1,720,966 research outputs found
The use of plant community attributes to detect habitat quality in coastal environments
Full text linkThe monitoring of biodiversity has mainly focused on the species level. However, researchers and land managers are making increasing use of complementary assessment tools that address higher levels of biological organization, i.e. communities, habitats and ecosystems. Recently, a variety of frameworks have been proposed for assessing the conservation status of communities or ecosystems. Among the various criteria proposed, all the protocols suggest considering (i) spatial aspects (range and area), and (ii) qualitative aspects of specific structures and functions. However, changes to ecological function are difficult to quantify and many protocols end up by using qualitative criteria. The aim of this work was to test the efficacy of some plant community attributes for the detection of vegetation quality in sand dune plant communities. We chose plant community attributes that either help to distinguish a habitat from others (diagnostic components) or play a significant role in habitat function and persistence over time. We used a diachronic approach by contrasting up-to-date vegetation data with data from previous studies carried out within the same areas. Changes in species composition were detected through detrended correspondence analyses (detrended correspondence analyses), Multi-Response Permutation Procedures and Indicator Species Analysis, while structural changes were analyzed by comparing species richness, total species cover, ecological groups of species and growth forms through null models. Ecological groups such as native focal species and aliens, and growth forms proved their efficacy in discriminating between habitat types and in describing their changes over time. The approach used in this study may provide an instrument for the assessment of plant community quality that can be applied to other coastal ecosystems
Assessing the effectiveness of the Natura 2000 Special Areas of Conservation strategy: the case of N-Adriatic sandy coastal ecosystem.
No full textCoastal sand dune landscapes hold habitats of high economic, social and ecological value on a global scale.
At the same time, they are among the most threatened ecosystems worldwide, facing escalating anthropogenic pressures, drawing attention to how to achieve trade-offs among society’s needs in land-use allocation and long-term biodiversity conservation. On the European scale, the most important conservation effort being so far implemented is the Natura 2000 Network (N2K) of protected sites.
According to Article 11 of the Habitats Directive, EU member states are asked to provide monitoring, management and impact assessment aiming at the maintenance of the natural habitats and species referred to in Article 2 with particular concern to priority habitat types and species.
To date, monitoring has primarily been tackled at wide scale, and a vast number of indicators are being established to provide bases for national and EU level biodiversity conservation assessment as well as for the implementation and evaluation of efficacy of the EC Biodiversity Strategy and Action Plans.
However, Article 6 also requires member states to take all the necessary measures to ensure a “favourable conservation status” (FCS) on individual N2K site level. As referred to in the Article 1, a sound assessment of FCS requires information on habitats’ structure and function, which reflect patterns and processes at local scale.
Therefore, the assessment of the conservation status of habitats’ structure and function necessarily claims for lower level, habitat-and site-based monitoring, as these variables are difficult to measure at coarser scales.
The study was undertaken on the North-Adriatic coastal landscape, which suffers from a severe and complex human utilization meanwhile holding high landscape, faunal and floral values.
As plant communities, because of their specific nature, are considered good indicators of overall biodiversity and of ecosystem integrity of coastal dune environments, effects of both human and natural disturbance have been analysed through a comparison between real and potential coastal vegetation.
To provide a comprehensive framework for sustainable coastal management and development, a multiscale method for the assessment of the conservation status of sandy coastal environment has been applied.
The assessing methodology focused first on floristic, vegetational and structural aspects of plant communities that were analyzed along the main environmental gradient, which develops moving inland from the sea edge.
At site level, analyses were carried out by means of structural and compositional indicators.
At a broader scale, that is, landscape level, we tried to apply some “Resource Use”
Indicators to characterise the pressures on coastal N2K sites.
Conservation status of N-Adriatic coastal zonation resulted fairly good at only few sites along the coast, mostly located where urban development and tourism are limited by legislation or simply because of the difficulty in reaching them.
Elsewhere, real vegetation is deeply different from the potential zonation erosion and tourism pressures truncate the first elements of the zonation, while towns and villages, coastal roads, pines plantations and agriculture truncate the last stages and sandy systems are trapped between erosion on the sea side and human settlements inlands, with no space for natural sediment dynamics and communities development
Actions for plant biodiversity improvement and recovery in lowland ancient woods and artificial forest stands
No full textItalian forest ecosystems, characterized by a long tradition of forestry and agro-pastoral practices that have guided their evolution, have ensured the preservation over time of significant aspects of naturalness to which important landscape,ecological (carbon stock) and recreational values are associated.
These functions have become increasingly important leading to the implementation of several reforestation projects. Nevertheless, the new forest stands, born on lands subject to agricultural use for a long time, evolve into ecologically sustainable ecosystems only in a very long time.
One of the main findings of this process is represented both by the structure of biological communities and their complexity, which remain greatly simplified for a long time.
In particular, nemoral herbaceous species, which represent the most valuable and ecologically significant component of a forest habitat, remain confined to the ―ancient forests‖. These species, closely habitat-specific and substantially unable to adapt to the environmental changes (Buffa and Villani in pubbl.; Eckert, 2002; Honnay et al., 1999), are in risk of local extinction due to the small size and isolation of their populations.
In order to preserve the venetian lowland ecotypes, some experiments were started in 2010 with the aim of producing some target species (Arum maculatum L., Allium ursinum L., Asparagus tenuifolius Lam., Carex remota L., Colchicum autumnale L., Mercurialis perennis L., Lamium orvala L., Leucojum vernum L., Loncomelos pyrenaicum (L.) Hrouda ex J. Holub s.l., Paris quadrifolia L., Ranunculus auricomus L., Viola reichenbachiana Jordan ex Boureau).
The peculiarities of the environment in which these species are adapted impose a continuous integration of autoecology knowledge with plant nursery techniques. Thus in situ (ancient forest) and ex situ (germination room and outdoors cultivation tunnel) germination tests were carried out to understand how soil variables (texture, pH, organic C, N, P), physical environment variables (quantity and quality of light radiation in the undergrowth) and microclimatic variables (soil T at 0 cm) allow to break dormancy, induce germination and promote seedlings recruitment.
The comparison of in situ and ex situ tests showed that for the majority of the species germinating output is significantly higher in natural conditions or artificial conditions that simulate more accurately the natural ones than in germination room.
Seeds of some species kept at 20 ° C in dry storage (eg. Leucojum vernum L., Mercurialis perennis L.) showed a reduction of viability even more than 80% in 6 months since the collection date, proving potential recalcitrance, and explaining the negative results for their germination tests.
The first results encourage further tests in order to implement the knowledge on the production of these species, which is desirable both in terms of biodiversity conservation, and for the reinforcement of existing populations or for the naturalization of artificial forests. A new frontier, finally, may be offered by their use in private gardens (for aesthetic and naturalistic reasons, in a sort of transposition of the bird-gardening practice within the conservation of nemoral species), with the activation of a production chain giving also employment benefits
Does flowering synchrony contribute to the sustainment of drygrassland biodiversity?
No full texttPhenological relationships among entomophilous species for pollination may play an important role instructuring natural plant communities.The main aim of this work was to test whether in dry grassland communities there is a non-randomflowering pattern and if the pattern influences the species richness, and the richness of subordinate andcommon species.Field sampling was carried out in temperate dry grasslands in NE Italy. Species composition and theflowering phenology were monitored in 45 2 m × 2 m plots randomly placed over dry grasslands.To quantify the degree to which insect-pollinated species overlap in their flowering time we developeda “co-flowering index” (CF-index). The significance of the observed flowering pattern was tested using anull model.A positive correlation was found between the synchronic flowering and the number of subordinatespecies. Subordinate species showed shorter flowering length than the common species and a mostlyspecialized pollination system.Our findings suggest that flowering synchrony might be a key characteristic which may contribute toshape dry grassland composition by favouring the long lasting maintenance of rare species populationswithin the community.The comprehension of such functional relationships between species of different trophic levels is ofgreat importance for the conservation of dry grasslands and the maintenance of the ecosystem servicesthat pollination provides
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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