Terrestrial palynology from marine cores as an indicator of environmental change for the Waipaoa Sedimentary System and north-eastern New Zealand

Diverse terrestrial palynomorph assemblages of Pleistocene to Recent age have been recovered from mainly marine sediment cores along the eastern New Zealand margin. These assemblages record a range of environmental changes including climate, deforestation, reforestation, rates of erosion, sediment provenance and age, volcanic activity, Polynesian and European settlement, strength and direction of ocean currents, astronomical cyclicity, and other major events many of which can be correlated with shorter onshore terrestrial sequences. As such, pollen yields valuable information on the dynamic New Zealand landscape, which is of particular relevance to a source-to-sink approach. This paper provides an integrated summary of published and unpublished late Pleistocene palynological studies off eastern North Island, New Zealand that gives context for an analysis of cores within and marginal to the Waipaoa Sedimentary System. Pollen assemblages faithfully reflect the last glacial vegetation dominated by grass- and shrub-land species together with elevated Tertiary pollen from enhanced erosion of the regolith. The glacial termination and Holocene were marked by establishment of podocarp forest, a mid-Holocene disappearance of sediment-trapping mangroves, and introduction of distal pollen with establishment of coastal current systems under rising sea level. These natural signals are overprinted by abrupt changes in pollen species caused by volcanic eruptions. Finally, endemic forest and shrub pollen were markedly reduced with human colonisation, associated land use changes and introduction of exotic species.