An OIS 5a to OIS 4 (or early OIS 3) Environmental and climatic reconstruction from the Northwest, South Island, New Zealand, using beetle fossils

A fossil beetle study is presented from the northwest coast, South Island, New Zealand. The samples were recovered from overbank deposits on a marine terrace situated 4 km east of Westport, New Zealand (41° 45' S, 171° 36' E). The age of the site is constrained to between 74 and 40 ka but discrepancies between luminescence and radiocarbon age results prevent more precise age control. The older of two samples indicates a closed canopy Nothofagus (southern beech) forest with deep litter and dead wood on the forest floor. The younger sample yields a similar Nothofagus forest environment with subalpine affinities and nearby tussock grassland. For the older sample, mean summer and winter minimum temperatures were similar to modern values. Mean summer temperature was ca. 3.0°C cooler than modern during the younger phase while mean minimum winter temperature was ca. 5.0°C cooler than present indicating both cooling and increased seasonality. Both samples suggest a 30-40% decrease in mean annual precipitation from modern values. Persistence of closed canopy Nothofagus forest during the period of 74-40 ka contrasts with regional pollen studies which imply widespread shrub-land at these times. This implies that this site may have served as a glacial refugium for Nothofagus forest. Copyright © 2007 John Wiley & Sons, Ltd