LATE HOLOCENE VEGETATION AND FIRE HISTORY OF DEVONSHIRE MARSH, BERMUDA

Analysis of palynomorphs and charcoal preserved in a core extracted from the peat of Devonshire Marsh, Bermuda, provides insight to the history of vegetation and fire occurrences, which can be interpreted in terms of a regional climatic history and anthropogenic effects. Changes in pollen spectra in the core indicate two cycles of wet and dry conditions during the past ~5000 years. These paleoclimatic changes are similar to those observed preserved in lake records in the Caribbean region and in marine sediments of the nearby Bermuda Rise, suggesting regional paleoclimate forcing. Climatic reconstructions are based primarily on proportional changes in the marsh vegetation, reflecting wetter versus drier environments. Wetter conditions occurred between ca. 4700 and 3800 yBP, and 1210 and 60 yBP, while drier conditions occurred between 3800 and 1750 yBP and the last 60 years. Results also indicate that over the past 400 years the vegetation in and adjacent to the marsh has been altered anthropogenically due to the introduction of non-indigenous plant species to the island.

Significant increases in charcoal deposition in the last 500 years indicate an increase in fire frequency. Assessment of historical data suggests that the increased fire frequency is related to permanent habitation of Bermuda beginning in 1609. All the subsequent major charcoal peaks can be directly related to large fires that impacted the marsh and/or surrounding areas. Similar increases in fire frequencies are noted in the Caribbean region and are also attributed to anthropogenic impact, but these fires cannot be as well documented as those on Bermuda.