Palynology, sedimentology and environmental significance of Holocene swamps at northern Kaitoke, Great Barrier Island, New Zealand.

Pollen and sediment analyses of two cores from coastal freshwater swamps at northern Kaitoke (Kaitoke Swamp and Police Station Swamp), Great Barrier I sland, show that c. 7300 calibrated yr B.P. Kaitoke Swamp was an estuary wi th tidal flats. Avicennia, now absent from the swamp area, was present in t he estuary. By c. 4500 yr B.P. fresh water conditions had developed at the Kaitoke Swamp site as marine influences decreased. Around the same time, fr esh water swamp conditions commenced at the Police Station Swamp site on th e surface of a low lying area of a tate Pleistocene dune. A sandy layer at Kaitoke may represent rapid infilling followed by a dry soil surface until c. 1000 yr B.P. Conifer-hardwood forest on the hills surrounding the sites c. 7300-c. 1800 yr B.P. was dominated by Dacrydium and Metrosideros. During this period, environmental conditions were relatively stable, with little change in forest composition. Between 1800 yr and 800 yr B.P. Kaitoke Swamp was reflooded, and the Police Station Swamp extended as a shallow lake ove r the nearby dune flat. These new shallow swamps were invaded by swamp fore st (mainly Dacrycarpus with some Laurelia). The presence of charcoal and Pt eridium spores above the Kaharoa Tephra suggests that major Polynesian defo restation at northern Kaitoke began c. 600 calibrated yr B.P.