Pliocene to Pleistocene palynoflora and vegetation in Italy: state of the art.

Fifty-four Italian pollen sites, spanning the last 5.3 Ma, have been the object of an updated synthesis. The chronostratigraphic framework of floral and vegetational events illustrates the development of cooler climates since the Pliocene. Floral and vegetational response to glacial/interglacial cycles, as well as major taxa replacements have been analysed with special attention to latitudinal and altitudinal gradients and to physiographic reorganizations. The pollen flora shows marked changes both at the beginning of the Pleistocene as well as at the time of the Mid-Pleistocene climate transition, when a major decrease in temperature, during both glacial and interglacial phases, occurred. Alternations of Artemisia steppe and thermophilous forest mark the overall glacial-interglacial vegetation changes. However, in northern Italy, the latter are rather expressed by an alternating spread of altitudinal coniferous forest (mainly Picea), without significant expansion of steppe vegetation, and thermophilous forest. More complex vegetational cycles than those pointed out by earlier syntheses are also testified by the detection of an alpine vegetation spreading during glacial phases and a wooded steppe in the earlier phases of interglacials, in some southern marine sections. Such diversified patterns could be associated with obliquity related warm/humid-cold/dry " interglacial" -" glacial" cycles superimposed by precession related warm/dry-cold/humid cycles. However, the role of depositional processes as well as taphonomic biases should not be ignored in the reconstruction of vegetation dynamics.