Pollen analysis from Lago Alimini Piccolo provides the first record of mid- and late-Holocene vegetation history of a coastal area in the easternmost region of southern Italy (Salento Peninsula). Terrestrial pollen taxa document expansions and declines of the Mediterranean forest, in relation to human activity and climate changes. Between 5200 and 4350 cal. BP a dense evergreen oak forest dominated the landscape; then a distinct opening of the forest is recorded (4350—3900 cal. BP). A new forest expansion (3900—2100 cal. BP) is characterized by an increase of Olea and evergreen shrubs, indicating a development of mediterranean climate conditions and increasing human disturbance. The Roman occupation period (2100—1500 cal. BP) shows a significant opening of the forest, expansion of halophytes and modest values of Olea. After 1500 cal. BP human impact causes a further decrease of the natural woodland in favour of an extraordinary expansion of Olea . The vegetation development at Lago Alimini Piccolo, interpreted in the light of other pollen records, provides new insights into climate evolution and evergreen vegetation development in the central Mediterranean region: (1) a temporary mid-Holocene deforestation at 4000 cal. BP, involving many Italian sites south of 43°N, was possibly caused by drought associated with an expansion or northward displacement of the North African high pressure zone; (2) the Bronze Age increase of Olea, coupled with a widespread increase of Mediterranean shrubs, suggests management of wild trees, while the beginning of intensive cultivation of olive trees is only found after the Roman time.

Geomorphologic, stratigraphic, faunistic, palynological and carbon isotope analyses were carried out in the area of the Tiber river mouth. The results depict a complex palaeoenvironmental evolution in the area of the Roman town of Ostia, ascertain the changes of the Tiber river delta over the last 6000 years and support a re-interpretation of some archaeologic issues. The wave-dominated Tiber delta evolved through three distinct phases. In the first step (5000–2700 yr BP) a delta cusp was built at the river mouth, which was located north of the present outlet. Subsequently (2700–1900 BP), an abrupt southward migration of the river mouth determined the abandonment of the previous cusp and the progradation of a new one. The third step, which is still in progress, is marked by the appearance of a complex cusp made up of two distributary channels. The transition from the first to the second evolution phase occurred in the seventh century bc and was contemporary to the foundation of Ostia, as suggested by historical accounts. However, the oldest archaeological evidence of the town of Ostia dates to the fourth century bc, when human activity is clearly recorded also by pollen data. We suggest that the first human settlement (seventh century bc) consisted of ephemeral military posts, with the aim of controlling the strategic river mouth and establishing the Ostia saltworks. Only after the fourth century bc the coastal environment was stable enough for the foundation and development of the town of Ostia.

It is well-known that the Holocene exhibits a millennial-scale climate variability. However, its periodicity, spatio-temporal patterns and underlying processes are not fully deciphered yet. Here we focus on the central and western Mediterranean. We show that recurrent forest declines from the Gulf of Gaeta (central Tyrrhenian Sea) reveal a 1860-yr periodicity, consistent with a ca. 1800-yr climate fluctuation induced by large-scale changes in climate modes, linked to solar activity and/or AMOC intensity. We show that recurrent forest declines and dry events are also recorded in several pollen and palaeohydrological proxy-records in the south-central Mediterranean. We found coeval events also in several palaeohydrological records from the south-western Mediterranean, which however show generally wet climate conditions, indicating a spatio-temporal hydrological pattern opposite to the south-central Mediterranean and suggesting that different expressions of climate modes occurred in the two regions at the same time. We propose that these opposite hydroclimate regimes point to a complex interplay of the prevailing or predominant phases of NAO-like circulation, East Atlantic pattern, and extension and location of the North African anticyclone. At a larger geographical scale, displacements of the ITCZ, modulated by solar activity and/or AMOC intensity, may have also indirectly influenced the observed pattern.