Climate, vegetation, and environmental change during the MIS 12-MIS 11 glacial-interglacial transition inferred from a high-resolution pollen record from the Fucino Basin of central Italy

Glacial Termination V (T-V) comprised a relatively rapid shift from glacial to interglacial conditions (MIS 12 glacial to the MIS 11c); it was one of the greatest climatic changes of the Pleistocene, and forms part of the major climatic reorganization known as the Mid-Brunhes Event (MBE). The Fucino Basin, located in the Central Apennine chain of central Italy, contains a continuous and well-preserved lacustrine sedimentary record of T-V and MIS 11, dated using tephrochronology. In this paper, we report a high-resolution palynological analysis, supported by geochemical proxies, from the lowermost section of the F4-F5 composite record, to improve understanding of T-V in this region. This record reveals a substantial transition between MIS 12 and MIS 11c at 424.5 ± 4.0 ka, from a very cold and dry environment indicated by the herbaceous and xerophytic association of Poaceae, Artemisia, Amaranthaceae, Ephedra, and Hippophäe, and sedimentation dominated by inorganic siliciclastic sediments, to a warm and humid period characterised by a significant increase in Abies and a deciduous tree association mainly formed by Betula, Carpinus, Corylus, Quercus, Ulmus, and dominated by more organic calcareous sediments. This transition was correlated with a significant lake-level rise, with an enhanced nutrient input into the lake between 425.0 ± 4.5 ka and 424.0 ± 3.9 ka, as inferred from the variance between algae, aquatic plants, and terrestrial herbaceous taxa. Following the MIS 11c temperature maximum at 424.2 ± 3.9 ka, a reduction in summer insolation occurred, provoking a significant increase in humidity that produced the widespread development of Abies. The results from this study suggest that, at Fucino, fluctuations in humidity are predominantly responsible for the vegetation changes observed during T-V.