Holocene prodelta lobes are key sedimentary archives of environmental change that can be used effectively for high-resolution palynological investigations, as they: (i) consist almost entirely of mud, (ii) represent stratigraphically expanded successions, and (iii) are strictly related to river dynamics, thus reflecting vegetation changes in river catchments. In this study, we focussed on the ~20 m-thick prodelta succession of the modern Po Delta (NE Italy), fed by two river branches (Volano and Goro) that were mostly active during the past two millennia, a period of rapid acceleration of natural resources’ exploitation and climate variability. Forty-eight samples with mean temporal resolution of 50 years were analysed. Eleven ecological groups and four pollen zones were identified, with distinct peaks of the secondary-primary pollen ratio marking major floods during the Volano-Goro lobe switching and the Little Ice Age. Five vegetation phases were detected since the 1 st century AD. In the framework of a patchy natural-cultural landscape, patterns of wetland expansion/contraction reflect the combined effect of cool-wet oscillations (LALIA – Late Antique Little Ice Age), land management (reclamations) and river avulsion. Forest dynamics document warm conditions during the so-called ‘Roman Climate Optimum’ and ‘Medieval Warm Period’, although minor cool-wet episodes occurred in tune with solar minima, and bipartite climate conditions (cool-moist followed by cool-dry) characterized the LALIA. Since the 14 th century, despite human-induced forest shrinking, peaks of montane vegetation followed a centennial-scale cyclicity likely influenced by solar minima and major plagues.

ABSTRACTFramed into a robust stratigraphic context, multivariate analyses on the Holocene palaeobiological record (pollen, benthic foraminifers, ostracods) of the Po coastal plain (NE Italy) allowed the investigation of microtidal ecosystems variability and driving parameters along a 35‐km‐long land–sea transect. Millennial‐scale ecosystem shifts are documented by coeval changes in the meiofauna, reflecting variations in organic matter–water depth (shallow‐marine environments) and degree of confinement‐salinity (back‐barrier settings). In‐phase shifts of vegetation communities track unsteady water‐table levels and river dynamics in freshwater palustrine areas. Five environmental–ecological stages followed one another crossing four tipping points that mark changes in relative sea level (RSL), climate and/or fluvial regime. At the culmination of Mediterranean RSL rise, after the 8200 event, remarkable growth of peatlands took place in the Po estuary, while low accumulation rates typified the shelf. At the transgressive–regressive turnaround (~7000 cal a bp), the estuary turned into a delta plain with tidally influenced interdistributary embayments. River flow regime oscillations after the Climate Optimum (post‐5000 cal a bp) favoured isolation of the bays and the development of brackish wetlands surrounded by wooded peatlands. The youngest threshold (~800 cal a bp), which led to the establishment of the modern delta, reflects a major avulsion of the Po River.

Mediterranean deltaic-coastal plains represent relatively underexplored depositional archives that record the Holocene response of vegetation and depositional systems to high-frequency climate changes. In this study, we examine a 25 m-thick succession of Holocene age (core EM2) recovered in the innermost portion of the Po delta plain of northern Italy, applying an integrated palyno-stratigraphic approach. The existence of a paludal, freshwater setting inland of the line of maximum marine transgression favoured a low degree of pollen transportation. Application of cluster analysis to this palynological record leads to the identification of pollen-derived biomes and seven (auto)ecological groups of taxa that discriminate environmental signal (depositional facies) and regional climate conditions within a well-dated coastal record. Percentage variations of hygrophytes, aquatics and pasture-meadow herbs reveal local environmental dynamics, enabling the detailed facies characterisation of the cored succession, especially in terms of water table conditions. Framed into a chronologically constrained, high-resolution facies context, the proportion of montane taxa (climate degradation indicator) relative to Mediterranean taxa and Quercus + other deciduous trees (climate optimum indicators) highlight a vegetation-climate variability in the plain that fits with Bond events, especially for the early-mid Holocene (i.e., Preboreal and Boreal Oscillation, 8.2 ka event), supporting a strong Mediterranean-North Atlantic climate connection. For the first time, pollen from a continental succession of the Adriatic area clearly depicts the effects of the 8.2 ka cooling event on vegetation patterns (progressive degradation in high altitude communities) and depositional dynamics (increased fluvial activity), assessing the major role played by climate changes in shaping coastal landscapes in addition to glacio-eustatic variations.

Palynological analyses, backed by meiofauna (ostracods and benthic foraminifers), sedimentological and radiocarbon data, enabled the identification of late Quaternary turnovers of depositional environments and coeval vegetation dynamics from a ca. 30 m-long core succession (core PA1), retrieved in the Arno delta area (N Italy), 2 km landwards of the innermost outcropping beach ridge. Based on the identification of 213 palynomorph taxa (pollen and spores), eleven ecological groups were elaborated and their relative frequencies stratigraphically plotted, allowing the identification of eight bio-sedimentary units (BSUs) and four vegetation phases dated to the late Pleistocene onwards. The former record palaeoenvironmental changes, mainly in terms of water-table level and salinity. The latter reflect different palaeoclimate conditions at both Milankovitch and sub-Milankovitch timescales, relying on the proportion of montane versus Mediterranean taxa. The vertically stacked pattern of BSUs reveals two transgressive-regressive cycles developed above an alluvial plain succession stratigraphically assigned to the penultimate glacial interval (Marine Isotope Stage-MIS 6). Both depositional cycles show a transgressive portion composed of swampy-lagoonal clays formed under interglacial conditions. Pollen (Mediterranean forest with increasing optimum-like conditions) suggests a MIS 5e age for the lowermost transgressive interval, whereas the palynological assemblage (Mediterranean/sub-Mediterranean forest) and radiocarbon ages consistently indicate an early Holocene age (ca. 9800-7400 cal yrs BP) for the uppermost one. A climate-driven phase of subaerial exposure, likely related to the onset of the last glacial period, affected the MIS 5e lagoon, as testified by the record of an open/sparse pine forest within pedogenised alluvial deposits sandwiched between the two lagoon intervals. By contrast, the early Holocene lagoon experienced a long-term trend of sedimentary filling by river inputs under rather stable interglacial, highstand conditions. Only at the end of climate optimum conditions, marked by a peak of Fagus dated around 5000 cal yrs BP, the lagoon turned into a delta plain. This study documents the successfully use of a multi-proxy, palynological-based approach to investigate the complex interplay between environments, vegetation and climate changes in alluvial-coastal plain contexts and within a sequence-stratigraphic perspective.

A thirteen-metres long sedimentary suite was recorded and sampled in the courtyard of Sant'Orsola Hospital in Bologna to reconstruct the surrounding area's paleoenvironmental evolution. Fourteen buried Soil Units (SU) were recognized, three of which were characterized by a peculiar darkening. Three stratigraphic markers allowed us to chronologically constrain the soil sequence between the Roman Age and 13230 +/- 70 calibrated years BP. The geomorphological study and the chemical multianalysis provided data for the understanding of the pedological palaeoenvironment, whereas the pollen analysis permitted to suggest the lowest buried soil (SU 14) to be a lateral equivalent of the lacking Bolling chronozone alfisol, proposed as a fundamental marker in the Emilia-Romagna regional chronostratigraphic scale. A small creek (Fossa Cavallina) was the main local morphosedimentary dynamic driver whereas the human settlement appears to have been a subordinate factor. These results highlight the importance of the integrated approach of geomorphology, pedology and palynology for the study of continental deposits.