This study examines the process of invasion of coastal dunes in north-eastern Italy along a 60-year time series considering alien attributes (origin, residence time, invasive status, and growth form strategy) and habitat properties (species richness, diversity and evenness, proportion of aliens, and proportion of focal species). Vegetation changes through time were investigated in four sandy coastal habitats, using a fine-scale diachronic approach that compared vegetation data collected by use of the same procedure, in four time periods, from the 1950s to 2011. Our analysis revealed an overall significant decline of species richness over the last six decades. Further, both the average number of species per plot and the mean focal species proportion were proved to be negatively affected by the increasing proportion of alien species at plot level. The severity of the impact, however, was found to be determined by a combination of species attributes, habitat properties, and human disturbance suggesting that alien species should be referred to as ''passengers'' and not as ''drivers'' of ecosystem change. Passenger alien species are those which take advantage of disturbances or other changes to which they are adapted but that lead to a decline in native biodiversity. Their spread is facilitated by widespread anthropogenic environmental alterations, which create new, suitable habitats, and ensure human-assisted dispersal, reducing the distinctiveness of plant communities and inducing a process of biotic homogenization.

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Italy is among the European countries with the greatest plant diversity due to both a great environmental heterogeneity and a long history of man-environment interactions. Trait-based approaches to ecological studies have developed greatly over recent decades worldwide, although several issues concerning the relationships between plant functional traits and the environment still lack sufficient empirical evaluation. In order to draw insights on the association between plant functional traits and direct and indirect human and natural pressures on the environmental drivers, here we summarize the existing knowledge on this topic by reviewing the results of studies performed in Italy adopting a functional trait approach on vascular plants, briophytes and lichens. Although we recorded trait measurements for 1418 taxa, our review highlighted some major gaps in plant traits knowledge: Mediterranean ecosystems are poorly represented; traits related to belowground organs are still overlooked; traits measurements for bryophytes and lichens are lacking. Finally, intraspecific variation has been little studied at community level so far. We conclude highlighting the need of approaches evaluating trait-environment relationship at large spatial and temporal scales and the need of a more effective contribution to online databases to tie more firmly Italian researchers to international scientific networks on plant traits.

Questions: In animal-mediated pollination, pollinators can be regarded as a limiting resource for which entomophilous plant species might interact to assure pollination, an event pivotal for their reproduction and population maintenance. At community level, spatially aggregated co-flowering species can thus be expected to exhibit suitable suites of traits to avoid competition and ensure pollination. We explored the problem by answering the following questions: (i) are co-flowering species specialized on different guilds of pollinators? (ii) do co-flowering pollinator-sharing species segregate spatially? (iii) do co-flowering pollinator-sharing species that diverge in anther position spatially aggregate more than those that converge in anther position? Study site: Euganean Hills (NE Italy).Methods: Plant composition, flowering phenology and interactions between each entomophilous plant species and pollinating insects were monitored every fifteen days in 40 permanent plots placed in an area of 16 ha. We quantified the degree of flowering synchrony, pollinator-sharing and spatial aggregation between each pair of entomophilous species. We then tested the relationship between the degree of co-flowering, pollinator-sharing and spatial aggregation, and between spatial aggregation and anther position.Results: Entomophilous species converged, at least partially in flowering time, and the phenological synchronization of flowering was significantly associated with the sharing of pollinator guilds. Coflowering pollinator-sharing species segregated spatially. Furthermore, co-flowering pollinatorsharing species that diverged in anther position aggregated more than those that converged in anther position. Conclusions:Reproductive traits that facilitate the coexistence of co-flowering species include specialization on different pollinator guilds and a phenological displacement of the flowering time.Furthermore, in circumstances of increased competition due to phenological synchronization, pollinator sharing and spatial aggregation, the chance of an effective pollination might depend on differences in anther position, resulting in a divergent pollen placement on pollinators' body. One of the most interesting results we obtained is that the presence of one mechanism does not preclude the operation of others and each plant species can simultaneously exhibit different strategies. Although Accepted ArticleThis article is protected by copyright. All rights reserved. more studies are needed, our results can provide additional information about plant-plant interactions and add new insights into mechanisms allowing the coexistence of a high number of plant species into local communities.

Several factors have been taken into account to explain the distribution of orchid species. We explored the extent to which plant community attributes affect the abundance and reproductive fitness of three orchid species (Anacamptis morio, Himantoglossum adriaticum and Ophrys sphegodes), native to dry grasslands. Structural attributes of plant community (e.g. cover and height) were assessed in ninety 4 m2 plots scattered on three hill massifs of the Veneto Region (NE Italy). For the three target orchid species, the height of the flowering stalk, the relative ramet height and the number of flowers and fruits were recorded in 203 tagged ramets. Generalized Linear Model revealed that plant community attributes such as cover and height of the herb layer exert a negative effect on the abundance of orchid populations. Furthermore, regression models indicated that O. sphegodes and H. adriaticum reproductive fitness, determined as fruit/flower ratio, was positively affected by relative ramet height. Our results revealed that local herbaceous vegetation structure influences the cover and fruit set of target orchid species. However, there can be substantial variation in the response of different species and variation in the structural attributes of surrounding vegetation may be associated with differences in the strength of selection. In order to achieve effective results in orchid species conservation, protocols for the in situ conservation must detail the range of vegetation covers and heights at which orchid species are favoured and can produce the most effective inflorescences

Coastal sandy ecosystems are increasingly being threatened by human pressure, causing loss of biodiversity and habitat degradation. Using phytosociological relevés we conducted a re-visitation study in order to analyse changes in floristic composition during the last twenty years along the central Adriatic coast. We observed a significant increase in cover of fore dune and thermophilic species. Even though human activities are major driving forces of change in coastal dune vegetation, the species' cover increase may also be due to a moderate increment in average yearly temperature over the last two decades.

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To detect changes in coastal ecosystems, we evaluated the variation over time in some vegetation features, such as species composition and structure (species richness, cover, growth forms). We found that ecological groups of species such as native focal species (species that provide essential ecological functions) and aliens (species that spread outside their natural distribution), and growth forms proved their efficacy in discriminating between habitat types and in describing their changes over time. The approach used in the current study may provide an instrument for the assessment of plant community quality that can be applied to other coastal ecosystems.