Alicia Teresa Rosario Acosta

Morphological analysis of herbaceous communities under different grazing regimes

A methodology for the morphological analysis of herbaceous communities is presented, together with an exam- ple of its application in montane grasslands in the province of C6rdoba (Argentina) subject to grazing and burning. The method, based on multivariate ordination and classifi- cation techniques, enabled the detection of morphological changes at three levels in response to disturbance: (a) charac- terization of the spatial structure of the vegetation; (b) identi- fication of morphological plant groups; and (c) quantification of morphological shifts among different individuals of a single species. The architecture of the vegetation changed toward a pro- gressive miniaturization of photosynthetic structures and con- centration of biomass close to the ground, as disturbance intensity increased. Six morphological plant groups (modes of response) showing different behaviour in relation to competi- tion for light and pressure from large herbivores were identi- fied. Some species, highly preferred by ungulate grazers, showed high morphological variability among morphs grow- ing in different grazing situations, whereas some others were morphologically uniform.

Are there habitats that contribute best to plant species diversity in coastal dunes

The following paper describes patterns of diversity across major habitat types in a relatively well preserved coastal dune system in central Italy. The research addresses the following questions: (a) whether different habitats defined on the base of a land cover map support similar levels of biodiversity in terms of vascular flora richness and number of rare and endangered species, and (b) how each habitat contributes to the total species diversity of the coastal environment. A random stratified sampling approach based on a detailed land cover map was applied to construct rarefaction curves for each habitat type and to estimate total species richness. In addition, the number of exclusive, rare and endangered species was calculated for each habitat type. Results highlight the importance of the coastal dune zonation (embryo-dune, main dune, transition and stabilized dune) in species conservation because they harbour progressively higher species richness. However, differences among these habitats were not significant, so no particular species rich “hotspots” could be evidenced. On the contrary, rarefaction curves show that the upper beach (strand) habitat sustains significantly smaller number of species, but surprisingly, it shows the highest rarity values and highest proportion of endangered species. Therefore, for the establishment of successful biodiversity conservation programs in these coastal environments, it is imperative not only to conserve biologically rich hotspots but also to include species poor habitats containing endangered or unique elements. Thus, the complete coastal vegetation mosaic including all coastal habitats is important to adequately characterize the plant species diversity of coastal dune ecosystems.

Community structure in montane grasslands of central Argentina in relation to land use

. We compared the responses of natural montane grasslands in central Argentina to two land-use patterns: cultivation - high intensity, low frequency, and short history of disturbance - and livestock raising - low intensity, high frequency and long history of disturbance. We analysed species composition, richness, and architectural traits in seven neighbouring sites under different land use. There were sharp floristic discontinuities between post-agricultural stages, whereas only minor shifts occurred among different grazing situations. Unlike cultivation, grazing did not produce significant differences in species richness and allowed very slight invasion by exotics. In post-cultivation situations, architectural differences were accounted for by species composition. In the case of different grazing intensities, they were mainly explained by morphological differences among populations of the same dominants. In view of the historical information and current ideas, we suggest that the differential responses to both land uses can be explained not only by the different frequencies and intensities of disturbance they represent, but also by their contrasting histories in the area. Accordingly, herbivory by ungulates should not be considered as a disturbance in these montane grasslands.

Vegetation changes along a precipitation gradient in Central Argentina

Changes in vegetation along a precipitation gradient in Central Argentina were studied. Floristic samples were taken along an east-west transect of about 300 km. Correlation analysis between precipitation and ordination axes was used to provide an environmental interpretation of vegetation variability. Floristic analysis produced an ordination of plant communities from evergreen forests (precipitation >500 mm) to desert shrublands and therophyte communities (precipitation <200 mm). Results showed a trend of floristic and structural impoverishment towards the west. There is a replacement of species along the transect and a shift in dominant growth forms. The first ordination axis is significantly, negatively correlated with annual precipitation.

Combining land cover mapping of coastal dunes with vegetation analysis

Abstract Question: Coastal dune systems are characterized by a natural mosaic that promotes species diversity. This heterogeneity often represents a severe problem for traditional mapping or ground survey techniques. The work presented here proposes to apply a very detailed CORINE land cover map as baseline information for plant community sampling and analysis in a coastal dune landscape. Location: Molise coast, Central Italy. Method: We analysed through an error matrix the coherence between land cover classes and vegetation types identified through a field survey. The CORINE land cover map (scale 1 : 5000) of the Molise coast was used with the CORINE legend expanded to a fourth level of detail for natural and semi-natural areas. Vegetation data were collected following a random stratified sampling design using the CORINE land cover classes as strata. An error matrix was used to compare, on a category-by-category basis, the relationship between vegetation types (obtained by cluster analyses of sampling plots) and land cover classes of the same area. Results: The coincidence between both classification approaches is quite good. Only one land cover class shows a very weak agreement with its corresponding vegetation type; this result was interpreted as being related to human disturbance. Conclusions: Since it is based on a standard land cover classification, the proposal has a potential for application to most European coastal systems. This method could represent a first step in the environmental planning of coastal systems. Nomenclature: Pignatti (1982). Abbreviation: CORINE = Co-ordination on Information of the Environment.

Environmental Factors Influencing Coastal Vegetation Pattern: New Insights from the Mediterranean Basin

Coastal dune ecosystems show strongly dynamic interactions between abiotic and biotic factors. The relationship between plant communities and environmental factors has been previously studied in oceanic dune systems, but few studies have been conducted along Mediterranean coasts. In this study we analyze the relative contribution of environmental factors associated with two of the main drivers of vegetation zonation: soil and wind. We chose two representative coastal dune systems in the western Mediterranean Basin subject to low levels of human disturbance. Within 54 plots we recorded floristic and environmental data. Vegetation zonation and relationships with environmental variables were investigated through unconstrained and constrained ordinations, correlation, and variance partitioning. Environmental factors shift along the gradient from coastal to inland dunes, concomitantly with the pattern of community types from annual beach communities to shrub-covered fixed dunes. This general gradient is similar both in the Mediterranean and in the oceanic coastal ecosystems, with the same factors that show similar trends along the dune profile. However, our results highlight some peculiarities of the Mediterranean dune systems in relation to the amount of variation explained by environmental factors. While most studies conducted in oceanic ecosystems find that wind-related parameters may control the vegetation zonation, in our study areas we observed a minor importance of the wind-related variables when compared to soil properties. In particular, organic matter and grain-size variability were found to be closely correlated with the distribution of plant communities along the gradient.

Spatial connectivity and boundary patterns in coastal dune vegetation in the Circeo National Park, Central Italy.

. Distribution patterns of coastal sand dune plant communities in the Circeo National Park (Central Italy) are quantified and compared by measuring spatial connectivity and richness of community boundaries along the dune profile. The purpose of this study is: (1) to evaluate patchiness and frequency of spatial links between communities; (2) to identify the communities most sensitive to disturbance; and (3) to predict probable changes due to modification of spatial zonation. Data were obtained using belt transects across the Holocene coastal dune zone. Vegetation zonation from the seashore to the foredune slacks is analysed in relation to chorological, phytosociological and life-form types. We found that under relatively undisturbed environmental conditions communities formed a sequence (communities 1 to 7), with the exception of a replacement community, which occupied gaps in the perennial vegetation. The spatial distribution of some communities was reduced as a consequence of disturbance; others became fragmented in small patches or even disappeared. In coastal environments with strong, complex gradients, the existence of certain communities depends on specific links (neighbourhood effects) and high connectivity values do not indicate better conservation conditions.

EU habitats of interest: an insight into Atlantic and Mediterranean beach and foredunes

We compared the Atlantic and Mediterranean beach and foredune habitats of European interest, focusing on floristic, structural and ecological features. We selected two representative sites of Atlantic (The Netherlands) and Mediterranean (Italy) coastal dunes. From a georeferenced vegetation database, samples of: (a) annual vegetation on drift lines (European Union habitat type 1210), (b) embryonic shifting dunes (2110), and (c) shifting dunes along the shoreline with Ammophila arenaria (2120), were selected. Floristic representativity and comparability of plot sizes were considered. For each habitat, the frequency and the fidelity of the species, the life form frequency spectra and Ellenberg ecological indicator values were assessed. We found a consistent floristic differentiation between the Atlantic and the Mediterranean coastal dune habitats and only a small set of shared species. The Italian and the Dutch annual vegetation of drift lines (1210) register a high structural similarity that strongly declines landwards. Floristic composition, life forms and Ellenberg indicator values show higher similarities among different foredune habitats of the same site than between homologous habitats of the Mediterranean and Atlantic coasts. The results confirm the current description and distribution of the habitat of European interest annual vegetation of drift lines (1210). On the other hand, the floristic, structural and ecological differences between the Atlantic and the Mediterranean embryonic shifting dunes (2110) and shifting dunes along the shoreline with Ammophila arenaria (2120) point at an inconsistency of the existing description of those habitats of European interest and highlight the need of adding in the Directive specific types that describe them in the Mediterranean basin. We suggest the introduction of two new habitat types named “Dunes along the Mediterranean shoreline with Ammophila arenaria” (new code 2280) and “Mediterranean embryonic dunes” (new code 2290) within the existing class “Sea dunes of the Mediterranean coast” (class 22 of the Annex I Habitats Directive 92/43/CEE).

Marine litter in Mediterranean sandy littorals: Spatial distribution patterns along central Italy coastal dunes

Sandy shores are generally considered important sinks for marine litter and the presence of this litter may represent a serious threat to biotic communities and dune integrity mostly due to cleaning activities carried out through mechanical equipment. In spring (April-May) 2012 we sampled 153 2×2m random plots to assess the spatial distribution patterns of litter on Central Italy sandy shores. We analysed the relationship between the presence of litter and coastal dune habitats along the sea-inland gradient. Our results showed that the most frequent litter items were plastic and polystyrene. Differences of marine litter spatial distribution were found between upper beach and fore dune habitats and fixed dune habitats: embryo dune and mobile dune habitats show the highest frequency of litter, but, surprisingly, marine litter did not impact fixed dune habitats, these possibly acting as a natural barrier protecting the inner part of the coast from marine litter dispersion.

VegItaly: The Italian collaborative project for a national vegetation database

Abstract Two years after its official start, the national vegetation database VegItaly, a collaborative project supported by the Italian scientific community and developed by a large group of scientists, is presented. This article offers a concise overview of the content of the database, currently consisting of 31,100 vegetation plot, including published and unpublished data. Some basic statistics are analysed; for example, data distribution in space and time, represented vegetation types expressed as physiognomic categories. Although rather young and still in progress, VegItaly already contains data from all the Italian regions and stands as an optimal candidate for the development of an Italian national vegetation database. Its main goals,theoretical basis, technical features, functionalities and recent progresses are outlined, showing glimpses of future prospects.