Late Quaternary environments, vegetation and agriculture in northern New Zealand

Abstract

A sedimentological and plant microfossil history of the late Quaternary is preserved in two sediment cores from early Polynesian ditch systems on southern Aupouri Peninsula. The study places human activities into a geomorphological and ecological context and allows comparison of natural and anthropogenic effects on two different geological settings: a floodplain and a relatively closed peat swamp. The data fill part of the current gap in the environmental record from northern New Zealand, namely MIS 3 (57 000 – 26 000 yr BP). There is evidence for an increase in fire frequency in the region after 40 000 yr BP, suggesting a shift to drier (and cooler) conditions. Pollen records show that conifer-hardwood forest dominated by podocarps (especially Dacrydium) prevailed prior to Polynesian arrival and deforestation within the last millenium, with Fuscopsora insignificant throughout.

Both cores show sections with gaps in deposition or preservation, possible flood-stripping of peat during the pre-Holocene and mechanical disturbance by early Polynesians. The identification of prehistoric starch grains and other microremains of introduced Colocasia esculenta (taro) in both cores supports indirect evidence that the ditch systems of far northern New Zealand were used for the extensive cultivation of this crop.

Keywords

Environmental change, plant microfossils, prehistoric agriculture, Colocasia esculenta, New Zealand.