Indagini floristico-vegetazionali e actuopalinologiche sul Lago Baccio e sul Lago del Greppo (Appennino Tosco-Emiliano)

Flora, vegetation and actuopalynological studies of Lago Baccio and Lago del Greppo (Iuscan-Emilian Apennines). - Two small lakes in the Tuscan-Ernilian Apennines, Lago Baccio (Modena) and Lago del Greppo (Pistoia) have been investigated from a floristic and a vegetational point of view. As a first step, the dimensions of the present time have been compared with the past: from the last sixty years the level of Lago Baccio has much increased and, as a consequence, the peat bog has came up against a large reduction; this fact is responsible for the disappearance of some species and for the alteration of some vegetation types. On the contrary the surface of Lago del Greppo has remained almost unchanged, nevertheless some species present in the past, have not found to day. The vegetation types living in the lake water, along the shores and on the peat bog have been pointed out and described using the phytosociological methodology. After the vegetation study, palynological analyses were carried out on surface samples of the peat bog with the aim to evaluate the recent pollen rain. Particular attenction was payed to the relationship between the pollen spectra (P) and the coverage of herbaceous plants (R) growing in the Caricetum nigrae at Lago Baccio, and in the Carici canescentis-Agrostietum caninae and Sphagnum f/exuosum community at Lago del Greppo. Whenever possible, the RfP index was calculated for the helophytes growing in the above-mentioned syntaxa. At Lago del Greppo the pollen percentages and the coverages of the main helophytic taxa were also considered with reference to the total surface of the lake basin and a mR/P index was elaborated. The pollen spectra vegetation of the peat bog is collectively well represented even if some species do not appear; this fact sets up a considerable limit in the reconstruction of the vegetation beginning from the recent pollen rain.