A Holocene pollen and sediment record of Whangape Harbour, Far Northern New Zealand

Abstract

The sediment record of Whangape Harbour shows that there were significant fluctuations in depositional energy in the harbour during the period from c. >8000 cal. yr B.P. to some time within the last millenium, and that fluvial influences increased as the harbour infilled. The pollen record (highly discontinuous) from Whangape Harbour indicates that mixed conifer-hardwood forest covered the hills surrounding the harbour during this period. The main canopy conifers were Dacrydium and Prumnopitys taxifolia, with some Libocedrus, Dacrycarpus and Phyllocladus. Agathis was also present. Common canopy hardwoods were Metrosideros and, in the latter part of the period, Elaeocarpus. Ascarina and Cyathea were abundant in the sub-canopy. Leptospermum grew on disturbed areas fringing the estuary. Marsh or swamp environments probably never developed on a large scale in the harbour.

Avicennia, extremely under-represented in the pollen flora, has been present on tidal flats in the harbour since at least c. 2500 cal. yr B.P. Large-scale anthropogenic deforestation by burning commenced in the Whangape catchment some time during or since 700-430 cal. yr B.P. The associated increase in erosion rates in the catchment resulted in a change towards a sandier sediment regime in the harbour which has continued to the present day. Weinmannia and Ackama, previously rare in the catchment, expanded in remaining forest.

Keywords

Palynology, sedimentology, Holocene, disturbance, Northland.