Pollen evidence of Late Holocene mangrove development in Bermuda

Abstract

Bermuda is the northern latitudinal limit for mangroves, but communities are diverse and productive. Two pollen diagrams from the largest mangrove area show vegetation changes over the last 5000 years. From 5000 to 2100 years ago this was a marsh wetland, and pollen evidence is also shown of the dryland endemic forest before colonisation of Bermuda. Establishment of mangroves has only occurred in the last 3000 years, when sea-level rise slowed from 26 to 7 cm/l00 years. Flotation experiments indicate that propagules could readily colonize from the Caribbean, and evidence both of cooler climate during the glacial and that none of Bermuda's many endemics utilize a mangrove habitat suggests that mangroves have had discontinuous presence in Bermuda through the Late Pleistocene. This study shows that mangrove ranges may be more plastic than was previously thought, subject to availability of habitats rather than dispersal capability.