Palaeoecology of three interstadial events during oxygen-isotope Stages 3 and 4: a lacustrine record from Lago Grande di Monticchio, southern Italy

Three interstadial events recorded in a pollen diagram from Lago Grande di Monticchio, southern Italy (40°56′40″N, 15′36″E), can be correlated with Dansgaard/Oeschger events 12, 14 and 20 of the GRIP (Summit) Greenland Ice Core. Based on a chronology of varve counts, the events are dated respectively to the intervals 37,600–40,000, 43,600–50,000 and 72,000–74,600 calendar yr BP. The interstadials are of unequal duration, the longest occupying 6400 years. They appear to begin and end abruptly. Each is characterised by a sequence of pollen changes in the mesic forest component. Similarities in these sequences of mesic forest trees imply similar patterns of climatic change within each interstadial. The sequences resemble that of the late-glacial interstadial at Monticchio. Although tree pollen abundance values reach as much as 60% during the interstadials, there is always a substantial proportion of herb pollen. Tree growth may have been constrained by low CO2 levels during the glacial phase of the last glacial–interglacial cycle. This record illustrates the potential of long continental records to present opportunities for detailed ecological and chronological analyses of sub-interglacial warming events during oxygen-isotope Stages 3 and 4.