Vegetation change following mid-Holocene marine transgression of the Torres Strait shelf: a record from the island of Mua, northern Australia

Abstract

The pollen and sedimentary record from a coastal backdune swamp on the island of Mua, Torres Strait, Australia, is presented. A 4.55 m core collected from the swamp centre provides a record of vegetation and landscape change spanning the postglacial marine transgression to present. Prior to 6000 radiocarbon years before present (yr BP) results show mangrove vegetation encroaching on the core site, periodically displacing non-mangrove taxa until the establishment of an extensive mangrove forest between 6000 yr BP and 3000 yr BP. Within the mangrove community a transition from lower-tidal Rhizophora forest to an upper-intertidal Ceriops community is evident. This is followed by the development of the current herbaceous freshwater swamp in the late Holocene. The dryland vegetation record is dominated by sclerophyll and rainforest elements with strongest forest representation occurring around the mid Holocene before a decline in tree density and the establishment of open woodlands in the late Holocene. The data suggest vegetation change accompanied marine transgression and a humid mid-Holocene climate, before stabilization of sea levels and the initiation of dominant on-shore catchment processes, signalling drier climatic conditions and possible human activity.