A Paleoecological History of West Pond on Great Abaco Island, The Bahamas, Based on Pollen and Charcoal Analysis of Lake Sediments

West Pond (26.2˚ N, 77.2˚ W, ca. 5 m elevation) is a shallow, alkaline pond within the pine rocklands and karst topography of Great Abaco Island, the Bahamas. For parallel core sections recovered from the pond in 2003 reveal marl sediments overlying peat deposits with a paleosol at the base. A radiocarbon date on a fragment of wood of Pinus caribaea Morelet from the paleosol indicates that the sediment record at West Pond spans the last ~2100 years.

Pollen grains preserved in the West Pond sediments indicate significant environmental change at the site. While pine pollen accounts for 85-99% of the pollen grains in samples from the upper half of the profile, samples from the lower half of the profile are dominated by the pollen of broadleaved taxa, with pine accounting for only 3-30% of total pollen. The shift in pollen assemblages from dominance by broadleaved taxa to dominance by pine roughly correlates within the change from peat to marl sedimentation, with both changes possibly indicating climate drying beginning after ~770 cal yr BP (midpoint of pine rise) or ~550 cal yr BP (transition to marl sediments). A peak in Rhizophora pollen between ~1190-110 cal yr BP may indicate an earlier dry phase.

Charcoal abundance is relatively low throughout the profile, indicating either low fire frequency or low charcoal production and transport in and following fires. The highest charcoal concentrations are in levels dominated by broadleaved taxa, and in the time of transition to pine-dominated vegetation. Taken together, the pollen and charcoal data suggest a shift from a tropical hardwood community characterized by a low-frequency, high intensity fire regime to a pine-dominated community characterized by more frequent but lower intensity fires. An initial peak in charcoal concentration at ~1190 cal yr BP may signal first human arrival on Great Abaco Island, possibly during a period of regional drought. No maize pollen or other conclusive evidence of prehistoric agriculture was found in the profile.