Extension of New Zealand kauri (Agathis australis)tree-ring chronologies into Oxygen Isotope Stage (OIS) 3

Abstract

New Zealand kauri (Agathis australis) is both long-lived and sensitive to climate so during the past two decades an extensive network of sites has been sampled for dendrochronological analyses. The network can be divided into three general groups based on the time period they cover - 'modern' kauri (MK), late-Holocene kauri (HK) and 'ancient' kauri (AK) from before the Last Glacial Maximum (LGM). Although the groups are restricted to northern New Zealand (i.e. having overlapping ranges) they occur at different elevations. Modern kauri sites tend to be along ridges and much higher than the two subfossil groups (i.e. HK and AK sites). We propose the modern kauri situation to be a typical artefact of anthropogenic activities. In contrast, the subfossil groups are the result of a complex process of dune migration, levee formation and water-table rise leading to bog formation driven by rising sea levels. Most of the 16 AK sites have radiocarbon ages clearly within Oxygen Isotope Stage (OIS) 3 and a preliminary group of chronologies have been developed that collectively cover 10719 yr. Analysis is ongoing, but there is clear potential to span a much greater time period and recover detailed palaeoclimatic information.