25. PHYTOLITHS AND MICROSCOPIC CHARCOAL FROM LEG 155: A VEGETATIONAL AND FIRE HISTORY OF THE AMAZON BASIN DURING THE LAST 75 K.Y.1

Dolores R. Piperno2

ABSTRACT

This preliminary phytolith and charcoal study of sediments from the Amazon Fan (Sites 932 and 933) shows changes that appear to reflect widespread climatic and vegetational oscillations in Amazonia over the last 75 k.y. The Pleistocene climate was much cooler than that of the present day, as arboreal taxa now confined mainly to elevations above 1200 m descended into the lowlands to form forests with novel species associations. The last glacial maximum appears to have been a significantly drier time than the postglacial era, with advance of open terrain vegetation, frequent grassland fire, and reduction of the seasonal forest. Forest and grassland fires have a deep history in the Amazon Basin. Data from the Amazon Fan support many of the interpretations of the Pleistocene in Amazonia based on paleobotanical study of scattered terrestrial sites.

1Flood, R.D., Piper, D.J.W., Klaus, A., and Peterson, L.C. (Eds.), 1997. Proc. ODP, Sci. Results, 155: College Station, TX (Ocean Drilling Program).
2Smithsonian Tropical Research Institute, Box 2072, Balboa, Republic of Panama (mail only: Unit 0948 APO AA 34002-0948). STRI.Tivoli.Pipernod@ic.si.edu