Gabriella Buffa

The response of plant community diversity to alien invasion: evidence from a sand dune time series

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.

Are the ancient forests of the Eastern Po Plain large enough for a long term conservation of herbaceous nemoral species

Abstract We analysed the effects of patch configuration and site history on vascular plants in ancient forests of the Eastern Po Plain, documented back to 1740. Despite their reduced size, all the forests are part of Natura 2000 Network and significantly contribute to the maintenance of a threatened habitat and support biological diversity of the Continental biogeographic region. The presence of some functional ecological plant species groups was correlated with patch configuration and age. Habitat quality, in terms of suitability for forest species, was found to be important in explaining the presence of species of high conservation value, but patch age (as an indicator for habitat quality) played a major role too. For core forest species, patch area is a redundant variable in explaining species richness relative to habitat quality and patch age and the extinction of specialists seems to occur mainly in a deterministic way. Even small forest fragments can be very important for maintaining plant species diversity, at least if they are of high habitat quality and if the forest management is appropriate. However, to achieve a long term conservation, management plans should also aim at an improvement of the anthropogenic matrix surrounding forest remnants.

Correlations among biodiversity, biomass and other plant community parameters using the phytosociological approach: A case study from the south-eastern Alps

Abstract The present study deals with the grassland complex of communities which may be found on the limestones in the south-eastern Alps; these communities show in fact a particular interest for their high biodiversity degree and for their importance for the traditional land-use economy of the south-European mountain regions. Phytosociological relevés corresponding to well-defined plant associations have been used in order to get information on the relationships among plant species diversity, biomass, chorotypes, pollination types, functional strategies and soil characteristics. The analysis was carried out both along an altitudinal and a soil evolution gradient. The analysis of the correlations among the variables and the application of the principal component analysis shows a positive correlation between soil parameters and biomass, eurichory, anemogamy and C- and R-strategies; on the contrary, a negative correlation among stenochory, entomogamy and S-strategy with the soil evolution seems to be present. This article shows how the phytosociological approach can be used to get information and knowledge on the correlations between several variables useful to understand the complex nature of the plant communities in order to support management plans.

Phytocoenotic originality of the N-Adriatic coastal sand dunes (Northern Italy) in the European context: The Stipa veneta-rich communities

Abstract The particular habitat of Stipa veneta, a priority species of the European Community Directive 92/43, is here described. The phytosociological analysis led to the description of a new association (Teucrio capitati-Chrysopogonetum grylli), endemic of the N-Adriatic fixed sand dunes. Given the high importance of the species, the conservation of its specific community should be included in a broad protection plan of this unique coastal system in the European context.

The use of plant community attributes to detect habitat quality in coastal environments

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.

Effects of disturbance on sandy coastal ecosystems of N-Adriatic coasts (Italy)

All coastal European Countries, and particularly those of the Mediterranean Basin (Curr et al., 2000; European Environment Agency [EEA], 1999), suffer from the loss and degradation of sand dune landscape which are leading to a dramatic biodiversity loss, caused by the alteration and disappearance of many habitats and the rarefaction and/or local extinction of the most typical and extremely specialized native species, sometimes replaced with alien species.

Distribution map of Ambrosia artemisiifolia L. (Asteraceae) in Italy

Abstract The spread of the invasive and allergenic Ambrosia artemisiifolia L. in Italy was analysed and mapped using distribution data from a wide range of sources. Ambrosia artemisiifolia occupies 1057 floristic quadrants which are mostly distributed in the Po plain. The distribution obtained represents the basis to implement urgent management strategies.

Habitat conservation in Italy: the state of the art in the light of the first European Red List of Terrestrial and Freshwater Habitats

The importance of taking into account ecosystems, plant communities and habitats for the development of biodiversity conservation strategies is increasingly acknowledged. Recently, the first ever European Red List of Habitats was produced, which provided an evaluation of the extinction risk of EUNIS-based natural and semi-natural habitats in Europe. As assessment unit, it used the habitat intended as a plant community, thus representing a landmark for the role of vegetation science in nature conservation. In the present paper, the results of the European Red List of Habitats are analyzed at the national scale with specific reference to the terrestrial and freshwater habitat types occurring in Italy. More than three-quarters of the assessed European habitat types were recognized for the Italian territory. The distribution of the threat categories reflects approximately the situation at the EU28 level. About 35% of the assessed habitat types are referred to a threat category; no critically endangered habitat is present in Italy. The most frequently used criteria are those related to a reduction in quantity. Some critical issues arising from the analyses are discussed. In particular, the presence of knowledge gaps is pointed out, with remarkable reference to the poor availability of spatial and quantitative data, severely affecting the application of the criteria adopted for the assessment. Descriptions of habitat types from Italy are reported, some of which are representative, emblematic or even exclusive to the Italian territory. The outcomes of the analysis represent the starting point for the future development of a national-scale Red List of Habitats. Results also emphasized how habitat types with a too broad definition pose a limit to a proper evaluation of the regional biogeographic variability, often very high in Italy, with local floristic and phytocoenotic peculiarities which do not find room in the adopted European typology. This is the reason why the development of national subtypes stands as a necessary step for the development of a realistic and effective assessment at the national scale.

Biogeographic variability of coastal perennial grasslands at the European scale

Question: Coastal environments have often been described as azonal. While this characteristic is clear for the foredune system, it seems less evident for more inland fixed dunes, which host habitats of major conservation concern, whose features seem to be more related to local climatic conditions. We hypothesized that, unlike other coastal habitats, dune perennial grasslands differ floristically and structurally across their European range and that patterns of variation are linked to the corresponding climate. Location: European coasts (Atlantic Ocean, Baltic, Mediterranean, Black Sea). Methods: We used a large data set of phytosociological releves, representative of coastal grasslands throughout their European range. The role of climatic variables (temperature, precipitation and continentality) in determining the variability in species composition and vegetation structure (by means of life forms) was investigated through CCA, DCA and GLM. The degree of concentration of species occurrences within groups was calculated through the Phi coefficient. Results: Through multivariate analyses we identified seven major types of coastal grassland, corresponding to different geographic areas. The groups significantly differed in their climatic envelope, as well as in their species composition and community structure. Conclusion: Our results confirm the hypothesis that coastal dune perennial grasslands are subjected to local climate, which exerts significant effects on both floristic composition and community structure. As a consequence, coastal grasslands are particularly prone to the effect of possible climate change, which may alter species composition and distribution, and lead to shifts in the distribution of native plant communities.

Carex ferruginea grasslands in the south-eastern Alps

ABSTRACT A phytosociological study carried out in the south-eastern Alps led to the description of the association Hormino pyrenaici-Caricetum ferrugineae. Its distribution area covers the Dolomites and the Carnic Alps. The association belongs to the alliance Caricion ferrugineae, order Seslerietalia caeruleae, class Elyno-Seslerietea and vicariates the northern Alpine Caricetum ferrugineae and the Illyrian Hyperico alpini-Caricetum ferrugineae. Based on floristic and ecological analyses, four subassociations can be recognised: typicum, willemetetosum stipitatae, valerianetosum montanae and ericetosum carneae. Data on the ecology and dynamical and catenal relations are provided.