A high-resolution Late-Glacial-Holocene pollen diagram from Pian di Gembro (Central Alps, Northern Italy)

The local and regional history of vegetation and climate, from the Late Glacial to the present, is represented in a new, high-resolution pollen diagram from Pian di Gembro (1350 m asl), ten C-14 dates providing a reliable time control. An open pioneer vegetation dominated by Artemisia, Gramineae, and Chenopodiaceae followed the retreat of the glaciers after the Last Glacial Maximum. Shrub vegetation with Juniperus, Alnus viridis, and Salix expanded soon after. Denser Betula-Pinus forests were present in Pian di Gembro around 12,320 B.P. Their extent was greatly reduced by the climatic cooling of the Younger Dryas, when open vegetation spread again. The beginning of the Holocene was marked by a considerable expansion in mixed oak taxa. Corylus immigrated to the site at 9,250 B.P. Picea and Abies expanded at 7,370 B.P., recording an abrupt change in the structure of the vegetational belts. A coeval climatic change is evidenced in the GRIP records and also detectable through oscillations of the timberline. Signs of human impact are present since late Atlantic, becoming more intense around 2,200 B.P. As pasture lands increased, Abies and Fagus slowly disappeared. The introduction of Castanea and Juglans is dated to Roman times, and Secale to the Middle Ages.