35,000-year record of pollen, charcoal and NPP from Bass Strait, southeast Australia

We reconstruct the last glacial vegetation (pollen record), fire (charcoal record) and lake levels (NPP record) for Bass Strait. Results show the Bass Strait area was characterized by Eucalyptus woodland and shrubland vegetation, with high fire activity and lake levels from 35,000 to 29,000 years ago. Grassland expanded at the expense of woodland after this period, with a decline in fire activity and lake levels.

Methods
Sediment core locations

Crystal Lagoon (-40.477381°, 148.350799°, ~8 m asl), truwana/Cape Barren Island, Bass Strait, southeast Australia.

Methods

For pollen analysis, samples were taken from sediment cores at 2–4-cm intervals and samples were processed following standard pollen preparation procedures, which included HCl, KOH and acetolysis treatments. At least 300 terrestrial pollen grains were identified on slides except for a few depths (60 and 64 cm) with extremely low pollen concentrations in which at least 100 pollen grains were counted. Pollen and spores were identified using the Australasian Pollen and Spore Atlas (http://apsa.anu.edu.au/) and PalaeoWorks reference collections at the Australian National University’s Archaeology and Natural History Laboratory. Microscopic charcoal particles (<125 µm) were also counted on pollen slides. For macrocharcoal ( >125 µm) analysis, contiguous sediment samples were taken from core and analysed, following the method of Whitlock & Larsen (2001).

Chronology is based on eight Accelerator Mass Spectrometry (AMS) 14C dates and age-depth model was created using ‘rbacon’, with SHCal20 calibration curve.

Reference

Whitlock, C., & Larsen, C. (2001). Charcoal as fire proxy. In J. P., Smol, et al. (Eds.), Tracking environmental change using lake sediments: terrestrial, algal, and siliceous indicators, 3. Kluwer Academic Publishers, Dordrecht, The Netherlands.