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Exploring the multiple effects of the invasive alien black locust tree
Full text linkBlack locust (Robinia pseudoacacia L.) is one of the most widespread invasive alien tree species in Europe and throughout the world. Its spread has been favoured by its ecological attitudes and economic relevance, with positive and negative implications. The aim of this thesis was to further develop knowledge on the black locust’s ecological and socio-economic drivers. A stand, landscape and national scale were considered. At the stand scale, ecological impacts on the plant community were assessed through a comparative approach, based on a sample of pairs of woodlands, invaded or non-invaded by black locust. A focus on a sample of three types of landscape (rural, riverine and urban) allowed black locust impacts to be compared across different environmental contexts. A second focus on a sample of three European cities (Berlin, Padova and Roma) allowed the impacts of both black locust dominance and urban matrix properties to be investigated across urban environments at different latitudes. Socio-economic drivers were investigated at a national scale in Italy, linking these factors with changes in both land cover and black locust distribution. Knowledge on the drivers of black locust spread and its effects on natural resources is deepened, offering insights into a desirable trade-off between biodiversity conservation and black locust socio-economic significance at multiple scales and contexts.La robinia (Robinia pseudoacacia L.) è una delle specie arboree aliene invasive più diffuse in Europa e nel mondo. La diffusione di questa specie è stata favorita dalla sua amplitudine ecologica e dai suoi diversificati interessi economici, determinandone conseguenze positive e negative. Lo scopo della tesi è di approfondire le conoscenze sui fattori ecologici ed economici che hanno causato e caratterizzano la sua distribuzione. Sono state prese in considerazione diverse scale di studio, una scala di popolamento, una di paesaggio e una nazionale. A scala di popolamento, sono stati valutati gli impatti ecologici sulla comunità vegetale seguendo un metodo comparativo, basato su un campione di coppie di boschi, invasi o meno dalla robinia. È stato condotto un confronto degli impatti di robinia in diversi contesti ambientali mediante un approfondimento su un campione di tre tipi di paesaggio (rurale, fluviale e urbano). Un secondo approfondimento su un campione di tre città europee (Berlino, Padova e Roma) ha permesso invece di indagare gli impatti della copertura di robinia e delle proprietà della matrice urbana in contesti urbani a latitudini molto diverse. I fattori socio-economici sono stati indagati al livello nazionale italiano, collegandoli con i cambiamenti della copertura del suolo e della distribuzione della robinia. Le conoscenze sulle cause della diffusione della robinia e dei suoi effetti sulle risorse naturali vengono approfondite offrendo spunti di riflessione su un auspicabile bilanciamento tra conservazione della biodiversità e valorizzazione socio-economica di questa specie, a molteplici scale e contesti
Population dynamics of the endangered shrub Myricaria germanica in a regulated Alpine river is influenced by active channel width and distance to check dams
No full textDespite its high conservation and indicator value, there is a lack of information on the long-term dynamics of Myricaria germanica (L.) Desv. (German tamarisk), and of factors affecting its population density and viability. Here we studied the dynamics of adult and juvenile M. germanica at 19 sites during a seven year period (2009-2015) along a 30 km long stretch of an Italian Eastern Alpine river, by assessing a set of anthropogenic and geomorphological factors. Adult (239-571 individuals) and juvenile (62-292 individuals) population numbers showed no significant difference between years, and a remarkably uneven distribution among sites. Yet, several remnant populations have declined or disappeared in recent years and a few populations have increased. We found a positive effect of the width of the active channel on adult and juveniles plants. This means that anthropogenic river narrowing is a leading cause of the decline of the species along river banks. For juveniles, abundance also decreased with distance from downstream check dams. We conclude that in the regulated river studied, the conservation of M. germanica appears to be possible not only as a result of natural flow dynamics, but also at an artificial sediment storage area with a semi-natural river dynamic that maintains favourable riverine habitats. Our results are useful in a decision-making framework for the conservation of M. germanica, for river restoration and for flood protection in alpine valleys
Relationships between native and alien vascular flora and landscape complexity in the province of Padova (North Italy)
No full textLandscape complexity is the basis of species diversity at regional scale. The arrangement of ecosystems in a landscape mosaic in space and time changes as a result of human pressure. This landscape mosaic may either be simplified or complicated by urbanization. Therefore, human pressure has a multi-faceted influence on richness and composition of vascular species. In this study, we investigated the relationships between landscape complexity and native and alien vascular flora in the entire province of Padova, North Italy (2,144 km2), over an atlas map composed by 81 squares of 25 km2.
The data, presence or absence of vascular species in each square, have been collected over several years, through excursions conducted by experienced botanists and have been recently stored in a geospatial vector database. Landscape complexity was calculated with the Shannon diversity index, using the proportion of the first level Corine Land Cover types. Each square was partitioned into subsets of landscape types identified through a hierarchical agglomerative clustering with Corine Land Cover proportions. Then, we performed an IndVal analysis to assess the degree of association of each species to each subset.
We used the LecoS plugin for the QGIS geographical information system to calculate the landscape metrics and the R software for the statistical analyses.
The alien flora showed a pattern of distribution similar to the native flora. As expected, the species richness in the hilly semi-natural areas was higher than in the agricultural-based urban plain. In the plain, species richness increased with increasing cover of artificial surfaces and decreased with increasing cover of agricultural areas. Landscape complexity has proven to be a good predictor of changes in the species richness. About fifty species were associated to some of these landscape types.
The occurrence of some species at local scale was a reliable indicator of larger scale landscape patterns. The variety of ecological attitudes of the alien species was one of the reasons for their widespread distribution regardless the landscape type. Landscape complexity was an additional determinant factor, which did not discriminate between native and alien species. We conclude that in the province of Padova distributional data of plants obtained from flora atlases at good resolutions help the identification of landscape emergent properties
Forest management and planning as an opportunity to control invasive alien tree species in Europe
No full textOn 1 January 2015 a new European regulation on invasive alien species entered in force. Key aspects of this regulation are the adoption of a list of invasive alien species which are of European Union concern, the requirement for specific prevention measures, the establishment of early detection and fast eradication measures, and the management of the widely spread invasive alien species. There are 73 invasive alien tree species in Europe, of which 28 have been used in forestry. An analysis of the most worrying alien species from the main European databases, DAISIE (www.europe-aliens.org) and EPPO (www.eppo.int), indicates that 4 tree species (Acacia dealbata, Ailanthus altissima, Prunus serotina, and Robinia pseudoacacia) are of particular concern. These species have detrimental effects on biodiversity and ecological processes. By taking appropriate measures, the forestry sector has the opportunity to become a major player in curbing future alien tree invasions. To support this idea, we performed a review of scientific literature on silvicultural measures aimed at reducing the spread of four main invasive alien tree species in Europe. This analysis highlighted the potential contribution of the forestry sector to promote the implementation of the European regulation; in fact prevention is one of the most important possible interventions foreseen by this new regulation, particularly given the role of the forestry sector as a potential introduction pathway. There is a wealth of experience on positive and negative responses of invasive alien species to forestry interventions. Indeed, several recent conservation projects aim at restoring habitats invaded by invasive alien trees of particular concern. This knowledge should be synthesized and further developed to help prevent and manage invasions in forests and adjacent habitats and to minimize the risks of invasive alien species. We thus recommend that decisions regarding the application of the regulation will include actors responsible for, or involved in, the management and use of forests and related semi-natural habitats in Natura 2000 sites and other protected areas
Boschi e siepi rurali planiziali: riflessioni alla luce della pianificazione regionale e della rete Natura 2000
No full textExploring the multiple effects of the invasive alien robinia tree: a PhD project presentation
Full text linkThe poster explains the background, research questions and objectives and methods of the PhD study on black locust (Robinia pseudoacacia) funded by the Linda Scattolin J:ROBIN project (2016-2019)
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
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