Water Fern (Azolla filiculoides Lam.) in Southern Chile as an Index of Paleoenvironment during Early Deglaciation

Abstract

In late glacial deposits in the Chilotan Archipelago (42°30′S), remains of water fern (Azolla filiculoides Lam.), a plant of temperate-tropical America, are an apparent added indication of the paleoenvironment of deglaciation following the last glacial maximum in southern Chile. The last glacial maximum was reached in the archipelago between about 14,800 and 13,900 14C yr BP. In conjunction with a diversification of arboreal plant species, as shown by the fossil pollen record, the presence of Azolla further reflects an abrupt, early deglacial temperature rise. This evidence of temperature increase estimated to be in the order of 6°C is compatible with the implication from the fossil beetle fauna of warming concomitant with a major transformation of plant communities. Full-glacial Subantarctic Parkland in the latitude of the Chilotan Archipelago was replaced by late glacial Transition Woodland and ultimately by North Patagonian Evergreen Forest. Azolla in the late glacial record dates from the time of earl...