Modern pollen/climate calibration for southern South America

摘要

Using the response surface technique a modern pollen/climate calibration is presented for the mid-latitudes in southern South America between latitudes 39°S and 44°S, extending from the west coast in Chile across the Andes into the Patagonian steppe region. The climate parameters identified that relate to the present-day pollen distribution of the nine most important pollen types (Nothofagus dombeyi-type, Nothofagus oblique-type, Podocarpus, Weinmannia, Caldcluvia/Eucryphia-type, Cupressaceae, Myrtaceae, Misodendrum and steppe-types) are summer precipitation, summer and winter temperatures. Using the modern pollen/climate data set, three fossil pollen records (Mallin Aguado and Lago Moreno, east of the Andes, and Caunahue, west of the Andes) are interpreted in terms of these three seasonal climate parameters. Despite intervals of no-analog fossil pollen assemblages, the reconstruction shows similar climate trends on both sides of the Andes during the last 21000 cal. yr BP (17000 YR BP), with summer precipitation as low or markedly lower than today prior to 17000 cal. yr BP (14500 yr BP), as high or higher than today between 15000 and 12500 cal. yr BP (12500 and 10500 yr BP), and again lower than today between 12500 and 8000 cal. yr bp (10500 and 7200 yr BP). summer and winter temperatures were low (or high) when summer precipitation was high (or low).