CAMEL LAKE - A 40000-YR RECORD OF VEGETATIONAL AND FOREST HISTORY FROM NORTHWEST FLORIDA

Camel Lake records the vegetation history of northwest Florida from approximately 40000 yr BP to the present. The Middle Wisconsin, from 40000 to 29000 yr BP, was a time of forests with abundant pine, oak, and diverse mesic tree species. Chestnut (Castanea) was an important element in the vegetation before 31000 yr BP. The Late Wisconsin forest (29000 yr BP to 14000 yr BP) was a species-poor pine forest. The Wisconsin-age forests varied greatly in species composition from time to time, probably because of climatic variation. From 14000 to 12 000 yr BP Picea (spruce) was present with northern aquatics in forest with abundant Carya (hickory) and other deciduous trees. This is believed to be the coldest phase recorded at Camel Lake, with a suggested climate of-5-degrees-C January mean temperatures. similar to southern Quebec today. After 12000 yr BP the forest was oak-dominated with diverse deciduous hardwoods, unlike northeast Florida, which at that time had a less mesic flora with some prairie development and low lake levels with many dried-out lake basins. Sedimentation in shallow water was continuous at Camel Lake in the early Holocene, but a sudden change in sediment type and pollen composition indicates a hiatus between 10020 and 7760 yr BP. After the hiatus modem turkey oak/long-leaf pine forests were present. There was a rise of some 4 m in the water table in the later Holocene, and cypress swamps and bayheads developed. The climates indicated by pollen data are in conflict with the simulations of published general circulation models (GCMs) for both the Late Wisconsin and the Holocene. Discrepancies may be explained by the particular boundary conditions used for the models, especially an assumption of little change in ocean temperatures at the latitude of Florida.