resolution multispectral imagery detects functional diversity patterns in coastal dune communities".(DOI 10.1111/jvs.13239)Authors: Eleonora Beccari, Carlos Pérez Carmona, Enrico Tordoni, Francesco Petruzzellis, Davide Martinucci, Giulia Casagrande, Nicola Pavanetto, Duccio Rocchini, Marco D'Antraccoli, Daniela Ciccarelli & Giovanni BacaroAnalyses are described in the main text of the paper. Further details regarding the spectral and functional samplings can be found in Appendix S1 available on the journal website.</p
A virtual species set for robust and reproducible Species Distribution Modelling tests
Full text linkPredicting species potential and future distribution has become a relevant tool in biodiversity monitoring and conservation. In this data article we present the suitability map of a virtual species generated based on two bioclimatic variables, and a dataset containing more than 700.000 random observations at the extent of Europe. The dataset includes spatial attributes such as, distance to roads, protected areas, country codes, and the habitat suitability of two spatially clustered species (grassland and forest species) and a wide spread species
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
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