Flavio Frignani

Using Multivariate Analyses to Assess Effects of Fluvial Type on Plant Species Distribution in a Mediterranean River

We propose a method to assess the distribution of plant assemblages along rivers delimiting homogeneous fluvial types using cluster analysis applied to morphological features, quantified with aerial photos and geographic information system software. A stratified random sampling design along the elevational gradient was used to analyze riparian plant species. Multivariate statistics were applied to detect patterns of variation in the species data, and among functional and ecological groups. Cluster analysis identified four fluvial types: headwater, low sinuosity, braided, and incised. Canonical Correspondence Analysis, INdicator SPecies ANalysis, and partial ordinations all suggested that fluvial types were characterized by well-defined indicator species. The differences found by Redundancy Analysis and non-parametric analysis of variance for functional and ecological groups also supported the fluvial type division, showing different distributional trends for annual and woody species, and the greatest ecological distance between braided and headwater types. Based on the ordination results, dividing fluvial types according to morphological features was justified by environmental and floristic differences, although plant species variability was only partially described. Our results illustrated that the fluvial type classification created using this methodology was consistent with natural plant species distribution patterns.

Abundance of orchids on calcareous grasslands in relation to community species, environmental, and vegetational conditions

The abundance of Orchidaceae on three calcareous grasslands is studied in relation to floristic composition, environmental and vegetational factors and plant traits (ecological and life forms). The aims are: (i) to identify a group of species that is significantly correlated with the abundance of Orchidaceae or with individual species of orchids on calcareous grasslands; (ii) to study the relationship between traits associated with habitat specialisation, community life forms and the abundance of orchids; (iii) to identify the main environmental and vegetational predictors of the abundance of orchids. A shortlist of species is found to be significantly correlated with the abundance of total orchids, Orchis pauciflora and O. morio. The life forms of the community species do not show any correlation with the orchids, with the exception of Orchis pauciflora, which tends to increase in communities rich in hemicryptophytes and poor in annual species. Analyses of Orchis morio seem to suggest that it has a high level of ecological tolerance. The most important predictors of the abundance of orchids are the substrate reaction (basic) and arid grassland with low herbaceous vegetation cover (i.e. high soil reaction and luminosity values, positive correlation with the cover of lichens and rockiness, negative correlation with tree cover and herbaceous layer). The least favourable sites were the least basic and most superficial and arid sites.

Contribution to the Karyological Knowledge of Mediterranean Romulea Species (Iridaceae)

Eighteen chromosome counts are reported in nine Mediterranean Romulea species. Among them, four species have a wide distribution range (R. bulbocodium, R. columnae, R. ramiflora and R. rollii) and five are narrow central Mediterranean endemics (R. bocchierii, R. ligustica, R. linaresii, R. requienii and R. revelieri). Chromosome numbers range from 2n = 3x = 27 in one R. columnae accession to 2n = 6x = 54 in R. linaresii. Our results only partially agree with previous reports, and the chromosome number records of R. bocchierii, R. ligustica, R. linaresii subsp. linaresii and R. revelieri presented here are completely new. According to our data and contrary to previous statements, x = 9 seems to be the basic chromosome number in this group of Mediterranean Romulea. Moreover, a highly significant negative correlation between the chromosome size and ploidy level was found.

Potamogeton schweinfurthii and similar broad-leaved species in Italy

Summary Potamogeton schweinfurthii A. Benn is recorded for the first time from peninsular Italy. This species was recently recorded from Sardinia and other Mediterranean islands, where it was confused with some other similar broad-leaved species of Potamogeton, in particular with P. lucens. The finding of P. schweinfurthii in two Tuscan localities (C Italy) initiated an investigation to verify the presence of further specimens of this plant among the material of similar Potamogeton species (P. lucens, P. alpinus, P. nodosus, P. gramineus) preserved in the main Italian herbaria. The herbarium survey allowed discovery of P. schweinfurthii also in Marche and Apulia regions. The distribution in Italy of four other similar Potamogeton species is specified through the herbarium investigation.

CORINE land cover and floristic variation in a Mediterranean wetland

The aims of the present study were to: (1) investigate whether CORINE land cover classes reflect significant differences in floristic composition, using a very detailed CORINE land cover map (scale 1:5000); (2) decompose the relationships between floristic assemblages and three groups of explanatory variables (CORINE land cover classes, environmental characteristics and spatial structure) into unique and interactive components. Stratified sampling was used to select a set of 100-m2 plots in each land cover class identified in the semi-natural wetland surrounding a lake in central Italy. The following six classes were considered: stable meadows, deciduous oak dominated woods, hygrophilous broadleaf dominated woods, heaths and shrublands, inland swamps, canals or watercourses. The relationship between land cover classes and floristic composition was tested using several statistical techniques in order to determine whether the results remained consistent with different procedures. The variation partitioning approach was applied to identify the relative importance of three groups of explanatory variables in relation to floristic variation. The most important predictor was land cover, which explained 20.7% of the variation in plant distribution, although the hypothesis that each land cover class could be associated with a particular floristic pattern was not verified. Multi Response Permutation Analysis did not indicate a strong floristic separability between land cover classes and only 9.5% of species showed a significant indicator value for a specific land cover class. We suggest that land cover classes linked with hygrophilous and herbaceous communities in a wetland may have floristic patterns that vary with fine scale and are not compatible with a land cover map.

Flora and vegetation in the catchment area of the stream “La Bolza” in the Merse valley (Siena, southern Tuscany)

Summary This study illustrates the results of a floristic and phytosociological study conducted in a small portion (375 ha) of the Merse valley. Following a brief description of the geomorphologic and climatic aspects, the bryological and vascular flora is presented, obtained through floristic field studies and bibliographic data. The bryological flora includes 25 moss species including Sphagnum subnitens and S. capillifolium, which are of interest from a conservationist viewpoint, and 5 liverworts; the vascular flora comprises 252 species (belonging to 68 families and 186 genera); there are only three endemic entities but many species considered as rare or of interest, including Anagallis minima, Blechnum spicant, Carex viridula, Dryopteris dilatata, Erythronium dens-canis, Juncus bulbosus, Osmunda regalis and Radiola linoides, thus highlighting the phytogeographical relevance of this biotope. Chorological analysis highlighted the dominance of eurosiberian and boreal elements. The principal vegetation types sampled can be ascribed to the following alliances: Cicendio filiformis-Solenopsion laurentiae (Isoetetalia, Isoeto-Nanojuncetea), Osmundo-Alnion and Alnion incanae (Populetalia albae, Querco-Fagetea), Erythronio dens-canis-Quercion petraeae and Teucrio siculi-Quercion cerridis (Quercetalia-pubescen- ti-petraeae, Querco-Fagetea), Sarothamnion scoparii (Cytisetalia scopario-striati, Cytisetea scopario-striati). There are three habitats of Community interest: alluvial forests with Alnus glutinosa (code 91EO), woods of Castanea sativa (code 9260) and rare short-lived small coenoses of Isoeto-Nanojuncetea (code 3130).