LATE QUATERNARY POLLEN RECORDS OF VEGETATION AND CLIMATE-CHANGE FROM KAITAIA BOG, FAR NORTHERN NEW-ZEALAND

A vegetational history and palaeoclimatic changes are established for the last 25,000 yr by pollen analysis of two peat cores from Kaitaia B og, far northern New Zealand. Twelve AMS radiocarbon dates provide a c hronology covering the Last Glacial Maximum to the late Holocene, ca. 2500 yr ago. Prior to 22,000 yr B.P. a tall, complex, conifer-beech-ha rdwood forest dominated by podocarp trees covered the region. The most abundant of these was Dacrydium cupressimum. Nothofagus (N. cf. trunc ata) was also an important element. Other common emergent trees includ ed Podocarpus, Prumnopitys feruginea, P. taxifolia, Dacrycarpus dacryd ioides, Libocedrius and Metiosideros. From 22,000 to ca. 14,000 yr B.P . regional forest was dominated by Nothofagus cf. truncata, and warm, moist elements such as Ascarina lucida and Agathis australis were scar ce. This Last Glacial Maximum forest cover contrasts with the open gra ss and shrub communities which dominated landscapes south of Auckland. Cool climate species such as Nothofagus cf. truncata began to decline towards the end of the Lateglacial, and from ca. 11,300 yr B.P. Ascar ina lucida started to increase rapidly. Replacement of conifer-beech-h ardwood forest with a conifer-hardwood association proceeded rapidly i n the Postglacial as Nothofagus cf. truncata retracted sharply and Dac rydium cupressimum increased in abundance. The regional expansion of A gathis australis followed rapidly. Regional forest in the mid- to late Holocene consisted of a conifer-hardwood association dominated by Dac rydium cupressimum, Podocarpus, Phyllocladus and Agathis australis. A mid-Holocene decline for Ascarina. lucida and coincident increased abu ndance of Prumnopitys taxifolia suggests somewhat cooler conditions pr evailed from this time. Nothofagus cf. truncata, though still present, assumed only a minor role as more favourable conditions allowed other species a competitive advantage. (C) 1998 Elsevier Science B.V.