The ancient port built along the Tyrrhenian coast by Roman Emperor Claudius (mid of 1st Cent. AD) and enlarged by Emperor Trajan (beginning of 2nd Cent. AD) was Rome¿s principal maritime port. The remains of the port and of the town raised in the close vicinity are at present ca. 3 km away from the present coastline, in the Tiber delta. The harbour town named Portus developed together with the port itself and expanded in the following centuries.
The study will take into consideration data already published from two cores drilled in the dock and canale Trasverso of the Claudius harbour (Mazzini et al., 2011. J. Paleolimnol. 46: 243-256; Pepe et al., 2013. Quat. Int. 303: 73-81; Sadori et al., 2010. J. Archaeol. Sci. 37: 3294-3305) and new data of one core taken in the centre of Trajan harbour, at present an artificial hexagonal lake. The chronological framing of the cores was carried out using magnetostratigraphy, radiocarbon dates, archaeological evidences and historical sources. The three cores, partly overlapping, cover different periods of time of the port history, from the middle of the first century onwards. Detailed sediment analyses were carried out on Trajan core.
Pollen, Non Pollen Palynomorph (NPP), microcharcoal and plant macroremain analyses will be integrated by dinoflagellate cysts, ostracod and foraminifer analyses to provide a detailed reconstruction of the air and water environments.
The plant landscape of the dock core is typical of a coastal environment and appears rather preserved. The human presence is clear, but not of great impact. The channel core records mainly a strong human impact related to the presence of Portus, the port town.
Preliminary data on the lake Trajan core show the clear evidence of the huge works for the port excavation and records the history of the area also after the abandonment of the port and its isolation from the sea, even recording the reclamation of the area occurred in the early twentieth century.
The present study will add a really important mosaic tessera for the reconstruction of the Tiber delta plant landscape in the last couple of millennia. No similar record is available for the region of Rome, cradle of one of the most important civilizations of the Mediterranean basin.
When dealing with a past plant landscape we have to consider that it is an open system, subdued to human and natural forcing. This is even more complicated if the open system is located in a marginal terrestrial area such as a river delta used as a harbour. Disentangle the two causes (natural and human) is not an easy task and both climate short term and abrupt changes played an important role in an ecosystem such as the Mediterranean one. Either abrupt changes in precipitation amount, in annual regime or human impact can in fact produce important changes in the forest canopy, but also forest clearance for agriculture, sheep-farming, mining, and metal production has similar effects. Today, the same forces continue to modify pollen production.
Considering the difficulty in ascertaining the cause of forest clearance, pollen based past climate reconstruction for the last millennia can have biases (see Sadori et al., 2013, Clim Past 9, 1969-1984). In absence of this limiting factor the climate of the past would be easier reconstructed. To do such reconstruction, a palaeoecologist has to use different environmental proxies such as synchronous hydrological changes detected from lake level changes, glacier advances/retreats, speleothems (see Giraudi et al., 2011, Holocene 21, 105-115; Zanchetta et al., 2012, Quat. Res., 7,: 236-247; 2014; Zanchetta et al., 2013, Quatern. Int., 303, 1-9 ).