Multidisciplinary study of a Lateglacial-Holocene sedimentary sequence near Bologna (Italy): insights on natural and anthropogenic impacts on the landscape dynamics

Abstract

This study investigated a Lateglacial to Holocene sedimentary sequence derived from a small catchment located at San Lazzaro di Savena in the surroundings of Bologna Emilia (Northern Italy), in which different buried soil horizons were investigated in order to delineate the physiographic evolution of the area. Several disciplinary/analytical approaches including pedostratigraphy, geochemistry, radiocarbon dating, archaeobotanical investigation and δ13C stable isotopes analyses were taken into account for the pedosequence characterization. This multidisciplinary approach allowed us to identify the main factors that affected the ancient environment over a prolonged time interval (∼12 ky); starting from 14 ky BP with a palaeosol ascribed to the Bolling period, cold-arid conditions characterized by a steppic vegetation gradually evolved toward a more humid (and slightly warmer) setting. This climatic change allowed the development of a forest constituted by abundant conifers at ca 10 ky BP. Humans also impacted on the environment, at least since 9 ky BP, as indicated by repeated traces of firing (plausibly for deforestation and land clearance). The data allow a comparison with findings provided by other neighbouring sites and contribute to the ongoing debate on the relationships between climatic and anthropogenic impacts on the landscape dynamic. The human impact on the landscape has been effective from the Mesolithic, earlier than usually considered in previous studies. Anthropogenic activities caused geomorphological and hydraulic instabilities within the basin, accelerating soil erosion as indicated by the increase of the estimated sedimentation rates and change in the type of geochemical, mineralogical and textural properties of the studied soils.