Environmental change and landscape evolution in roman and early medieval Lisbon inferred from palynological and sedimentological analyses

Abstract

Landscape evolution and environmental change in Lisbon have been addressed by the use of multi-proxy analysis, including pollen, non-pollen-palynomorphs and sedimentological data preserved in a sedimentary core retrieved in a sub-tidal area of the northern Tagus margin. Four radiocarbon dates indicate that the record covers from 1st century cal AD to late 6th century cal AD. Data cross-check with available archaeological information of the city enables for the reconstruction of palaeoenvironmental dynamics during circa 600 yr period at high resolution. Main results evidence that the area of Lisbon was an open landscape with little woodlands and high human impact at least since the 1st century cal AD. A higher influence of human activity has been identified in early 3rd century cal AD. A change in the sedimentary record has been identified in early 3rd century cal AD that can be related with natural events or higher human activity. A marked sedimentological change occurred in early 4th century AD, coincident with the late Roman period, and suggesting a change in the behaviour of the Tagus tributaries. A new phase of increase human impact has been identified in late 5th century cal AD. The diverse rhythms of environmental change occurred in accordance with social and political evolution of the area and evidence the usefulness of transdisciplinary and multi-proxy approach in landscape archaeology studies.