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Aim Urbanization as a major global trend profoundly changes biodiversity patterns, and homogenization of urban biotas due to expanding exotic species and declining native species is of increasing concern. Previous studies on this topic have mostly taken place at large scales that include high habitat heterogeneity. Here, we aimed at disentangling the effects of urbanization and plant invasion on species composition through the analysis of similarity patterns of urban plant assemblages at the community scale where species interact. \ud Location Berlin, Germany\ud Methods We analyzed how different levels of urbanization, specific components of the urban matrix and the dominance of a native (Betula pendula) versus an exotic tree species (Robinia pseudoacacia) affect alpha and beta diversity of urban woodland understory vegetation in 68 100-m² plots.\ud Results Exotic dominance reduced alpha diversity but not beta diversity of the total species pool. Comparing beta diversity among different species groups revealed significant but divergent effects of exotic dominance, habitat connectivity and levels of urbanization in native and nonnative species assemblages. In particular, urbanity proved to homogenize the native species pool, whereas the beta diversity of the nonnative species pool showed a more pronounced response to exotic dominance.\ud Main conclusions Our data provide evidence that both the urban context and the dominance of exotic species can modify homogenization processes at the community level. These novel insights into the mechanisms of biotic homogenization of urban floras may contribute to mitigating the effects of urbanization on biodiversity

On 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. We highlight the potential contribution of the forestry sector to promote the implementation of this regulation. There is a wealth of experience on positive and negative responses of invasive alien species to forestry interventions. 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

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Agro-pastoral decline in European mountain areas has recently caused changes to traditional landscapes with negative consequences on semi-natural grassland conservation and the associated biodiversity and ecosystem services. In the Italian Alps, grassland patches enclosed in a forest matrix are progressively disappearing. Two alpine valleys (Pesio and Pejo), having similar land-use history, were chosen as representative of management conditions of western and eastern Italian Alps, respectively. This study aims at interpreting the effect of abandonment on grassland patch plant diversity, considering land cover changes of the last 60 years, and assessing the role of ecological, topographic, management and landscape configuration on current grassland species richness. The total area of grassland patches has declined by 54% and 91% at Pesio and at Pejo, respectively. Actual grassland patch species richness was mostly influenced by ecological factors, such as quantity of light, soil moisture and reaction, then by topographic features, especially slope, and finally by management intensity. Landscape factors exerted a slightly significant effect on plant diversity. In the two valleys, differences on management practices were detected. Even though in the western valley the conservation of several grazing activities contributed to slow down the process of patch reduction, many species-rich grasslands were generally under-grazed. Conversely, in the eastern valley, despite a denser road network, the stronger decline of grassland patch extension was linked to the hay making decline. At the same time, overuse of grassland patches near farms reduced plant species richness. As a conclusion, plant species richness was weakly related to the area of grassland patches and current and historical landscape configuration were of relatively lower importance than ecological, topographic and management factors, when evaluated at patch-level.

The maggenghi are mid slope meadows typical of all the southern and of great parts of the northern European Alps, for centuries managed with traditional and low intensity techniques. Usually, they are scattered patches in surrounding forests. The spontaneous expansion of trees and shrubs, favored by the recent decline of mountain agriculture, lead the maggengo patches patterns and shapes to change. Our objective was to analyze the effect of this change on current plant diversity of the remnant patches, as the adaptive response could be slow and possibly related more to historical than to current landscape patterns. We analyzed the trend of the size, shape, elongation, fractal dimension and connectivity of maggengo patches of a Central-Eastern Italian Alpine district, in four time steps, from 1973 to 2006, and in 1859, when mountain agriculture was still widespread. Then, we studied the relationships between those landscape metrics and two current patch-level plant diversity measures: interior species richness and species density. Aerial photographs were used to investigate that trend, while a historical cadastral map was used to assess the landscape metrics in 1859. As expected, in the last 30 years, the total size of maggenghi has been reduced by 57% while their shapes have been progressively simplified. Interior species richness was positively related to size, both in 2006 and over the past 30 years, but not to any 1859 measures. Conversely, species density was positively correlated only with 1859 size, shape index and connectivity. We conclude that the historical shape, size and connectivity are some of the key variables affecting the plant species density of maggengo patches, but not of their interior plant species richness

Improvements in the management of Natura 2000 sites are essential to achieve the targets set out by the Habitats and Birds Directives of the European Union. A current focus is on the development of management plans, which are fundamental instruments in the implementation of conservation measures. This study explores the viability of using existing forest plans to assist in this purpose. As case study, we consider the regulatory framework of the Veneto Region, northern Italy. We collected quantitative and qualitative data on forest plans at the regional and at three sub-regional spatial scales: local, district, and biogeographical. Forest plans cover about 54% of the terrestrial area of Natura 2000 sites in Veneto, and 75% of Sites of Community Importance in the Alpine biogeographical region. At the local scale of analysis, metrics from forest plans represent a valuable historical record which can be used to interpret the current state and future trends, especially for forests with long management records. These data can be used to assess biodiversity indicators for the monitoring of Natura 2000 forest and non-forest habitats, in compliance with Article 17 of the Habitats Directive. Moreover, the heterogeneous stand conditions which are promoted by some forest management approaches can improve the conservation efforts for some habitats and species. The scale of local forest plans are typically the most appropriate for implementing habitat management strategies. From this study, we conclude that management authorities should take advantage of the wide spatial coverage and distribution of existing forest plans, especially in mountain areas inside and outside the Natura 2000 network, for the successful conservation of European Union habitats and species

The woody component along field edges often provides the only permanent elements of structural and biological diversity in landscapes that have lost much of their naturalness to agriculture and urban use. The main aims of this study were (i) to investigate how four hedge stand types, i.e., systems of management distinguished on the basis of the natural and managed growth forms of trees and shrubs (low single-storied, high single-storied, two-storied and multi-storied), differ in their biometric parameters and (ii) to identify the primary management-related determinants of native woody species richness. The study used a large dataset of hedgerows (n=538) sampled in seven sites in Northern Italy. The four hedge stand types exhibited highly significant differences in size and biometric parameters. The multi-storied hedges, associated with the highest stand structural diversity index values, supported the highest number of tree species, followed by high single-storied hedges. The low single-storied hedge stand type contained the lowest number of species. We found a positive effect of hedge area as well as a marginal negative effect of basal area on native woody species richness. The management implications addressed by our study include conversion of single-storied into two- or multi-storied types, increasing hedge size and controlling hedge stand basal area