1,720,991 research outputs found
The syntaxonomic position of Santolina etrusca: multivariate analysis
No full textThe results of multivariate analysis of the syntaxonomic role of Santolina etrusca (Lacaita) Marchi et D'Amato, a species endemic to Tyrrhenian central Italy, are reported. Classification was performed by polythetic divisive analysis using two-way indicator species (TWINSPAN). Ordination analysis was performed by correspondence analysis (CA). Classification and ordination showed that although Santolina etrusca grows prevalently in communities of Rosmarinetalia Br.-Bl, ex Molinier 1934, it is ecologically correlated and associated with entities of unstable nitrophilous communities subject to frequent disturbance belonging to an order, Helichryso-Santolinetalia Peinado and Martinez-Parras 1984, with western eumediterranean distribution. However it does not have a well defined sociological role, as it is constant in all community groups
The phytocoenosis of consolidated alluvium: a syntaxonomical and synecological study in the braided streams of southern Tuscany (Italy)
No full textThe outer terraces of braided streams of southern Tuscany consist of con solidated detritus, often with a thin layer of humus. In these a new association of the alliance Bromion erecti (Seselio tortuosi-Brometum erecti) and fragments of Coronillo valentinae Ampelodesmetum (Oleo-Ceratonion), a thermo-xerophilous Ampelodesmos mauritanicus community, are recognized. The association Seselio-Brometum erecti is widespread on the inner sites and is characterized by a group of relatively mesophilous species. On the contrary, the Ampelodesmos mauritanicus communities are found along subcoastal water courses char acterized by several Stenomediterranean species. Both these hemicryptophyte coenoses are ecologically and floristically distinct from Santolino etruscae-Saturejetum montanae s.l. which includes the chamaephyte communities of the lower terraces. Statistical analysis are shown that the main abiotic factors affecting the pattern of riparian vegetation in these sites are height and distance from running water, and to a greater degree, changes in soil texture and bioclimate
The vascular flora of the Lake Burano Nature Reserve (Grosseto, southern Tuscany, Italy) [La Flora vascolare della Riserva Naturale Lago di Burano (Grosseto, Toscane meridionale)]
No full textLake Burano is in Tuscany, near the border with Latium (Capalbio municipality, Grosseto province, Italy). The results of a survey of the flora of the Lake Burano Nature Reserve in the period 1995-99 are reported. Data from the literature and specimens collected in the early 1990s during mycological studies were also considered. The landforms, climate and vegetation of the area are described, followed by a list of vascular plants with explanatory notes on entities of phytogeographical and/or conservation interest. The list consists of 522 taxa with 492 spontaneous or naturalised plants, 10 recently introduced species and 20 species found in the literature but not confirmed in the field. Spontaneous flora belongs to 301 genera and 81 families. Entities of phytogeographical interest for Tuscany and often for Italy include: i) endemic species and species close to the limit of their distribution, such as Dorycnium rectum, Fumaria bicolor, Linaria purpurea subsp. cossoni, Polygonum romanum and Quercus frainetto; ii) psammophiles such as Crucianella maritima, Euphorbia paralias, Medicago marina, Matthiola sinuata and Stachys maritima, most of which are in the Tuscan list of threatened species; iii) rare species and species with fragmented distribution linked to wet areas (salt and freshwater), such as Aeluropus littoralis, Artemisia coerulescens var. palmata, Carex ext ens a, C. riparia, Cladium mariscus, Eleocharis uniglumis, Euphorbia palustris, Halimione portulacoides, Hydrocotyle vulgaris, Orchis palustris, Plantago cornuti, Ranunculus sceleratus, Spartina juncea, Spirodela polyrrhiza and Stachys palustris. The data show that many years of protection have made the reserve one of the best conserved sectors of the Tuscan coast, with regard to flora
Relationships between vegetation and morphology in the Radicofani calanchi (southern Tuscany)
No full textThe vegetation of the calanchi of Radicofani (southern Tuscany) is described on the basis of 50 phytosociological relevés carried out in areas with uniform erosion. Twelve vegetation types were identified. The pioneer vegetation (Parapholido-Artemisietum cretaceae) was only found in extreme environments with severe erosion. Grasslands dominated by Elytrigia atherica and those dominated by Dactylis hispanica, Phalaris coerulescens and Hedysarum coronarium were associated with deposition area. Grasslands of Bromus erectus and those dominated by Brachypodium rupestre were found on several morphologies. Scrub communities at different stages of evolution were also recorded on different morphological types, whereas woods with Ulmus minor and woods dominated by Quercus pubescens and Q. cerris were recorded along impluvium lines and on original slops respectively. Pioneer coenoses linked to moist environments were found on valley floors
Evaluation and monitoring of the flora in a nature reserve by estimation methods
No full textWe tested the use of non-parametric estimators of species richness to evaluate the flora of a relatively large (431 ha) nature reserve, using a sampling area much lower than that used in previous studies. Different estimation methods were applied to floristic data obtained from 50 random plots: the number of observed species, the extrapolated accumulation curves based on the Michaelis–Menten model and the non-parametric estimators based on incidence data (Chao2, first-order Jackknife, second-order Jackknife and bootstrap). To test the performance of the estimators, five data sets were created on the basis of life-forms. The estimates were compared with reference values obtained by traditional floristic and vegetation sampling. The power of the different estimation methods could not definitively be determined, but the first- and second-order Jackknives seem to be the most precise. Although total species richness was underestimated, the sample-based approach provided accurate information for quantitative comparison of time series of data related to ecological changes, vegetation dynamics and environmental changes. This sample-based data included basic statistics on species richness and species frequency distributions as well as the life-form spectrum, at the plot and the whole site scales
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