Quaternary vegetation landscapes in Piedmont and in the Aosta valley with particular reference to the Holocene

BIOGEOGHAPHIA — val. XIX - 1997 (Pubblicalo il 31 oftobre 1998) (iii effetti delle variazioni climatiche pleistoceniche sulla dinamica dei popolamenti animali e vegelali nella Penisola italiana Quaternary Vegetation landscapes in Piedmont and in the Aosta Valley with particular reference to the Holocene ROSAN NA CARAMIELLO, CONSOLATA SINISCALCO Dipzzrtimemfo di Biologizz Vegetzzle, Universitiz di Torino zziale Mzzztio/i, 25 — 10125 Torino Keywords: Holocene, N-Italy, Palaeobotany, Palynology, Quaternary, Vegetation, W—Alps. SUMMARY Reconstruction oF some Piedmontese plant landscapes during the Quaternary is proposed on the bases of the palaeobotanical data on the Italian side of Western Alps and on the adjoining flatlands. Studies starts with the informations that can be drawn from the Villafranchian typical deposits and the deposits regarded as Villafranchian semu /zzta: these data allow to reconstruction of thermophilous forests and of hydrophilous herbaceous vegetation communities. Data are then referred to the progressive extinction of thermophilous elements based both on palynological and on palaeocarpological data from Upper Pliocene to Lower and Middle Pleistocene and to the beginning of the glaciations. The literature is very poor with regard to the Middle Pleistocene and it is necessary to arrive to the Riss—Wfirm interglacial to have data on vegetation with the presence oha mesophilous deciduous forest, characterised by an absence of archaic entities. Numerous plant landscapes are then proposed for the last interglacial and to the interstadials, both at high and at low altitudes; some are referred to the old Penclt and Bruckner nomenclature, some refer to a more recent division in glacial peaks and interstadials. Literature becomes very rich for the Post—Glacial, For which reconstruction of landscapes is possible and easier than for the previous periods. Particular detail is so far dedicated to the last 13,000 years plant landscapes in Piedmont also comparing our data to the other Central and Eastern Alps observations and to the migration of tree species. Completion of the temporal panorama and quantitative and qualitative correlation of the vegetational data with the changes in the climate will allow the formulation of hypotheses concerning its variations in the decades ahead. Data on recent small temperature swings of the order of 1—1,5 °C have been correlated to relatively rapid altitudinal oscillations of vegetation, especially of the timberline. The concepts of stability of plant communities may be modified by reconsidering the extensive potential of rapid vegetational dynamism. Reconstruction of Piedmontese plant landscapes during the Quaternary is based on consultation of the palaeobotanical studies of the Italian side of the \Western Alps and the adjoining flatlands. The geology of this sector has been the subject of numerous in—depth investigations. Works on vegetation, on the other hand, have been sporadic and frequently confined to specific points. Discussion of the results in the light of the latest chronological knowledge is rare.