LATE HOLOCENE CLIMATIC CHANGES IN WESTERN EQUATORIAL AFRICA INFERRED FROM POLLEN FROM LAKE-SINNDA, SOUTHERN CONGO

Pollen analysis of two cores from the Lake Sinnda, located in one of t he driest areas of the southern Congo, reveals a history of vegetation and climate in this region during the past 5000 yr. A major change ce ntered around 3000-2500 yr B.P. is indicated by an abrupt decrease in forest pollen and by a corresponding increase in grassland pollen. Con current drying up of the lake shows that climate, in particular aridit y, was the major cause of this change. This paleoclimatic reconstructi on conforms with evidence for drier conditions in other parts of weste rn equatorial Africa, such as the development of isolated enclosed sav annas and of heliophilous forested formations. The aridity is recorded more fully at Lake Sinnda than at the previous studied ones. It proba bly lasted longer, from 4200 to 1300 yr B.P., and was more progressive than previously inferred. The aridity predates agriculture marked by pollen of the oil palm at Lake Sinnda. (C) 1998 University of Washingt on.