Vegetation and climate near Lago Llanquihue in the Chilean Lake District between 20200 and 9500 14C yr BP

Abstract

Radiocarbon-dated pollen records of two adjacent sediment cores from Canal de la Puntilla (40°57′09″S, 72°54′18″W) in the Chilean Lake District reveal that a sparsely vegetated landscape prevailed during the portion of the Last Glacial Maximum between 20200 and about 14800 14C yr BP. Dominating the vegetation was Nothofagus, Gramineae and Compositae, along with taxa commonly found today above the Andean treeline (Perezia-type, Valeriana) and in Magellanic Moorlands (Donatia, Astelia). Nothofagus expanded between 20200 and 15800 14C yr BP, interrupted by a reversal at 19200 14C yr BP and followed by a prominent increase in Gramineae pollen between 15800 and about 14800 14C yr BP. A major increase in Nothofagus started at about 14800 14C yr BP, followed by an abrupt expansion of thermophilous Valdivian/North Patagonian Rain Forest taxa (Myrtaceae, Lomatia/Gevuina, Hydrangea, etc.) at about 14000 14C yr BP. An opening of the rain forest and an expansion of Podocarpus nubigena, Misodendrum, and Maytenus disticha-type subsequently occurred between 11000 and 10000 14C yr BP. These results suggest that mean annual temperature was 6–7°C colder than at present, with twice the modern annual precipitation between 20200 and 14000 14C yr BP, implying a northward shift and intensification of the westerlies storm-tracks. Slight climate warming occurred between 20200 and 15800 14C yr BP, featuring cooling reversals at 19200 14C yr BP, and later at 15800 14C yr BP. The warming of the last termination started at about 14800 14C yr BP, and reached a total temperature rise of ≥5°C by 12400 14C yr BP, followed by cooling between 11000 and 10000 14C yr BP. © 1997 John Wiley & Sons, Ltd.