A Late Holocene pollen record from marine sediments in SE Sicily

The new pollen record from marine core SW104_ND2-ND2, collected in the Sicily Channel 20 km from the coast, is presented. The central position of this marine record in the Mediterranean Basin is strategic to investigate past climate variability and ecological changes in a transitional climatic zone, highly sensitive to hydroclimatic variations. The intricate interplay of the climatic patterns acting over the Central Mediterranean, North Africa, and continental Europe determines a complex bioclimatic configuration, which is also reflected in the floristic richness and vegetational diversity of SE Sicily. Our analysis provides a detailed reconstruction of palaeoecological changes in relation to climatic variability and human impact over the last 3000 years. The pollen record depicts a permanent open vegetational landscape with several fluctuations of land cover, corresponding to alternate forests expansions and reductions. This pattern is consistent with fluctuations in solar activity and the cyclicity of independent stratigraphic evidence at a global scale. The palynostratigraphy of the study record, based on changes in vegetation structure and floristic composition, reflects the main climatic events in historical times. During the Roman Period, a forest development is observed that suggests a centennial-scale humid climate, matching the so called Roman Humid Period. In contrast, a marked decrease in arboreal pollen percentages and concentration is observed since the 14th century AD, suggesting dry climatic conditions during the Little Ice Age. The comparison of our palaeovegetational reconstruction with independent palaeoclimate proxies reveals the recurrence of arid phases concomitant with negative or declining positive phases of the North Atlantic Oscillation (NAO), underlining the pivotal role of this forcing in determining precipitation distribution at centennial to decadal scales. At the same time, the detection of African taxa in the pollen record, testifying the southwestern provenance of air masses, suggests an interaction of northward shifts of North African high pressures with NAO-determined synoptic conditions. Extra-regional pollen inputs are especially frequent during the last millennium, indicating an increasing influence of the North African anticyclone over the Central Mediterranean region. The SW104_ND2-ND2 pollen record offers new detailed information on the extent of human impact on the landscape in relation to historical management policies and land use, and provides insights into past vegetation trends, atmospheric dynamics, and hydroclimatic conditions, which contribute to a better understanding of Late Holocene climate variability in the Central Mediterranean.