Au9816890 Dendrochronology and Radiocarbon Dating Of

* AU9816890

DENDROCHRONOLOGY AND RADIOCARBON DATING OF CONIFER TREES AND BURIED LOGS FROM THE STANLEY RIVER, TASMANIA

by

EDWARD COOKi, MIKE BARBETTI2, BRENDAN BUCKLEY3,MIKE PETERSON*, GILLIAN TAYLOR2, ZHAO YTJ2, BRUCE THOMSON2 and LLOYD WEEKS2

'Tree Ring Laboratory, Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA

2The NWG Macintosh Centre for Quaternary Dating, Madsen Building F09, University of Sydney, NSW 2006, Australia

^Institute of Antarctic and Southern Ocean Studies, University of Tasmania, GPO Box 252C, Hobart, Tasmania 7001, Australia

^Forestry Corporation, Hobart, Tasmania 7001, Australia

Dendrochronological studies are being carried out on two endemic conifer species in the Stanley River area of western Tasmania. Living trees are growing along the river banks, adjacent floodplain areas, and occasionally on the lower hill-slopes. Many ancient logs are exposed in the bed and banks of the river, and several major excavations have been carried out in floodplain sediments up to a hundred metres distant from the present river channel.

A tree-ring chronology for Huon pine {Lagarostrobos franklinii) now extends from the present back to 571 BC. This chronology has been constructed using cores from living trees (up to 1400 years old), sections from trees felled during logging operations in the early 1980s, and sections from subfossil logs in the river banks and floodplain sediments. Living celery-top pine (Phyllocladus aspleniifolius) trees are up to 500 years old, and a short chronology is being developed for this species as well.

Large excavations have been carried out over several years in floodplain sediments, and sections have now been taken from a total of 350 subfossil logs. Both Huon and celery-top pine are represented in the collection. 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. A floating tree-ring chronology for Huon pine has been established for the period ca. 7200-3500 cal BP, and is gradually being augmented.

In the collection of about 350 ancient conifer logs from the Stanley River, about 150 currently have known ages while the remaining 200 have yet to be studied. Most of them have ages less than 9000 cal BP, but about 10% of them are older. Four of them are more than 30,000 years old, and may be Last Interglacial in age. Nine of them are known to be between 18,000 and 10,000 years old, and six are between 10,000 and 9,000 years old. Our augmented collection has become an increasingly important archive for further tree-ring and carbon isotope studies.

PAPER NO. 35 STANLEY RIVER HUON PINE HOLOCENE TREE-RING CHRONOLOGIES AND 1 4C-DATED SUB-FOSSIL WOOD

1.5

ID SR684 SR700 C5RR47-SR157* SR627 17K SR701 I£K SR462- 10.5K i Q 15K , 13K .

•NOT HUON PINE

0.5 4 0

I • I ./s. I . I I. I 7-1 I -18000 -16000 -14000 -12000 -10000 -8000 -6000 -4000 -2000 YEARS BP Figure 3. Plots of the cross-dated Huon pine tree-ring chronologies from Tasmania and radiocarbon-dated logs in the late glacial period. The chronologies have been smoothed with a 20-year low-pass filter for plotting purposes. The annual sample size (N) of each chronology is provided below the chronologies.