The Upper Lente River Valley (Southern Tuscany): a contribution to the floristic and vegetation knowledge.

摘要

A botanical survey in the valley of the Lente River in the volcanic area of Fiora basin in Southern Tuscany (Italy) was carried out by means of phytosociological method and floristic collections. This survey led to the description of a peculiar pattern of spatial arrangement of the forest vegetation along the steep flanks of the valley, basically determined by a strong thermic inversion. Several forest types have been recognized along this gradient, and a rich vascular flora including 257 plant taxa was recorded. Of these types, 9 are listed as habitats of European interest (Dir. 92/43/CE). Of special relevance are the mesophytic woods with Fagus sylvatica, Carpinus betulus, Tilia sp. pl, Acer and Ulmus occurring in the bottom of the valley under conditions of elevated atmospheric and edaphic humidity. These phytocoenoses have a relict origin and still harbour numerous herbaceous plants occurring with heterotopic populations, such as Festuca gigantea and Cardamine kitaibelii. Another worthy type of vegetation are the xerophytic coenoses with Quercus ilex, Acer monspessulanum and sclerophyllous shrubs developed on the top and on the ridges of the steep slopes of the valley. Pastures and meadows are restricted in terms of surface but they harbour some rare plant taxa such as Rorippa pyrenaica, Trifolium strictum, Anchusella cretica and Agrostis pourretii, which is here recorded for Tuscany for the first time.