Radiocarbon variations from Tasmanian conifers: Results from three Early Holocene logs

Dendrochronological studies are being carried out on two conifer species in the Stanley River area of western Tasmania. The chronology for Huon pine (Lagarostrobos franklinii), with living trees up to 1400 yr old, extends back to 571 BC. Living celery-top pine (Phyllocladus aspleniifolius) trees are up to 500 yr old. Apart from living or recently felled trees, sections have been taken from 350 subfossil logs preserved in floodplain sediments. They range in age from >38 ka to modern, with good coverage for the periods 9-3.5 ka and from 2.5 ka to the present. We report here on C-14 measurements of decadal samples from three early Holocene logs, between 10 and 9 ka BP, providing short (ca. 300-yr) records of atmospheric C-14 variations when plotted against ring numbers. The southern hemisphere data from Tasmania can be compared and wiggle-matched with published C-14 calibration curves from German oak and pine. One set of measurements covers the period, ca. 9280-8990 cal BP, overlapping the link between the Hohenheim ''Main 9'' and middle Holocene master oak chronologies. The other sets of measurements from Tasmania coincide; they span the period, ca. 9840-9480 cal BP, overlapping the end of the German Preboreal pine and the beginning of the oak chronologies. Our measurements confirm that this part of the calibration curve is a gently sloping C-14-age plateau (ca. 8900-8700 sp, between 10,000 and 9500 cal BP), and suggest interhemispheric C-14 differences close to zero.